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THE TECHNOLOGY OF
BREAD-MAKING

INCLUDING

The Chemistry and Analytical and Practical Testing

of Wheat Flour, and Other Materials Employed

in Bread - Making and Confectionery.

WILLIAM JAGO, F. I. C, F. C. S.,

Of Lincoln's Inn, Barrister-at-Law:

Senior Examiner in Bread-Making and Confectionery to the City and Guilds
of London Institute for the Advancement of Technical Education;
Cantor Lecturer on "Modern Developments of Bread-Making"
and "Chemistry of Confectioners' Materials and Pro-
cesses" to the Society of Arts, London, etc.

and
WILLIAM C. JAGO, F. C. S.,

Food Manufacturing Chemist.

LIVERPOOL

THE NORTHERN PUBLISHING CO., Limited

1921
Copyright All Rights Reserved

PREFACE.

THE intervention of war conditions has sadly interfered with the
developments of this book, which the Authors had hoped to in-
corporate in a new edition.

In order to meet the insistent demands on the part of both
bakers and millers for its reappearance it has been decided to issue
a slightly abridged reprint of the previous edition, with certain cor-
rections and additions rendered necessary by advances in knowledge
during the past few years.

This has been rendered possible by the action of The Bakers'
Helper Company, which has thrown itself into the breach at a time
when the publication of a technical work is fraught with great diffi-
culties and considerable risk. To that company in America, and
The Northern Publishing Company, Limited, of Liverpool, well
known as the proprietors of "MILLING," the Authors are indebted
for the promise of every effort as publishers to bring the book to
the notice of the milling and baking trades.

The Authors wish to make every acknowledgment, with their
most sincere thanks, of the valuable help they have received from
Miss Morris, of the staff of The Bakers' Helper Company, who has
read the proofs and checked the passage of the book through the
press in a most efficient manner.

WILLIAM JAGO.

WILLIAM C. JAGO.
Hove, England, 1921.

PREFACE TO 1911 EDITION.

THE volume now offered to the reader must be regarded as a
development of the writers' former works on the same subject,
which appeared in 1886 and 1895. The general mode of treatment
is, therefore, to some extent governed by that of its predecessors.
It should be remembered that the requirements of the student of
the technology of bread-making, whether miller or baker, have been
the first consideration; and accordingly the arrangement is that
which seems most likely to be of service and assistance to him. In

865780

vi PREFACE

addition the authors have endeavoured to make the book as com-
plete a work of general reference as possible.

In the preparation of the present treatise the writer has had the
benefit of the assistance of his son, Mr. William C. Jago, whose
name, together with his own, appears on the title-page. Mr. William
C. Jago's wide experience of the practical application of chemical
methods in the mill and the factory has been of much advantage.
So also has been his knowledge of the dairying industries gained
in Denmark, and of modern biology and bacteriology acquired in
the laboratories of Professor Jorgensen in Copenhagen. The
writer is further indebted to him for the investigation and verifi-
cation of many references in the original French, German and
Danish.

Since 1895 much valuable original work has been done in this
country, and also in Europe and America, on bread-making and
cognate subjects. The authors have tried to place this as fully as
possible on record. In so doing they have adopted the method of
giving a resume of each investigator's work and conclusions, fol-
lowing the same where necessary by any comments of their own.
In pursuance of this plan, new chapters have been written on the
Strength of Flour, the Bleaching of Flour, Wheat Flour and Bread
Improvers, the Nutritive Value and Digestibility of Bread, and the
Weighing of Bread. Subjects such as "Standard" Bread, and the
use of additions to flour and bread, have been critically and ex-
haustively examined. The application of chemical and other tests
to routine mill practice has been dealt with in a special chapter.
Following on the inclusion of Confectionery in the programme of
the City and Guilds of London Institute for the Advancement of
Technical Education, a chapter has been added on the Chemistry
of the Confectioners' Raw Materials and Processes.

Again, the Authors desire to express their thanks to the number
of millers, bakers, and scientists who by personal communications
and in many other ways have rendered them so much assistance
in the preparation of this volume. The numerous instances of help
of this kind will be evident on a perusal of the following pages.

In a work of such magnitude, the Authors cannot hope to have
altogether avoided mistakes, and in such cases they confidently
appeal to the generous consideration of their readers.

WILLIAM JAGO.
London, E.G.,

1, Garden Court, Temple,
July, 1911.

CONTENTS.

CHAPTER PAGE

I INTRODUCTORY I

II DESCRIPTION OF THE PRINCIPAL CHEMICAL ELEMENTS, AND THEIR INOR-

GANIC COMPOUNDS 28

III DESCRIPTION OF ORGANIC COMPOUNDS 41

IV THE MICROSCOPE AND POLARISATION OF LIGHT .57

V CONSTITUENTS OF WHEAT AND FLOUR— MINERAL AND FATTY MATTERS . 68

VI THE CARBOHYDRATES 74

VII THE PROTEINS 92

VIII ENZYMES AND DIASTATIC ACTION 121

IX FERMENTATION 144

X BACTERIAL AND PUTREFACTIVE FERMENTATIONS 181

XI TECHNICAL RESEARCHES ON FERMENTATION 197

XII MANUFACTURE OF YEASTS 223

XIII PHYSICAL STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN . . .240

XIV CHEMICAL COMPOSITION OF WHEAT 254

XV THE STRENGTH OF FLOUR 267

XVI COMPOSITION AND PROPERTIES OF FLOUR AND OTHER MILLING PRODUCTS . 291

XVII BREAD-MAKING 308

XVIII BAKEHOUSE DESIGN 396

XIX THE MACHINE BAKERY AND ITS MANAGEMENT 412

XX ANALYTIC APPARATUS 463

XXI COMMERCIAL TESTING OF WHEATS AND FLOURS . . . . .472

XXII DETERMINATION OF MINERAL AND FATTY MATTERS 503

vii

viii CONTENTS

CHAPTER PAGE

XXIII SOLUBLE EXTRACT, ACIDITY AND PROTEINS 512

XXIV ESTIMATION OF CARBOHYDRATES . 531

XXV BREAD ANALYSIS 558

XXVI ADULTERATION AND ADDITIONS 564

XXVII ROUTINE MILL TESTS 571

XXVIII CONFECTIONERS' RAW MATERIALS 579

INDEX . .617

THE TECHNOLOGY OF
BREAD- MAKING v;;v

CHAPTER I.

INTRODUCTORY.

1. General Scope of Work. — The object of the present Work is to
deal, in the first place, with those branches of knowledge which together
constitute the scientific foundations of Bread-making as a science in
itself. Paramount among these is —

Chemistry.

With which is closely associated-
Heat and its properties.

Fermentation and the Biology of Micro-organisms.
Vegetable Physiology in its relation to the Wheat Plant.
Microscopy.

Next, viewing Bread-making as an Art or Industry, the design of
Bakeries and adaptation of Machinery for various purposes is discussed.
Following on this is a description of the various processes and operations
involved in the Commercial Manufacture of Bread, together with an
investigation of the many important practical problems connected there-
with.

The more purely analytical section of the work includes detailed
directions for the commercial testing and valuation of flour, yeast, and
other bread-making materials ; in addition to which there are also given
approved methods for the commercial and complete chemical analysis
of such substances. A number of analyses and other chemical investi-
gations have been recently made for the purpose of this book, and are
here published. The work concludes with a description of the chem-
istry of confectioners' raw materials.

It is not proposed to adhere to any very rigid classification, but so to
arrange the subject matter as seems most likely to meet the requirements
of the majority of readers.

2. Matter. — The bodies with which we are surrounded present an
almost endless diversity of colour, appearance, and other characteristics.
One property they however all possess in common, and that is the prop-
erty of weight. All bodies are attracted by the earth, and any substance
is said to be heavy because of the resistance which it offers to this earth-
attraction or gravitation. Not only are solid bodies, such as iron and
wood, possessed of weight, but so likewise are liquids, such as water and
oil, and also gases, such as, for example, common air, or coal gas. It is
convenient to have one name for all bodies which possess weight, and for
this purpose, in English, the term Matter is employed. Matter, then, is
anything which possesses weight (i.e., is acted on by gravitation), and
exists in three distinct forms, namely, as solids, liquids, and gases.

2 THE TECHNOLOGY OF BREAD-MAKING.

3. Force. — The definition of matter just given would seem at first
sight sufficiently comprehensive to embrace everything of which we can
take cognisance, but yet a moment's reflection shows the existence of
other things besides matter. An illustration best demonstrates this fact —
A hammer-head is known to consist of matter because it possesses weight ;
but if with this hammer-head you give a series of blows to a small piece
of nail-rod, you have given the nail-rod something which is not matter.
The hammer-bead- is not lighter, nor is the nail-rod heavier — still the
blows are something, as otherwise they could produce no effect. For one
thii'g*, the«nail-r(vd' will have been flattened and altered in shape ; further,
and which is of far more present importance, it will have become hot to
the touch. Again, to make use of another illustration, if a dry brick be
carefully weighed and then made red-hot in a furnace, it will be found to
weigh when hot precisely the same as it did when cold. Further, this
brick, if allowed to become cold, imparts heat to surrounding objects, and
nevertheless remains unaltered in weight. Here, then, is something very
definite which a body can receive and again yield, and which is not mat-
ter. This something has, however, a very direct relation to matter; in
the first illustration the blows were struck by the moving hammer-
head, which consists of matter in motion. The more rapid the motion,
the more violent would be the blows; in fact, the force of the blow
depends both on the quantity of matter and the rapidity of its motion.
A number of considerations lead to the belief that the hot iron of the
nail-rod and also the hot brick differ from the same substances in the
cold state, in that their component particles are in a state of movement ;
as these substances cool, the particles once more enter into a condition of
comparative rest. This something beyond matter is closely associated
with motion, and is termed force. Force is defined as that which is
capable of setting matter in motion, or of altering the direction or
velocity of matter already in motion. The motion of bodies may be
divided into two classes : there is, first, that of the body as a whole, as
in the case of the moving hammer-head ; second, the internal movements
of the particles of a body, as when it becomes hot.

ELEMENTS OF HEAT.

4. Heat, its Nature and Effects. — Among generally observed facts
with regard to heat, one of the first and most important is that it induces
the sensation of warmth. According to the character and degree of this
sensation, a body is said to be cold, warm, or hot. The conditions which
produce this sensation of warmth also cause other well-marked changes
in the physical condition of substances. The general effects of heat are
to cause bodies as they get hot to expand in volume; further, solids are
reduced to the liquid state; and, with still further increments of heat,
liquids are converted into gases. The opposite series of changes occur as
heat is abstracted from bodies. From the explanation of Force given
in the preceding paragraph, it will be understood that these changes are
not accompanied by any addition or diminution of weight. On the
contrary, Heat is viewed as a form of Force, and is regarded as a mode
or variety of internal motion of the particles of bodies — the hotter they
are, the more violent and energetic is this motion.

5. Measurement of Heat: Temperature. — The earliest and most
accessible measure to be applied to heat is that of the sensation of warmth
before referred to, and according to whether a body to the touch is hot
or cold, it is said to be of high or low temperature. Temperature is, in

INTRODUCTORY. 3

fact, the measure of what is popularly termed ' ' how hot a body is " ; it
will be seen on consideration that this depends on the power the body
has of imparting heat to another body. Thus if, when the hand is
thrust into water, the water is able to yield heat to the hand, it is said
to be "hot," while if it robs the hand of heat it is said to be "cold."
The measure of this power is termed temperature, and is more exactly
embodied in the following definition : — The temperature of a body is a
measure of the intensity of its heat, and is further defined as the
thermal state of a body considered with reference to its power of
communicating heat to other bodies.

6. The Thermometer. — For scientific, and also for most technical,
purposes, the sensations are not sufficiently accurate methods of measur-
ing temperature ; accordingly temperature is usually measured by certain
of the effects which heat produces : the most convenient for this purpose
is the expansion of liquids with an elevation of temperature. For the
general purposes of temperature measurement, the metal mercury is the
most convenient substance. This liquid, enclosed in a suitable vessel,
constitutes the temperature-measuring instrument termed a thermometer.
In constructing a thermometer, a bulb is blown at one end of a glass tube
of very narrow bore; the bulb and tube are next filled with carefully
purified mercury ; this is boiled, and thus all air and moisture are driven
out of the tube; the open end is then hermetically sealed by fusing the
glass itself. At this stage the bulb and a .portion of the tube are filled
with mercury, the remainder of the tube being a vacuum, save for the
presence of a minute quantity of mercury vapour. On heating the bulb
of this instrument, the mercury expands and rises considerably in the
stem. Throughout any body, or series of bodies in contact with each
other, heat has a tendency so to distribute itself that the whole series
shall be at the same temperature; consequently if the thermometer be
placed in contact with the body whose temperature it is desired to
measure, a redistribution of heat occurs, until the two are at the same
temperature. That is to say, if the body be the hotter, it yields heat to
the thermometer; and if it be colder, it receives heat from the ther-
mometer, until the temperature of both is the same. The two being in
efficient contact, this stage is indicated by the mercury becoming sta-
tionary in the thermometer. Now the volume of mercury is constant for
any one temperature ; therefore, to register temperature, it is only nec-
essary to have further a scale, or series of graduations, attached to the
stem of the instrument, by which the temperature may always be read.

7. The Pyrometer. — The ordinary mercury thermometer is not well
adapted to the measurement of comparatively high temperatures, since
the mercury boils at a temperature considerably below that of a dull
red heat. In consequence other instruments have been devised for that
purpose, to which the name of pyrometers has been given. The pyrometer
may therefore be regarded as a high temperature thermometer. The
pyrometers used for measuring the temperature of some types of bakers'
ovens consist usually of a rod and casing constructed of materials which
expand at different rates with an increase of temperature. The differen-
tial expansion actuates a needle moving in front of a dial plate.

8. Thermometric Scales. — Subject to certain precautions, the tem-
peratures of melting ice and of steam in contact with boiling water are
constant. The height at which the mercury stands when immersed in
each of these is marked on most thermometers ; for the registration of
other temperatures some system of graduation must be devised. The one

THE TECHNOLOGY OF BREAD-MAKING.

most commonly employed in England is that of Fahrenheit, while
for scientific purposes that of Celsius, or the Centigrade Scale, is almost
universally adopted. Fahrenheit divided the distance between the melt-
ing and boiling points of his thermometer into 180 degrees; degrees of
the same value were also set off on either side of these limits. At 32
degrees below the melting point he fixed an arbitrary zero of tempera-
ture from which he reckoned. On this thermometer scale, the melting
point is 32°, while the boiling point is 32 + 180 = 212°. Degrees below
the zero are reckoned as — (minus) degrees, thus — 8° means 8 degrees
below zero, or 40 degrees below the melting point; degrees above 212
simply reckon upwards, 213, 214° F., etc.

The Centigrade Scale is much simpler, the melting point is taken as
0° or zero, and the boiling point as 100° ; temperatures below the melting
point are reckoned as — degrees.

The conversion from one to the other of the Centigrade and Fahren-
heit Scales may be easily performed.

180 Fahrenheit degrees = 100 Centigrade degrees.
9 ,, „ — 5 ,, ,,

1 „ degree = 5/9 „ degree.

9/5 ,, „ = 1 „ „

There is this important difference between the two scales — Centigrade
degrees count from the melting point, while Fahrenheit degrees are
reckoned from 32 below the melting point.

30° C. = 30 X 9/5 = 54 Fahrenheit degrees.

Therefore 30° C. are equivalent to 54 Fahrenheit degrees above the melt-
ing point, but as the melting point is 32, that number must be added on
to 54; temperature Fahrenheit equal to 30° C. is 86°. By the reverse,
operation, Fahrenheit degrees are converted into degrees Centigrade.
The following formulae represent the two operations : —

+ 32==F°.

(F°.— 32) X5

= C(

The following table gives the equivalent readings on the two thermo-
metric scales for some of the most important temperatures : —

—40°
-17.7
0

15.5

21.1

26.6

37.7

C.=

— 40° F

0 „

32 „

59 „

60 „
68 „
70 „
77 „
80 „
86 „
95 „

100 „

104 „

113 „

122 „

131 „

140 „
149

70°

93.3

95
100
150
200
232.2
250
260
287.7
300
316.6
350
400

C.=

158° F

167

176

185

194

200

203

212

302

392

450

482

500

550

572

600

662

752

INTRODUCTORY. 5

9, Quantity of Heat. — Temperature is not a measure of quantity of
heat, for a thermometer would indicate the same temperature both in a
vessel containing a pint, and one containing a gallon of boiling water,
although it is evident that one must contain eight times as much heat as
the other ; further, to raise the gallon of water to the boiling point, eight
times the amount of heat necessary to similarly raise the pint is required.
This leads to the mode of measuring and registering quantity^ of heat.
Quantity of heat is measured by the amount necessary to raise a cer-
tain weight of some body from one to another fixed temperature. The
amount of heat necessary to raise 1 gram of water from 0° to 1° C. is
termed a Unit of Heat. For the phrase Unit of Heat, a distinctive term,
"Calorie," is now frequently employed. From this it follows that to
raise 2 grams of water from 0° to 1° C. will require 2 Units of heat, or 2
H.U., or 2 Calories. Between the freezing and the boiling points, approx-
imately the same amount of heat is necessary to raise 1 gram of water
through any 1 degree of temperature, so that to raise 1 gram through 2
degrees will require approximately 2 H.U. For practically all purposes,
it may be taken that the weight of water in grams X degrees of tem-
perature through which it must be raised — the number of H.U. or
Calories required.

10. Specific Heat. — The quantity of heat necessary to raise the
same weight of different substances through 1 degree of temperature
varies very considerably. The quantity of heat necessary to raise 1
gram of any substance through 1 degree of temperature is termed its
Specific Heat. From this definition it follows that the specific heat of
water at 0° C. is 1.00, or unity. The following table gives the specific
heat of various substances : —

Substance. Specific Heat.

Water 1.00000

Alcohol 0.61500

Glass 0.19768

Iron 0.11379

Copper 0.09391

Mercury 0.03332

If equal weights of water at different temperatures are mixed to-
gether, the result is a mixture having a temperature the mean of the two ;
thus a gallon of water at 20° C. mixed with a gallon at 50° C. will pro-
duce a mixture at the temperature of 35° C. But if equal weights of
two substances of different specific heats be thus mixed, the temperature
of the mixture of the two will not be a mean of those of the substances,
but will be nearer that of the substance having the higher specific heat.
The most important mixture with which the baker has to do is that of
flour with water, as the temperature of the resultant dough is a matter
of vital concern to him. The results are complicated by the presence of
other ingredients, as salt and yeast, and also in practice by loss of heat
through absorption by the surroundings of the dough, and heat generated
by chemical action among the ingredients. The following are the results
of laboratory experiments made by mixing flour and water only, and
carefully taking the temperatures, but not allowing for loss of heat
absorbed by containing vessels. specific Heat.

500 grams of flour at 67° F.

500 „ water at 145° F.

500 „ flour at 67° F.

500 „ water at 104° F.

500 flour at 67° F.

= 1000 at 118° F. 0.53

500 „ flour at 67° F. _1nnn af noo ^ n 42

500 water at 104° F. =

™ QCO ™ = 1000 at 80.5° F. 0.40

500 water at 86° F.

6 THE TECHNOLOGY OF BREAD-MAKING.

The specific heats are calculated from the above experiments in the
following manner : — in the first experiment 500 grams of water have
fallen from 145° to 118°, that is 27°, during which they must have
afforded 500 X 27 =13,500 H.U. At the same time 500 grams of flour
have been raised from 67° to 118°, that is through 51°, which is equal
to 500 X 51 = 25,500 grams through 1°, and to do this 13,500 H. U. have
been utilised ; then to raise 1 gram through 1° there has been taken

therefore 0.53 is the specific heat of flour as derived from this experiment.
A number of observations have also been made on the temperatures
of mixtures made in the bakehouse on the large scale for manufacturing
purposes. The doughs were machine-mixed, and no allowance is made
for the salt and compressed yeast, quantities of which were the same in
all cases. The quantities, temperatures, and calculated specific heats are
given in the following table : —

WATER. FLOUR. DOUGH. FLOUR.

Specific
Quarts. Lbs. Temp. Lbs. Temp. Temp. Heat.

53 132.5 95° 205 52.5° 79.0° 0.39

51 127.5 90° 205 50.0° 77.0° 0.30

53 132.5 98° 205 53.0° 79.0° 0.45

53 132.5 89° 205 53.0° 76.0° 0.36

The whole of these figures, it must be remembered, are those obtained
in experiments made under conditions such as hold in the bakehouse, and
represent rather the result of actual working, than theoretic specific heats
with all disturbing causes eliminated. In the case of the mixtures made
at the higher temperatures, there is naturally a greater loss of heat, and
this causes an increase in the corresponding apparent specific heats. In
consequence of this, the No. 1 Laboratory Experiment gives a remark-
ably high figure ; but the whole of the others lie fairly closely together.
Comparing those above given with a large number of observations on the
manufacturing scale made, practically all the specific heat results range
between 0.36 and 0.45, with a mean "of 0.40, to which the majority ap-
proach most closely. Taking 0.40 as the working specific heat of flour,
1 unit by weight of water in falling through 1° raises 2.5 units by weight
of flour through the same increment of temperature.

11. Sources of Heat. — Directly or indirectly all available terrestrial
heat is practically derived from the sun : its immediate source, however,
for manufacturing operations is the combustion of different kinds of fuel ;
these give out different amounts of heat according to their composition.
The following table gives the number of heat units evolved by the com-
bustion of one gram of each substance in oxygen : —

HEAT DEVELOPED DURING COMBUSTION.

Substance Formula. Heat Units.

Hydrogen ...... H9 34,462

Carbon ........ C 8,080

Carbon Monoxide . . . . CO 2,634

Marsh Gas ...... CH4 13,063

Olefiant Gas ...... C2H4 11,942

Alcohol ........ C2H5HO 6,909

INTRODUCTORY. 7

HEAT DEVELOPED DURING COMBUSTION — Continued.

Substance. Heat Units.

Welsh Coal about 8,241

Newcastle Coal „ 8,220

Derbyshire Coal „ 7,773

Coke „ 7,000

Wood (dried in air) . . . . . . . . ,, 3.547

12. Expansion by Heat. — It has already been mentioned that in most
cases bodies expand under the influence of heat. Solids expand the least,
and at a definite rate for each particular solid ; liquids have a higher rate
of expansion, each still having its own special rate; while gases expand
at a far higher rate than either liquids or solids. The following table
gives what are termed the

COEFFICIENTS OF LINEAR EXPANSION FOR 1° BETWEEN 0Q AND 100° C.

Glass 0.000008613 Brass 0.000018782

Platinum . . . 0.000008842 Lead 0.000028575

Iron 0.000012204 Zinc 0.000029417

These figures mean that each of these substances expands at the rate ex-
pressed by its own coefficient : thus 1 foot of glass at 0° C. becomes
1.000008613 feet long at 1° C., and so for each degree rise in temperature.
When a body is heated, its whole three dimensions of course increase, and
the coefficients of cubical expansion of solids for practical purposes, may
be taken as three times their coefficients of linear expansion.

The apparent expansion of liquids is not so great as the real, because
the vessels in which they are contained also expand. The following table
gives the

TOTAL APPARENT EXPANSION OF LIQUIDS BETWEEN 0° AND 100° C.

Mercury 0.01543 Fixed Oils 0.08

Distilled Water. . 0.0466 Alcohol 0.116

The coefficient of apparent expansion for 1° C. is obtained by dividing
these numbers by 100, thus that for mercury is 0.0001543. Mercury ex-
pands at a practically constant rate from 36° to 100° C. ; water, however,
contracts in rising from 0° to 4°, and then expands from 4° to 100° C.

13. Expansion and Contraction of Gases. — There are certain reasons
which lead us to suppose that at a temperature of — 273° C. bodies would
be entirely devoid of heat. This point — 273° C. is therefore often
termed the absolute zero of temperature; and temperature reckoned
therefrom is termed "absolute temperature." The absolute temper-
ature of a body is its temperature in degrees C. -|- 273. All gases expand
with increase, and contract with diminution, of temperature. The
amount of expansion and contraction is the same for all gases be-
tween the same limits of temperature, provided the temperature is
considerably higher than that at which they condense to liquids. The
volume of all gases is directly proportional to their absolute tempera-
ture. Because of this variation with temperature it is necessary to fix
a temperature which shall be considered as a standard in expressing
the volume of gas : 0° C. is commonly adopted for this purpose.

Knowing the volume of a gas at any one temperature, its volume at
any other may be easily calculated ; thus, a vessel was found to contain
750 c.c. of air at 15° C. ; it is required to find its volume at the standard
temperature.

8 THE TECHNOLOGY OF BREAD-MAKING.

15° C. + 273 = 288° Absolute Temperature.

0° C. + 273 = 273°
As 288 : 273 : : 750 : 711 c.c. of gas at standard temperature.

14. Relation of Pressure and Volume of Gases. — It is convenient here
to note that the volume of a gas is also affected by the pressure to which
it is subjected : this variation is governed by what is called Boyle and
Marriotte's Law — The volume of any gas is inversely proportional to
the pressure to which it is subjected. The most important variations of
pressure to which gases are liable are those resulting from the changes
in pressure of the atmosphere. The height of the mercury column of the
barometer is a direct measure of the pressure of the atmosphere, there-
fore that pressure is commonly expressed in the number of millimetres
(m.m.) which that column is high. For purposes of comparison it is
also necessary to reduce all pressures to one standard; that selected is
an atmospheric pressure which causes the barometer to stand at 760
millimetres.

The temperature and pressure quoted as standards for gas measure-
ment 0° C. and 760 m.m. are often termed normal temperature and pres-
sure; for this expression the abbreviation, "N. T. P, " is frequently
used.

The laws governing the relation between the volume and temperature
and pressure of gases must not be regarded as absolutely exact, since they
are subject to certain small but well-marked departures. These varia-
tions, however, have no direct bearing on the present subject.

15. Transmission of Heat. — It is well known that when one part of a
body or place is heated, the other parts also become hot more or less
quickly. Some explanation of how such transmission is effected must now
be given. There are three methods by which heat can be transmitted
from one point to another, which are termed respectively Convection,
Conduction, and Radiation.

16. Convection. — As the word convection implies, a part or mass is
heated by the heated matter being conveyed from one part to another.
This kind of heating can only occur in liquids or gases where the particles
of matter can move freely. One of the best illustrations of convection is
the heating of an ordinary vessel of water by the placing of a fire under-
neath ; the layer of water at the bottom first gets hot, and consequently
expands and becomes of lower specific gravity. As a result of being
lighter, it therefore rises to the surface, and its place is taken by other
water which is colder and denser. This in its turn is heated -and rises;
continuous currents, of warm water ascend through the liquid, and colder
water descends to take its place. In this way the whole mass is gradually
made hot. The heating of the water in a supply cistern on the top of a
building by currents through flow and return pipes from a small boiler in
the basement is due to convection. So, too, the ventilation of a building
is naturally caused in the same way — heated air ascends and makes its
way through exits at the highest point, while cold air enters through the
joints of doors and windows or apertures specially provided for the pur-
pose. Among other illustrations may be mentioned the warming of a
building or room by hot-water pipes miming close to the floor. The air is
thereby heated and ascends; the cooler air falls and takes its place. Con-
versely, a mass of water or air is best cooled by the application of cold at
the upper surface. Thus, given a vessel of hot water and a coil of pipes
at the surface, through which cold water is passing, the cold water lowers
the temperature of the upper layer in the vessel ; this consequently

INTRODUCTORY. 9

descends and its place is taken by hotter water. In this way a series of
currents is set up whereby the whole mass of water is uniformly cooled.
It will be seen that convection is a mode of distributing heat through a
mass of either liquid or gas by means of moving currents, such currents
being usually produced by differences in density due to expansion
caused by the source of heat itself.

17. Conduction. — Instances are well known in which the application
of heat to any one point of a solid causes the whole mass to become hot.
Thus, if the end of a bar of iron be placed in the fire, the other end gradu-
ally increases in temperature. This cannot be due to convection, but is
due to the heating effect which the hot particles of the body have on the
contiguous particles. In these cases the heat is said to be transmitted by
conduction. Conduction is that method of transmitting heat in which
the heat passes from the hotter particles of a body to the colder ones
lying in contact with them, and so throughout the whole body.

There are wide differences in the power of conducting heat displayed
by various substances ; thus, if a bar of copper be heated in the same way
as suggested for the iron, the further end becomes hot far more rapidly. If,
instead, a rod of glass or porcelain be heated, the outer end gets hot only
with extreme slowness. It must therefore be remembered that some sub-
stances conduct heat much more rapidly than others. The metals as a
class are good conductors, although there are great differences between
them. Porcelain, tiles, glass, and earthy substances are generally bad
conductors, so also are most bodies of animal or vegetable origin, as, for
example, felt, wool, and wood. Water is a bad conductor, and so are the
gases. Air is one of the worst heat conductors known, consequently
porous masses, as slag-wool and fossil earth, conduct very badly, not only
from their own non-conducting power, but because of the air retained in
their interstices. Owing to their very slight conducting properties, wool,
glass, bricks, and similar bodies are frequently termed non-conductors.
The following table gives the comparative conducting power of a few sub-
stances, silver being taken as 100.

COMPARATIVE POWERS OF CONDUCTIVITY.

Silver 100

Copper . . . . . . . . . . . . . . 75

Iron 10

Lead

Marble . . . . . . . . . . . . about 2

Porcelain * . . . . . . . . . . . . „ 1

Brick Earth „ 1

18. Radiation, — It has been already explained that when a substance
is hot, its particles are in a state of motion : under circumstances in which
transmission of heat by convection and conduction is impossible, one body
may yet be heated by another. The explanation now generally accepted
is, that all space is permeated by a highly elastic body to which the name
of ether has been given, which is capable of being set in undulatory motion
by appropriate agitation. The violently moving particles of a hot body
in the act of vibration strike against this ether, setting up in it a series
of waves. These waves spread in all directions, and on impingeing against
a cold body, cause its particles also to assume a state of vibration — that
is, they make the substance hot. In this way heat passes from one body
to the other, not, however, as hot matter, but as a peculiar wave-like

10 THE TECHNOLOGY OF BREAD-MAKING.

motion in the substance called ether > This is known as "Radiation" of
Heat, and is independent of the temperature of the medium through
which radiation occurs.

Radiation occurs in straight lines in all directions from the body
which is evolving heat, and follows the same general laws of reflection as
those which govern light. At the same temperature different bodies radi-
ate heat at different rates. The rate of radiation is affected both by the
nature of the radiating material and also the condition of its surface,
whether rough or smooth. Highly polished surfaces radiate less rapidly
than those which are roughened. Being maintained at the same tempera-
ture, the following table gives the comparative radiating power of differ-
ent bodies.

COMPARATIVE POWER OF RADIATION.

Lampblack (Soot) 100

White Lead 100

Tarnished Lead . . . . . . . . . . 45

Polished Iron . . . . . . . . . . 15

Burnished Silver 2.5

When hot, surfaces of clay and brick are good radiators of heat, so also
are those of flannel and other like substances.

In order that bodies may be heated by radiant heat, it is necessary
that they possess the power of absorbing such heat — like radiation, this
power of absorption also varies with different bodies. Those which are
good radiators of heat are good absorbents, and practically the table
showing power of radiation equally applies to power of absorption.

A good illustration of the different modes of transmission of heat is
furnished by the action of one of the pipes of a steam oven. This pipe
contains a certain quantity of water sealed up in the pipe. The pipe is
built into the oven on a slight incline so that the lower end is in the fur-
nace, and the upper one in the baking chamber of the oven. The fire
of the furnace or the heated gases thereby produced are in contact with
the pipe. By conduction the heat finds its way through the iron walls of
the pipe and into the water. This is heated by convection currents, and
ultimately the steam finds its way into the upper parts of the pipe which
are in the oven. The metal is consequently heated by conduction and by
conduction the heat passes through to the outer surface. There it partly
warms the air by a process of conduction and also sets up radiation by
which anything placed in the oven to bake is in due course heated.

19. Mechanical Equivalent of Heat. — It has already been stated that
heat is produced when mechanical work is absorbed by friction or per-
cussion, as when nail-rod is heated by repeated blows of the hammer. Care-
ful measurements have shown that the work done by 1 Ib. falling
through 772 feet (or 772 ft.-lbs.), is capable of raising the temperature
of 1 Ib. of water 1° F.: this amount is therefore termed the Mechanical
-Equivalent of Heat. From this the value in degrees Centigrade is easily
calculated, being 9/5 of 772=1390 ft.-lbs. of work to raise 1 Ib. of water
through 1° Centigrade,

INTRODUCTORY CHEMICAL PRINCIPLES.

20. Definition of Chemistry. — Chemistry has well been defined as
that science which treats of the composition of matter, of changes pro-
duced therein by certain natural forces, and of the action and reaction

INTRODUCTORY. 11

of different kinds of matter on each other. It follows that the Chem-
istry of Wheat, Flour, and Bread may be defined as that branch of the
science which treats of the composition of these bodies, of the changes
they undergo when subjected to the action of certain natural forces,
and of the action and reaction of these and other kinds of matter on
each other.

21. Introductory Study Necessary. — An elementary course of study
of the general principles of chemistry must precede that of any particular
branch of the applied science. Such a course should include the prepara-
tion and properties of the commoner elements and their compounds, the
principles of qualitative analysis, and the simpler laws governing chem-
ical action and combination. For this purpose Jago's "Elementary
Chemistry," and "Advanced Chemistry/' published by Messrs. Long-
mans & Co., may be employed. For convenience of reference and in
response to a widely expressed wish, a short description follows of the
most important chemical laws, and also of such elements and compounds
as are closely connected with the chemistry of wheat, flour, and bread.
This brief account must not, however, be accepted as a substitute for a
systematic course of study of elementary chemistry.

22. Indestructibility of Matter. — Chemical changes are often accom-
panied by very great alterations in the appearance and properties of
the bodies involved; for example, when a candle is burned it almost
entirely disappears, but although it no longer remains in the solid state,
all its constituents exist as gases, and these weigh exactly the same as
did the candle, plus the oxygen of the air with which they have combined.
Matter is indestructible, and, consequently, the same weight of material
remains after any and every chemical change as there was before its
commencement.

23. Preliminary Definitions. — It is important that at the outset accu-
rate and concise ideas are gained of the meaning of various chemical
terms. Although matter assumes so many diversified forms, yet all bodies,
on being subjected to chemical analysis, are found to consist of one or
more of a class of about eighty substances, which are termed * t elements. ' '

An Element is a substance which has never been separated into two
or more dissimilar substances.

Recent chemical researches go to show that some of the bodies now
regarded as elements, may after all be composed of more than one sub-
stance. However interesting such investigations may be, they are not
likely to have any bearing whatever on our present subject.

While the letters of the alphabet are few, the number of words which
can be formed from them is practically infinite ; so, in a somewhat similar
fashion, from the comparatively small number of elements which consti-
tute the "alphabet" of chemistry, there may be built up an immense
number of chemical compounds.

A compound is a body produced by the union of two or more ele-
ments in definite proportions, and, consequently, is a substance which
can be separated into two or more dissimilar bodies, Compounds differ
in appearance and characteristics from their constituent elements.

The term "Mixture" is applied to a substance produced by the mere
blending of two or more bodies, elements or compounds, in any propor-
tion, without union. Each component of a mixture still retains its own
properties, and separation may be effected by mechanical means.

24. List of Elements. — The following is a list of some of the more
important elements, together with their symbols and other particulars : —

THE TECHNOLOGY OF BREAD-MAKING.

Name. Symbol.

Aluminium Al

Barium . . . . . . Ba

BORON B

BROMINE Br

Calcium Ca

CARBON C

CHLORINE Cl

Chromium . . • . . . . Cr
Copper (Cuprum) . . . . Cu

FLUORINE F

HYDROGEN H

IODINE I

Iron (Ferrum) . . . . Fe
Lead (Plumbum) . . . . Pb

Magnesium Mg

Manganese Mn

Mercury (Hydrargyrum) Hg
NITROGEN . . . . . . N

OXYGEN O

PHOSPHORUS . . . . P

Platinum Pt

Potassium K

SILICON Si

Silver (Argentum) . . Ag

Sodium (Natrium) . . Na

SULPHUR S

Tin (Stannum) . . . . Sn
Zinc Zn

25. Recently Discovered Elements. — Considerable interest attaches
to certain elements which have been comparatively recently discovered.
Among these are argon and other allied elements which exist in the
atmosphere, and radium, a constituent of pitch-blende. As none of these

bodies has apparently a bearing on the chemistry of bread-making they
are not dealt with in this work.

Combining or Atomicity or
Atomic Weight. Quantivalence.
Old. New.

27 26.0 IV

137

136.4

10.9

79.36

39.8

11.91

35.5

35.18

51.7

63.1

18.9

1.0

126

125.9

55.6

205

205.35

24.18

54.6

199

198.5

13.93

15.88

30.77

193

193.3

38.86

28.2

107

107.12

22.88

31.83

118

118.1

64.9

26. Metals and Metalloids.— The

groups, termed respectively "Metals,"

elements are divided into two
and ' ' Metalloids ' ' ,or non-metals.
The non-metals are distinguished in the foregoing table by being printed
in small capitals. The line of division between the two classes is not very
marked, the one group gradually merging into the other. The metals,
as a class, are opaque bodies, having a peculiar lustre known as metallic ;
they are usually good conductors of heat and electricity. Two of the
elements, mercury and bromine, are liquid at ordinary temperatures,
while hydrogen, oxygen, nitrogen, and chlorine are gaseous.

27. Symbols and Formulae. — The symbols are abbreviations of the
names of the elements, and, where practicable, consist of the first letter
of the Latin names. When two or more elements have names commencing
with the same letter, it becomes necessary to distinguish them from each
other by restricting the initial letter to the most important element and
selecting two letters as the symbol of each of the others. Thus, carbon
and chlorine each commence with " C," that letter is chosen as the symbol
of carbon, while that of chlorine is Cl.

INTRODUCTORY. 13

As all compound bodies consist of elements united together, they may
be conveniently expressed symbolically by placing side by side the symbols
of the constituent elements ; the symbol of a compound is termed its
formula. Thus, common salt consists of chlorine and sodium ; its for-
mula is accordingly written, NaCl.

28. Further Uses of Symbols and Formulae: law of chemical com-
bination by weight. — Simply as abbreviations of the full names, symbols
and formulae are of great service; this, however, is but a small part of
their significance and value to the chemist. Their further use may best
be explained by reference to certain information gained by experiment,
to which careful attention is requested. On analysis, it is found that
36.5 ounces of the substance known as hydrochloric acid consist of 1 ounce
of hydrogen, combined with 35.5 ounces of chlorine; also, that in 58.5
ounces of common salt there are 35.5 ounces of chlorine to 23 of sodium.
Taking water as another instance of a hydrogen compound, analysis shows
that its composition may be expressed by the statement, that 18 ounces of
water consist of 2 ounces of hydrogen combined with 16 ounces of oxygen.
In the table given on page 12 there is a column headed "Combining or
Atomic Weight " ; on referring to this it will be found that the numbers
opposite hydrogen, chlorine, sodium, and oxygen, are, respectively, 1, 35.5,
23, and 16, being (with one exception) identical with those that have just
been given as the numbers obtained by analysis of the compounds under
consideration. It is possible to assign to every element a number,
which number, or its multiple, shall represent the proportionate
quantity by weight of that element which enters into any chemical
compound. These numbers are termed the "Combining or Atomic
Weights" of the elements, and are deduced from results obtained on
actual analysis. In addition to its use as an abbreviated title of any
element, the symbol represents the quantity of the element indicated by
its combining weight ; where multiples of that quantity exist in a com-
pound, the fact is expressed by placing a small figure after the symbol
and slightly below the line. In the table of elements there are two col-
umns of combining weights given, headed respectively "Old" and
"New"; the second column gives those obtained as a result of the most
recent research and which represent the most exact determinations as yet
made. For most purposes, the weights given in the first column are suf-
ficiently accurate.

As previously stated, the formula of sodium chloride is NaCl, and it.
contains 23 of sodium to 35.5 of chlorine. The formula of hydrochloric
acid is HC1, and it contains 1 of hydrogen to 35.5 parts of chlorine. Water
consists of 2 parts of hydrogen to 16 of oxygen ; the fact that it contains
twice the combining weight of hydrogen is expressed by writing the for-
mula H20. Again, ammonia contains 3 parts by weight of hydrogen to
14 parts of nitrogen, consequently it has the formula, NH3 ; the substance
commonly termed carbonic acid gas consists of 32 parts, or twice the com-
bining weight, of oxygen to 12 by weight of carbon, the formula is con-
sequently CO2. The quantity of an element represented by its combin-
ing weight is termed "one combining proportion" of that element.

29. Constitutional Formulae. — In addition to simply showing the
number of atoms of each element present, formulae are frequently so writ-

- ten as to show the probable constitution of the resultant compounds ; such
formulae are termed ' ' Constitutional Formulae. ' '

30. Chemical Equations. — Chemical changes are most conveniently
expressed by what are termed "chemical equations": these consist of

14 THE TECHNOLOGY OP BREAD-MAKING.

the symbols and formulas of the bodies participating, placed before the
sign =, while those of the resultant bodies follow. As an instance it may
be mentioned that, when a solution of potassium iodide is added to one
of mercury chloride, potassium chloride and mercury iodide are produced.
The equation representing this chemical action is written thus: —
2KI + HgCl2 2KC1 + HgI2.

Potassium Iodide. Mercury Chloride. Potassium Chloride. Mercury Iodide.

Having access to a table of combining weights, the chemist learns from
this equation that two parts of potassium iodide, each containing one
combining proportion of potassium weighing 39, and one of iodine weigh-
ing 126 together with one part of mercury chloride, containing one com-
bining proportion of mercury weighing 199, and two of chlorine each
weighing 35.5, together yield or produce two parts of potassium chloride,
each consisting of one combining portion of potassium weighing 39, and
one of chlorine weighing 35.5, and one part of mercury iodide, containing
one combining proportion of mercury weighing 199, and two combining
proportions of iodine each weighing 126. As no chemical change affects
the weight of matter, the weight of the quantity of a compound, repre-
sented by its formula, must be the sum of that of the constituent elements :
so, too, the weight of the bodies resulting from a chemical change must be
the same as that of the bodies before the change, whatever it may be, had
occurred. Although from a chemical equation and table of combining
weights, it is possible to state what relative weight of each element is con-
cerned in any chemical action, it must never be forgotten that the com-
bining weights were first determined by experiment and then the table
compiled therefrom. The statement of premise and deduction is, that
hydrogen and chlorine have respectively the combining weights of 1 and
35.5 assigned to them, because analysis shows that they combine in those
proportions : not that hydrogen and chlorine have as combining weights
3 and 35.5, and therefore they must combine in those proportions. The
combining weights are simply a tabular expression of results obtained by
practical analytic investigation.

31. Atoms and Molecules. — The fact that the quantity of every ele-
ment which enters into combination is. either a certain definite and
unchangeable weight, or a multiple of that weight, led chemists to regard
this weight of a combining proportion of an element as being in some way
associated with its physical nature. The first step toward the explanation
of this question is due to Dalton, who enunciated what is termed the
Atomic Theory. He assumed that all matter is built up of extremely small
particles, which are indivisible, and that when elements combine, it is
between these particles that the act of union occurs. These ultimate parti-
cles of matter are termed ' ' Atoms. ' ' The name ' ' atom ' ' is derived from
the Greek, and signifies that which is indivisible. Atoms of the same ele-
ment are supposed to be of the same size and weight. With the absolute
weight of atoms the student of bread-making chemistry has but little to
do : the principal point of importance for him is their relative weights
compared with each other. For chemical purposes, an atom may be
defined as the smallest particle of an element which enters into, or is
expelled from, a chemical compound. For the phrase, " combining pro-
portion," hitherto used, the term "Atom" may be substituted; the com-
bining weight then becomes the relative weight of the atom of each ele-
ment compared with that of hydrogen, which, being the lightest, is
taken as unity. Though the atomic theory does not admit of absolute
proof, yet it so amply and consistently explains all the phenomena of
chemistry that its essential principles are universally recognised.

INTRODUCTORY. 15

The little group of atoms represented by the formula of a compound
is termed a "molecule." A molecule is the smallest possible particle of
a substance which can exist alone. In the case of chemical compounds
the molecule cannot be further subdivided, except by separation into the
atoms of its constituent elements, or into two or more molecules of some
simpler chemical compound or compounds. When elements are in the
free or uncombined state, their atoms usually combine together to form
elementary molecules : thus with oxygen, two atoms unite to form a mole-
cule of oxygen ; the formula of the oxygen molecule is written, 02.

The molecules of the following elements contain two atoms : — hydro-
gen, chlorine, oxygen and nitrogen.

As all elements normally exist in the molecular state, it is frequently
advisable to use equations in which the lowest quantity of any element
present is a molecule. Thus, H2 -j- C12 = 2HC1, should be written as the
equation representing the combination of hydrogen and chlorine, rather
than H -|- Cl = HC1. This rule applies more especially to the gaseous
elements, as their molecular constitution has been definitely ascertained.
But in the case of the solid elements the number of atoms in the molecule
is not so well-known and therefore such elements are usually written as
so many single atoms, and not as molecules.

32. Avogadro's Law. — The fact that all gases, whether elementary
or compound, expand and contract at the same rate, when subjected to
variations of temperature and pressure, has an important bearing on
their probable molecular constitution. Their similarity in this respect
has led to the assumption expressed, in the ' ' Law of Avogadro ' ' : —
' ' Under similar conditions of temperature and pressure, equal volumes
of all gases contain the same number of molecules. ' ' From this it f ol-
lows, that at the same temperature and under the same pressure, the
volume of any gaseous molecule is the same whatever may be the nature
and composition of the gas. The density of a gas being known, its mole-
cular weight is easily calculated. The density of a gas is the weight of
any volume, compared with that of the same volume of hydrogen,
measured at the same temperature and pressure, and taken as unity. It
has already been stated that the molecule of hydrogen contains two
atoms ; its molecular weight, expressed in terms of its atomic weight, is
consequently 2. The molecular weight of any gas is the weight of
that volume which occupies the same space as do two parts by weight
of hydrogen; or is identical with the number obtained by doubling the
density. Similar conditions of temperature and pressure are always
understood in speaking of the comparative weights of gases. Con-
versely, as the molecular weight is the sum of the weights of the con-
stituent atoms, the densit}^ of a gas may be calculated from its formula.
Thus, carbon dioxide gas has as its formula, CO2 ; its molecular weight

is 12 -f (16X2=) 32 = 44; the density is^- = 22. Here again it

must be remembered that the molecular weight is primarily determined
from the density, and not the density from the molecular weight.

33. Absolute Weight of Hydrogen. — As hydrogen is taken as the
unit of comparison for other gases, it is necessary that its absolute
weight be determined with the greatest exactitude. Experiment has
shown that 1 litre of hydrogen, at normal temperature and pressure,
weighs 0.0896 gram; or 11.2 litres weigh 1 gram. The student must
make up his mind to remember this figure ; to quote Hof mann, the fact
that at 0° C. and 760 m.m. pressure, 1 litre of hydrogen weighs 0.0896

16 THE TECHNOLOGY OF BREAD-MAKING.

gram, should be impressed "as it were with a graving tool on the mem-
ory. ' ' The weight in grams of a litre of any gas is its density X 0.0896.

Thus, the density of carbon dioxide gas is 22; the weight of a litre is
22 X 0.0896 = 1.9712 grams.

34. Laws of Chemical Combination by Volume. — Not only does
chemical combination follow definite laws, so far as weight is concerned,
but also equally definite laws govern the proportions by volume in the
case of gaseous bodies. For example, experiment shows that one volume
of hydrogen unites with one volume of chlorine to form two volumes of
hydrochloric acid gas. So, too, two volumes of hydrogen unite with one
volume of oxygen to form two volumes of water-gas (steam). Again,
ammonia consists of three volumes of hydrogen, united with one of nitro-
gen, to form two volumes of ammonia. The reactions are expressed in
the following equations : —

H2 + C12 2HC1.

Hydrogen. Chlorine. Hydrochloric Acid.

2H2 + 02 2H20.

Hydrogen. Oxygen. Water.

3H2 + N2 2NH?.

Hydrogen. Nitrogen. Ammonia.

It will be observed that in the first equation one molecule of hydrogen
unites with one molecule of chlorine to form two molecules of hydrochloric
acid : the application of Avogadro 's Law, therefore, teaches that these ele-
ments will unite in equal quantities of one volume to form two volumes
of hydrochloric acid. In the same way, the proportions by volume in
which chemical changes occur between gaseous bodies are always
expressed in the equation, it being remembered that all gaseous mole-
cules occupy the same space when measured at the same temperature
and pressure. The following is a useful method of writing such equa-
tions, when the object is to show the proportions by volume in a chemical
change in which any gaseous body is involved.

H2 + C12 2HC1.

1 volume. 1 volume. 2 volumes.

2H2 + 02 2H20.

2 volumes. 1 volume. 2 volumes.

3H2 + N2 2NH3.

3 volumes. 1 volume. 2 volumes.

35. Acids, Bases,and Salts. — The name acid is a familiar one, because
it is continually applied in everyday parlance to anything which is sour.
A number of bodies possess this distinction in common; to the chemist,
the sourness of an acid is but an accidental property, as, according to his
definition of these bodies, substances are included as acids that are not
sour to the taste. An acid may be denned as a body which contains
hydrogen, which hydrogen may be replaced by a metal (or group of
elements equivalent to a metal), when presented to the acid in the form
of an oxide or hydroxide (hydrate). As a class, the acids are sour;
they are also active chemical agents ; most acids are characterised by the
property of changing the colour of a solution of litmus, a naturally blue
body, to a red tint. Oxygen is a constituent of most acids. These are
termed "oxy-acids.'' A few in which it is absent are termed "hydr-
acids." Hydrochloric acid, HC1, is an example of these bodies. Most of
the oxy-acids are produced by the union of water with an oxide — thus,
oxide of sulphur and water form sulphuric acid : —

SO8 + H20 H2S04.

Sulphur Trioxide. Water. Sulphuric Acid.

The oxides, which by union with water form acids, are termed anhydrides,

INTRODUCTORY. 17

or anhydrous acids. They are usually non-metallic oxides, but sometimes
consist of metals combined with a comparatively large number of atoms
of oxygen.

A Base is a compound, usually an oxide or hydroxide, of a metal (or
group of elements equivalent to a metal , which metal (or group of ele-
ments) is capable of replacing the hydrogen of an acid, when the two
are placed in contact. The greater number of metallic oxides are bases.
Bases, as well as acids, differ considerably in their chemical activity.
Certain bases are characterised by being soluble in water, to which they
impart a peculiar soapy feel. These bases are termed "alkalies," and
possess the property of restoring the blue colour to reddened litmus. The
most important alkalies are sodium hydroxide, NaHO, and potassium
hydroxide, KHO. The bases, lime, CaO, baryta, BaO, and magnesia,
MgO, are more or less soluble in water, and also turn reddened litmus
blue. They, with SrO, constitute the group known as the "Alkaline
Earths." Hydroxides are compounds of oxides with water, thus: —

Na20 + H20 2NaHO.

Sodium Oxide. Water. Sodium Hydroxide.

When an acid and base react on each other, the body, produced by
the replacement of the hydrogen of the acid by the metal of the base, is
termed a Salt. Water is also produced during the reaction. When the
acid and base which have thus reacted are both of something like the
same degree of strength, the resultant salt is commonly without action on
litmus; that is it does not affect the colour whether it be red or blue.
The salt is then said to be neutral. For example, when sulphuric acid, a
strong acid, acts on potassium hydroxide, a strong base, the resultant salt,
potassium sulphate, has no action on litmus. But when the acid is strong
and the base feeble, or vice versa, the resultant salt will be governed in its
degree of neutrality by the predominant component. Thus when potas-
sium hydroxide combines with carbonic acid (a weak acid) the salt, potas-
sium carbonate, is strongly alkaline to litmus. That is, it vigorously
restores the blue colour to litmus which has been reddened. The action
of acid and base on each other is illustrated in the following equation :—

HC1 + NaHO NaCl + H20.

Acid. Base. Salt. Water.

36. Compound Radicals. — At times a group of elements enters into
the composition of a body, and performs functions very similar to those
of an atom of an element. Such groups are not only found to form num-
bers of very definite compounds, but may be even transferred from one
compound to another without undergoing decomposition. Groups of
atoms of different elements which possess a distinct individuality
throughout a series of compounds, and behave therein as though they
were elementary bodies, are termed "Compound Radicals."

37. Quantivalence or Atomicity. — Referring back to the three com-
pounds of hydrogen mentioned in paragraph 34, it will be observed that
one atom each of chlorine, oxygen, and nitrogen, combines respectively
with one, two and three atoms of hydrogen. If chlorine and oxygen com-
pounds be classified and compared, it is found that oxygen in almost every
instance combines with just double as many atoms of the other element
as does chlorine. The atom-combining power of elements varies — Quan-
tivalence or Atomicity is the measure of that combining power. Among
the elements, hydrogen, sodium, and chlorine are characterised by the
fact that one atom of each rarely combines with more than one atom of
any other element. Their atomicity is unity, and as every other element

18 THE TECHNOLOGY OF BREAD-MAKING.

forms a chemical compound with one or more of these, the atomicity of
any element can usually be determined by observing with how many
atoms of one of these three elements an atom of the element in question
enters into combination. The atomicity of the different elements is given
in the table included in paragraph 24. Elements with an atomicity of
one are termed monads ; of two, dyads ; three, triads ; four, tetrads ; five,
pentads ; and of six, hexads. It is often convenient to express the atomicity
of an element graphically. This is done by attaching a series of lines to
the atom, according to its atomicity. These lines may be viewed as indicat-
ing the number of links or bonds with which the particular atom can com-
bine with other atoms. Of the actual nature of the force which holds
atoms together in chemical compounds, nothing can be here stated : the
bonds must only be viewed as indications of the number of such units of
atom-combining power. The following are examples of these graphic
symbols : —

H— Cl— —0— — B= =C=

Hydrogen. Chlorine. Oxygen. Boron. Carbon.

The same two elements often form a series of two or more compounds
with each other ; under these circumstances the atomicity must vary. In
the great majority of such compounds, the atomicity increases or dimin-
ishes by intervals of two — that is, the atomicity is either even or odd for
an element throughout all its compounds. This is sometimes accounted
for by the supposition that two of the bonds of an element may, by their
union, mutually satisfy each other. This is not, however, invariably the
case, as certain well-marked exceptions to this rule are known. The
highest known atomicity of an element is termed its "absolute" atom-
icity; the atomicity in any particular compound is the "active" atom-
icity; the absolute, less the active, atomicity is the "latent" atomicity.

38. Basicity of Acids. — In order to form salts, different acids require
different quantities of a base : the measure of this quantity is termed
the "basicity" of the acid. The basicity of an acid depends on the
number of atoms of hydrogen it contains that may be replaced by the
metal of a base. In forming salts, one atom of hydrogen is replaced by
one atom of a monad metal, two atoms of hydrogen by an atom of a dyad,
and so on. In the case of acids which contain more than one atom of
replaceable hydrogen, salts are sometimes formed in which a part only of
the hydrogen is replaced ; such salts are termed * ' acid ' ? salts, while those
in which the whole of the hydrogen is replaced are termed "normal"
salts. The following are typical examples of acids and the corresponding
salts : —

MONOBASIC ACID. DIBASIC ACID. TRIBASIC ACID.

HN03. H2S04. H3P04.

Nitric Acid. Sulphuric Acid. Phosphoric Acid.

NaNO3. Na2S04. Na3P04.

Sodium Nitrate. Sodium Sulphate. Sodium Phosphate.

HNaS04. Na2HP04.

Acid Sodium Sulphate. Disodic Hydrogen Phosphate.

Ca(NO3)2. CaS04. Ca3(P04)2.

Calcium Nitrate. Calcium Sulphate. Calcium Phosphate.

It is often convenient to view the acids in the light of their being com-
pounds of the anhydrides with water : the corresponding salts may then
be written as compounds of the bases with the anhydrides. This method
is almost invariably employed when calculating the relative quantities of
metals and acids in bodies when subjected to analysis. Subjoined are the

INTRODUCTORY. 19

formulae, written in this manner, of the acids and salts previously given
as examples: —

H20, N205. H20, S03. (H20)3, P205.

Two Molecules of Sulphuric Acid. Two Molecules of

Nitric Acid. Phosphoric Acid.

Na20, N2O5. Na20, S03. (Na20)3, P205.

Two Molecules of Sodium Sulphate. Two Molecules of

Sodium Nitrate. Sodium Phosphate.

Na2O, H20, (S03)2. (Na20)2H20,P205-

Two Molecules of Two Molecules of Disodic

Acid Sodium Sulphate. Hydrogen Phosphate.

CaO, N205. CaO, SO3. (CaO)3, P2O5.

One Molecule of Calcium Sulphate. One Molecule of

Calcium Nitrate. Calcium Phosphate.

39. Chemical Calculations. — Most of the chemical calculations neces-
sary in analytic work may be readily made by the help of chemical for-
mulae and equations, together with a table of combining weights. The
following are illustrations of some of the most important of these cal-
culations.

40. Percentage Composition from Formula. — Chemists usually
express the results of analysis of a substance in parts per cent., so that in
the case of a chemical compound it is often necessary to be able to cal-
culate its chemical formula from the percentage composition; or con-
versely, the percentage composition from the formula. The latter
operation, as being the simpler, shall be first explained. It is possible
from the formula of any body to arrive at the molecular weight of the
compound, and the relative weight present of each element. Thus, to
find the percentage composition of acid sodium sulphate : —

The formula is

Na H S O4

23 + 1 + 32 + (16 X 4 = ) 64 = 120.

From the combining weights, given beneath each element, with their sum
at the end, it is seen that the molecule weighs 120, and contains 23 parts
of sodium. Knowing that 120 parts contain 23, it is exceedingly easy to
calculate the number of parts per 100, as the problem resolves itself into
one of simple proportion : —

As 120 : 100 :: 23 : 19.17 per cent, of sodium.

As 120 : 100 :: 1 : 0.83 „ „ hydrogen.

As 120 : 100 :: 32 : 26.66 „ „ sulphur.

As 120 : 100 :: 64 : 53.33 „ „ oxygen.

99.99

Precisely the same method of calculation has been applied to the deter-
mination of the percentages of hydrogen, sulphur, and oxygen. As the
results seldom work out to a terminated decimal, the added percentages
usually amount to only 99.99 ; but by continuing the calculation, any
additional number of 9 's could be obtained, and as 0.9 recurring is equal
to 1.0, so 99.9 recurring is equivalent to 100.00. As another example,
let it be required to determine the percentage of base and anhydrous acid
respectively in calcium phosphate. This salt is represented by —

(Ca 0 )3
(40+16^)56X3

~168~ + 142 = 310

20 THE TECHNOLOGY OP BREAD-MAKING.

The molecule, which weighs 310, contains 168 of lime (CaO) and 142 of
phosphoric anhydride (P205), consequently

As 310 : 100 :: 168 : 54.19 per cent, of lime.

As 310 : 100 : : 142 : 45.81 „ „ phosphoric anhydride.

100.00

41. Formula from Percentage Composition. — Let the following rep-
resent the results of analysis of a body : —

Sodium 16.79 per cent.

Nitrogen 10.22

Hydrogen 3.65

Phosphorus 22.63 „

Oxygen 46.71

100.00

As a first step toward obtaining the formula, divide the percentage of
each element by its atomic weight ; the result will be a series of numbers
in the ratio of the number of atoms of each element—

iM5_ = 0.73 of Sodium.

10 29

' = 0.73 of Nitrogen.

3.65

1
22.63

- 3.65 of Hydrogen.

- 0.73 of Phosphorus.

^1 = 2.92 of Oxygen,
lo

It is next necessary to find the lowest series of whole numbers that corre-
spond to these; such a series may be obtained by dividing each number
by the lowest one of the series :—

0 73

' = 1 atom of Sodium.
U. i o

0.73

— — — 1 atom of Nitrogen.

U. to

ll— = 5 atoms of Hydrogen.

U. i o

0.73

— — = 1 atom of Phosphorus.

U. to

2 92

' = 4 atoms of Oxygen.
U.Yo

The formula of the compound is, therefore, NaNH5P04; its name is
" hydrogen ammonium sodium phosphate." The formula obtained in this
way is the simplest possible for the body in question : it is evident that
the percentage composition would be the same if there were double or any
other multiple of the number of atoms of each element in the molecule.
Other considerations are taken into account in determining whether the
correct molecular formula is really the simplest thus obtained, by cal-
culation, from the percentage composition, or a multiple of the same.
Such simplest possible formula is termed an Empirical Formula,

INTRODUCTORY. 21

42. Calculations of Quantities. — An exceedingly common type of
calculation is that in which it is required to know the quantities of one or
more substances required to produce a certain quantity of another body.
Thus, hydrogen is commonly obtained by the action of zinc on sulphuric
acid; suppose that 10 grams of hydrogen are required for some opera-
tion : what weights respectively of zinc and sulphuric acid are necessary
for the purpose ? Here, again, the equation gives the relative weights of
each element and compound participating in the reaction. In every such
calculation it is absolutely necessary that the equation and combining
weights be known; but granted these, no other difficulties arise beyond
those which can be readily overcome by an intelligent application of the
principles of proportion.

In the case in question the equation is : —

Zn + H2 S -04 = Zn S 04 -f H...

65 2+32+64 65+32+64 2.

Zinc. Sulphuric Acid. Zinc Sulphate. Hydrogen.

To produce two parts by weight of hydrogen, 65 of zinc and 98 of
sulphuric acid are required, then —

As 2 : 10 : : 65 : 325 grams of zinc required.

As 2 : 10 : : 98 : 490 ,, ,, sulphuric acid required.
Another instance may be given, in which not only weights but also
volumes of gases have to be calculated. It is required to know how much
carbon dioxide gas in cubic centimetres and in cubic inches is evolved by
the fermentation of 28.35 grams (= 1 ounce) of pure cane sugar, the gas
being measured at a temperature of 20° C. and 765 millimetres pressure ;
it being assumed that the whole of the sugar is resolved into alcohol and
carbon dioxide. The chemical changes involved in this process may be
represented by the following equations : —

C12 H22 On + H2 O 20,11,3 06.

144+22+176 2+16 72+12+96

342 18 2X180=360

Cane Sugar. Water. Glucose.

In the first place one molecule, equalling 342 parts by weight of cane
sugar, is converted into two molecules of glucose, each weighing 180, or
the two weighing 360.

2C6H1206 = 4C2H,H 0 + 4C O2.

72+12+96 24+5+1+16 12+32

2X180=360 4X46=184 4X44=176

Glucose. Alcohol. Carbon dioxide.

The two molecules of glucose, weighing 360, are next decomposed into
four molecules of alcohol, having a total weight of 184; and four mole-
cules of carbon dioxide, each weighing 44, and the whole 176. From 342
parts by weight of cane sugar, 176 parts by weight of carbon dioxide are
produced ; then —

As 342 : 28.35 : : 176 : 14.59 grams of carbon dioxide, yielded by
28.35 grams of cane sugar.

The next step is to determine what is the volume of 14.59 grams of
carbon dioxide at N.T.P. The molecular weight of carbon dioxide being
44, its density must be 22; one litre of hydrogen weighs 0.0896 grams,

22 THE TECHNOLOGY OF BREAD-MAKING.

and therefore 1 litre of carbon dioxide must weigh 0.0896 X 22 = 1.9712
grams; then —

= 7.401 litres at N.T.P.

Applying the laws previously given by which the relations between the
volume and temperature and pressure of a gas are governed ; then —

As 273 : 293 : : 7.401 ) __ 293 X 760 X 7.401
765 : 760 ]~ 273 X 765

= 7.891 litres at 20° C. and 765 m.m. pressure = 7891 cubic centimetres
As 16.39 c.c. = 1 cubic inch, then

-^ =481.7 cubic inches.
j-b.oy

28.35 grams or one ounce of cane sugar would yield, according to the
question given, 7891 c.c. or 481.7 cubic inches of carbon dioxide gas at
20° C. and 765 m.m. pressure.

The weight of sugar necessary to yield a certain volume of gas would
be calculated on the same principles ; as an illustration, the reverse of the
calculation just made is appended. Required to know the weight of cane
sugar necessary to produce 481.7 cubic inches or 7891 cubic centimetres
of carbon dioxide gas at 20° C. and 765 mm. pressure.

•«• at N-T-p- = 7-401 ut«»-

7.401X1.9712 = 14.59 grams of C02.
As 176 : 14.59 : : 342 : 28.35 grams of cane sugar required.

43. Gaseous Diffusion. — It is a well-known fact that gases mix with
each other with remarkable readiness. For instance, if in a large room a
jar of chlorine is opened at the level of the floor, the presence of the gas
may be detected by its powerful odour, within a few seconds, in every
part of the room. The natural process by which the chlorine is thus
disseminated through the air is termed " gaseous diffusion"; it takes
place between gases, even though the heavier is at first at the lower level.
In other words, a heavy gas will diffuse up into a superincumbent light
gas, while the light gas will make its way downwards and mix with the
heavier one. In this way different gases, when placed in the same space,
rapidly produce of themselves an uniform mixture. This process of dif-
fusion will also go on through a porous membrane, as, for example, a thin
diaphragm of plaster of Paris or porous earthenware. Thus, if a vessel
be divided into two parts by a thin partition of porous material, and
the one half be filled with one gas and the other with another, they will
be found after some time to have become thoroughly intermixed with
each other. The rate of diffusion of all gases through such a diaphragm
is not the same, but depends on their densities. The rate of diffusion
of gases is inversely as the square root of their density. Thus, hydro-
gen and oxygen have respectively densities of 1 and 16 ; hydrogen dif-
fuses four times as rapidly as does oxygen.

44. Solution. — When certain solid substances, of which salt is a
convenient example, are added to water, the solid disappears, and is
said to be dissolved. The liquid which has been used for dissolving the
substance is said to be a solvent, the substance which is dissolved is
called a solute, and the liquid which as a result contains the .dissolved

INTRODUCTORY. 23

substance is termed a solution. Solutions may be prepared of gases,
liquids and solids. A liquid solution may be defined as a homogeneous or
uniform liquid mixture of a gas, a liquid, or a solid with a liquid. The

act of solution is not in itself one of chemical combination between
the dissolved substance and the solvent (although solution may be fol-
lowed in addition by chemical combination). Thus when a solution of
salt in water is heated, the water may be driven off and the whole of
the salt recovered in an unchanged condition.

45. Gaseous Solution. — Gases vary very greatly in their degree of
solubility in water. In the following table is given the volumes of each
gas dissolved in 100 volumes of water, at the temperatures of 0° and
15° C. respectively—

o°c. is°c.

Hydrogen 2.15 . . 1.91

Nitrogen 2.03 . . 1.48

Oxygen 4.11 . . 2.99

Chlorine solid . . 23.68

Carbon dioxide . . . . 179.67 . . 100.20

Sulphur dioxide .. .. 6886.1 .. 4356.4

Hydrochloric acid . . . . 50590.0 . . 45800.0

Ammonia 104960.0 . . 72720.0

Comparatively small quantities of hydrogen, nitrogen, and oxygen are
thus dissolved, but that of oxygen is sufficiently large to have most im-
portant results in the economy of nature. Carbon dioxide is much more
soluble, water absorbing about its own volume at ordinary temperatures.
The last mentioned gases are examples of extremely soluble gases ; their
various solutions have important applications in chemistry and the arts.
It will be observed that all the gases mentioned are less soluble in water
at 15° than at 0° C., and as the temperature is raised the solubility still
further diminishes. Most gases may, in fact, be entirely expelled from
water by the act of boiling. The weight of a gas dissolved by water is
increased by pressure, and is governed by an interesting law, viz., that it
is directly proportional to the pressure exerted. As the volume of a gas
is in inverse ratio to the pressure, it follows that the volume of a gas
dissolved by water is the same at all pressures. The so-called mineral or
aerated waters are prepared by forcing carbon dioxide into the water
under pressure. On the release of the pressure the gas escapes and
causes the familiar effervescence. Most of the gases mentioned in the
foregoing table are much more soluble in alcohol than in water ; thus 100
volumes of alcohol at 15° C. dissolve 28 volumes of oxygen and 320 vol-
umes of carbon dioxide respectively.

46. Solution of Liquids. — Some liquids on being placed together
mix or are said to be "miscible" in all proportions ; an example of these
is found in alcohol and water. Others practically refuse altogether to
mix, as, for example, water and oil. Others again are to a limited extent
soluble in each other. One of the best illustrations of these is that of
water and ether ; if these be shaken together in about equal proportions
and then allowed to stand, the ether being the lighter, separates out as a
layer on the surface of the water. On examination, however, the ether
will be found to have water dissolved in it to the extent of about 3 per
cent. ; and the water will have dissolved about 10 per cent, of ether.
(As a matter of fact, oils and water are also very slightly soluble in each
other, but the amount of oil so dissolved is so minute as to be a negligible
quantity, while traces only of water are dissolved by oil.)

24 THE TECHNOLOGY OF BREAD-MARINO.

47. Solution of Solids. — Solids vary very greatly in their degree of
solubility in water. Among the mineral salts, barium sulphate is almost
absolutely insoluble ; calcium sulphate is dissolved to the extent of 1 part
in 700 parts of water; while at the other end of the scale 2 parts of
crystallized magnesium sulphate are dissolved by 3 parts of water at
ordinary temperatures. In the majority of instances the solubility of
substances in water is increased by an elevation of temperature, but this
is not an absolute rule. Lime, for example, is much more soluble in cold
than in hot water. Salt is almost equally soluble in cold and hot water ;
at 0° C. water dissolves 35.5 per cent, of salt, and 41.2 per cent, at 109.5°
C., the boiling point of the solution. Sugar, on the other hand, is soluble
in about half its weight of cold water, and in boiling water in all pro-
portions. In order to determine the solubility of any particular sub-
stance, it must be allowed to remain in contact with the solvent until
the latter has dissolved as much as it possibly can, and leaves the excess
in contact with the solution. Under such conditions, the solvent takes
up a definite proportion of the dissolved body for each particular tem-
perature.

A perfect solution is quite clear and free from any cloudiness, as the
solid particles will have completely disappeared from sight. Any tur-
bidity is caused by the presence of minute solid or liquid particles in
suspension. It is incorrect, therefore, to speak of a mixture of a perma-
nently solid substance with water in the form of a creamy mass as a
solution. Similarly one does not dissolve yeast in water; one is simply
broken down into an intimate admixture with the other. Water dissolves
many of the mineral salts, but does not dissolve resins or fatty matters.
The resinous bodies, of which shellac may be taken as an example, are
soluble in alcohol ; while fats may be readily dissolved by ether, chloro-
form, and light petroleum spirit. Water, on the other hand, dissolves
certain gelatinous and gummy bodies, but such solutions have special
characteristics to which further reference is made in the following para-
graphs.

48. Osmose and Dialysis. — Liquids which are miscible with each
other in somewhat the same way as gases, also undergo diffusion more
or less rapidly. The laws governing diffusion of liquids are more com-
plex than those affecting the diffusion of gases : not only gases, but also
liquids, are capable of diffusion through a porous diaphragm; such dif-
fusion is termed "Osmose." Some of the most remarkable and impor-
tant phenomena of liquid diffusion are those exhibited by aqueous solu-
tions of different substances. Thus, let a sort of drum-head be made by
stretching and fastening a piece of bullock's bladder, or either animal
parchment or vegetable parchment paper, over a cylinder of some imper-
vious material, as glass or gutta percha. Float this in a vessel of pure
water, and pour inside it a strong solution of common salt. The brine
and the pure water will only be separated from each other by the thin
membrane of bladder or other similar material. After the lapse of some
hours it will be found that the solution of salt will have diffused out
through the membrane until the liquid both outside and inside the float-
ing vessel has the same strength. By repeatedly changing the water in
the outer vessel, the whole of the salt might be removed from the solution
within the cylinder. On the other hand, if a solution of gum arabic
were placed within the parchment drum, and subjected to precisely the
same treatment, the gum would be found incapable of diffusion through
the membrane. If a mixture of brine and gum were placed in the cylinder

INTRODUCTORY. 25

with parchment bottom, and then floated on the surface of water, the
salt would diffuse out and the gum remain behind ; in this manner a com-
plete separation of the two might be effected. The separation of bodies
by their respective ability or inability, when dissolved, to diffuse-
through a porous membrane, is termed " Dialysis."

49. Crystalloids and Colloids. — All bodies, soluble in water, are
capable of being divided into two great classes, known respectively as
"crystalloids" and "colloids." Crystalloids are substances which, on
changing from the liquid to the solid state, assume a crystalline form.
Bodies are said to be crystalline when they consist of crystals, and for
chemical purposes a crystal may be denned as matter which has spon-
taneously assumed during the act of solidification a definite geometric
form. In crystals there is also a definite internal molecular arrange-
ment related to the crystalline form by certain determinate laws. Solu-
tions of crystalline bodies are usually, but not invariably, free from
any marked viscosity. Crystalline bodies are only soluble to a definite
extent in water, the quantity dissolved depending more or less on the
temperature, as has been already explained. Jelly-like substances, as
gum and gelatin, are termed ' ' Colloids, ' ' and do not acquire a crystal-
line form when assuming the solid state. The colloids form, when
treated with water, sirupy, viscous, or jelly-like solutions. They may be
said to be soluble in water in all proportions. Thus, if a few drops
of water be added to a piece of dry gelatin, the water will be absorbed
by the gelatin, and after a time will be uniformly diffused throughout the
whole mass. Successive portions of water may thus be absorbed by the
gelatin, which will become gradually softer, assuming the consistency of
a jelly; further addition of water produces a solution with more or less
viscosity, depending on the degree of concentration. Crystalloids are
especially susceptible of dialysis; colloids exhibit under similar treat-
ment very little tendency to pass through a porous membrane. The
probable reason for this inability on the part of colloids is that their solu-
tion particles are too large to readily pass through the interstices in the
porous membrane. The membranes used for dialysis consist of colloid
substances : gelatin in the jelly-like form at times is a very convenient
dialysing agent. The apparatus used for the purpose of effecting dialysis
is termed a dialyser. The phenomena of liquid diffusion have an exceed-
ingly important bearing on many chemical changes which occur during
bread-making.

50. Measures of Weight and Volume. — It will be here convenient
to furnish a statement of the different systems of weights and measures
usually employed for scientific purposes. The chemist, as a rule, prefers
the metric system, jjs in common use in France, to the very complicated
system of weights and measures employed in this country. One reason is
that the metric system is extremely simple ; another, that the measures of
weight and volume are directly connected with each other. If the authors
simply followed their own predilections, metric weights and measures
only would be used throughout this work, but it having been strongly
represented to them that the introduction of the English equivalents of
the different weights employed would be a help to some of their readers,
they also have been, in most cases, given. The authors are conscious that

' the result of this intermixture is often incongruous, but to those familiar
with the metric system this will present no difficulty, while to those who
are unacquainted with it, it will be an assistance. It is nevertheless
urged that the metric system be mastered ; this may be easily done in a

THE TECHNOLOGY OF BREAD-MAKING.

quarter of an hour ; much time will then be saved which otherwise would
have to be spent in making calculations.

51. The Metric System. — The unit of the metric system is a
''metre," which is the length of a rod of platinum that is deposited in
the archives of France. The metre measures 39.37 English inches. The
higher and lower measures are obtained by multiplying and dividing by
10, thus:—

1000 metres 39370 inches.

100 „
10

Kilometre

Hectometre

Decametre

Metre

Decimetre

Centimetre

Millimetre

= 39370
3937
393.7
39.37
3.937
0.3937
0.03937

0.1 metre

0.01 „ 0.3937 inch.

0.001 „

In the above, and all other measures of the metric system, the prefixes
"kilo, hecto, and deca" are used to represent 1000, 100, and 10 respec-
tively ; and ' l deci, centi, and milli, ' ' to represent a tenth, hundredth, and
thousandth. The decimetre is very nearly 4 inches in length, and the
millimetre very nearly one twenty-fifth of an inch: remembering this,
measures of the one denomination can be roughly translated into those of
the other. The exact length of a decimetre is shown in Fig. 1.

Each side of this square measures

1 Decimetre, or
10 Centimetres, or
100 Millimetres, or
3.937 English inches.

A litre is a cubic measure of 1 decimetre in the side, or a cube
each side of which has the dimensions of this figure.

When full of water at 4° C. a litre weighs exactly 1 kilogram

or 1000 grams, and is equivalent to 1000 cubic centimetres ; or to
61.027 cubio inches, English.

A gram is the weight of a centimetre cube of distilled water ;
at 4° C. it weighs 15.432 grains.

4 inches.

FIG. 1.

The unit of the measure of capacity is the "litre," which is the vol-

ume of a cubic decimetre.

INTRODUCTORY.

Kilolitre == 1000

Hectolitre =
Decalitre :
Litre
Decilitre
Centilitre =
Millilitre =

100
10

Cubic Inches.

litres = 61027
„ = 6102.7
„ = 610.27
61.027
6.1027
0.61027
0.06102

Pints.

1760.7
176.07
17.607
1.7607
0.17607
0.017607
0.00176

Fluid Ounces.

35214
3521.4
352.14
35.214
3.5214
0.3521
0.0352

0.1 litre --

0.01 „

0.001 „

The decimetre being 10 centimetres in length, it follows that a cubic
decimetre must be equal to 1000 cubic centimetres, and that the millilitre
has a volume of a cubic centimetre. The name "cubic centimetre," or

its abbreviation '

is almost always used in preference to millilitre ;

thus, a burette or pipette is said to deliver 50 c.c., while a litre measure is
often termed a "1000 c.c." measure.

A cubic inch is equal to 16.38 cubic centimetres.

The unit of the measure of weight is the ' ' gramme, " or " gram ' ' ; this
is the weight of a cubic centimetre of distilled water at its maximum
density (4° C. = 39.2° F.) :—

Grains. Avoirdupois Ounces.

= 1000 grams = 15432.3 35.2739

100 „ 1543.23 3.52739

=. 10 „ = 154.323 0.35273

0.03527
gram =

Kilogram

Hectogram

Decagram

Gram

Decigram

Centigram

Milligram

0.1

0.01

0.001

1543.23
154.323
15.4323
1.54323
0.15432
0.01543

0.00352
0.00035
0.000035

A kilogram is just over 2 Ib. 3^4 oz., and a hectogram is very nearly
3*/2 oz. An ounce avoirdupois equals 28.35 grams, and 1 lb., 453.6 grams.

The relation between the weight and volume of water is a very simple
one, the volume being the same number of c.c. as the weight is grams.
With other liquids the volume in c.c. X specific gravity = weight in
grams.

52. English Weights and Measures. — Familiarity with English
weights and measures is assumed, still the following particulars will most
likely be of service — one gallon of pure water at a temperature of 62° F.
(16.6° C.) weighs 10 pounds or 160 ounces or 70,000 grains; the pint,
therefore, weighs 20 ounces. The measure termed a "fluid ounce" is
derived from the weight of a pint of water. A fluid ounce is a measure
of volume, not of weight, and equals one-twentieth part of a pint. The
fluid ounce bears the same relation to the avoirdupois ounce as does the
cubic centimetre to the gram. A gallon is equal to 277.274 cubic inches.
An ounce avoirdupois weighs 437.5 grains.

53. Specific Gravity. — The same volume of different substances
varies considerably in weight. Water is commonly taken as the unit of
gravity for the purpose of stating that of other liquids and of solids.
The specific gravity of any liquid or solid is the weight of that volume
which in the case of water at a standard temperature and pressure
weighs 1 unit. Thus the cubic centimetre of water weighs 1 gram, the
cubic centimetre of mercury weighs 13.59 grams, and 13.59 is accordingly
said to be the specific gravity of mercury. At times the specific gravity
of water is taken as 1000 instead of 1 ; this is convenient in the case of
bodies which are lighter than water. The specific gravity multiplied by
10 gives the weight of a gallon of any liquid. Thus alcohol and milk
have respectively the specific gravities of 0.79350 and about 1.030. The
gallon of each would weigh 7.935 and 10.30 Ibs.

CHAPTER II.

DESCRIPTION OF^-HJMmmCIPAL CHEMICAL ELEMENTS AND
THEIR INORGANIC COMPOUNDS.

54. Description of Elements and Compounds. — It is intended in
this chapter to give a very brief description of those elements and their
inorganic compounds, which are more or less directly connected with the
chemistry of wheat, flour, and bread, and to which reference may be
made in the latter part of this work. Such descriptions as are here given
must not be viewed as being in any way a substitute for a careful study
of elementary chemistry. It is thought, however, that to many readers,
more particularly those who may not have the time for such a systematic
course, an account such as is to follow will be found of service.

55. Hydrogen, H2. — This element is a gas, and is the lightest sub-
stance known; it is consequently selected as the standard by which the
density of other gases is measured. One litre of hydrogen at N.T.P.
weighs 0.0896 gram. Hydrogen has the lowest atomic weight of all the
elements, and is therefore also selected as the unit of the modern system
of atomic or combining weights. (For certain reasons, the atomic weights
are sometimes calculated' to the basis of 16.00 as the atomic weight of
oxygen.) Hydrogen is colourless, odourless, tasteless, and non-poisonous.
It is not capable of supporting respiration, and therefore animals placed
therein quickly die through lack of proper air to breathe. Hydrogen is
inflammable and burns with a pale blue flame ; it does not support com-
bustion. Hydrogen is only very slightly soluble in water.

56. Oxygen, 02. — This element is a colourless, odourless, and non-
inflammable gas. Its most remarkable feature is that it supports combus-
tion and also respiration. Bodies which burn in ordinary air do so
because that substance is a mixture of oxygen and nitrogen; they burn
with much increased brilliancy in oxygen. The respiration or breathing
of animals consists of a removal of oxygen from the air, and a return
thereto of water vapour and carbon dioxide gas : the activity of oxygen
renders it injurious to breathe in a pure state : in air, the nitrogen acts
as a diluting agent, without modifying the essential characteristics of the
gas. Oxygen is soluble in water to the extent of three volumes of the
gas in one hundred volumes of water at 15° C. This quantity, though
small, is of vast importance, as it thus supports the life of fishes, and has
also a most important action on fermentation. Although oxygen is
such an essential to most forms of life, there are some of the lower micro-
scopic organisms towards which it acts as a most energetic poison. Com-
pounds produced by the union of elements with oxygen are termed
"oxides."

57. Ozone, 03. — This body is a gaseous substance consisting of pure
oxygen, but having a density of 24 instead of 16. This is due to there
being 3 atoms of the element in the molecule, instead of 2 as in ordinary
oxygen. Ozone has a peculiar odour ; and is produced during the work-
ing of a frictional electric machine, when its smell is recognized. Traces

ELEMENTS AND INORGANIC COMPOUNDS. 29

of this gas exist in the air in mountainous districts, and by the seaside.
By exposure to a temperature of 237° C. ozone is transformed into ordi-
nary oxygen. Ozone is a powerful oxidizing agent, and is inimical to the
growth and development of germ life. Ozone has ,been proposed as a
bleaching agent for flour ; its employment for that purpose will be dis-
cussed in full at a later stage.

58. Water, H20. — This most important compound consists of two
volumes of hydrogen united to one volume of oxygen, to form two
volumes of water-gas or steam. By weight, water contains 16 parts of
oxygen to 2 of hydrogen. Water in the pure state is odourless and taste-
less ; viewed through thick layers it has a blue colour. At temperatures
below 0°C. water exists in the solid state ; on being heated, ice expands
until a temperature of 0° C. is reached. At this point the ice begins to
melt; the temperature remains stationary until the whole of the ice is
melted, but in order to effect the change from the solid to the liquid con-
dition as much heat is required as would be sufficient to raise 79 times the
weight of water from 0° to 1° C. Ice in melting contracts in bulk; 10.9
volumes of ice producing 10 volumes of water. As the ice-cold water is
further heated, contraction continues until a temperature of 4° C. is
reached : at this point water is at its maximum density, and any given
weight of it occupies its minimum volume. With further application of
heat the water expands, and also rises steadily in temperature. In metal
vessels open to the air, water boils at a temperature of 100° C. Continued
heating now converts the whole of the water into steam, but does not raise
the temperature. The quantity of heat necessary to convert the whole of
the water at 100° C. into steam at the same temperature would raise 537.2
times the weight of water from 0° to 1° C. Steam in being further heated
expands, and may have its temperature raised indefinitely ; steam follows
the same law of expansion on increase of temperature as do other gases.
Steam, on being cooled, passes through a series of changes which are the
exact converse of those just described. At all temperatures water gives
off vapour, but with much greater rapidity as the temperature approaches
the boiling point. This vapour exerts a definite pressure, the pressure
increasing steadily with the temperature ; at the boiling point, the pressure
exerted by the vapour of water is exactly equal to that of the atmosphere ;
consequently, if the atmospheric pressure be diminished, the boiling point
of water, and also that of all other liquids, is lowered. Advantage is taken
of this property in many operations in the arts ; thus, in driving off the
water from sugar solutions, as in the preparation of malt extract, the boil-
ing is effected in a vacuum, and so the temperature prevented from rising
to any great height. On the other hand, by subjecting water to pressure,
its boiling point may be raised to any temperature attainable, the only
limit being the capacity, for resisting the pressure, of the material of the
vessel. The tubes of steam ovens are constructed on this principle — a cer-
tain quantity of water is sealed up in them, which, on being heated, is
converted into steam having a sufficiently high temperature to effect the
baking of bread. The boiling point of water also depends on any sub-
stances it may have in solution. Salt and other non-volatile bodies raise
the temperature of the boiling point, but do not affect that of the steam
produced, which immediately falls to 100° C. Admixture of volatile bodies
lowers the boiling point ; thus, a mixture of water and alcohol boils at a
temperature below 100° C. until the whole of the alcohol has been expelled.

59. Solvent Power of Water. — Water is, of all bodies, pre-eminently
the solvent in nature. As a result of this property, water is never found

30 THE TECHNOLOGY OF BREAD-MAKING.

in a state of purity in nature. Even rain is found to have dissolved out
traces of solid matter that were suspended in the air, while river and
spring water is always more or less impure from saline and other matter
dissolved from the soil and rocky strata from whence it is obtained. In
addition to the solid matter there is also invariably more or less gas held
in solution in natural waters. A further account of natural waters, hav-
ing particular reference to their fitness for bread-making, is given in a
future chapter. For chemical purposes all such water is purified by dis-
tillation, that is, it is converted into steam, and re-condensed ; the solid
impurities then remain behind. This treatment does not, however, free
the water from gases or from volatile impurities. For certain purposes,
where rigidly pure water is a necessity, special modes of preparation have
to be adopted ; these will be described in detail hereafter.

60. Hydrogen Peroxide, H202. — In addition to water, there is also
known a higher oxide of hydrogen, to which the name of hydrogen per-
oxide is given. In the pure state, hydrogen peroxide is a colourless,
odourless, and somewhat sirupy liquid having a peculiar metallic taste.
It is extremely unstable, readily giving off oxygen, and leaving a residue
of pure water. When diluted with water, hydrogen peroxide is much
more stable, and this stability is increased by the addition of a small quan-
tity of acid. But on heating, this solution is changed into water and free
oxygen. This readiness to give up oxygen causes the peroxide to be a
powerful oxidizing agent, and as such it possesses active bleaching proper-
ties. The semi-molecule of hydrogen peroxide, HO, enters into the com-
position of a large number of compounds, and has received a specific
name, hydroxyl.

61. Chlorine, C12. — This element is, at ordinary temperatures, a gas
of a greenish yellow colour, with a most pungent, acrid, and suffocating
odour and taste. The presence of comparatively small quantities renders
air irrespirable. Chlorine is non-inflammable ; but, to a limited extent,
supports combustion. Hydrogen burns in it readily, but carbon is incap-
able of direct combination with chlorine. Chlorine does not exist in the
free state in nature ; it has so great an attraction for hydrogen that it
slowly decomposes water, combining with the hydrogen and liberating
oxygen in the free state. Water dissolves 2.368 volumes of chlorine at
15° C. ; the solution has a powerful bleaching action on vegetable colours,
and also is a most efficient disinfectant. Chlorine forms compounds,
termed ' ' chlorides, ' ' with all other elements.

62. Hydrochloric Acid, HC1. — This, the only known compound of
hydrogen and chlorine, is a gaseous body. Hydrochloric acid gas is col-
ourless, fumes on coming in contact with moist air, has a most pungent
smell, and is neither inflammable nor a supporter of combustion. One
volume of hydrogen unites with one volume of chlorine to produce two
volumes of hydrochloric acid gas. The gas dissolves readily in water, one
volume of which at 15° C. holds in solution 454 volumes of the gas. The
concentrated solution fumes on exposure to air, and smells strongly of the
gas ; it has an extremely sour taste, and turns litmus solution red. The
commercial solution has a specific gravity of about 1.16, and contains
about 33 per cent, (one-third) by weight of hydrochloric acid. Hydro-
chloric acid attacks many of the metals, forming chlorides, with the evolu-
tion of hydrogen. Hydrochloric acid and the bases when placed in con-
tact form the salts known as chlorides. Hydrochloric acid and the chlo-
rides may be recognised when in solution by their giving a curdy white

ELEMENTS AND INORGANIC COMPOUNDS. 31

precipitate on the additions of dilute nitric acid, and nitrate of silver

solution.

63. Chlorides. — Common salt, or sodium chloride, NaCl, is the most
important of the chlorides, and is largely used as an antiseptic or pre-
ventative of putrefaction ; its effect during fermentation of dough will be
discussed hereafter. Other chlorides, as calcium chloride, CaCl2, will be
referred to as occasion arises.

64. Bleaching Powder, or Chloride of Lime, CaOCl2.— This body is
produced by the union of lime (calcium oxide) with chlorine. The addi-
tion of almost any acid, even carbon dioxide, is sufficient to effect its
decomposition, liberating free chlorine. Chloride of lime is consequently
largely used for disinfecting and bleaching purposes.

65. Carbon, C. — This element is only known in the solid state, being
incapable of liquefaction or vaporisation at the highest temperatures at
our command (except possibly at the highest temperatures of the electric
arc). It exists in nature, uncombiiied with other elements, in two forms
or varieties most strikingly different from each other. One of these con-
stitutes the gem known as the diamond, the other is graphite, or black-
lead. Both these bodies are almost pure carbon. Carbon also occurs plen-
tifully as a constituent of animal and vegetable substances, as flesh, bones,
fat, wood, leaves, seeds, and the almost numberless bodies that may be
obtained from them. Limestone, marble, and chalk rocks contain a large
percentage of carbon; so also does coal, which is essentially fossilised
wood. From flesh, bones, wood, and many other substances, carbon may
be obtained by heating them to redness in a closed vessel : this form of
carbon is termed "charcoal," that from bones being "animal/' and that
from wood "vegetable charcoal." Carbon prepared in this manner, or
charcoal, is a black substance. The operation of thus heating a substance
in a closed vessel to a temperature sufficiently high to effect its decomposi-
tion into volatile liquid and gaseous products, with usually, as in this case,
a non- volatile residue, is termed "destructive distillation." All forms of
carbon are inflammable. When burned with an insufficient supply of oxy-
gen, carbon monoxide, CO, is produced ; with excess of oxygen, carbon
dioxide, or CO2, is formed. Charcoal possesses a most remarkable prop-
erty of absorbing and condensing gases within its pores; thus, freshly-
burnt wood charcoal is capable of absorbing about ninety times its volume
of ammonia gas. Charcoal also absorbs considerable quantities of oxygen ;
and among other gases, those evolved during the putrefaction of animal
and vegetable bodies. The gases resulting from putrefaction are largely
composed of carbon and hydrogen, and, when thus brought by their
absorption within the charcoal so closely in contact with oxygen, are
rapidly burned or oxidised to carbon dioxide, water, and more or less of
other inodorous and innocuous substances. Charcoal thus acts as a rem-
edy for bad smells, and acts not by masking them by a more powerful
odour, but by absorption of the deleterious vapours, and their conversion
into harmless products. In this way charcoal is also capable of removing
evil smells from water ; for instance, water from a stagnant pond on being
shaken up with charcoal loses its disagreeable odour. Not only does char-

M coal act as an absorbent of gases, but it also removes many colouring mat-
ters from solution ; thus, a syrup of dark brown sugar on being shaken up
with animal charcoal, and then filtered, may be made almost colourless.
These properties of charcoal have led to its finding much favour as a
filtering medium for the purification of water ; for this purpose it is, when

32 THE TECHNOLOGY OF BREAD-MAKING.

fresh, of great efficacy, but after a time loses its activity by being sat-
urated with the bodies it is intended to remove. All niters require from
time to time to be taken apart, and the filtering medium removed and
replaced by some fresh and pure material. Charcoal may be renovated
by being heated to redness in a closed vessel. With these precautions,
charcoal forms one of the best filtering agents; but without attention to
continuous cleaning, filters, so far from purifying water, become positive
sources of the most serious and dangerous impurities. Charcoal is fre-
quently used in the laboratory for decolourising purposes.

66. Carbon Monoxide, CO. — This compound is a colourless, odourless
and exceedingly poisonous gas. It is formed when carbon dioxide gas
passes over or through red-hot charcoal, as it frequently does in a clear
coke or charcoal fire. The carbon monoxide thus produced burns with a
blue flame on the surface of the fire. Carbon monoxide is also formed,
together with free hydrogen, when steam is passed through a red-hot car-
bon mass, such as a fire of burning coke. The gas is inflammable, and in
burning yields carbon dioxide. Carbon monoxide has no action on lime-
water.

67. Carbon Dioxide, C02. — This gas plays a most important part in
the chemistry of bread-making. It is colourless, has a sweetish taste, and
peculiarly brisk and pungent odour. As carbon dioxide is an essential
constituent of aerated waters, its taste and smell are familiar, being those
perceived on opening and tasting the contents of a bottle of soda-water.
Carbon dioxide is neither inflammable, nor under ordinary circumstances
a supporter of combustion. The gas is poisonous to breathe, but may be
taken into the stomach without injury. Liquids containing carbon dioxide
gas in solution are marked by a pleasant brisk flavour. Carbon dioxide
has a density of 22, and is 1.527 times as heavy as ordinary air. In the
absence of air currents, it consequently has a tendency to remain a con-
siderable time in a layer on the surface of liquids from which it is being
evolved, particularly when they are in somewhat confined spaces. Carbon
dioxide is soluble in about its own volume of water ; as has already been
explained (paragraph 45), when measured by volume the solubility is
independent of the pressure to which the gas is subject. Concentrated
solutions of carbon dioxide gas in water are prepared by pumping the gas
under pressure (some 10 or 12 atmospheres) into a strong vessel, in which
it is agitated with water. The solution thus obtained is permanent under
pressure, but on its relaxation the carbon dioxide is again liberated in the
gaseous state. Carbon dioxide may be obtained in a variety of ways ; the
simplest is by the burning of carbon, or organic bodies containing carbon
in air or oxygen—

C + 02 C02.

Carbon. Oxygen. Carbon Dioxide.

It is also produced when chalk, limestone, or marble (calcium carbonate)
is heated to full redness —

CaC03 CaO + C02.

Calcium Carbonate. Calcium Oxide (Lime). Carbon Dioxide.

Likewise, by gently heating sodium bicarbonate or ammonium carbonate —
2NaHC03 — Na2C03 + H20 + C02.

Sodium Bicarbonate. Sodium Carbonate. Water. Carbon Dioxide.

(NH4)2C03 = 2NH3 + H20 + C02.

Ammonium Carbonate. Ammonia. Water. Carbon Dioxide.

Another method of obtaining carbon dioxide is by treating any carbonate

ELEMENTS AND INORGANIC COMPOUNDS. 33

with an acid : the following equations represent a few of the principal of
such reactions —

CaC03 + 2HC1 CaCl2 + H2O + C02.

Calcium Carbonate. Hydrochloric Acid. Calcium Chloride. Water. Carbon Dioxide

CaC03 + H2S04 = CaSO4 + H2O + CO2.

Calcium Carbonate. Sulphuric Acid. Calcium Sulphate. Water. Carbon Dioxide.

Na2C03 + 2HC1 = 2NaCl + H2O + CO2.

Sodium Carbonate. Hydrochloric Acid. Sodium Chloride Water. Carbon Dioxide.

(Common Salt)

2NaHC03 + H2C4H406 = Na2C4H406 + 2H20 + C02.

Sodium Bicarbonate. Tartaric Acid. Sodium Tartrate. Water. Carbon Dioxide.

Carbon dioxide is also evolved during alcoholic fermentation, and the
putrefaction and decay of organic bodies. In addition, carbon dioxide is
produced during the respiration of animals, and is an important con-
stituent of the exhaled breath. An aqueous solution of carbon dioxide
gas changes the colour of litmus solution from full blue to a port wine
tint ; such a solution has feebly acid properties and forms with bases the
salts termed carbonates. The solution in water may be viewed as car-
bonic acid, H2C03 ; hence the gas is frequently called carbonic anhydride.
Formerly the term acid was applied, by some chemists, indifferently to
the anhydrides and their compounds with water; carbon dioxide then
received the name of ' ' carbonic acid gas, ' ' by which it is still popularly
known. Modern definitions of an acid preclude this name being now cor-
rectly applied to what are properly termed anhydrides.

68. Carbonates. — With the exception of those of the alkalies, all car-
bonates are insoluble in water; many are, however, dissolved by water
containing carbon dioxide in solution. The most interesting example of
this is the solution of considerable quantities of carbonate of lime in nat-
ural waters obtained from the chalk and other limestone deposits. Such
waters, although perfectly clear, become turbid on being boiled from
fifteen to thirty minutes : the boiling drives off the carbon dioxide, and the
calcium carbonate is precipitated in the insoluble state. The formation of
carbonates is exemplified by the passage of carbon dioxide gas into lime
water, i.e., a solution of lime in water, CaH202 ; the insoluble calcium car-
bonate, or carbonate of lime, is produced, and turns the clear solution
milky. This forms a useful and convenient test for the presence of carbon
dioxide in any mixture of gases. Most carbonates are easily decomposed
by the addition of an acid, with the formation of the corresponding salt
of the acid used. Several instances of this action have been given when
describing methods for the production of carbon dioxide. The acid- or
bi-carbonates have one-half only of the hydrogen replaced by a metal ; they
may be produced by passing carbon dioxide gas to excess through a solu-
tion of the normal carbonates of the alkalies. The bicarbonates are readily
decomposed by heat into normal carbonates, free carbon dioxide, and
water.

69. Compounds of Carbon with Hydrogen. — These are exceedingly
numerous ; an account of some of those of most importance will be given
when describing the organic bodies more particularly associated with our
subject. As a group, they are termed " hydrides of carbon."

70. Nitrogen, N,. — This gas constitutes about four-fifths, by volume,
of the atmosphere; it is also a constituent of ammonia, of nitric acid
and its salts, and of many animal and vegetable substances. Nitrogen is
colourless, odourless, tasteless, non-inflammable, and a non-supporter of
combustion. It does not readily enter into combination with other ele-
ments, but may be caused to combine with oxygen by passing a sparking

34 THE TECHNOLOGY OF BREAD-MAKING.

or flaming discharge through a mixture of the two. In the free state
nitrogen is marked rather by its neutral qualities than by any positive
characteristics. In the uncombined state its principal function is that of
a diluting agent in the atmosphere. Although not an active element,
nitrogen forms an extensive series of compounds.

71. The Atmosphere. — It has already been stated that the atmosphere
consists essentially of oxygen and nitrogen; these gases are not united
in any way, but simply form a mechanical mixture. In addition to the
nitrogen and oxygen, air contains small quantities of carbon dioxide,
water vapour, and traces of other substances. Subjoined is a table show-
ing its average composition : —

Oxygen, 02 20.61

Nitrogen, N2 77.95

Carbon Dioxide, CO2 0.04

Aqueous Vapour, H2O 1.40

Nitric Acid, HN03 ]

Ammonia, NH3 J-Traces.

Hydrides of Carbon .* . .J

In J Sulphuretted Hydrogen, SH2 . . . . £

towns [Sulphur Dioxide, S02 j "

Air, freed from moisture and carbon dioxide, contains the following
percentage of nitrogen and oxygen : —

By Measure. By Weight.

Nitrogen 79.19 . . 76.99

Oxygen 20.81 . . 23.01

100.00 100.00

Argon, and the other members of the allied group of elements, are
here included with the nitrogen. They altogether amount to about 0.94
per cent, of atmospheric air.

In addition to the bodies already mentioned, air in most localities con-
tains germs of microscopic organisms.

72. Ammonia, NH,. — Traces of this gas, either in the free state or as
salts, are found both in air and in water. Its great natural source is the
decomposition of animal and vegetable substances which contain nitro-
gen as a constituent. In this way, ammonia is continually being formed
in nature by the decay of refuse nitrogenous matter, such as the urine
and excreta of animals, and other bodies. Many nitrogenous vegetable
and animal substances also evolve ammonia on being strongly heated ;
among these is coal, which thus forms the principal source from which
ammonia is now derived. Ammonia is a colourless gas, with a most pung-
ent and characteristic odour : in the concentrated state the gas acts as an
irritant poison, but when diluted with air possesses a smell rather pleas-
ant than otherwise. Ammonia does not support combustion, and at ordi-
nary temperatures does not burn in air. The gas is very soluble in water ;
the solution has the odour of the gas, and constitutes what is commonly
known as liquor ammonice; this must not be confused with the gas con-
densed by pressure in the absence of water, and which is termed "liquid
ammonia." Ammonia acts as a powerful alkali, neutralising the strong-
est acids, and restoring the blue colour to reddened litmus.

73. Ammonium Salts. — On the addition of an acid, such as either
sulphuric or hydrochloric acid, to ammonia, the odour disappears, and

ELEMENTS AND INORGANIC COMPOUNDS. 35

the acid, as above stated, is found to be completely neutralised. The
reaction may be expressed thus : —

NH3 + IIC1 NH4C1.

Ammonia. Hydrochloric Acid. Ammonium Chloride.

2NH3 + H2S04 (NH4)2S04.

Ammonia. Sulphuric Acid. Ammonium Sulphate.

On comparing, in each case, the formula of the resulting compound
with that of the acid, it will be seen that the group NH4 replaces the
hydrogen of the acid. This compound, NH4, cannot exist in the free state,
but occurs in a number of chemical compounds, and can be transferred
from one to another without undergoing decomposition. It is conse-
quently viewed as a compound radical, and has received the name
"Ammonium." The solution of ammonia in water may then be repre-
sented as ammonium hydroxide, NH4HO ; this body, which is alkaline to
litmus, is then seen to be analogous to sodium hydroxide, NaHO, the am-
monium occupying a corresponding place to the sodium. This is seen the
more clearly when a comparison is instituted between the action of the
same .acid upon each : —

NH4HO + HC1 NH4C1 + H20.

Ammonium Hydroxide. Hydrochloric Acid. Ammonium Chloride. Water.

NaHO + HC1 NaCl + H20.

Sodium Hydroxide. Hydrochloric Acid. Sodium Chloride. Water.

Ammonium is often represented by the symbol "Am." instead of NH4.
The stronger bases, as lime, CaO, or soda, NaHO, decompose ammonium
salts with the liberation of ammonia : —

NH4C1 + NaHO NaCl -f NH3 + 11,0.

Ammonium Chloride. Sodium Hydroxide. Sodium Chloride. Ammonia. Water.

All ammonium salts volatise on being heated, leaving no residue, unless
the acid be non-volatile, in which case the acid remains behind.

74. Oxides and Acids of Nitrogen. — No less than five distinct com-
pounds of nitrogen with oxygen are known. The following is a list of
their names and formulae —

Nitrous Oxide ............ N.,O

Nitric Oxide .......... NO (or N20~2)

Nitrogen Trioxide, Nitrous Anhydride . . . . N2Os

Nitrogen Peroxide ........ NO2 or N2O4

Nitrogen Pentoxide, Nitric Anhydride . . . . N205

Two of these oxides, the trioxide and pentoxide, form acids with water —
the acids being nitric acid, HNO3, and nitrous acid, HNO2.

The first and last of this series of oxides have little or no connection
with our present subject, but the intermediate three are of much interest
and importance as being the agents of a successful flour bleaching process.
For this reason a brief description of their properties is necessary.

75. Nitric Oxide, NO. — Formerly, N2O2 was considered possibly to
represent the constitution of the molecule of this body, but from its
density, the molecule must be regarded as consisting of NO. The N2O2
formula is given above in brackets, in order to show the relationship in
composition between this and the other oxides of nitrogen. When nitric
acid is added to metallic copper, an abundance of ruddy fumes is evolved ;
but if the operation be conducted in a flask fitted in the ordinary way with
a thistle funnel and leading tube, the coloured fumes are seen to be swept
out of the flask, which soon becomes filled with a colourless gas, which

36 THE TECHNOLOGY OF BREAD-MAKING.

may be collected over water in the pneumatic trough. This colourless gas
is nitric oxide. If a gas jar be partly filled with nitric oxide and then
oxygen admitted bubble by bubble, a red colour is seen to develop with
each introduction. This rapidly disappears, and simultaneously the water
rises in the jar. By careful addition of oxygen the whole of the gas
(assuming its purity) may be thus rendered soluble. Nitric oxide is only
very slightly soluble in water, and possesses the property of immediately
combining with free oxygen to produce nitrogen peroxide, N02. Nitrogen
peroxide is a ruddy coloured gas, and is very soluble in water. A con-
venient method of preparing nitric oxide consists of allowing nitric acid
to drop into a solution of ferrous sulphate, and at the same time passing
a current of air through the solution. The air comes over, carrying with
it the gas ; the proportion of the latter may be regulated by adjusting the
rate at which the nitric acid is allowed to drop into the solution. The fol-
lowing is the nature of the chemical change : —

8HN03 + 6FeS04 = 2Fe2(SOJ3 + Fe2(NO3)6 + 2NO + 4H2O.

Nitric Acid. Ferrous Sulphate. Ferric Sulphate. Ferric Nitrate. Nitric Oxide. Water.

In the presence of air, the nitric oxide is immediately converted into
the peroxide.

76. Nitrogen Peroxide, N03.— At a temperature of 26.7° C., this gas
has a density which indicates that about 80 per cent, of its molecules con-
sist of N204, the remaining ones being composed of NO2. As the tempera-
ture of the gas is raised, the density diminishes, and at 140.0° is 23.00,
which corresponds to the whole of the gas being dissociated with N02
molecules. Nitrogen peroxide is absorbed and decomposed by water; in
the presence of very small quantities of the latter nitrous and nitric acids
are thus formed : —

N2O4 + H20 HN03 + HN02.

Nitrogen Peroxide. . Water. Nitric Acid. Nitrous Acid.

At ordinary temperatures, and with water in excess, nitric acid and
nitric oxide are produced thus : —

3N02 + H20 2HN03 -f NO.

Nitrogen Peroxide. Water. Nitric Acid. Nitric Oxide.

From the ease with which nitrogen peroxide loses an atom of oxygen
and becomes nitric oxide, it is a powerful oxidising agent. Its efficiency
as such is greatly increased by the property possessed by nitric oxide
of at once combining with free oxygen and again producing nitrogen per-
oxide. In this way a very small quantity of nitrogen peroxide, by its
successive reductions and oxidations, may act as a carrier of oxygen to a
relatively large quantity of oxidisable material.

77. Nitrogen Trioxide, N203. — Nitrogen trioxide is a very unstable
compound which can only exist at low temperatures, and readily decom-
poses into a mixture of nitric oxide and nitrogen peroxide. With water
it forms nitrous acid, HN02, and this in turn yields salts known as
nitrites. These bodies are fairly stable, and potassium nitrite, KN02, is
an example. Nitrites are found in many drinking waters as an interme-
diate product in the oxidation to nitrates of nitrogenous matter that may
have been present.

78. Nitric Acid, HN03.— This is by far the most important oxy-
compound of nitrogen. Its usual source in nature is the oxidation of
animal matter in the soil. The nitric acid thus produced is found in
combination with some base, usually as potassium or calcium nitrate.
Pure nitric acid is a colourless fuming liquid; commonly, however, the

ELEMENTS AND INORGANIC COMPOUNDS. 37

acid is of a slightly yellow tint, from the presence of some of the lower
oxides of nitrogen. The pure acid has a specific gravity of 1.52, and
mixes with water in all proportions. Nitric acid is a most powerful
oxidising agent, and attacks most animal and vegetable tissues with great
vigour. It also freely dissolves most of the metals, forming nitrates.
Gold and platinum are not affected by this acid when pure, but are dis-
solved with the formation of chlorides by a mixture of nitric with hydro-
chloric acid. Reducing agents convert nitric acid into nitrous acid, or
some one or more of the oxides of nitrogen containing less oxygen. Under
favourable circumstances, nitric acid may even be reduced to ammonia ;
that is, the whole of its oxygen may be removed, and its place occupied
by hydrogen.

79 Nitrates. — The principal of these is potassium nitrate, KNO...
Like nitric acid, the nitrates are powerful oxidising agents.

80. Sulphur, S2. — This element, in its common form, is a brittle yel-
low solid, which burns in air or oxygen with the formation of sulphur
dioxide, SO2. The principal interest of sulphur, in connection with our
present subject, lies in its compounds. In addition to its occurrence in
many inorganic bodies, sulphur is one of the constituents of albumin and
other animal and vegetable substances.

81. Sulphuretted Hydrogen, SH2. — This body is a colourless gas,
having a most disgusting odour, resembling that of rotten eggs ; the gas
is soluble in water, which at 15° C. dissolves 3.23 volumes of sulphuretted
hydrogen. During the decomposition of substances, either of animal or
vegetable origin, containing sulphur, sulphuretted hydrogen is one of the
bodies evolved ; it is from the presence of this gas that rotten eggs acquire
their characteristic odour. Sulphuretted hydrogen is inflammable, and
produces water and sulphur dioxide by its combustion. Moist sulphur-
etted hydrogen undergoes, in the presence of oxygen, slow oxidation, with
the formation of water and deposition of free sulphur : —

2H2S + 02 S2 + 2H20.

Sulphuretted Hydrogen. Oxygen. Sulphur, Water.

82. Sulphur Dioxide, S02. — This gas is produced by the combustion
of sulphur in either air or oxygen : it is colourless, has a pungent odour,
recognised as that of burning sulphur ; is neither inflammable nor a sup-
porter of combustion. Sulphur dioxide is soluble in water, which at a
temperature of 15° C. dissolves 47 volumes of the gas ; the solution thus
formed tastes and smells of the gas, it reddens and finally bleaches a solu-
tion of litmus. Sulphur dioxide is one of the most powerful antiseptics
known. The gas is easily condensed to the liquid state by either cold or
pressure. Liquid sulphur dioxide is supplied commercially in syphons,
similar to those used for soda water.

83. Sulphurous Acid, H2S0.5, and the Sulphites. — Sulphur dioxide
when dissolved in water produces a somewhat unstable acid, H2S03. The
sulphites, or salts of this acid, are mostly insoluble in water, the principal
exceptions being sodium sulphite, Na2S03, and potassium sulphite. In
addition to the normal sulphites, acid or bisulphites occur ; these may be
produced by passing excess of sulphur dioxide into a solution of the nor-
m,al salts. The bisulphites readily evolve sulphur dioxide on being
heated. Calcium sulphite is insoluble in water, but dissolves in a solution
of sulphurous acid, forming calcium bisulphite, or, as commonly called,
''bisulphite of lime." Bisulphite of lime is largely used as an antiseptic.
Under the influence of oxidising agents, sulphurous acid and the sul-
phites are oxidised to sulphuric acid and sulphates.

38 THE TECHNOLOGY OF BREAD-MAKING.

84. Sulphuric Acid, H2S04, and the Sulphates. — Sulphuric acid is one
of the most useful chemical compounds known, forming as it does the
starting point in the manufacture of a number of substances of vast
importance in the arts. When in the pure state, sulphuric acid is a col-
ourless, odourless liquid of an oily consistency : this latter property has
led to its receiving the popular name of ' ' oil of vitriol ' ' ; the acid, how-
ever, is in no way connected chemically with the class of bodies known as
fats or oils. Sulphuric acid is nearly twice as heavy as water, having a
specific gravity of 1.842 ; it boils at a temperature of 338° C. Sulphuric
acid has a great attraction for water, with which it combines to form
definite hydroxides (i.e. chemical compounds with water) ; considerable
heat is evolved during the act of union. In consequence of this affinity
for water, sulphuric acid is largely used as a desiccating or drying agent ;
on exposure to the air the acid rapidly increases in weight by absorption
of water vapour, and the air becomes dry ; hence, if a vessel of sulphuric
acid be placed under a bell jar, it speedily produces a dry atmosphere
inside. Less concentrated varieties of the acid form staple articles of
commerce. Owing to this attraction for water, sulphuric acid is a most
corrosive body; wood, paper, and most vegetable and animal substances
are vigorously attacked by it; the acid combines with the hydrogen and
oxygen of the substance in the proportions in which they form water, and
leaves behind a mass of carbon, together with any excess of either hydro-
gen or oxygen that may have been present. This, of course, does not in
all cases represent the whole of the chemical action that may have
occurred. Dilute sulphuric acid contains water in. excess, and therefore
does not exhibit this dehydrating tendency when placed in contact with
other bodies ; it is well to remember this, because in a number of reactions,
where dilute sulphuric acid is employed, it produces not merely less ener-
getic action, but action absolutely opposite in character to that of the con-
centrated acid. The dilute acid, if allowed to evaporate in contact with
paper, etc., acts in a similar manner to the strong acid, as the water dries
off. Sulphuric acid forms a normal and an acid series of salts, of which
Na2S04, sodium sulphate, and NaHS04, acid sodium sulphate, are, re-
spectively, examples. Most of the sulphates are more or less soluble in
water ; calcium sulphate is only slightly so ; barium sulphate is insoluble
in water and dilute acids. Sulphuric acid and the sulphates may be
detected in solution by the addition of hydrochloric acid and barium
chloride, when they produce a white precipitate of BaS04.

85. Bromine, Br2 ; Iodine, I2 ; and Fluorine, P2. — These three elements
are very closely allied in properties to chlorine ; they have no very inti-
mate connection with the chemistry of wheat and flour. Bromine is a
liquid; iodine, at ordinary temperatures, is a solid body. Iodine is
slightly soluble in water, readily soluble in alcohol or a solution of potas-
sium iodide, KI. Iodine, or its solution, produces a characteristic blue
colour with starch : this reaction is of great delicacy, and is an exceed-
ingly valuable test both for starch and iodine. Fluorine forms an acid
with hydrogen, hydrofluoric acid, HF, which is characterised by its power
of attacking and dissolving glass and the silicates generally. •

86. Silicon, Si; Silica, Si02; and the Silicates. — Silicon is an element
somewhat resembling carbon in some of its properties;. all that at present
need be stated about it is that it forms with oxygen an oxide, Si02,
analogous in composition to that of carbon, C02. This oxide, Si02, is
termed silica, or at times, silicic anhydride. Flint and quartz are almost
chemically pure forms of silica ; in this form silica is insoluble in water
and all acids, and mixtures of acids, except hydrofluoric acid. On being

ELEMENTS AND INORGANIC COMPOUNDS. 39

fused with an alkali as KHO, or an alkaline carbonate, K2C03, silica pro-
duces a glassy substance entirely soluble in water : this body is potassium
silicate, K4Si04, and from it, silicic acid, H4Si04, may be obtained. Silicic
acid is soluble in water and is tasteless and odourless; on being gently
evaporated it first forms a jelly, and then, as the whole of the water is
driven off, the silica remains as a white powder, once more insoluble in
water and acids. As silica produces a compound with water which, by
action 611 bases, forms salts, silica is rightly viewed as an anhydride. The
silicates are the principal constituents of the great rock masses of the
earth and of soil. The natural silicates usually contain two or more of
the following bases — iron oxides, alumina, lime, magnesia, potash, and
soda. With the exception of those of potash and soda, the silicates are
mostly insoluble.

87. Phosphorus, P4; Phosphoric Acid, H3P04; and the Phosphates.—
Like several other elements, phosphorus assumes more than one distinct
form. The commoner variety is a crystalline body, often called yellow
phosphorus. In addition there is an amorphous variety, which from its
colour is frequently known as red phosphorus. In properties, the ordi-
nary or yellow phosphorus is one of the most striking of the elements ; its
attraction for oxygen is so great that it has to be kept under water in
order to prevent its oxidation. In process of manufacture, the ordinary
phosphorus is usually cast into sticks of a light yellow colour and the con-
sistency of wax ; a piece of phosphorus appears luminous in the dark
when exposed to air ; this is caused by its slow combustion. A slight ele-
vation of temperature, or even friction, suffices to cause phosphorus to
burn vigorously ; it then produces a vivid light, and forms, by union with
oxygen, phosphorus pentoxide, P2O5, or, as it is sometimes termed, phos-
phoric anhydride. Phosphoric anhydride, as thus formed, is a white
powder, which combines with water with great avidity to form phos-
phoric acid, H3P04. Phosphoric acid is principally of interest because of
its salts, known as phosphates : of these the most important to us are cal-
cium phosphate, Ca3(POJ2; and potassium phosphate, K3P04. Calcium
phosphate is the principal constituent of the mineral matter of bones, and
hence in some form or other is an absolutely essential article of food.
Phosphates occur in some parts of all plants, and is derived by them from
the soil. In wheat, the phosphoric acid is mostly combined with potas
sium. The alkaline phosphates are soluble in water ; the others are insol-
uble, but may be readily dissolved by the addition of nitric or hydro
chloric acid.

88. The Metals and their Compounds. — Within the limits of this
work it would be impossible to give even the briefest systematic descrip-
tion of these bodies. An account follows of calcium and potassium, but
such other metallic compounds as have any bearing on our subject will
be described when reference to them is made.

89. Calcium, Ca, and its Compounds. — Until comparatively recently,
calcium was scarcely more than known in the free state. It is a silver-white
metal, and has such an attraction for oxygen that it very readily becomes
oxidised on exposure to moist air, with the formation of calcium oxide
There are two oxides of calcium, but only the monoxide is of practical
importance in connection with the present subject. This body, CaO, is
that commonly spoken of as "quicklime." The salts of calcium are some-
times referred to as salts of lime ; this is not strictly correct, but in most
cases makes no real difference. To this there is one exception. Chloride
of calcium, or calcium chloride, is CaCL, ; chloride of lime is a very differ-
ent body, CaOCl2. Calcium oxide is a whitish-grey substance, usually

40 THE TECHNOLOGY OF BREAD-MAKING.

obtained by the action of heat on the carbonate; it is infusible at the
highest temperatures. Calcium oxide combines readily with water, with
the evolution of considerable heat, forming slaked lime, or calcium hydrox-
ide, CaH202. Calcium hydroxide occurs as a dry, white powder, which
is soluble in water to the extent of one part in 600. This solution is that
known as "lime-water," and is employed as a test for carbon dioxide.
The solution of lime has a decidedly alkaline reaction, turning reddened
litmus blue. Calcium produces an extensive series of salts ; of these cal-
cium carbonate has been already referred to when describing carbon
dioxide. The next most important salt is calcium sulphate ; this body is
only slightly soluble, one part being dissolved by about 400 parts of
water. The phosphate and chloride have already been referred to; the
latter has a great affinity for water, and consequently is often used as a
drying agent; it can be frequently used where sulphuric acid would be
unsuitable from its other properties.

90. Potassium, K, and its Compounds. — Potassium is a soft bluish
white metal, which has so great an attraction for oxygen that it has to be
kept from contact with the air, and even liquids as water, which contain
oxygen as one of their compounds ; for this purpose the potassium is gen-
erally preserved in mineral naphtha, a compound of carbon and hydro-
gen. The normal oxide of potassium is K20 ; this body has such affinity
for water that it practically never occurs in the anhydrous state, but usu-
ally as the hydroxide, KHO. Potassium hydroxide is a white crystalline
solid substance ; it melts at a red heat, and is supplied commercially
either in sticks, or in lumps produced by breaking up fused slabs of the
compound. Potassium hydroxide is a powerfully caustic body, and rap-
idly destroys animal tissues. It is one of the most' powerful alkalies
known, restoring the blue colour to reddened litmus, and forming salts
with acids. Potassium hydroxide decomposes ammonium salts with the
liberation of ammonia; sodium hydroxide and lime behave similarly in
this respect. Potassium hydroxide is very soluble in water ; the solution
has a peculiar soapy feel to the fingers. Potassium hydroxide has a great
attraction for carbon dioxide; its solution absorbs that gas with great
rapidity, forming potassium carbonate, K2C03. Potassium carbonate is a
white deliquescent body; i.e. one that readily becomes moist through the
absorption of water. Like other deliquescent bodies, potassium carbonate
is very soluble in water ; the solution is strongly alkaline to litmus,
although the salt is of normal constitution. As already explained, the
very strong bases produce with certain weak acids normal salts, in which
the alkaline compound may be said to predominate. Potassium carbonate
was at one time almost exclusively obtained from wood ashes. An acid
potassium carbonate, KHC03> is also known; this body is neutral to
litmus, and is less soluble in water; it is at a temperature of 80° C.
decomposed into the normal carbonate and free acid.

91. Sodium Compounds. — Sodium forms a series of compounds which
closely resemble those of potassium ; of these the most familiar are sodium
hydroxide, NaHO ; sodium carbonate, Na2C03 ; acid sodium carbonate,
NaHCO3 ; and sodium chloride, NaCl. Sodium hydroxide is a somewhat
less powerful base than potassium hydroxide.

CHAPTER III.
DESCRIPTION OF ORGANIC COMPOUNDS.

92. "Organic" Chemical Compounds. — Chemical science is com-
monly divided into two branches, known respectively as ' * Inorganic ' ' and
"Organic" chemistry. Certain substances, whether they occur in nature,
or are prepared in the laboratory, are obtained from mineral sources : the
bodies described in the preceding chapter are instances of such com-
pounds. There are, on the other hand, bodies which are obtained either
from the animal or vegetable kingdom. Animals and vegetables are
organised bodies, that is, they have definite organs which adapt them for
that series of processes which constitutes what is called ' ' life r ' ; hence
chemical compounds having a vegetable or animal origin are termed
' ' organic. ' ' Those which are not thus obtained from organic sources are
termed ' * inorganic ' ' compounds : the two names have also been given to
the branches of chemistry which treat respectively of these two classes of
bodies, and of their properties and reactions. It was formerly supposed
that the so-called organic bodies could only be obtained from organic
sources; but chemical investigation has demonstrated that many such
compounds can be produced by artificial means from the elements of
which they are composed, without the intervention of living organ-
isms, and even under such conditions as render the existence of living
organisms an impossibility. Alcohol and its derivatives are examples.
The definition of an organic body as one produced as a result of ' ' life ' ' is
evidently no longer tenable, and chemists have endeavoured, with more or
less success, to frame new definitions of organic chemistry. As all or-
ganic compounds contain carbon, it has been proposed to define it as
the "chemistry of the carbon compounds"; again, as many organic
bodies are well defined compound radicals, the phrase "chemistry of
the compound radicals" has been proposed. These definitions have not
been found entirely satisfactory, as they are either too wide or too nar-
row. They present the further difficulty that they are not modifications
or explanations of the term organic chemistry, but are totally new
phrases. As this branch of chemistry is still called organic chemistry,
and the compounds included in its scope are still called organic com-
pounds, the student of the chemistry of bread-making may regard
Organic Chemistry as that branch of the science which treats of the
composition and properties of those compounds whose usual or original
source is or was either animal or vegetable. This explanation of the
meaning of organic chemistry has the defect that it does not include all
those substances now known as organic compounds ; but all such com-
pounds thus excluded are without any direct bearing on the chemistry
of wheat, flour, or bread.

93. Organised Structures. — Although organic compounds can be
prepared by artificial means, it must be clearly understood that no
chemical processes have as yet been found capable of producing an
organised structure ; further, all evidence hitherto obtained, so far as it
goes, tends to prove the impossibility of such structures being formed
other than through living agencies. For instance, starch is found, when

42 THE TECHNOLOGY OF BREAD-MAKING.

viewed under the microscope, to have a structural organisation peculiar
to itself. Starch may be dissolved, and after such solution again obtained
in the solid state ; but the solid thus produced shows no trace of the orig-
inal structure of the grains of starch ; neither is there known any arti-
ficial process by which the starch may again be built up into structures of
the same kind as those in which it originally occurred. Similarly, it is
impossible to artificially produce a blood corpuscle. The same law applies
to minute organisms, as yeast, bacteria, etc. ; none of these can be gener-
ated otherwise than through the agency of previously existing living
beings of the same type. So far as any problem can be proved scientific-
ally, this fact of the impossibility of spontaneous generation is abund-
antly demonstrated; experimental evidence of a most conclusive char-
acter has shown as certainly as scientific research can, in any case, pos-
sibly show, that living organisms can only be formed by means of sim-
ilar pre-existing organisms.

94. Composition of Organic Bodies. — Organic compounds, generally,
have a much more complicated chemical composition than have inorganic
compounds; they are mostly, however, restricted to comparatively few
elements. All organic bodies contain carbon ; many are composed of car-
bon and hydrogen only, a greater number consist of carbon, hydrogen,
and oxygen; while others contain the four elements, carbon, hydrogen,
oxygen, and nitrogen. The majority of organic compounds belong to one
or other of these series. Carbon, more than any other element, is remark-
able for the property of, in compounds, combining directly with itself,
and so forming most complicated bodies out of comparatively few ele-
ments.

95. Classification of Organic Compounds. — The number of these is
so bewildering that, without some classification, it would be impossible to
grasp their relationship to each other: recent chemical science has suc-
ceeded in very clearly demonstrating the constitution of a vast number of
these bodies. There are, in the first place, large numbers of well defined
compound radicals, consisting of carbon and hydrogen : it has been found
possible to group these into distinct families, the members of each of
which may be represented by a common formula.

96. Organic Radicals. — The most important series of these is that
known as the ' ' Methyl, " or " Ethyl ' ' series ; these have the common for-
mula (CnH2n+1)2. This formula signifies that in the first place the mole-
cule consists of two semi-molecules that are similar in composition ; sec-
ondly, that in each semi-molecule the number of atoms of hydrogen is one
more than double the number of atoms of carbon. The following is a list
of a few of the radicals of this series : —

Methyl .. Me2 .. J £j**3

C9ll . fCHJ . ( CMeH,

T-1J.1 1 TlA. \ C9Hr: (CHol

Ethyl .. Et2 .. | c*H5>,or ^^

Propyl . . Pr,
Butyl . . Bu,

Amvl Atr ' ^5AMl

Amyl .. Ay2 .. } .^^
Caproyl . . Cp2 . . ] £•*{

C3H7 J CEtIL
C8H7 ' ° I CBtH.
C4H9

C.H,

6AA13

ORGANIC COMPOUNDS. 43

Each semi-molecule of these radicals behaves in compounds as though
it were an atom of a monad element ; the atomicity is shown by the fol-
lowing graphic formulae —

II II H

H— C- H— C— C—

Methyl. Ethyl.

Prom these formulae it is seen that in each case there is one of the carbon
bonds free ; in the free state two semi-molecules unite by these bonds to
form the molecule. The graphic formula also show how each of the
higher radicals of the series may be viewed as compounds of the next
lower radical with an additional CH2. The temperature of the boiling
points of these bodies increases as the series is ascended.

97. Hydrides of Organic Radicals (Paraffin Group). — These bodies
are compounds of the radicals with hydrogen ; those of the series already
referred to have the general formula CnH2n+2. Among them there is, as
the lowest, methane or methyl hydride (marsh gas), CH3H or CH4; from
this the series ascends regularly to C16H34. These compounds are distin-
guished by their not being readily attacked by the most powerful oxidis-
ing agents, they consequently have received the name of ''paraffins"
(from the Latin, parum affinis, having little affinity). The lower mem-
bers of the series are gases, the middle are liquids, and the higher mem-
bers are solid at ordinary temperatures. The paraffins are produced by
the destructive distillation of wood, coal, and many other organic sub-
stances, and also occur in rock-oils. Some varieties of American petroleum
consist almost entirely of paraffins. In distilling the crude petroleum, it
is found that the temperature of the vapour produced rises as the opera-
tion progresses. The more volatile portions distil off first; the distillate
may be collected in separate portions or fractions ; the operation is then
termed "fractional distillation." The lighter or more volatile paraffins
constitute what is known as light petroleum spirit ; this substance, when
carefully freed from solid impurities, is of great use as a solvent for fatty
substances, both in the arts and chemical analysis. Good light petroleum
spirit should distil entirely at a temperature of 70° C. Such spirit is a
mixture of several of the lower paraffins. The petroleum of commerce
consists of a somewhat higher fraction, and mineral lubricating greases
and "vaseline" of a yet less volatile portion. The least volatile portion
of all constitutes, when pure, the hard white solid substance known as
"solid paraffin," or paraffin "wax."

98. The Alcohols. — In constitution, these bodies bear the same rela-
tion to the organic radicals as do the metallic hydroxides to the metals.
This is clearly seen on writing representative formulae of the two side by
side : —

C2H,HO NaHO

Ethyl, or ordinary, Alcohol. Sodium Hydroxide.

Certain chemists carry this analogy so far as to regard the alcohols as
hydrates (hydroxides) of the radicals, and term ordinary alcohol,
uethylic hydrate." To this the objection has been taken that the alcohols
* do not contain water, and that the hydroxides are really hydrated oxides,
or oxides formed by the union of water with the normal oxide, as, for
example : —

Na0 -HO = 2NaHO.

44 THE TECHNOLOGY ,OF BREAD-MAKING.

The argument is, however, addressed to the composition of these
bodies rather than to the mode of formation; and it is clear that these
bodies may be regarded as compounds of the organic radicals with
hydroxyl (HO). It is then simply a matter of definition whether or not
the term hydrate or hydroxide shall be understood to mean a compound
with hydroxyl. The alcohols are sometimes conveniently regarded as
substitution products of the paraffins; thus ethyl alcohol may be viewed
as ethane, C2H6, in which hydroxyl is substituted for one of the atoms of
hydrogen. In this manner the relationship between the alcohols and the
paraffins is clearly seen. Like metallic hydroxides, the alcohols enter into
combination with acids to form organic salts. Thus ethyl alcohol, being
C2H5HO, is converted by the action of hydrochloric acid into C2H5C1,
ethyl chloride. This reaction is analogous to that by which sodium
hydroxide is converted into sodium chloride, as is shown by the respective
equations : —

C2H5HO + HC1 C2H5C1 + H20.

Alcohol or Ethyl Hydroxide. Hydrochloric Acid. Ethyl Chloride. Water.

NaHO + HC1 NaCl + H2O.

Sodium Hydroxide. Hydrochloric Acid. Sodium Chloride. Water.

Of the various alcohols, those of the methyl series are the most im-
portant, and are represented by the formula, CnH2n+1HO. Subjoined are
a few examples of these compounds : —

Methyl Alcohol, CH3HO, or j

Ethyl „ C2H5HO, or j

Propyl „ C3H7HO. Melissic „ C30HeiHO.

The lower members of the series are liquid, and the higher solid.

99. Methyl Alcohol, CH3HO.— This body, in an impure form, is
yielded on the destructive distillation of wood, and hence is commonly
known as "wood spirit," or "wood naphtha." This crude preparation
has a nauseous flavour, which renders it unfit for drinking: the pure
methyl alcohol has, on the contrary, a purely spirituous taste and odour.
Methyl alcohol mixes in a)l proportions with water, ethyl alcohol, and
ether; it has at 15° C. a specific gravity of 0.8021.

( OH

100. Ethyl Alcohol, j CHHO or C2H5H0-— This body constitutes

the active ingredient of beer, wine, and of all spirituous liquors, as
brandy, whisky, etc. The term ' * alcohol, ' ' when used without any prefix,
is always understood to refer to this compound, which is known popularly
as "spirits of wine." Alcohol may be produced artificially from its ele-
ments by purely chemical means, but is always manufactured by the
process of fermentation, of which a detailed account is hereafter given.
Pure ethyl alcohol is a colourless, mobile liquid, having an agreeable
spirituous odour, and a burning taste. Alcohol is inflammable, and burns
with a scarcely luminous smokeless flame, evolving considerable heat ; it
is on this account largely used in ' i spirit ' ' lamps as a fuel. Alcohol rap-
idly evaporates at ordinary temperatures, and when pure, boils at 78.4°
C. (=173.1°) F. At a temperature of 15.5° C., alcohol has a specific
gravity of 0.79350 ; that of water, at the same temperature, being taken as
unity. Alcohol mixes with water, and also ether, in all proportions : for
the former compound it has a great affinity, and evolves considerable heat
on the two being mixed ; the volume of the mixture is less than that of the
two liquids taken separately. As previously mentioned, alcohol is manu-
factured by fermentation; this process is only capable of producing a

ORGANIC COMPOUNDS. 45

comparatively dilute solution of alcohol in water. In order to obtain a
stronger spirit, the fermented liquid is distilled; as alcohol boils at a
lower temperature than water, the earlier portions of the distillate are the
stronger in spirit, until finally no alcohol remains in the liquid being dis-
tilled. It is not possible to obtain in this manner alcohol free from water,
as even the very first portions of spirit which distil over carry water with
them. By several times distilling the spirit it is possible to obtain a mix-
ture containing about 90 per cent, of the pure spirit; special distilling
arrangements have resulted in the production of a distillate containing as
much as 95 per cent, of alcohol. In order to remove this small quantity
of water, the spirit is treated with quicklime or potassium carbonate, and
then allowed to stand, and after a time distilled : in this manner alcohol
can be obtained in which there is only the most minute trace of water.
This desiccated alcohol is termed "absolute" alcohol. Alcohol is of very
great use as a solvent, particularly for many organic bodies ; it also acts
as an antiseptic, and hence is employed for the preservation of biological
and other specimens. The solvent power of alcohol is modified consider-
ably by its admixture with more or less water : for many purposes alcohol
of a certain definite strength is necessary. As water and alcohol have
different densities, and as density is easily measured, it is a usual method
of testing the strength of alcohol to take its specific gravity. Tables have
been prepared giving the strength in percentages of alcohol present for
different densities. Three distinct standards of strength of alcoholic
spirit are commercially recognised. The ' ' rectified spirit of wine ? ' of the
British Pharmacopoeia is the strongest spirit that can be produced by
the ordinary methods of distillation: such spirit should contain 84 per
cent, by weight of absolute alcohol, and should have a density of 0.838.
* ' Proof spirit " is a term that has survived its original application : it is
now legally defined as spirit of such a strength that 13 volumes of it shall
weigh at 51° F. the same as 12 volumes of water at the same temperature.
Proof spirit has at 15.5° C. a density of 0.91984, and contains 49.24 per
cent, by weight of alcohol and 50.76 of water. Weaker spirits are defined
as being so many degrees "under proof" (U.P.), while stronger spirits
are referred to as being so many degrees "over proof" (O.P.). A spirit
of 10 degrees U.P. is such that it contains 90 per cent, of proof spirit and
10 per cent, of water ; spirit of 10 degrees O.P. is of such a strength that
it may be made up to 110 volumes by the addition of water, and would
then have the same percentage of alcohol as proof spirit. Absolute alco-
hol is that, as before stated, which contains no water. For chemical pur-
poses it is usual to specify the strength of alcohol, either as so much per
cent, spirit, or by its density. When for any purpose it is -directed that
alcohol of a certain strength must be employed, particulars will be given
as to its density; for complete tables of densities and corresponding
strengths, the larger treatises on chemistry must be consulted.

101. Detection of Alcohol. — Alcohol when present in any quantity is
easily recognised by its smell ; in liquids which contain traces only, it is
best to distil and then examine the first portions of the distillate. When
using a Liebig's condenser, it will be seen, at the point where the vapour
begins to condense, that when alcohol is present, the distillate trickles
down the sides of the tube in peculiar oily looking drops or ' ' tears. ' ' This
appearance ceases as soon as the whole of the alcohol has distilled off.
Very minute quantities of alcohol suffice to produce this effect. Another
and more delicate method for its detection depends on the production of
iodoform. This body has the symbol CHI3, and is similar in constitution
to chloroform, CHC13. The liquid under examination should first be

46 THE TECHNOLOGY OF BREAD-MAKING.

distilled, and the tests applied to the first portion of the distillate. Ten c.c.
are to be taken and rendered alkaline by the addition of about a quarter
of a c.c. (five or six drops) of a 10 per cent, solution of sodium hydrox-
ide ; the liquid must next be warmed to about 50° C., and then a solution
of potassium iodide, saturated with iodine, added drop by drop until a
slight excess of free iodine is present ; this is indicated by the liquid
acquiring a permanent sherry yellow tint. The liquid must next be just
decolourised by the addition of a minute quantity of the sodium hydrox-
ide solution. If there be any alcohol present, a yellow crystalline pre-
cipitate of iodoform gradually forms. Certain other organic compounds,
however, are capable of producing the same reaction.

102. Methylated Spirits of Wine. — Alcoholic liquors are subject to a
high duty; consequently, for purposes other than the production of
drinkable spirits, the Excise authorities permit the sale, duty free, of a
mixture of rectified spirit with some substance which imparts a flavour
sufficiently nauseous to render the whole absolutely undrinkable, except
to the palates of the most debased dipsomaniacs. Formerly spirit was
thus "denatured" by the addition of one volume of commercial wood
spirit to nine volumes of rectified spirit. Being produced by the addition
of crude methyl alcohol, the mixture was known as "methylated spirits of
wine. ' ' Other bodies are now used for ' ' methylating, ' ' among them being
some of the lighter paraffins. For most laboratory operations, methylated
spirits can be used as a substitute for rectified spirits of wine : for deli
cate purposes it is well to re-distil the spirits prior to use. On diluting
the distilled spirit to about 70 per cent, strength, opalescence is produced.
This is due to paraffin which distils over, and is insoluble in the mixture
of spirit and water. As the cloudiness is due to the presence of a volatile
substance, it does not interfere with many, or even most, uses to which
the spirit is applied. Methylated spirits may be rendered almost abso-
lute by adding about one-third of its weight of recently burned quicklime,
and thoroughly shaking ; the mixture must be allowed to stand some three
or four days, and the shaking repeated two or three times daily. The
spirit must then be distilled, precautions being taken to prevent the tem-
perature unduly rising. The still should be fixed in a water bath, con-
sisting of an iron saucepan containing brine. The clear portions of the
spirits should first be poured into the still, without disturbing the sedi-
ment, and distilled to dryness by application of heat to the water bath.
Care must be taken that the bath does not boil dry. . The pasty mass of
lime may next be placed in the still, preferably in small quantities at a
time, and heated by the bath so long as any alcohol distils over. An
efficient condensing worm must be used, and the tube connecting it with
the still ought to be a long one. At the close of the operation the lime
may be removed from the vessel used as a still by soaking with water.

103. Propyl, Butyl, and Amyl Alcohols. — These bodies are produced
in small quantities during fermentation. They all boil at a higher tem-
perature than ethyl alcohol, and are found in the residual liquor after
most of the spirit has been distilled over. Propyl alcohol occurs in the
residues of the distillation of the fermented liquor of the marc of grapes
in the production of low-class brandy. Normal butyl alcohol occurs in
genuine cognac, from which it may be obtained by fractional distillation :
it has a boiling point of 116.8° C., and possesses an agreeable odour. But
spirits from potatoes, beet-root, maize, and certain other substances con-
tain isobutyl alcohol, an isomeride of the normal alcohol. Isobutyl alcohol
has a disagreeable fusel-oil-like odour. The following formulae indicate
their difference in constitution : —

ORGANIC COMPOUNDS. 47

CH2CH2CH3 CH/01*3

I '

CH2HO CH2HO

Normal Butyl Alcohol. Isobutyl Alcohol.

Iii addition to isobutyl alcohol, amyl alcohol is also produced as a bye-
product during the manufacture of alcohol from potatoes or grain. Amyl
alcohol is an oily looking liquid, which does not mix with water, but with
alcohol and ether in all proportions ; it boils at 137° C. Amyl alcohol has
a strong, disagreeable smell, and burning taste. Its intoxicating effects
are similar to those of ethyl alcohol, but a small quantity of amyl alcohol
suffices to produce all symptoms of intoxication; it has been estimated
that amyl alcohol is fifteen times as intoxicating as is ethyl alcohol.

104. Fusel or Fousel Oil. — This name is applied to the oily mixture
of spirits above referred to as being formed during fermentation. The
fusel oil of potato and grain spirits principally consists of amyl alcohol.

105. Glycerin, C3H.(HO)3. — In constitution this body is an alcohol,
and may be regarded as the paraffin propane, C3H8, in which three of the
hydrogen atoms have been replaced by three groups of hydroxyl. When
pure, glycerin is a colourless, odourless, and thick sirupy liquid, having
a sweet taste, and boiling at a temperature of 290° C. Glycerin is one of
the substances produced during the normal fermentation of sugar, and
also is the basic constituent of fats and oils.

106. Mannitol, C6H8(HO)6. — This is a substance possessing a sweet
taste and found in the sap of certain plants, which sap when dried consti-
tutes what is known as manna. In constitution mannitol is a hexahydric
alcohol, and is of interest from its relationship to the sugars and other
carbohydrates. Mannitol is regarded as being derived from the paraffin
hexane, C6H14, by the replacement of six atoms of hydrogen by six
hydroxyl groups.

107. The Ethers. — These bodies are the oxides of the organic rad-

!P TT
£2Tj~'O. When

the term "ether" is employed without any qualification, it is this body to
which reference is made. From its mode of preparation, ether is often
termed "sulphuric ether"; sulphuric acid, of course, does not enter into
its composition. Ether is a colourless, very mobile liquid, having a pecu-
liar, penetrating, and characteristic smell. This smell has given rise to
the term "ethereal odour." Ether has a specific gravity of 0.736, it does
not mix with water; but, on being added, forms a layer on the surface.
The ether dissolves a certain quantity of water, while the water, on the
other hand, holds a portion of the ether in solution. Ether boils at 34.5°
C., and is very volatile at ordinary temperature. The vapour is inflam-
mable ; and, as may be gathered from the formula, is very heavy. Great
care must be taken when working with ether to keep all lights at a safe
distance. The high density of the vapour causes it to flow as a dense
layer along a level surface for a considerable distance ; in this way there
is danger of the vapour communicating with a light that may be placed
even at the further end of a long table. The rule should invariably be
adopted of having no more of the liquid in the immediate neighbourhood,
where experiments are being made, than is necessary for the purpose in
hand ; the store bottle should not be kept in the laboratory. Ether is of
great use as a solvent for fats, resins, and other organic bodies.

108. Esters or Ethereal Salts. — These bodies are produced by the
displacement of the hydrogen of acids by organic radicals ; the acid may

48 THE TECHNOLOGY OF BREAD-MAKING.

be organic or inorganic. The compounds of such radicals, with chlorine,
bromine, and iodine, are at times viewed as a sub-class of these bodies,
and are termed "haloid" esters. The esters were at one time called
"compound ethers," but the newer name "ester" is now employed in
order to differentiate them from the true ethers or oxides of organic rad-
icals. The following are formulae of examples of esters : —

C2H5C1. C2H5C2H302. CsHiAHaO.,.

Ethyl Chloride. Ethyl Acetate. Amyl Acetate.

NaCl. NaC2H3O2. NaC2H3O2.

Sodium Chloride. Sodium Acetate. Sodium Acetate.

The corresponding sodium salts are written underneath in order to
show their similarity in constitution. Amyl acetate is the confectioner 's
well-known jargonelle pear flavouring, while pineapple essence consists of
another ester, ethyl butyrate, C2H5C4H702.

On appropriate treatment with sodium hydroxide, the esters are split
up with the formation of a sodium salt, thus : —

C2H5C2H3O2 + NaHO = NaC2H3O2 + C2H5HO.

Ethyl Acetate. Sodium Hydroxide. Sodium Acetate. Alcohol (Ethyl Hydroxide).

The reaction is similar to that of sodium hydroxide on a weaker inorganic
base, as ammonium: —

NH4C1 + NaHO , NaCl + NH4HO.

Ammonium Chloride. Sodium Hydroxide. Sodium Chloride. Ammonium Hydroxide.

109. Chloroform, CHC13. — In a number of organic compounds it is
possible to replace the atoms of certain elements present by those of
others ; in this way what are called * * substitution products ' ' are formed.
Starting with methyl hydride, CH4, the hydrogen of this body may be
replaced atom by atom by chlorine until CC14 is formed. The replace-
ment of three atoms of hydrogen by chlorine results in the production of
chloroform, CHC13. This compound is at ordinary temperatures a heavy
volatile liquid, having a specific gravity of 1.48. The vapour of chloro-
form has a peculiar but pleasant smell, and when inhaled produces in-
sensibility to pain, while in less quantities it causes stupefaction. No
danger need, however, be apprehended during any ordinary working
with this substance. Chloroform boils at a temperature of 60.8° C. Chlo-
roform, like ether, acts as a solvent of many organic bodies; it is only
slightly soluble in water, and after being shaken up with that liquid more
or less quickly subsides and forms a layer at the bottom.

110. lodoform, CHI3. — This is a yellow solid body, analogous in con-
stitution to chloroform.

111. Organic Acids. — These bodies constitute a numerous class of
organic compounds • like the radicals, they are capable of subdivision into
distinct families, the members of which exhibit considerable resemblance
to each other. Several of these groups of acids are derivatives from cor-
responding series of alcohols.

112. Fatty Acids, or Acids of Acetic Series. — These acids may be

( C* TT —1—1

represented by the general formula, !nTT ^he lowest member of

( IT
the series is formic acid, TT > or HCH02. The next and best known

is acetic acid, r^ or HC2H3O2. Acetic acid is the derivative from

ethyl alcohol. It will be of service to place side by side for comparison
the formulae of ethyl and some of its principal derivatives : —
(C2H5 JC,H5O

{c2H5 idn5

Ethyl. Ethyl Oxide or Ether.

ORGANIC COMPOUNDS. 49

i r- CH3

, or jCH2HO |COH COHO

Ethyl Hydroxide or Alcohol. Acetic Aldehyde. Acetic Acid.

By oxidising agents, two atoms of hydrogen may be removed from alcohol
with the formation of acetic aldehyde. This body is formed as an inter-
mediate step between alcohol and acetic acid. Aldehyde readily combines
with another atom of oxygen to form acetic acid. Further reference is
made subsequently to the aldehydes as a class.

113. Acetic Acid. — This body is a liquid which boils at a tempera-
ture of 117° and freezes at 17° C. ; it has a sharp but pleasant smell, and
is well known in a dilute form as vinegar. Vinegar is manufactured by a
species of fermentation from alcohol : its interest in connection with our
present subject, lies in the fact that during many fermenting processes
acetic acid is produced.

114. Butyric Acid, JQQHQ ' or HC4H7°2-— Tnis body bears tne same

relation to butyl alcohol that acetic acid does to that of ethyl. Butyric
acid occurs in rancid butter, sweat, and many animal secretions. It is
also one of the products of putrefaction, or putrid fermentation, of many
organic substances ; for instance, it may be formed in considerable quan-
tity by the action of putrid cheese on sugar. Butyric acid is a liquid
having a sharp odour resembling that of rancid butter.

115. The Higher Fatty Acids. — These have received their special
name because of their occurrence as constituents of many natural fats;
among those thus found are butyric acid (above described) ; palmitic acid,

COHO' or HCieH3i02; margaric acid, ' or HCiTH3302; and

stearic acid, nr > or HC18H3502. These latter bodies are at ordinary

temperatures fatty solids, melting into oily liquids with an increase of
temperature. Physically, they bear little resemblance to acetic acid ; but
the formulae at once show their similarity in constitution.

116. Fats and Soaps, or Salts of Higher Fatty Acids.— Most natural
fats are salts of the higher fatty acids, with glycerin as the base; for
example, mutton fat is essentially composed of the stearate of glycerin.
This body may be artificially produced by heating together stearic acid
and glycerin, according to the following equation —

3HC18H3502 + C3H5(HO)3= C3H5(C18H3502)3 + 3H2O.

Stearic Acid. Glycerin. Glycerin Stearate. Water.

Some natural fats contain an excess of the fatty acid over and above that
sufficient to combine with the whole of the glycerin present.

In addition to the "fatty" acids, acids of another group, known as
the oleic series, are found as constituents of natural oils and fats. Oleic
acid, HC18H3302, is the product of oxidation of an alcohol of the family
CnH2n_1HO series : it will be noticed that the formula of the acid differs
from that of stearic acid by containing two atoms less of hydrogen : this
difference follows from the difference in the typical formulae of the two
series of alcohols. The oleates of glycerin constitute the oils or liquid
portions of fats.

By the action of alkalies, as soda or potash, the fats are decomposed,
with the formation of sodium or potassium salts of the fatty acids, and
the liberation of glycerin in the free state. These salts constitute the
bodies known technically as "soaps," those of sodium are the "hard,"
and those of potassium ' * soft ' ' soaps. The separation of fats into glycerin
and the fatty acids may also be effected by forcing a current of steam

50 THE TECHNOLOGY OF BREAD-MAKING.

through the melted fat. The glycerin distils over with the steam. This
operation of decomposing fat by the aid of alkalies is termed ' ' saponifica-
tion, ' ' and, in addition to its great use in the commercial manufacture of
soap, constitutes a valuable method of investigating the composition and
properties of natural fats and oils.

Some few other organic acids of interest yet remain to be described :
among these there is : -

117. Lactic Acid, HC3H503. — This body occurs in sour milk, and is
also produced in greater or less quantities during fermentation with ordi-
nary commercial yeast. Lactic acid is a sirupy liquid of specific gravity
1.215, colourless and odourless, and having a very sharp sour taste. It
forms a well-defined series of salts.

118. Succinic Acid, H2C4H404.— Succinic acid is a white solid body,
soluble in water. It is one of the bodies produced during the normal alco-
holic fermentation of sugar. On being heated, succinic acid evolves dense
suffocating fumes.

119. Tartaric Acid, H2C4H406. — This body occurs naturally as a
constituent of the juice of the grape, and in various other plants. It is
when pure a white solid crystalline body, soluble in water, and possessing
a pleasant sour taste. On being heated, tartaric acid evolves an odour of
burnt sugar. Tartaric acid is dibasic, and forms both an acid and a nor-
mal series of salts, termed ' ' tartrates. " The well-known substance
"cream of tartar" is acid potassium tartrate, KHC4H4O6; this body has
an acid reaction, and, like tartaric acid, decomposes sodium carbonate
with the evolution of carbon dioxide gas. As, however, one-half the
hydrogen has been already replaced in cream of tartar by potassium, that
salt has only half the power, molecule for molecule, of decomposing
sodium carbonate that is possessed by free tartaric acid. When acid
potassium tartrate is neutralised by the addition of sodium carbonate so
long as effervescence occurs, there is produced a double tartrate of potas-
sium and sodium, KNaC4H4OG. This body is soluble in water, and is
known as ' ' Rochelle salt. ' '

120. Definition of Homologues, etc. — At this stage of the subject it
will be convenient to explain the meaning which is attached to "homo-
logue" and other similar terms used in describing organic bodies.
Series of bodies are termed homologous, in which their general constitu-
tion may be represented by a typical formula; thus, the organic radi-
cals of the methyl series are homologous, so too are the corresponding
alcohols, and also the fatty acids. The melting and boiling points of the
members of a* homologous series usually rise as the series is ascended.
When capable of being vapourised, their density in the gaseous condition
increases with the ascent of the series. In many cases, the lower members
of a series of homologues are more chemically active than are the higher
members.

Many organic bodies are known which not only contain the same ele-
ments, but also contain them in the same proportion, while their physical
and chemical character show them, nevertheless, to be distinct com-
pounds. Distinct compounds, having the same percentage composition,
are said to be "isomers," or "isomeric with each other." Isomerism
may be of different kinds. Thus, bodies may have the same percentage
composition, and yet have different molecular weights : in these cases
the molecular weights are multiples of the simplest possible molecular
weight that can be deduced from the percentage composition. Bodies
having the same percentage composition, but different molecular
weights, are said to be "polymers," or "polymeric" with each other.

ORGANIC COMPOUNDS. 51

The following are instances of polymeric bodies : —

Ethylene — C2H4.

Propylene — C3H6.

Butylene — C4H8.

In addition to isomerism of the above type there is yet another more
striking variety. When distinct chemical compounds have not only the
same percentage composition, but also the same molecular weight, they
are said to be "metamers," or "metameric" with each other. As exam-
ples of metameric compounds, the following three bodies may be cited—
propylamine, methylethylamine, and trimethylamine. These three bodies
all have the formula NC3H9. That they are distinct compounds contain-
ing the same proportions of carbon and hydrogen, but united together to
form different organic radicals, is seen when the formulae are written as
below : —

fC3H7 fCH3 fCH

N-jH N-j C2H5 1SN CH

IH LH ICHS

Propylamine. Methylethylamine. Trimethylamine.

The nature and constitution of these bodies are described in paragraph
127.

121. The Aldehydes. — One of the members of this group, acetic alde-
hyde, has already been mentioned in a previous paragraph ; as explained,
its preparation is effected by the removal of hydrogen from the cor-
responding alcohol. Hence the name aldehyde, derived from "aZcohol
dehydrogenatum. " The lowest aldehyde of the ethyl series is that
derived from methyl alcohol according to the following equation : —

CH3HO HCOH + H2.

Methyl Alcohol. Methyl or Formic Aldehyde (Formaldehyde). Hydrogen.

The oxygen of the aldehydes is directly united to the carbon, and is
not present as hydroxyl as in the alcohols. This is shown in the com-
parative graphic formulae given subsequently.

Formic aldehyde is a powerful and well-known disinfectant ; its solu-
tion in water, termed formalin, is employed both as a disinfectant and
preservative.

122. The Aldoses. — Closely allied to the aldehydes are the bodies
collectively known as aldoses. Among these is hexose, which is an aldose
containing six atoms of carbon, and having the formula

H2COH.4HCOH.COH, or C6H1206.

There are several hexoses, one of the number being the well-known sugar,
glucose. Hexose and the homologous aldoses have formula which are
multiples of that of formic aldehyde. They all contain the CO group.

123. The Ketones. — A group of substitution compounds is produced
by the replacement of the hydrogen of an aldehyde by a radical of the
ethyl series; thus acetone results from the substitution of methyl for
hydrogen in acetic aldehyde : —

CH3COH. CH3COCH3.

Aldehyde. Acetone.

These bodies are called ketones, the name being derived from acetone.
It will be observed that the independent CO group is still present. An
important ketone is butyl-methyl ketone, of which the formula is
C4H9.CO.CH3.

124. The Ketoses. — The ketoses may be regarded as ketones in
which the hydrogen of the radical has in part been replaced by hydroxyl.
By this replacement butyl-methyl ketone becomes the ketose, fructose or
hevulose, of which the formula is

CH2OH.CHOH.CHOH.CHOH.CO.CH2OH.
Laevulose is a form of sugar. The relationship of these various

THE TECHNOLOGY OF BREAD-MAKING.

bodies to each other is of importance as throwing light on the chemical
constitution of the sugars and other allied compounds, to which in subse-
quent chapters extended reference is made. The following graphic for-
mulas show how these bodies are related to each other.
H H

H— C— H

H— C=

Methyl Alcohol.

Methyl, or Formic, Aldehyde.

H H H

H— C— H H— (

3— H H— C— H

H— C— H H— (

3=0 H— C— H

H— C— H

Hri f\
V,' V-7

Ethyl Alcohol. Acetic Aldehyde. Butylaldehyde.

H— C— H

H— C— 0— H

H— C— II

H— C— 0— H

H— C— H

— 0— H

H— C— H

H— C— 0— H

H— C— H

H— C— 0— H

H— C— H

H— C— 0

•

Hexylic Alcohol.

Hexose, Glucose.

H— C— H

H— C— 0— H

H— C— H

|
H— C— 0— H

H— C— H

H— C— 0— H

H— C— H

H— C— 0— H

siU

H— C— 0— H

Butyl-Methyl Ketone.

Ljevulose (Ketose).

ORGANIC COMPOUNDS. 53

The relationship between methyl alcohol and its corresponding alde-
hyde is very simple, one atom of hydrogen and one group of hydroxyl are
replaced by an atom of dyad oxygen. The same holds good with regard
to ethyl alcohol and acetic aldehyde. An inspection of the formula shows
that while in the alcohol the ethyl radical is intact and is combined with
an extraneous group of hydroxyl, in the corresponding aldehyde the oxy-
gen atom has made an inroad into the ethyl group and has replaced one
of its atoms of hydrogen. The aldehyde is not that of the intact CnH?n+1
radical, but that of the next higher member of the series. Similarly, butyl
is C4H9, but butyl aldehyde is C3H7COH as shown in the graphic for-
mula.

Coming next to the hexose as a member of the aldoses, the formula of
hexylic alcohol is given beside it in order that the two types may be com-
pared. In the case of five of the carbon atoms, an atom of hydrogen has
been replaced by hydroxyl, while with the remaining carbon atom the
same change has occurred as in the conversion of alcohols into aldehydes.

The formation of ketones is rendered clear by the before given for-
mulae of aldehyde and acetone. Turning to the more complicated ketones,
the formula of butyl-methyl ketone is given, but the principle of the
nomenclature is not quite the same. Butyl aldehyde is C3H7COH, in
accordance with the rule of naming other aldehydes, but that part of the
formula of butyl-methyl ketone above the dotted line which is on the pat-
tern of the formula of an aldehyde, in composition reads C4H9CO — , that
is to say, the butyl radical is intact with the aldehydic carbon atom added
on to it. Following the same rule as in aldehydes generally, this
would be regarded as the aldehyde of the next higher radical, amyl,
C5H]t. One must, therefore, regard these ketones as combinations of the
group CO (carbonyl) with the intact radicals from which the name is
derived.

In the ketoses, a portion of the hydrogen of the ketone is replaced by
groups of hydroxyl, and examination of the formulae shows the ketoses to
bear much the same relation in composition to the ketones as do the
aldoses to the corresponding alcohols.

125. Pentose and Pentosan. — Passing mention must be made of the
pentose group of aldoses. These contain five atoms of carbon, the formula
of pentose being Cr,H1005. By condensation with elimination of water,
the pentoses furnish the corresponding pentosans thus : —

C5H1005 = C5H804 + H20.

Pentose. Pentosan. Water.

These bodies are found in the woody fibre of the outer envelope of wheat,
and by hydrolysis yield pentose sugars.

126. Nitrogenous Organic Bodies. — Many organic compounds, both
from animal and vegetable sources, contain nitrogen as one of their con-
stituents. The constitution of the majority of these bodies has not as yet

• been completely investigated ; a large number of them are, however, basic
in their character, and hence are known as nitrogenous organic bases, or
"alkaloids."

127. Amines, Substitution, or Compound, Ammonias. — Many of the
nitrogenous organic bodies are built upon the same type as ammonia, and

^ may be viewed as ammonia in which one or more of the atoms of hydro-
gen are replaced by compound radicals. These compounds are termed
* * amines, " or ' ' substitution ammonias. ' ' The three bodies, propylamine,
methylethylamine, and trimethylamine, whose formulae are given in a
preceding paragraph, are examples of amines. The methylamines are

54 THE TECHNOLOGY OF BREAD-MAKING.

gases at ordinary temperatures, having a strong ammoniacal and fish-like
smell. Trimethylamine is produced by decomposing proteins, and is the
source of the characteristic smell of fish.

128. Alkaloids. — This name is applied to a class of organic bodies,
most of which contain nitrogen, carbon, hydrogen, and oxygen. All these
bodies are basic, while many are able to neutralise even the strongest
acids, as sulphuric acid. They are, as a class, remarkably energetic in
their action on animals ; thus, quinine and morphine are most powerful
medicines, while strychnine and brucine are among the most violent
poisons ; but little is understood of the constitution of the alkaloids ; it is
probable that they are of the same type as the compound ammonias. For
the sake of uniformity in chemical nomenclature, it has been proposed to
restrict the termination "ine" to the alkaloids; for this reason, glycerin,
dextrin, etc., should never be written glycerine, dextrine, etc.

129. Amino-acids. — The ammo-acids are bodies intermediate in
character between an acid and a weak base, fulfilling under different cir-
cumstances the functions of either. They have no acid taste, do not red-
den litmus, and are derivatives from organic acids in which hydrogen of
the acid radical is replaced by amidogen.

Among members of this group are glycine, or amino-acetic acid,
C2H5N02, the relation of which to acetic acid is shown in the following
graphic formula : —

H H

0=C— 0— H O=C— 0— H

Acetic Acid. Amino-Acetic Acid.

Aspartic acid, amino-succinic acid, C4H7N04, and glutamic acid, amino-
glutaric acid, C5H9N04, are members of this group. So also are leucine,
amino-caproic acid, C6H13N02, and tyrosine, amino-oxy-phenyl-propionic
acid, CgH^NOg. All these bodies are important constituents and decom-
position products of the proteins. Leucine is soluble at 12° C. in 48 parts
of water and 800 of alcohol ; and insoluble in ether. Tyrosine dissolves
in 150 parts of boiling water and is insoluble in alcohol and ether.

130. Amides. — Amides may be regarded as derivatives of acids in
which amidogen, NH2, replaces hydroxyl, HO ; or they may be looked on
as ammonia in which one or more of the hydrogen atoms are replaced by
organic radicals. Urea, CON2H4, is a typical amide. It may be viewed
as a derivative of carbonic acid, CO(HO)2, in which case the two groups
of HO are replaced by two groups of NH2; or on the other hypothesis
may be regarded as two molecules of ammonia, NH3, with a pair of hydro-
gen atoms replaced by CO, thus : —

H\ /H

\ /

N— C— N = CON2H4

/ \ Urea. Carbamide.

H/ 6 \II

The amides are distinguished from the amines by the latter being
incapable of derivation in constitution from an acid.

Among amides found in plants are asparagine, C4HSN203, and gluta-
mine, C5H10N203. Asparagine is the amide of amino-succinic acid. The

ORGANIC COMPOUNDS. 55

relation between succinic acid, amino-succinic acid, and the amide aspar-
ag'ine is shown in the following formula : —

0=C— 0— H 0= C— O— II O=C— 0— H

H— C— H H— C— N/H H— C—

H— C— H H— C— H H— C— H

0=C— 0— H 0— C— 0— H 0=C— N

Succinic Acid. Amino-Succinic Acid. Asparajdne (Amide).

The amides are crystalline, diffusible bodies. Asparagine is soluble in
hot water, but not in alcohol or ether.

131. Phenylhydrazine. — Among the compounds of nitrogen with
hydrogen is that known as hydrazine, N2H4. Further, there is a com-
pound of hydrogen and carbon named benzene, C6H6. This body is re-
garded as a combination of a radical, phenyl, C6H5, with hydrogen. The
generally accepted view of the composition of the bodies of this group is
that suggested by Kekule, who regarded the carbon atoms as forming a
closed chain, as shown in the following formula: —

I
H C II

w \/

c c

l M
c c

H C H

I
H

Benzene or Phenylhydride.

If one of the atoms of hydrogen in hydrazine be replaced by phenyl,
C6H5, phenylhydrazine is produced, and has the formula, C6H5NHNH2.
This body is of importance because of the "great value it has been in the
investigation of the composition of the sugars.

132. Phenylhydrazones or Hydrazones. — Phenylhydrazine is capable
of entering into combination with aldehydes, al doses, ketones and ketoses,
in the proportions of one molecule of each with the elimination of a mole-
cule of water. The bodies thus produced are termed phenylhydrazones.
or more briefly, hydrazones. The formation of two of these bodies ia
shown in the following equations : —

CH3COH + N2H3C6H5 CH3CN2H2C6H5 + H20.

Aldehyde. Phenylhydrazine. Aldehyde-hydrazone. Water.

H2COH(HCOH)4COH + N2H3C6Hg=

Hexose, Glucose. Phenylhydrazine.

H2COH(HCOH)4CN2H2C6H5 + H20.

Glucose-hydrazone. Water.

The hydrazones occasionally serve as means of identifying sugars, but
are far exceeded in value for that purpose by the compounds described
in the next paragraph.

56 THE TECHNOLOGY OF BREAD-MAKING.

133. Phenylosazones or Osazones. — When an aqueous solution of
either an aldose or ketose is heated together with phenylhydrazine acetate
in the proportion of one molecule of the former to three molecules of the
acetate, a somewhat complicated reaction ensues. Among its products is
a compound consisting of two molecules of phenylhydrazine with one of
the aldose or ketose, which body is a phenylosazone, or more shortly
osazone. Taking the example of glucose, the following is the formula of
the phenylglucosazone : —

H,COH(HCOH)3CN2HC6H5CN2H2C6H5.

Phenylglucosazone.

Two groups of phenylhydrazine have become incorporated in the mole-
cule of glucose with the elimination of two molecules of water. There are
other secondary chemical changes which need not be further described.
The osazones have well marked chemical characteristics in the direction
of opticity and other properties. These are of great service in identifying
particular sugars, the modus operandi being to prepare the osazone, and
then through the properties of this body to identify the sugar.

CHAPTER IV.
THE MICROSCOPE, AND POLARISATION OF LIGHT.

134. Object of Microscope. — A description of the microscope, and
method of using1 it, is given at this early stage, because the student will
continually find it requisite to have recourse to this instrument from time
to time, while going on with his study of the chemical properties of the
various grain constituents. In order to thoroughly understand the
physical construction of bodies it is necessary to see them. The micro-
scope is an instrument to enable us to see points of physical construction
which are so minute as to escape the unaided vision.

135. Description of Microscope. — The demand for good microscopes
has led to the supply by a number of makers of really excellent instru-
ments. In consequence, the microscope is not now, even to the general
public, an unfamiliar piece of apparatus. These pages are not the place
where an exhaustive description of microscopes could with fitness be
given, but as the instrument should be in the hands of every miller and
baker, a few hints as to how to use it for such purposes as those occurring
during milling and bread-making will naturally find a place in this work.

Every reader will probably be familiar with the general appearance
of the instrument as shown in the illustration. The microscope proper
consists of the stand, to which is attached the main tube of the instru-
ment, by means of a sliding "dove-tail" arrangement, that can be raised
or lowered by a rack and pinion : the pair of milled heads, D, actuate this
pinion. Below is another pair of milled heads, E, which are more delicate
in their action, and constitute what is known as the "fine adjustment."
The stage, G, is that part of the instrument arranged for the reception of
the object being examined. It consists of a flat surface at right angles
to the axis through the tube of the microscope, and carries on it a pair
of spring clips, r, by means of which the glass on which the object is
mounted is held on the stage, G, and thus may be shifted in any direction
by the fingers. Underneath the stage is a contrivance known technically
as the sub-stage, H : this is also fitted with a rack and pinion, and may be
raised or lowered by the milled head, i. The central aperture of the sub-
stage is arranged to take either a sub-stage illuminator (Abbe condenser),
a series of diaphragms, the polariser of a polarising apparatus, or other
desired sub-stage fittings. Beneath this again is a concave glass mirror,
j, so mounted as to be easily placed in any required position. The tube
of the microscope, together with the stage and mirror, can be turned at
any angle to the tripod stand, from the vertical to the horizontal. Within
the main tube is fitted a second, B, known as the "draw tube," which can
be pulled out if required, thus increasing the distance between the eye-
piece and object glass. A scale is engraved on the side of the draw tube,
by which the amount of withdrawal can be observed and noted. The
lower end of the main tube is provided with an internal screw at c, for
the purpose of receiving the combinations of lenses known as "object
glasses," or "objectives." The objectives of all the best makers are now
cut with the same screw thread, and so are interchangeable. The "eye-
piece," A, also a lens combination, slides into the top of the draw tube.

THE TECHNOLOGY OF BREAD-MAKING.

The objectives are named according to their focal length, and are conse-
quently termed "1-in. objectives," etc. One of these is shown in position
at L. The greater the focal length, the less is the magnifying power of an
objective. The eye-pieces also vary in magnifying power, and are usually
referred to as "A," "IV eye-pieces, and so on; the magnification
increases with each successive letter of the alphabet, commencing with A.
The student will require a series of objectives, consisting of the 2-inch,

FlG. 2. — The Microscope.

1-inch, and 1/3-inch ; these will be found to answer most purposes,
although for bacteriological work a 1/12-inch oil immersion objective in
addition is exceedingly useful. In working with a microscope it is fre-
quently necessary to change from a high to a low magnifying power. In

THE MICROSCOPE. 59

order to do this rapidly, microscopes are now provided with a carrier, K,
which screws into the tube at c, and to which a number of objectives, L,
Ll, L2, is attached. By rotating this carrier the various objectives may
be quickly exchanged for each other. In the following description it will
be assumed that the instrument is fitted with such a carrier. For ordi-
nary work the A eye-piece is sufficient, but a C eye-piece is also at times
useful. The following accessories are requisite : one or two dozen glass
slides, 3 inches by 1 ; some thin glass covers — these may be round or
square, and should be about % inch diameter, or square ; a pair of fine
forceps; one or two needles set in handles; a glass rod drawn out to a
point at one end, and a small piece of glass tubing. All these may be
obtained from the maker of the microscope, and are usually supplied in
the case with the instrument. Other useful pieces of additional apparatus
will be mentioned as necessity arises for their employment.

A word may be said in the first place about the preserving of the
instrument from injury. When not in use it should either be kept in its
case, or, what is more convenient, under a glass shade, as then it can be
readily used when required. A mounted longitudinal section of a grain
of wheat should be purchased at the same time as the instrument ; this is
a very useful slide to possess, and will give the student an opportunity of
learning how to use his microscope before he proceeds to mounting
objects for himself.

136. How to Use the Microscope. — To commence using the instru-
ment, remove it from the case, take the 2-inch objective out of its box and
screw it into the bottom of the tube ; next insert the eye-piece in its place.
The lenses, if dusty, may be very gently wiped with either an old silk
handkerchief that has been often washed, or a piece of wash-leather. One
or other of these should be kept solely for this purpose. The less, how-
ever, that the lenses require wiping the better, as, being made of soft
glass, they easily scratch. When working on yeast, temporarily mounted
in water or other liquid substance, it is necessary to set the stage hori-
zontal, as otherwise the liquid flows downward. But with fixed and
permanent objects, the microscope should be inclined to an angle of about
45 degrees, as in such a position the eye is much less fatigued during
observation. The next requisite is light. In the daytime choose a room
that is well lighted, if possible not by direct sunlight, but by a bright
cloud. At night an incandescent gas burner, especially if enclosed in a
ground glass globe, makes a good source of light. Raise the microscope
tube by turning the pinion, by means of the milled head, D, until the end
of the objective is about 2 inches from the stage. Place the mounted
wheat grain slide on the stage, and arrange the clips to hold it firmly.
Next turn the mirror so as to throw the spot of light on the object. Now
look down the eye-piece and lower the microscope tube until the object
is focussed; that is, until its outlines are seen clearly without being
blurred. A word may here be said about the amount of light advisable ;
generally speaking, the rule may be laid down that it is wise to work with
no more light than necessary. The light should not be bright enough to
dazzle the eye in the slightest degree ; on the other hand, it should be
sufficient for the object to be seen comfortably. The 2-inch objective will
show the greater portion of the grain of wheat occupying the whole of the
field of vision. Any object when' seen through the microscope is inverted ;
that is, the top is seen at the bottom, and the left side at the right. By
pulling out the draw tube the object is still further magnified.

In the next place rotate the carrier so as to substitute the 1-inch for
the 2-inch objective. The microscope tube will now have to be lowered

THE TECHNOLOGY OF BREAD-MAKING.

until the object is again in focus. A smaller portion only of the wheat-
g'rain is seen in the field, but that portion is magnified to a much greater
degree.

The illumination is much less than with the 2-inch object glass. Notice
that more of the details of the object can be distinguished.

The V8-inch objective may now be tried. Unless the section is a very
thin one, it will not, however, show up well. Having exchanged the inch
for this power, lower the microscope tube until the end of the object glass
is within an eighth of an inch from the slide ; then move the milled head
D, very slowly and carefully, watching all the time until the object is
again in focus : for this purpose it is wrell to move the slide until a portion
of the skin of the grain is in view. The milled head, E, may now be used
for making the final adjustment of the focus. This latter milled head is
termed the "fine adjustment," while that by means of the rack and pin-
ion is spoken of as the "coarse adjustment." For the lower powers the
coarse adjustment is sufficient.

This exercise with the three powers will have showrn the student the
mode of using his microscope. He must accustom himself to moving the
object about on the stage, so as to get any portion he wishes in view ; this
presents some little difficulty at first, because the movement must be made
in the opposite direction to that in which it is desired that the magnified
image shall travel.

Any experimenting with the oil or water immersion objective had
better be postponed until the student arrives at the stage of examining
bacteriological specimens.

137. Measurement of Microscopic Objects. — The microscope is not
merely used for the purpose of seeing small objects, but, with the addi-
tion of certain accessories, is also employed for measuring their size. The
first object requisite for this purpose is a "stage micrometer"; an eye-
piece micrometer should also be procured. The
stage micrometer may consist of a fraction of an
inch further divided up into tenths and hun-
dredths, or preferably of a millimetre similarly
graduated. The scale for this purpose is accu-
rately photographed on a glass slip, the same as
an ordinary slide. It will be remembered that
the millimetre is very nearly the twenty-fifth
part of an inch, consequently the tenth or hun-
dredth of a millimetre may be taken as equal to
the two hundred and fiftieth, or two thousand
five hundredth part of an inch. Working with
low powers, it is sufficient for rough purposes to
place the stage micrometer face downwards on
the object to be measured, and then to read the
number of divisions of the micrometer over
which the object to be measured extends. This
can only be done with powers sufficiently low to
permit the lines on the micrometer, and the
object under examination, to be in focus, or
nearly so, at the same time. The eye-piece mi-
crometer is, for all purposes, far preferable. This
instrument consists of a scale engraved on a cir-
cular piece of glass, as shown in Fig. 3, which is fixed in a specially
adapted eye-piece, also figured. The top of the eye-piece draws out, and
the micrometer scale is dropped in, so as to rest on the diaphragm shown

FIG. 3. — Eye-Piece
Micrometer.

THE MICROSCOPE. 61

in section midway of the eye-piece. The figures, of course, must be
uppermost, so as to read rightly on looking down the microscope. The
scale being in position, the sliding tube of the eye-piece itself is drawn
up or down until, on looking through it, the graduations are sharply
iocussed. With the eye-piece in position, on looking down the micro-
scope, both the eye-piece scale and the object are seen in focus together.
The scale looks as though it were simply superposed on the object. The
value of this scale varies with each different power employed, but may be
determined in the following manner — place the lowest power into position
on the microscope; put the stage micrometer on the stage, and read off
carefully in tenths and hundredths of a millimetre the value of one
division of the eye-piece micrometer. Next repeat the same measurement
in exactly the same way with each of the other objectives. In these deter-
minations the draw tube must invariably be in the same position ; it is best
to have it always closed when the microscope is being used for measuring
purposes. Thus, for example, with one of the microscopes in the posses-
sion of the authors one division of the eye-piece has the following values
with different objectives : —

Objective. M.m. M.k.m. Inch.

AA, Zeiss 0.0286 . . 28.6 . . 0.00126

A „ .... . . 0.01734 . . 17.34 . . 0.00068

DD, „ 0.004098 . . 4.098 .. 0.00016

One-twelfth oil immersion. 0.001265 . . 1.265 . . 0.00005

One-twentieth „ „ 0.001087 . . 1.087 . . 0.000043

Supposing that an object, under examination with the highest power,
on being measured is 3.2 eye-piece divisions in length, then its real length
is 0.001087 X 3.2 = 0.00348 m.m., or 0.000137 inch.

138. The Micromillimetre. — When the dimensions of minute objects
are expressed either in inches or in millimetres they require such a num-
ber of figures that it is difficult to at first realise the value of the dimen-
sion. It has therefore been proposed to employ the one-thousandth part
of a millimetre as a unit of length for microscopic measurements. This
unit is called a micromillimetre, for which the following abbreviation,
"mkm.," may be used. The mkm. is also sometimes called a "/*" (Pro-
nounced mu) ; its value in inches is very nearly 1/25400 inch. The eye-
piece measurements given in the preceding paragraph have also their
values expressed in micromillimetres.

139. Magnification in Diameters. — There remains to be explained a
convenient method of measuring the magnifying power of objectives and
eye-pieces. A common method of expressing the value of particular com-
binations of these two is to say that they magnify so many diameters. A
moment's reflection will show that the image seen with a microscope will
vary in actual dimensions, according to whether it be supposed to be near
to or far from the eye. The only real measurement, in fact, is the visual
angle it subtends. This being the case, the measurement in diameters is
always expressed with the understanding that the object is supposed to
be ten inches from the eye.

Here for a moment a slight digression must be made. Most beginners
when looking through a microscope close the eye not in use. This is a bad
plan, as the eyes are thereby much more fatigued. Both eyes should be
^kept open. At first the surrounding objects are continually being seen
'with the unoccupied eye, and it is apparently a hopeless case to see the
object under the microscope at all. Practice overcomes this, but the
authors have found the best plan is to fix to the microscope tube a piece

62 THE TECHNOLOGY OF BREAD-MAKING.

of dead black cardboard, so that the unoccupied eye sees only a black sur-
face. The object will now be observed with the greatest readiness, and
probably not one quarter the fatigue. In a very short time the cardboard
shield may be dispensed with, and the trained eyes so behave that the one
is transmitting the view of the microscopic object to the brain, while the
other is remaining idle and resting. The student should accustom him-
self to use either eye indifferently ; he will soon find that he will no more
think of closing one eye when looking through his microscope than he
would of tying his left hand behind his back before he shakes hands with
his right.

Now, the object of our momentary departure will be evident ; the idle
eye can, at will, be used for looking at something else, so that the one eye
is looking at the microscopic object, the other, if wished, at say a piece of
paper. Place the stage micrometer in focus, and fix a piece of stiff paper
or cardboard as near as possible to the microscope, at right angles to its
axis, and ten inches from the eye-piece. Look down the tube with the one
eye, and with the other at the piece of paper. The magnified micrometer
scale appears as though drawn on the paper. Still using both eyes, trace
with a pencil on the paper the exact position of each line representing the
tenths or hundredths of the millimetre. Next measure on the paper the
distance between the two marks traced from, say, the tenths of a milli-
metre ; suppose that this distance is five millimetres, then that particular
combination of eye-piece and objective has a magnifying power of fifty
diameters. Measure each other combination possible with the various
eye-pieces and objectives in your possession in the same way.

140. Microscopic Sketching and Tracing. — The above method of
measuring is very useful, because with small objects occupying a portion
only of the field, it is possible to trace them on the paper in the manner
described, and such tracings are then known to be magnified to the extent
ascertained by previous measurement as directed. Such sketching by
actual tracing is very desirable in microscopic work, as otherwise the
student is extremely likely to draw an object either too large or too small ;
this is to be avoided, as one object of microscopic examination is to
definitely ascertain the size of objects. It is the authors' practice when
working without sketching to note the measurements with the eye-piece
micrometer. When sketching they make tracings of sufficient at least of
the object to give its actual dimensions, but a process similar in principle
to that already described.

141. Camera Lucida. — For tracing with the microscope an appliance
has been invented, which is known as a "camera lucida"; there is also a
modification termed a neutral tint camera. An ingenious combination of
eye-pie.ce and camera lucida in one piece of apparatus is shown in section
in Fig. 4. The principal portion of the figure consists of the ordinary
eye-piece, a, l>, with its upper and lower lenses, c, d • the central dotted
line, e, f, is the direct axis of vision through the microscope. At the top
right hand of the figure is a glass prism, cj, of peculiar shape. The angles
of this are so arranged that a ray of light, passing in the direction h, i, is
totally reflected at i, in the direction ?, k, and again at k is totally
reflected in the line k, I. The result is that the eye placed over the aper-
ure of the eye-piece, at m, receives both rays of light, /, e, and h, i, k, I,
which ent6r the eye parallel to each other. In consequence, the eye sees
simultaneously with the object under the microscope any other object
placed in the direction of the line /, h; both are combined and appear to
be in the direct line of vision through the instrument, Consequently if a

THE MICROSCOPE.

sheet of paper be placed under ?', h, it and the microscope image appear
to the eye to coincide.

When wishing to use the camera, place
the microscope in a vertical position, di-
rectly facing the source of light, and turn
the camera so that the prism, g, is at the
right-hand side (as figured). Procure a
box or other convenient stand of such a
height that its upper surface, when placed
beside the microscope, is of the same height
as the microscope stage. Place this box
on the right-hand side of the instrument,
under the prism, g, so that the line, i, h,
points to it. For drawing purposes the
most convenient arrangement is a small
drawing "block" of hot pressed paper,
sheet after sheet of which can be removed
as finished. Place this on the stand, under
i, h, and look through the instrument ; both
object and paper should be seen in com-
bination ; that is, the image should appear
to be superposed on the paper. To prop-
erly get this effect the paper and image
should, as nearly as possible, be equally
illuminated. As the paper is usually
brighter than the image, provision is made
for cutting off some of the light from it by
introducing plates of neutral tinted glass
in the path of i, h, just below the prism g.
On the other hand, the illumination of the object may be adjusted by
means of the reflecting mirror of the microscope.

As a preliminary to tracing with the camera, place the stage micro-
meter in focus, and the microscope and paper in their respective positions.
Then, by means of a pencil, mark on the paper the length of the milli-
metre or fraction of the millimetre, and calculate out once for all the
magnification in exact number of diameters. This is very easily done, as
the lines of the object appear to be drawn on the paper ; the pencil point
being also seen, the operation of tracing simply consists of going over
lines apparently already on the paper. With the same powers and eye-
pieces, and microscope and paper in the same relative positions, the mag-
nification is always the same. In actual sketching it is usually sufficient
to trace in the principal outlines ; the details may then be added with
sufficient accuracy by the ordinary method of judging dimensions by the
eye, as in freehand drawing.

142. Microscopic Counting: the Haematimeter. — For certain pur-
poses it is highly important to be able to count the number of small solid
particles suspended in a fluid. Among them is the counting of blood cor-
puscles, and of yeast cells suspended in water or fermenting liquid. An
instrument was first devised for this purpose, in order to count blood cor-
puscles, and hence is called a haematimeter ; the same appliance is adapted
to the counting of yeast cells, and is illustrated in Fig. 5. The instru-
*ment consists of a stout glass slide, on which is cemented a cover-glass
with a circular opening, thus constituting a cell. On the glass slide, and
in the centre of this cell, is arranged a raised circle of glass, on which is

Fie. 4. — Combination of Eye-Piece
and Camera Lucida.

THE TECHNOLOGY OF BREAD-MAKING.

engraved a series of lines at right angles to each other, thus marking its
surface off into a number of squares. A representation of this part of the
apparatus is given on the left of the figure, showing its appearance when
viewed through the microscope. Each of the larger squares has an area
°f Yioo (0.0025) square millimetre. The inner circle of glass, and tjie

FlG. 5. — The Haematimeter.

outer glass, are so arranged that the former is exactly ]/10 m.m. the
thinner ; so that when the cover-glass is brought down into absolute con-
tact with the outer glass, the space between the lower surface of one and
the upper of the other is exactly 0.1 m.m. in thickness. Therefore the
cubic contents of the space above each square on the inner glass is

0.0025 X O-1 == 0.00025 == V4000 cubic m.m.

To perform a counting operation on yeast, for example, an average
sample must be taken, diluted, and shaken up until the cells are uni-
formly distributed through the liquid. Hansen considers that the liquid
most suitable for this purpose is dilute sulphuric acid, 1 part to 10 of
water: for yeast the authors prefer to employ 1 part sulphuric acid, 1
part glycerin, and 8 of water. The viscid nature of the glycerin enables
the liquid to keep the cells uniformly suspended through it for a longer
time. The method of employing the haematimeter is best explained by
giving an actual example. From a sample of compressed yeast, 0.25
gram was weighed off and made up to 50 c.c. with dilute glycerin and
sulphuric acid. The yeast was broken down and thoroughly mixed with
the liquid by violent shaking for some time in a flask. A droplet was
then removed by means of a pointed glass rod, and placed on the centre
of the glass of the haematimeter, and immediately covered with the cover :
this is held in close contact either by a pair of small spring clips or by a
weight put on. (The minute drop for this purpose must not be more
than sufficient to nearly fill the space between the two glass surfaces : it
must not be enough to run over into the outside annular space.) The
apparatus is placed aside in a horizontal position to rest sufficiently long
for the suspended cells to fall to the bottom of the layer of liquid. The
yeast cells having settled down, say in ten minutes, place the haematimeter
on the horizontal stage of the microscope, and prepare to commence
counting, using about 1/6 inch objective (Zeiss D). The yeast cells will
be seen lying on the engraved squares, some within the squares, and
others directly on the dividing lines. Commence counting the cells within

THE MICROSCOPE. 65

the top left-hand square, and make a note of the number, then go on
along- the line, come back, and count those on the squares of the next line,
and so on. The cells lying on the lines must also, of course, be counted,
but only once ; that is, all lying on the horizontal lines must be counted in
the squares above them and all on vertical lines in the squares to the right
of them. The counting must be continued until a sufficient number of
squares have been taken to give a true average. By experiment it should
be ascertained how many squares must be counted in order that an addi-
tional number has no influence on the average obtained. It is usually
sufficient to count some 50 or 60 of the squares. It is convenient to have
the liquid of such a degree of dilution that about 8-10 cells occur in each
square. Approximately the accidental errors amount —

by counting 200 cells, to 5 per cent, of the total result,

1250 „ 2

5000 „ 1

In the experiment being described, 100 squares were counted and
contained 738 yeast cells.

Now the space above each square = 0.00025 cubic mm.

Therefore 100 spaces — 0.025 cubic m.m., and contain 738 cells.
Therefore 4000 spaces == 1.000 cubic m.m., and contain 7.38 X 4000 =
29,520 cells.

Therefore 1 c.c. = = 1000 cubic m.m. and contains 29,520 X 100° =

29,520,000 cells.

But 1 c.c. contained 0.005 gram of yeast, and therefore 1 gram contains
29,520,000 X 200 = 5,904,000,000 cells.

But 1 Ib. avoirdupois == 453.59 grams, and therefore 1 Ib. of the yeast
contained : —

5,904,000,000 X 453.59 = 2,677,995,360,000 cells.

The smaller grained starches may also be counted in the same manner.

143. — The methods of using the microscope having been briefly de-
scribed, directions for its use for special purposes will be given as occa-
sion arises. For fuller descriptions of the instrument itself, its accesso-
ries and the method of using them, the student is referred to one of the
many excellent works already published on the subject.

144. Polarisation of Light. — There are many substances which exert
a special action on ' ' polarised light ' ' ; among these are a variety of crys-
talline compounds, and certain organic bodies. It will be necessary at
this stage to give a short description of the nature of a ray of light, and
the way in which its character may be altered by the action of these sub-
stances just mentioned. As is well known, light travels in straight lines
called rays. The actual motion of such a ray of light is somewhat like to
that of a sea wave, or the ripples produced on the smooth surface of a
pond by throwing a stone therein. In waves, the water itself does not
move forward, but only the undulating motion of the surface; this is
readily seen by floating a cork on the water ; each little wave in its pass-
age onward simply raises and depresses the cork, but leaves it in the same
position as it found it. Light, then, also travels in waves, these waves
being undulations in a substance filling all space, and known by the name
of "ether." The waves of light differ remarkably in one particular from
those on the surface of water; the undulatory motion in the latter is
simply up and down, or, to use the scientific term, in a vertical plane. If
the actual movements of the ether in a ray of light could only be ren-
dered visible, a much more complicated motion would be perceived. Just
as in the case of the water wave, the particles would move across, or

66 THE TECHNOLOGY OF BREAD-MAKING.

transversely to, the direction of the path of the ray. Some of the parti-
cles would rise and fall like those in the water wave, but others would
swing from side to side, or horizontally instead of vertically ; further than
this, others again would vibrate at every intermediate angle. This con-
dition of things is expressed in the statement that the undulations of a
wave of light are in a plane transverse to the path of the ray, and that
the ether particles vibrate in every direction in that plane.

For our present purpose it will be sufficient to regard the wave of
light as composed of two sets of vibrations, the one vertical, and the other
horizontal, and therefore at right angles to each other ; the intermediate
vibrations may be ignored. The character of the undulations of a wave
of light is not greatly altered by passing through glass, water, arid many
other bodies ; the same does not, however, hold good with all transparent
substances — of these one of the most striking is a mineral named tourma-
line. Let two thin plates be cut from a crystal of this substance in a cer-
tain direction ; on examination each is seen to be fairly transparent. Let
one be placed over the other, and then slowly twisted round. In one
particular position light passes through them both as readily as througli
either taken singly ; but as one of the pair is turned round, less and less
light is transmitted ; until, when it has been rotated through an angle of
90 degrees, no light whatever passes. As the revolution is continued, the
plates allow more and more light to pass; until, when an angle of 180
degrees has been reached, the combination of two plates is again trans-
parent. A further revolution of 90 degrees once more causes opacity.
This peculiar effect is due to the fact that tourmaline plates, such as
described, permit the passage through them of only the vibrations of light
in one plane, so that the ray of light, after passing through the tour-
maline, instead of having its vibrations in all directions of the plane,
has them occurring in one direction only; the ray may then be com-
pared to a water wave. Such a ray of light is said to be "polarised,"
and the change effected is termed the " polarisation of light."

The tourmaline plate may be compared to a sieve composed of a set
of wires in but one direction. Using this similitude, only those vibrations
which are in the same direction as the wires of the sieve succeed in effect-
ing a passage. The second tourmaline plate being set so that its wires are
parallel to those of the first, the light which passed through the one suc-
ceeds also in passing through the other. But when the second tourmaline
is turned at right angles to the first, then the light which passed through
the one is cut off by the other, and so the two together refuse to transmit-
any light whatever.

Persons who are acquainted with the beautiful mineral known as Ice-
land spar, know that when a single dot is looked at through a piece of the
spar, it is seen double ; this is due to the fact that the spar splits the ray
of light into two distinct rays; further, the light of each of these sub-
rays is polarised in such a manner that the plane of polarisation (that is,

FIG. 6. — Nicol's Prism.

the direction in which the vibrations occur) of the one ray is at right
angles to that of the other. When pieces of Iceland spar are cut and re-
joined in a particular manner, as shown by the oblique line in Fig. 6, they

THE MICROSCOPE. 67

transmit the one only of these two rays, the other being lost by internal
reflection within the crystal. Such pieces of spar are termed "Nicol's
prisms, ' ' and may be used for the same purpose as the tourmaline plates ;
they have the great advantage of being composed of material as transpar-
ent as glass, while the tourmaline is usually only semi-transparent, apart
from its polarising properties. The first Nicol's prism placed in the path
of a ray of light is termed the polariser, because it effects the polarisa-
tion ; the second is known as the analyser, because it enables us to deter-
mine the direction of the plane of the polarised ray. The attachments
for a Nicol's prism are shown in Fig. 7, which is an illustration of the
polariser and analyser of a microscope. The polariser, in use, is fitted to
the sub-stage, and the analyser to the eye-piece.

FlG. 7. — Polariser and Analyser of Microscope.

Returning again to the similitude of the sieves, suppose that, with the
two. at right angles to each other, it were possible to take the light after it
had passed through the one, and was thus polarised, and twist or rotate
its plane of polarisation through an angle of 90° before it came to the
second, it would evidently then be able to pass through that also. Certain
substances possess this remarkable property: among those of immediate
interest in connection with the present subject are starch, sugar, and
other of the carbohydrates. It is further found that while some com-
pounds twist the polarised ray to the right, or in the direction of the
hands of a watch, others rotate polarised light to the left. If two Nicol 's
prisms were so arranged as to give absolute darkness, and then a plate of
sugar were placed between them, light would be transmitted. If the
analyser were next turned around in a right-handed direction, the point
of absolute darkness would again be reached, and then by measuring the
angle of rotation, the number of degrees through which the plane of
polarisation of light had been rotated by the sugar could be ascertained.
Instruments are constructed for the purpose of making this measurement
with great delicacy, and are termed * l polarimeters. ' ' The exact point at
which maximum light and darkness is reached during the rotation of the
analyser cannot be observed with great accuracy; recourse is therefore
had to observing some of the other characteristics of polarised light more
easily detected by the eye. In the analytic section of this work, an expla-
nation is given of the principles which guide chemists in the application
of the rotation of the plane of the polarisation of light by sugar and other
bodies to their estimation ; a practical description then follows of one of
the best forms of polarimeter and the method of using it. For micro-
scopic purposes a polariser is fitted underneath the stage, and an analyser
either within the body of the tube or over the eye-piece. The object
under examination is thus illuminated by polarised light. For further
information on the polarisation of light, the student is referred to
Ganot's, or some other standard work on physics.

CHAPTER V.
CONSTITUENTS OF WHEAT AND FLOUR.

MINERAL AND FATTY MATTERS.

145. Construction of Wheat Grain. — Having given a brief outline of
the principles and theory of Chemistry, in so far as they are more or less
connected with the present subject, our next object must be to describe
the chemical properties of the different compounds found in the grain,
and to trace them out in the history of the flour and offal. The "cereals,"
to which wheat belongs, is the name given to the grasses which have been
cultivated for use as food. The grain, as is of course well known, is the
seed of the plant; although not strictly chemical information, it will be
well to give here a short description of its various parts. The most im-
portant portion of the seed is the embryo or germ ; this, which is a body
rich in fatty matters, is that part of the seed which grows into the future
plant. The interior of the seed contains a quantity of starch and other
compounds, designed for the nutrition of the young plant during its
earliest stages of growth. The whole is enclosed in an envelope, made up
principally of woody fibre, and arranged in a series of coats, one outside
the other, somewhat like those of an onion, only on a much finer scale.
During the process of milling, the grain is divided into flour and what is
technically known as offal. This latter substance, or group of substances,
includes the germ, bran, pollard, etc. The bran and pollard are the dif-
ferent skins of the grain broken up into fragments of various sizes. This
department of the subject will be dealt with fully in a subsequent part
of the work.

146. Constituents of Wheat. — A large number of chemical com-
pounds may be obtained from grain : these naturally divide themselves
into Mineral or Inorganic Constituents, and Organic Constituents. The
inorganic portions of wheat consist of water and the mineral bodies found
in the ash. The organic compounds may be conveniently grouped into
— fatty matters, starch, and allied bodies having a similar chemical com-
position, and nitrogenous bodies or proteins. Of these substances the fats
have the simplest composition, next come the starchy bodies, and lastly,
the proteins, whose constitution is extremely complex.

147. Mineral Constituents. — The properties of water are already
sufficiently described ; the actual amount present in grain varies from
about 10 to 15 per cent. In sound wheats and flours there is no percepti-
ble dampness, the water being chemically combined with the starch, which
body probably exists in grain as a hydroxide. The other mineral constit-
uents are usually obtained by heating the powdered grain to faint redness
in a current of air; the organic bodies burn away and leave an ash con-
sisting of the inorganic substances present. The ash of wheat has been
made the subject of prolonged investigations and research, conducted
principally, however, from an agricultural point of view. Land being
impoverished by the growth of crops, the constitution of the ash of
wheaten grain and straw is an indication of what mineral matters are
removed from the soil by wheat crops, and therefore also affords informa-
tion as to what additions have to be made to an exhausted soil in order to

MINERAL AND FATTY MATTERS.

replenish its necessary mineral components. Lawes and Gilbert have
from time to time published elaborate tables of results obtained on their
experimental farm at Rothampsted ; the following table is abstracted from
a communication of theirs to the Chemical Society (Chem. Soc. Jour., vol.
xlv., page 305 et seq.}. It gives the composition of the grain-ash of
wheat, grown on the same land, in four characteristic seasons — 1852,
1856, 1858, and 1863 ; the land being treated with farmyard manure : —

Weight per bushel of grain, 11).

Iron Oxide, Fe.,().,

Lime, CaO

Magnesia, MgO

Potash, K20

Soda, Na,O

Phosphoric Anhydride, P20r,

Sulphuric Anhydride, SO,

Chlorine, Cl., . . .'.

Silica, SiO, "

Total

HARVESTS —
1852. 1856. 1858. 1863.

58.2 58.6 62.6 63.1

PERCENTAGE COMPOSITION OF ASH

0.95

0.86

0.90

0.43

2.79

2.53

2.61

2.34

12.77

11.71

11.17

11.41

27 22

29.27

31.87

31.54

(145

0.42

0.28

0.66

54.69

54.18

51.88

52.04

0.14

0.23

0.75

0.93

trace

0.07

0.06

trace

0.99

0.75

0.49

0.65

100.00 100.02 100.01 100.00

The ash constitutes about 1.5 per cent, of wheat, and about 0.4 per cent,
of the finished flour, while bran yields from 5 to 7 per cent, of ash. It
will be noticed that more than half the wheat ash consists of anhydrous
phosphoric acid; this is principally in combination with potash, forming
potassium phosphate. The magnesia is also present as a salt of phos-
phoric acid. The greater part of wheat ash, therefore, consists of potas-
sium phosphate, and is soluble in water.

148. Composition of the Ash of a Wheat and its Mill Products, Teller.

—The following series of ash analyses was made for the purpose of ob-
taining some further information concerning the distribution of various
ash ingredients in the wheat grain and in the different products of mod-
ern flouring mills. The figures given in the table indicate in per cent, of
total ash, the amount of each constituent named.

Constituents.

Silica

Patent
Flour.

2,33

Straight
Flour.

1.28

Low
Grade.

0.50

Dust
Room.

1,34

Shit)
Stuff.

0.49

Bran.

0.97

Wheat.

1.04

Alumina

0.41

0.15

0.12

0.04

0.18

0.07

0.11

Ferric Oxide

0.47

0.26

0.25

0,30

0,37

0.27

Potash

38.50

36.31

32.27

30.85

28.03

28.19

29.70

Soda

0.00

Lime

5.59

5.65

4.51

3.53

2.80

2.50

3.10

Magnesia
Phosphoric Acid . .
Sulphur Trioxide
Chlorine

4.39
48.05
0.16

6.44
49.32
0.52

9,33
53.10
0.00

12.90
49.94
0.58

13.27
54.62
0.00

14.76
52.81
0.10
0.01

13.23
52.14
0.22
0.01

Zinc Oxide

—

0.04

—

0.46

0,36

0.27

0.24

Total

Per cent, total ash
in each .

99.90 99.97 100.08 99.94 100.12 99.95 100.06

0,31 0.40 0.70 2.50

3.08 5.25

1.62

70 THE TECHNOLOGY OF BREAD-MAKING.

Among the variations in composition in the ash from different parts
of the wheat grain, the most noticeable are the very marked increase in
the proportion of potash and lime toward the interior of the grain, and
the still greater decrease in the proportion of magnesia in the same direc-
tion, that is, from the bran to the whitest flour. (Bulletin, Arkansas
Agric. Expt. Station, 1896.)

149. Organic Constituents : Fatty Matters. — Of the numerous organic
bodies found in wheat, fat has not been chosen as the first to be described
because of its importance as a grain constituent, but because it has the
simplest composition of the organic bodies present, and therefore may
fitly serve as an introduction to the chemistry of the more complicated
compounds to follow. All grains contain more or less fat; rice has the
least quantity, viz. 0.1 per cent. ; maize and oats have respectively 4.7 and
4.6 per cent. ; wheat occupies a medium position with a percentage of 1.2
to 1.5. The fat of wheat is not equally disseminated through the grain,
but is almost entirely contained in the germ and husk or bran. An
analysis by Church gives the quantity of fat in "fine wheat flour" as 0.8 ;
it is, however, doubtful if this analysis were made since the time when
the problem of degerming flour has received so much attention from the
miller.

It has been already explained that the fats are salts of certain acids,
with glycerin as a base. They are characterised by their unctuous nature,
and by leaving a greasy stain on paper or linen. Fats are insoluble in
water, and from their low specific gravity float on the surface of that
liquid. On the other hand, all fatty bodies dissolve readily in either ether
or light petroleum spirit. As food stuffs, the fats occupy a high posi-
tion ; in tables giving the relative nutritive value of different articles of
food, fat heads the list. If this were the only point to be considered, the
presence of fats in wheat and flour would be highly advantageous. They
have, unfortunately, one great drawback, and that is that they become
rancid on standing. This effect is particularly noticeable in flour imper-
fectly freed from germ. The rancidity is due to slow oxidation of certain
constituents of the fat; this change may proceed sufficiently far to
seriously affect the flavour of the flour, without the fat as a whole
being very greatly changed. The fat of wheat is of a light yellow tint,
melts at a low temperature, and gradually darkens in colour on being
kept. This change proceeds rapidly in the fat when maintained at a
temperature of 70 or 80° C.

Konig states that the fat of rye, a grain very similar to wheat, has the
following composition : —

Glycerin . . . . . . . . . . 1.30 per cent.

Oleic acid 90.60

Palmitic and stearic acids . . . . . . 8.10 „

According to Konig, therefore, the fat of rye consists largely of free
fatty acids, the glycerin present being insufficient to neutralise but a
small proportion of the acids present.

Stellwaag states that the fat of barley as extracted by ether has the
following composition : —

Free fatty acids . . . . . . . . 13.62 per cent.

Neutral fats .. .. 77.78

Lecithin . . . . . . . . . . 4.24 „

Cholesterin 6.08

MINERAL AND FATTY MATTERS. 71

An examination of wheat fat in the authors' laboratory gave the fol-
lowing results : A sample of perfectly fresh wheat germs was obtained
from the miller and extracted repeatedly with light petroleum spirit in
the cold. The extract was filtered, the spirit distilled off, and the residue
heated very gently until completely free from the odour of petroleum.
A light yellow oil, which in twenty-four hours deposited a trace of crys-
talline fat, was the result. The following analytic data were obtained on
the thoroughly mixed oil and fat : —

Free fatty acids 5.92 per cent.

Neutral fats .... . . 94.08

100.00
More detailed analysis gave the following results : —

Lower fatty acids (reckoned as butyric) . . 0.11 per cent.
Higher fatty acids (palmitic, stearic, etc.) . . 20.72 ,,
Oleic acid ' . . 52.24

The fat completely saponified very readily.

Spaeth (p. 233, Analyst, 1896) gives the following analytic data as to
the properties of wheat fat : —

Specific Gravity at 100° C. (water at 15°=1) . . 0.9068

Melting Point of Fatty Acids 34°

Saponification Value . . , . . . . . 166.5

Iodine Value 101.5

Reichert Meissl Value 2.8

Refractive Index at 25° C 1.4851

„ „ 011 Zeiss's Refractometer Scale 92.0

150. Wheat Oil : de Negri, and Frankf orter and Harding. — A some-
what exhaustive examination of the oil of wheat has been made by
de Negri, who found the separated germs of wheat to contain 12.5 per
cent, of fatty matter, of which 8 per cent, could be extracted by petro-
leum spirit. On removal of the solvent by distillation in a vacuum, there
remained a clear yellow-brown mobile oil having a peculiar smell resem-
bling that of wheat. This oil solidifies at 15° C. It is soluble in ether,
petroleum ether, chloroform, and carbon disulphide; but is insoluble in
cold absolute alcohol, though soluble, however, in thirty parts of hot
alcohol. Glacial acetic acid dissolves at 65° C. an equal volume of oil.
It is only slowly saponified by alcoholic potash.

Colour reactions: Haydenreich's reaction, orange-yellow with violet
spots. Brulle's reaction, red tinge becoming blood red. Schneider's and
also Baudoin's reaction gave no colour. Becchi's as well as Milliau's re-
action gave a pale brown colour. The oil easily turns rancid. After
standing a year a sample contained 43.86 per cent, of free acid calculated
as oleic acid. Germs of different origin were found to give oils with vary-
ing constants.

Frankforter and Harding state that the oil extracted from the germ
by ether has a golden yellow colour, and a characteristic odour of freshly
ground wheat. Warmed to 100° C., the oil becomes reddish brown. It is
a non-drying and not readily oxidisable oil. The following are the more

72 THE TECHNOLOGY OF BREAD-MAKING.

important constants and particulars of composition as determined by
de Negri, and Frankforter and Harding, respectively : —

Frankfurter
Data. De Negri. and Harding.

Specific Gravity at 0° C ......... 0.9374

15° C ......... 0.9245 0.9292

Solidification Point .......... 15° C.

Melting Point of Fa.tty Acids ...... 139.5° C.

Solidification Point of Fatty Acids . . . . 29.7° C.

Saponification Value ........ 182.81 188.83

Iodine Value of Oil .......... 115.17 115.64

Fatty Acids ...... 123.27

Refractometer Value (Zeiss-Wollny) . . . . 74.5

f 4.07*
J20.

Free Acid calculated as Oleic Acid . . . . 5.65 20.46

Glycerol (glycerin) . . . . . . . . . . 7.37

Lecithin .. . ......... 1.99

Paracholesterol . . . . . . . . . . 2.47

The figure marked by an asterisk is the amount per cent, of potassium
hydroxide, KHO, required to neutralise the free acid. This figure )
5.027 = - the acidity calculated as oleic acid. It will be seen that this
sample is about four times as acid as that of de Negri. But like other
oils, the acidity varies considerably with age and other conditions, (de
Negri, Chem. 'Zeit., 1898,- 22, 976,' and Frankforter and Harding, Jour.
Amer. Chem. Soc., 1899, 758.)

It is unusual to find germ oil with any brown tint as described by
de Negri ; pure germ is very pale yellow in colour and so also is the oil
extracted therefrom. Possibly the germ on which cle Negri worked con-
tained a slight amount of bran from which the oil derived its colour.

Further explanation of the various analytic data will be given when
dealing more fully with fats in the confectionery section of this work,
Chapter XXV11 L

EXPERIMENTAL WORK.

151. The student who proposes to master for himself the contents of
this work, should endeavor to verify as many as possible of the various
statements and descriptions by direct experiment. The following outline
of experimental work is intended as a laboratory course of study on the
subject.

152. Mineral Constituents.— Take a small quantity of whole wheaten
meal, heat it to redness over a bunsen in a shallow platinum capsule or
basin. At first the volatile constituents of the grain burn with flame,
leaving a black mass of carbon and ash. Continue the application of heat
until the carbon entirely burns away, leaving behind a greyish white ash.
To this, when cool, add water ; notice that most of it dissolves ; add a few
drops of hydrochloric acid, filter the solution, and make a qualitative
analysis of it; test specially for calcium, magnesium, potassium, and
phosphoric acid. It is well to test direct for these two latter constituents
in separate small portions of ash. To test for potassium, dissolve up a
portion in hydrochloric acid, filter and add a few drops of platinum
chloride to some of the solution in a watch-glass ; the presence of potas-
sium is demonstrated by the formation of the yellow precipitate of the
double chloride of platinum and potassium. Dissolve another portion of

MINERAL AND FATTY MATTERS. 73

the ash in nitric acid, filter and add nitric acid and ammonium molybdate
solution ; after standing for some time in a warm place, phosphoric acid
throws down a canary-yellow precipitate.

153. Fat. — In a tightly corked or stoppered bottle, shake up together
some wheat meal and ether (or light petroleum spirit), allow the mixture
to stand for an hour, giving it an occasional shake meanwhile. At the
end of that time filter the solution through a paper into a clean evaporat-
ing basin and allow it to spontaneously evaporate. Notice that it leaves a
small quantity of fat in the basin. Remember that the greatest care must
be taken in all experiments with ether to avoid its taking fire. It is best
to make this experiment in a room where there are no lights.

CHAPTER VI.
THE CARBOHYDRATES.

154. Definition of "Carbohydrates." — This name has been applied
to a class of bodies composed of carbon, hydrogen, and oxygen, in which
the latter two elements are present in the same proportion as in water,
namely, two atoms of hydrogen for every one of oxygen. Thns, for ex-
ample, starch contains to the six atoms of carbon, ten atoms of hydrogen
to five atoms of oxygen. The carbohydrates comprise, among their num-
ber, bodies differing considerably in physical appearance and character,
but yet exhibiting signs of close chemical relationship. Subjoined is a
table of the more important carbohydrates, arranged into three groups,
according to their empirical or simplest possible formula? : —

CLASSIFICATION OF CARBOHYDRATES.

1. Glucoses. Hexoses 2. Sucroses or Saccharoses, Di-hexoses 8. Amyloses. Poly-hexoses

(C6H];06). (C^H^O,,). » (C(,H100K).

-)-Dextrose -j-Cane Sugar -\- Starch

— Laevulose -{-Lactose -(-Dextrin

-fGalactose -j-Maltose Cellulose

Gums

155. Constitution of Carbohydrates. — Some reference has already
been made to the glucoses in the chapter on organic compounds. It is
there shown that closely allied to the aldehydes is a family of compounds
known as aldoses. Of these, the formula of hexose, one form of which is
glucose, has been given and explained. In both aldehydes and aldoses,
there occurs the carbonyl (CO) group in which the oxygen is directly
united to the carbon by its two links or bonds. It will be noticed that
this group is attached to the free end of the open chain of carbon atoms.
Glucose has been regarded as an aldehyde of mannitol, and may be
formed by processes of moderate oxidation from that alcohol : —

'CH2HO fCH,HO

CHHO CHHO

CHHO O = : or

CHHO | CHHO

CH2HO [COH

Mannitol. Oxygen. Glucose. Water.

Conversely upon reduction, glucose takes up two atoms of hydrogen and
is converted into mannitol. The formula given shows the composition
and relationship of glucose, which name is now more specifically applied
to dextrose. La?vulose, called also fructose, has the same simplest formula
as dextrose, C,,H1206, and like it contains the radical carbonyl. There is,
however, this difference, the carbonyl is attached not to one of the free
atoms of the carbon chain, but to the last but one, thus showing lasvulose
to be a ketose and closely allied to butyl-methyl ketone.

The sucroses may be regarded as bodies formed by the union of two
molecules of the glucose type, with the elimination of a molecule of water,
a reaction, however, which does not occur anything like so readily as the

THE CARBOHYDRATES.

decomposition of a sucrose into its component molecules of glucose. Thus
under the influence of weak acids cane sugar splits up into glucose and
fructose : —

C12H22On+H20=CH2HO.(CHHO)4.COH-f-

Cane suRar. Glucose, Dextrose.

CH2HO.(CHHO)3.CO.CH2HO.

Fructose, La'vulose.

The structural composition of cane sugar is not indicated in the above
equation, but the formulae of the resultant products show them to be
respectively an aldose and a ketose. Owing to their composition, the
sucroses are regarded as di-hexoses.

The amyloses are much more complex bodies than are the preceding
groups. They depart still further from the simplest hexose type, inas-
much as another molecule of water has been eliminated. This is clearly
shown in the following specially written formulae : —

C12H24012.

Two Molecules of Glucose.

C12H220U.

One Molecule of Sucrose.

Two "Units" of Amylose.

The molecules of the amyloses are high multiples of the unit group,
C6H1005. From their complexity they are termed poly-hexoses.

Brown and Morris in 1888 and 1889 contributed to the Chemical So-
ciety's Journal important papers on the Molecular Weights of the Carbo-
hydrates. Their researches were based on Raoult's investigations on the
lowering of the freezing point of a solvent by the solution in it of any
substance. (Thus, salt water freezes at a lower temperature than pure
water.) Raoult found that equivalent molecular proportions of different
compounds cause under the same conditions a similar depression of the
freezing point of the solvent. This offers a valuable means of determin-
ing molecular weight, as, knowing that of one body dissolved, that of
others may be determined. Brown and Morris applied this method to the
investigation of the carbohydrates.

MOLECULAR CONSTITUTION OF CARBOHYDRATES.

Substance.

Dextrose

Cane Sugar

Cane Sugar, same solution after inversion*

Maltose

Lactose, Milk Sugar

Arabinose . .

Raffinose

Mannite or Mannitol . .

Galactosef

Maltodextrin

Amylodextrin

Lowest or Stable Dextrin J
Soluble Starch

Molecular

Formula of Molecule.

Weight.

C6H1206

180

342

C!H"O"

180

C^Ho-jOn

342

C12H22011

342

C8H100.

150

Hf\ HTT C
09 Wig, O-Ll.)l_

)

594

'C8H8(HO)6

182

C6H1206

180

C12H2Ai

(C12H200JO)2

990

c12H2Ai

(C12H,Ao)6

<T)

,286

20C12H20010

6,480

5(C12H20010)20

,400

* Cane Sugar after inversion is split up into dextrose and laevulose, and
dextrose having a molecular weight of 180, so must lasvulose, and be represented
by the formula CeHinOc.

t Galactose is the "dextrose" of lactose.

$ The molecular weight, not only of the lowest or stable dextrin, is repre-
sented by the formula (Ci2H2oOin)2n, but so also are those of the so-called higher
dextrins, of which Brown and Morris examined a series. They find that "the
numbers obtained with dextrins occupying very different positions in the series
are strikingly identical."

7G THE TECHNOLOGY OF BREAD-MAKING.

The above table contains the results of their determinations, which
molecular weights, with the exception of that of starch, were obtained by
direct estimations. In this latter case the direct method was inapplicable,
and, accordingly, recourse was had to an indirect method, based on the
generally accepted hypothesis that the starch molecule must be at least
five times the size of the dextrin molecule produced under certain condi-
tions. Mannitol, having such an intimate relationship in constitution to
the carbohydrates, is also included in the table.

It will be seen that, commencing with those most simple in constitu-
tion, the glucoses come first, and the amyloses last in order. In nature
also no doubt the simpler bodies are first produced, and from these those
which are more complex. In flour as a product of the finished and
ripened grain, by far the greater part of the carbohydrates present is in
the form of starch, and the chemistry of these bodies, in so far as bread-
making is concerned, deals with the degradation or breaking down of the
starch molecule into simpler substances, rather than with its building up.
For this reason it will be preferable to begin our study of the carbo-
hydrates with the amyloses, and then proceed to the other members of the
family.

CELLULOSE, ?iC8H,00,,.

156. Occurrence and Physical Properties. — This body, of which there
are numerous physical modifications, constitutes the framework or skele-
ton of vegetable organisms, in which it acts as a sort of connective tissue,
binding and holding together the various parts and organs of plants.
Woody fibre consists largely of cellulose and one or two closely allied sub-
stances, among which is lignin, a harder and more resistant body than
cellulose, but of somewhat similar composition.

The pith of certain plants is nearly pure cellulose. Manufactured
vegetable fabrics, as cotton and linen goods, and likewise unsized paper,
are also cellulose in an almost pure form. Chemically pure Swedish filters
consist of cellulose with only the most minute traces of other bodies. The
horny part of certain seeds, such as ' ' vegetable ivory, ' ' consist of a form
of cellulose, which is of interest as being a "reserve" store of nutriment,
as starch is in wheat and other seeds.

Pure cellulose is white, translucent, of specific gravity of about 1.5,
and is insoluble in water, alcohol, ether, and both fixed and volatile oils.
An ammoniacal solution of copper hydroxide dissolves cellulose com-
pletely ; this reagent may be prepared by precipitating copper hydroxide
from the sulphate, by sodium hydroxide, and then dissolving the thor-
oughly washed precipitate in strong ammonia. This solution dissolves
cotton wool, or thin filtering paper, forming a sirupy solution ; on the
addition of slight excess of hydrochloric acid, the cellulose is precipitated
in flaky masses ; these, on being washed and dried, produce a brittle horny
mass. This re-precipitated cellulose is not coloured blue by iodine, and
still presents the same chemical properties as ordinary cellulose.

157. Behaviour with Chemical Reagents. — Cellulose, on being boiled
with water under pressure, is converted into a body bearing some resem-
blance to dissolved starch, inasmuch as it is coloured blue by iodine. The
same effect is produced more rapidly by treatment with acids. Boiling
with dilute sulphuric or nitric acid, or strong hydrochloric acid, breaks
up cellulose into a flocculent mass, but without any change in composi-
tion. Treatment with stronger nitric acid changes cellulose into nitro-
substitution products called gun cottons or pyroxylin ; while that acid, in
a yet more concentrated form, oxidises cellulose to oxalic acid. By the

THE CARBOHYDRATES.

i i

action of strong sulphuric acid, cellulose is converted into a form of sugar
known as cellobiose, C]2H22On. Concentrated solutions of potash or soda
also dissolve cellulose, with the formation apparently of the same com-
pound. Sulphuric acid, diluted with about half or quarter its bulk of
water, has a most remarkable action on unsized paper. The paper on
being dipped in the acid for a few seconds, and then washed with weak
ammonia, is found to be changed into a tough, parchment-like material,
which may be used for many of the purposes to which animal parchment
is applied. This body is familiar to confectioners, as being sold under
the name of parchment paper for tying down pots containing jam and
other substances. Filter papers, on being momentarily immersed in
nitric acid of density 1.42, are remarkably toughened, the product being
still pervious to liquids and therefore suitable for filtering purposes.
Such papers are recommended for filtering bodies that have to be removed
from the paper while wet, and are now sold commercially for that
purpose.

158. Existence in Wheat. — There are three forms of cellulose pres-
ent in wheat, of which the following is a brief description : —

1. The lignified or woody cellulose of the bran, which is entirely
removed in the process of making white flour. In whole-meal, which
contains the bran, the lignified cellulose undergoes no change in the
operations of bread-making, nor afterwards during the processes of
human digestion.

2. The parenchymatous cellulose, which forms the cell-walls of the
endosperm. This disappears during germination of the grain, and is far
more easily dissolved by all reagents than is lignin or woody cellulose.

3. So-called starch cellulose constitutes the envelopes or cellulose-
skeleton of the starch cells. It is this form which is most readily con-
verted into the starch-like body, giving a blue colouration with iodine.

159. Composition. — The formula, CBH10O5, is the simplest that can
be derived from the percentage composition of cellulose, but there is little
doubt that the molecule really consists of a number of groups of C(,H10Or,
united together, and is at least as complex as that of starch.

STARCH,

(C12H20010)20
(C]2H20010),0
(C12H20010)20

( L'12.tl20U10 ) 20

(C]2H20010)20

160. Occurrence. — The starchy matters of wheat are of vast impor-
tance as constituting the greatest portion of the whole seed. Starch is
not only found in wheat, but also in other seeds ; and in fact in most
vegetable substances used as food. From whatever source obtained,
starch has the same chemical composition, but varies somewhat in physical
character.

161. Physical Character. — Starch, when pure, is a glistening, white,
inodorous granular powder. Tf a pinch be taken and squeezed between
the thumb and finger, a peculiar "crunching" (crepitating) sound is
heard. Starch has a specific gravity of from 1.55 to 1.60. Starch is
extremely hygroscopic, absorbing moisture with avidity ; in the form in
which it is usually sold it contains about 18 per cent, of water. Wheat
starch after drying in a vacuum still retains about 11 per cent, of water.
Heating in a current of dry air to a temperature of 110° C. renders it
practically anhydrous.

THE TECHNOLOGY OF BREAD-MAKING.

PLATE!

Jttccto.
MICROSCOPIC SKETCHES OF VARIOUS STARCHES.

THE CARBOHYDRATES. 79

162. Microscopic Appearance. — The microscope shows starch to be
composed of minute grains, each having a well defined structure. These
grains are respectively termed starch cells, granules, or corpuscles. Care-
ful examination reveals that each cell consists of an outer coating or
pellicle formed of a very delicate type of cellulose, to which the name
' l starch cellulose ' ' is applied. This envelope is built up of several layers,
arranged concentrically one over the other, and contains within its inte-
rior a substance which may be called starch proper, in distinction from
the enclosing matter. This starch proper is also termed "starch granu-
lose " or " amylose. ' ' On careful examination these separate coats appear
as a series of more or less concentric rings, having for a nucleus a dark
spot or cross, termed the "hilum." The actual size and shape of starch
cells vary with the source from which the starch is derived; thus the
grains of starch from potatoes are comparatively large, while those of rice
are extremely minute. When examined by polarised light certain starches
exhibit characteristic appearances — these are referred to in detail in the
table following. A description of the phenomena of polarisation is given
in Chapter IV. It is possible in many instances to determine the origin
of a sample of starch by its microscopic characteristics; it follows that
impurities may similarly be detected ; also, as all vegetable adulterants of
flour contain starch, admixture of other grains, as maize, rice, etc., is in
this manner revealed.

In Plate I is given the appearance of the more important starches as
seen under the microscope.

MICROSCOPIC CHARACTERS OF VARIOUS STARCHES.

163. Wheat. — Wheat starch is extremely variable in size, the diam-
eter of the corpuscles being from 0.0022 to 0.052 m.m. (0.00009 to 0.0029
inch). Many observers point out that medium sized granules are com-
paratively absent. The grains are circular, or nearly so, being at times
somewhat flattened. The concentric rings are only seen with difficulty;
the hilum is not so visible as in certain other starches. Polarised light
shows a faint cross. In old samples of wheat or flour the granules show
cracks and fissures : this applies more or less to all starches.

164. Barley. — Granules more uniform in size than those of wheat,
also somewhat smaller; average diameter 0.0185 m.m. (0.00073 inch) ; a
few exceptionally large granules may be found measuring as much as
0.07 m.m. Shape, slightly angular circles. Concentric rings and hilum
either invisible or only seen .with difficulty.

165. Rye.— Diameter of granules from 0.0022 to 0.0375 m.m.
(0.00009 to 0.00148 inch). Taking a whole field, the average size of
granules is usually somewhat higher than those of wheat. Shape, gran-
ules are almost perfectly round, here and there show cracks. Concentric
rings and hilum only seen with difficulty.

166. Oats.— Diameter of granules, 0.0044 to 0.03 m.m. (0,00017 to
0.00118 inch). Granules are angular in outline, varying from three to
six-sided.

167. Maize. — Diameter of granules, average size, 0.0188 m.m.
(0.00074 inch). Shape, from round to polyhedral, mostly elongated hex-
agons, with angles more or less rounded. Concentric rings scarcely visi-
ble, hilum star-shaped.

168. Rice.— Diameter of granules from 0.0050 to 0.0076 m.m. (0.0002
to 0.0003 inch). Granules are polygonal in shape, mostly either five or

80 THE TECHNOLOGY OF BREAD-MAKING.

six-sided, but occasionally three-sided. Are usually seen in clusters of
several joined together. A very high magnifying power shows a starred
hilum.

169. Potatoes.— Diameter of granules from 0.06 to 0.10 rn.m. (0.0024
to 0.0039 inch). The granules vary greatly in shape and size; the
smaller ones are frequently circular; the larger grains are mussel or
oyster shaped. The hilum is annular, and the concentric rings incom-
plete, but, especially in the larger granules, clear and distinct. The rings
are distributed round the hilum in very much the same way as the mark-
ings show on the outside of a mussel shell. With polarised light a very
distinct dark cross is seen, the centre of which passes through the hilum.

170. Canna Arrowroot, or Tous les mois. — Diameter of granules
varies from 0.0469 to 0.132 m.m. (0.0018 to 0.0052 inch). The shapes
differ considerably, from round to more or less elongated ovals. The
hilum is eccentric; the rings are incomplete, extremely fine, narrow and
regular. Under polarised light a more distinct cross is seen than with the
potatoes.

171. Preparation and Manufacture of Starch. — For experimental
purposes, starch can readily be obtained from wheateii flour by first pre-
paring a small quantity of dough ; this is then wrapped up in a piece of
fine muslin, or bolting silk, and kneaded between the fingers in a basin of
water. The milky fluid thus produced deposits a white layer of starch on
the bottom of the vessel, which may be carefully air-dried. The starch of
barley and the other cereals may be obtained in a sufficiently pure form
for microscopic study in the same manner. Potatoes require to be first
scraped, or rubbed through a grater, into a pulp ; this pulp must then *be
enclosed in the muslin and the starch washed out.

On the manufacturing scale, starch is obtained from wheat and other
grains by first coarsely grinding and then moistening the meal with water.
This is allowed to stand, and after three or four days fermentation sets
in, more water is then added, and the putrefactive fermentation allowed
to proceed for some three or four weeks. By the end of this time the
gluten and other nitrogenous matters are dissolved. They are then readily
separated from the starch by washing, after which the starch is dried.
Starch is now largely manufactured from rice by a process in which the
grain is subjected to the action of very dilute caustic soda, containing
about 0.3 per cent, of the alkali ; this reagent dissolves the nitrogenous
bodies and leaves the starch unaltered. The so-called "corn flour" is the
starch of maize prepared after the same fashion. Potato starch is ob-
tained by first rasping the washed potatoes into a pulp by machinery ; the
pulp is next washed in a sieve, the starch is carried through by the water,
and after being allowed to subside is dried on a tile floor at a gentle heat.

172. Gelatinisation of Starch. — Starch is insoluble in cold water,
and cannot be dissolved by any known liquid without change ; this follows
from its having a definite organic structure; when this is destroyed, as
must of necessity be the case whenever a solid is rendered liquid, it cannot
by any artificial means be again built up in the same form.

As previously stated, the starch granules consist of an outer envelope
of cellulose, enclosing what is termed ' ' amylose, ' ' or starch proper. This
latter body is soluble, and although pure starch in the granular form
yields no soluble substance to water, yet if the cellulose envelopes be rup-
tured by mechanical means, it is then found that on treatment with water
at ordinary temperatures a soluble extract is obtained. When, however,
starch is subjected to the action of boiling water a marked change ensues :

THE CARBOHYDRATES. 81

under the influence of heat the little particles in the interior, by swelling,
burst the containing envelope, and dissolving in the water form a thick
and viscous liquid, which on cooling1, if sufficiently concentrated, solidifies
into a gelatinous mass. This solution of starch is somewhat cloudy, owing
to the undissolved particles of starch cellulose remaining in suspension.
These may be, in great part, removed by nitration.

This bursting of the starch granules is frequently spoken of as the
"gelatinisation" of starch, and the resulting substance as "starch-paste."
The temperature at which this change occurs varies with the nature and
origin of the starch.

The following table gives particulars as to the gelatinising tempera-
tures of starch from different sources. The figures to the left are those of
Lippman, while to the right are given the results of a series of later deter-
minations made by Lintner, and published in 1889. It may be taken that
Lintner ?s temperatures are for complete gelatinisation.

TEMPERATURE OF GELATINISATION OF STARCH.

Source of Starch.

Barley

Maize

Rye

Potato

Rice

Wheat

Green Malt

Kilned Malt

Oats

These temperatures of gelatinisation assume that the walls of the
starch-containing cells have been broken down, and that excess of water is
present ; otherwise the temperature of gelatinisation is considerably
higher: thus, in stiff bis"cuit doughs, and even in bread, much of the
starch remains ungelatinised even after being baked.

There is doubt as to whether or not gelatinised starch is in a state of
true solution. When filtered, the clear filtrate gives a blue colouration
with iodine (a characteristic reaction of starch), but on dialysis through
an animal or vegetable membrane, or even filtration through porous
earthenware, the starch is removed. This has led to the view that the
starch in starch paste is simply in a state of extremely fine division, but
more probably the state is one of true solution, and the removal by filtra-
tion is due to the highly colloid nature of starch.

173. Soluble Starch. — On treating starch with dilute acids in the
cold, the starch loses its power of gelatinisation, and becomes what is
known as "soluble starch.7' In this form no change of appearance is
observed in the granules, but the starch readily dissolves in hot water to a
clear limpid liquid. Lintner directs soluble starch to be prepared in the
following manner : Pure potato starch of commerce is taken and mixed
with a sufficient quantity of 7.5 per cent, hydrochloric acid to cover it,
and allowed to stand either at ordinary temperatures for seven days, or
for three days at 40° C. By that time the starch will have lost the power
of gelatinisation, and is repeatedly washed with cold water until every
trace of acid is removed. It is then air-dried, and is readily and com-
pletely soluble in hot water to a bright and limpid solution.

Granules
Swollen.

37.5 99.5

Complete
Gelatinisation •> Gelatinisation,
Commenced. Completed. Lintner.

57.2 135 62°2 144 80 176

50.0

122.0

55.0

131

62.2

144

167

45.0

113.0

50.0

122

55.0

131

176

46.1

115.0

58.3

137

62.2

144

149

53.8

129.0

58.3

137

62.2

144

176

50.0

122.0

65.0

149

67.2

153

176

185

176

185

82 THE TECHNOLOGY OF BREAD-MAKING.

Soluble starch is probably a polymeride of ordinary starch, and when
dissolved, then known as "starch solution," closely resembles "starch-
paste" in its chemical behaviour.

174. Action of Caustic Alkalies on Starch. — Treatment with cold
dilute solutions of potash or soda causes starch granules to swell enor-
mously ; the volume of starch grains may thus be made to increase 125-
fold. This reaction also serves for the differentiation of the various
starches. H. Symons recommends the use of soda solutions of different
strengths : a small quantity of the starch is shaken up in a test-tube for
ten minutes with one of the soda solutions, and then a drop of the liquid
is examined under the microscope. The following is a table of results
thus obtained : —

A few Starch granules The greater number All

dissolved in a solution of dissolved in a solution of dissolved in a solution of

Potato . . . . 0.6 per cent. 0.7 per cent. 0.8 per cent.
Oats . . . . 0.6 „ 0.8 „ 1.0

Wheat . . . . 0.7 „ 0.9 „ 1.0

Maize . . . . 0.8 „ 1.0 „ 1.1

Rice . . . . 1.0 „ 1.1 „ 1.3

175. Action of Zinc Chloride. — Treatment with zinc chloride also
causes a remarkable swelling of the granules of starch; this reaction,
when viewed under the microscope, serves admirably to show the struc-
ture of the corpuscles. Some concentrated solution of zinc chloride is
tinged with a trace of free iodine. A few grains of the starch are placed
on a glass slide, together with a small drop of this solution. No change is
observed until a little water is also added. -They then assume a deep blue
tint, caused by the iodine, as explained in a subsequent paragraph, and
gradually expand. A frill-like margin developes round the granule, the
foldings of this frill open out in their turn, until the granules at last
swell up to some twenty or thirty times the original volume, and then
appear as limp-looking sacs. These changes, so far as can be seen, are
not accompanied by any expulsion of the inner contents of the cell.

176. Properties of Starch in Solution. — A solution of starch is col-
ourless, odourless, tasteless, and perfectly neutral to litmus. Starch is a
highly colloid body, and can be readily separated by dialysis from crys-
talline substances. On evaporating a solution of starch, it does not re-
cover its original insolubility. Starch solution causes right-handed rota-
tion of polarised light. Starch amylose is insoluble in alcohol, and may
be entirely precipitated from its aqueous solution by the addition of
alcohol in sufficient quantity. Tannin precipitates both starch-paste and
soluble starch, the precipitate being re-dissolved on heating. Barium
hydroxide gives an insoluble compound with solution of starch, and is
used in this way in some processes of starch estimation.

Soluble starch, owing to the formation pf a hydriodide of starch
(C24H400.,0I)4HI, is coloured an intense blue by the addition of iodine in
extremely small quantities. This blue colouration disappears on heating
the solution, but reappears on its being cooled. This reaction is exceed-
ingly delicate, and is practically characteristic of starch. For the pur-
pose of this test, the iodine may be dissolved in either alcohol or an
aqueous solution of potassium iodide; for most purposes preferably the
latter. For the occurrence of this reaction, the presence of water is
apparently essential ; for if wheaten flour be moistened with an alcoholic
solution of iodine no colouration is produced other than the natural
brownish yellow tint of tincture of iodine. But with a potassium iodide
solution the flour assumes a blue colour so intense as to be almost black.

THE CARBOHYDRATES. 83

The iodine colouration of starch is only caused by free iodine, not by
iodine compounds ; and is not produced except in the presence of hydri-
odic acid or an iodide. Potash or soda in solution, when added to dis-
solved iodine, immediately combine therewith to form iodides and iodates ;
consequently, the iodine test for starch is inapplicable in an alkaline
medium. In case a solution to be tested for starch is alkaline to litmus,
cautiously add dilute sulphuric acid, until neutral or very slightly acid ;
the test for starch may then be made. The only compounds usually likely
to interfere with the iodine reaction for starch are some of the dextrins ;
these bodies combine with iodine, forming either colourless or brown com-
pounds ; but unless present in large quantities do not prevent the detec-
tion of starch. Iodine combines with starch more readily than with
dextrin, consequently the iodine should in such cases be added in very
small quantities at a time, when the blue colouration due to the starch
will appear before the brown tint produced by dextrin. In testing for
starch the addition of iodine solution should be continued until an excess
of iodine is present in the solution.

In bodies such as starchless biscuits, of which washed gluten may
form a constituent, it is sometimes found, on dropping a solution of iodine
on the broken surface of the biscuit, that a blue colouration is produced,
but that prolonged boiling fails to yield a solution which gives an iodine
colouration. The probable explanation seems to be that under the influ-
ence of heat traces of starch cellulose in the biscuit products are con-
verted into the soluble variety, and hence give a colouration in situ, but
are in such small quantity and so firmly imprisoned within the cellulose
as not to be liberated by boiling. It is not sufficient in making starch
tests 011 solid substances to trust to adding iodine to the substance itself :
the substance should also be extracted with boiling water, and the test
made on the filtered solution.

Starch does not cause .a precipitate with Fehling 's solution, that is, it
does not reduce an alkaline solution of copper sulphate in potassium
sodium tartrate. See paragraph 183, on Reducing Power.

Starch under the influence of heat, and readily when treated with cer-
tain other bodies, is transformed into others of the carbohydrates.

DEXTRIN, 20C1oH20010, or 40C6H1005, + H,0 = ^{Fft0^80

£V_/6n12w6.

177. Occurrence. — Dextrin is principally known as a manufactured
article, but also occurs in small quantities as a natural constituent of
wheat and most bodies containing starch.

178. Physical Character. — In appearance, dextrin is a brittle trans-
parent solid, very much resembling the natural gums, as gum arabic. It
is colourless, tasteless, and odourless. Dextrin is a colloid body, and is
very soluble in water, and it is also soluble in dilute alcohol; but it is
insoluble in absolute or even concentrated alcohol, by means of which it
may be precipitated from its solutions. Dextrin is also insoluble in ether.
Surfaces moistened with a solution of dextrin, and then allowed to dry in
contact with each other, adhere firmly. Commercial dextrin has usually
a more or less brown tint from the presence of caramel in small quantity.

179. Preparation. — Dextrin is usually prepared by the action of
heat, with or without certain reagents, on starch. The starch may be
maintained at a temperature of about 150° C. until it assumes a brown
colour : treatment with water then dissolves out dextrin in an impure
form. If the starch be first moistened with water containing a minute
quantity of nitric acid? the change proceeds much more rapidly; the

84 THE TECHNOLOGY OF BREAD-MAKING.

starch should in this case be heated to about 200° C. The substance thus
yielded is that known as British gum, and is largely used for sizing cali-
coes and other purposes in commerce. If starch solution be boiled with
dilute sulphuric acid until it no longer gives a blue colouration with
iodine, dextrin will be found in the solution, but mixed with maltose.
Certain nitrogenous bodies also possess the power of converting starch
into dextrin and maltose.

180. Chemical Character. — Dextrin was formerly supposed to con-
sist of a mixture of polymeric bodies of closely similar chemical charac-
ter. These several dextrins were separated into two groups by their dif-
ference in behaviour when treated with iodine solution. The members of
one of these groups, known as ' ' erythro-dextrins, ' ' were found to strike a
reddish-brown colouration on treatment with iodine ; while the others,
which were classified as " achroo-dextrins, " yielded no colouration when
iodine was added. It has already been stated that Brown and Morris in
1889 investigated the molecular weights of the carbohydrates, and that
they found the results given by the various dextrins were practically
identical. The formerly held theory assumed that the erythro-dextrins
contained in the molecule 8 and 9 respectively of the group C12H20010 ;
while the molecular formula of the achroo-dextrins included from 2 to 7
of the C12H2(,010 group. In face of Raoult's method, giving identical
molecular weights for the whole of the dextrins, the view of their being
polymeric bodies is no longer tenable. The iodine colouration, produced
by the so-called erythro-dextrins, is due to the presence of certain other
bodies, termed "amyloms, " which will subsequently be described.

Dextrin has a powerful action on polarised light, twisting the ray to
the right : its name is derived from this property. A solution of dextrin
in some respects resembles one of starch ; they are, however, distinguished
by the dextrin giving no blue colour when treated with iodine. Dextrin
was formerly supposed to exercise no reducing action on Fehling's solu-
tion, and that in that respect its behaviour was similar to that of starch.
But more recent observers, among whom are Brown and Millar (Jour.
Chem. Soc., 1899), point out that dextrin has a reducing power of about
R 5.8.

THE SUGARS — Maltose, Cane Sugar, Milk Sugar, and Glucose.

181. General Properties. — As already explained, the sugars are a
subdivision of the class of bodies known as carbohydrates ; they are char-
acterised by having a more or less sweet taste, and are soluble in water.
Many are natural products occurring both in the animal and vegetable
kingdom.

182. Maltose, C12H.,2011.— This bod}' occurs in company with dextrin
in starch solutions which have been treated with dilute sulphuric acid
until the solution no longer yields a blue colouration with iodine. It
forms a most important constituent of malt extract, amounting to from
60 to 65 per cent, of the total solid matter. In the pure state, maltose
consists of small hard crystalline masses or minute needles, which are
soluble in water and dilute alcohol. Maltose, being a crystalline body,
may be separated from dextrin by dialysis, and also by precipitating the
dextrin by means of strong alcohol. A solution of maltose causes a right-
handed rotation of a ray of polarised light. Maltose gives no colouration
with iodine, but, in common with certain other of the sugars, exercises a
reducing or deoxidising' action on some metallic salts.

THE CARBOHYDRATES. 85

183. Reducing" Power. — This reducing action is most commonly
tested by means of the reagent known as "Fehling's solution/' which
consists of sulphate of copper, tartrate of potassium and sodium, and
sodium hydroxide, dissolved in water. If sodium hydroxide be added to
a solution of copper sulphate, a precipitate of copper oxide, CuO, com-
bined with water, is thrown down ; the sodium and potassium tartrate
redissolves this and forms a deep blue solution, which may be boiled for
some minutes without alteration. Now certain varieties of sugar reduce
the CuO to CuL>0 ; that is, they take away oxygen, the change being repre-
sented by 2Cu~0 == Cu20 + 0. The oxygen is taken by the sugar, and
for our present purpose need not be traced further. The Cu2O, or copper
sub-oxide, thus formed is insoluble in the Fehling's solution, and hence is
precipitated, first as a yellow and then as a brick-red powder. The
cupric oxide reducing power, or, more shortly, the cupric reducing power
of a substance, has been defined by 0 'Sullivan as ' ' the amount of cupric
oxide calculated as dextrose, which 100 parts reduce" from Fehling's
solution under usual conditions of analysis. By careful experiment it
has been found that —

100 grams of dextrose reduce 220.5 grams of CuO.
100 „ maltose „ 137.8

If in the case of maltose the reduced CuO be assumed to be caused by
dextrose, and calculated as such, then—

137.8 X 100

~ = 62-0 = cupric reducing power of maltose.

Another way of expressing the same thing is — The cupric oxide
reduced by a given weight of dextrose being 100, the amount reduced by
the same weight of any other body is taken as the cupric oxide reducing
power of that body.

For cupric reducing power the symbol K or K is employed, that is to
say, the amount of reducing sugars calculated as dextrose from the CuO
or Cu20 precipitate — K.

In the case of sugars resulting from changes produced in starch, the
present more widely adopted rule is to take the reducing power of maltose
as 100, and that of other bodies in terms of that of maltose. For the
cupric reducing power thus expressed, the symbol R is employed. For
example, if starch is converted into a mixture of bodies, one-fifth of which
is maltose, and the remainder without reducing action, then the cupric
reducing power of the mixture would be R 20.

184. Cane Sugar, C^H^O,,. — Cane sugar is widely spread in nature :
it is found in certain roots, as beet-root, in the sap of trees, as the maple,
and in the juice of the sugar cane. These natural solutions are first puri-
fied, and then the sugar obtained by crystallisation. The sugar found in
perfectly sound wheat is either identical with, or closely allied to, cane
sugar. Pure cane sugar is colourless, odourless, and soluble in water, to
which it imparts a sweet taste. Boiling water dissolves sugar in all pro-
portions, while cold water dissolves about three times its weight. Sugar
is insoluble in ether, chloroform, and petroleum spirit; but is very
slightly soluble in absolute alcohol, and sparingly soluble in rectified
spirits of wine. The purest commercial form of sugar is that sold by the
^grocers as "coffee sugar," and consists of well defined crystals about
three-sixteenths of an inch across. This, when dried at 100° C. to expel
any water that may be present, is sufficiently pure for most experimental

86 THE TECHNOLOGY OF BKEAD-MAKING.

work with sugar. A solution of cane sugar exercises a right-handed rota-
tion on a polarised ray of light. Cane sugar produces no colouration
with iodine, neither does it cause any precipitate in Fehling's solution.
By the action of heat, cane sugar melts, and if then allowed to cool, forms
the solid termed * ' barley-sugar " ; a prolongation of the heat results in
giving the sugar a deeper colour. Many sweetmeats consist of sugar thus
treated. The darkening in colour is due to the fact that at moderately
high temperatures (210° C. = 410° F.) sugar begins to undergo decom-
position. Watery vapour and traces of oily matter are evolved, leaving
behind a substance soluble in water, to which it imparts a rich brown tint.
The characteristic sweet taste of sugar has then disappeared, and the
liquid is no longer capable of fermentation by yeast. The change has
resulted in the formation of a brown substance, termed caramel, to which
the formula C12H1809 has been given. Caramel is, however, rather a mix-
ture of bodies than a definite chemical compound. The browning of
dextrin and starch when heated is also due to the formation of caramel.

185. Milk Sugar or Lactose, C^H^O^. — This sugar is principally of
interest as being that present in milk, which contains quantities of it
varying from 4 to 5 per cent.

It will be noticed that the three sugars — maltose, cane sugar, and milk
sugar — have all the same formula.

186. The Glucoses or Hexoses, C6H1206. — Several modifications of
glucose exist ; of these, two only are of importance in connection with the
present subject, viz., glucose, otherwise known as dextrose or dextro-
glucose, and fructose, called also laevulose or lasvo-glucose.

187. Glucose or Dextrose. — This form of sugar exists as a natural
product in the juices of many fruits, notably the grape and sweet cherry.
The former yields about 15 per cent, of grape sugar. Glucose also occurs
in the flowers of certain plants, and is derived from these by bees in the
shape of honey, of which the glucoses are the principal constituents.
Glucose is also found in large quantity in the urine of diabetic patients ;
some doubt exists as to whether this sugar is absolutely identical with the
glucose of fruits. Glucose, when pure, occurs in crystalline masses: it
lias a sweet taste ; but, weight for weight, is said to possess much less
sweetening action than does cane sugar. (But see Chap. XXVIII.) A
solution of glucose exercises a right-handed rotation on a ray of polarised
light, and from this property has received the name of dextrose. Among
the sugars, glucose is specially noticeable for the great ease with which it
undergoes alcoholic fermentation. Like maltose, glucose exercises a
reducing action on Fehling's solution, producing a red precipitate of
cuprous oxide.

188. Fructose or Laevulose. — This sugar occurs in company with glu-
cose in certain fruits, and also in honey. Fructose crystallizes from an
alcoholic solution in long crystals ; it possesses greater sweetening power
than glucose, and offers more resistance to alcoholic fermentation. A
solution of Isevo-glucose exercises a left-handed rotation on a ray of polar-
ised light, thus distinguishing it from dextro-glucose ; the two names are
based on the respective right- and left-handed rotary power of these glu-
coses. Lsevo- and dextro-glucose both reduce Fehling's solution, but the
reducing power of fructose is rather the less of the two.

189. Commercial Glucose. — Glucose, in a more or less pure form, is
largely manufactured for commercial purposes. Under the names of
"saccharum," "invert sugar," etc., it is used as a substitute for malt by
brewers and distillers. Various forms of confectionery and fruit jams

THE CARBOHYDRATES. 87

contain glucose as an important constituent. Glucose occurs in two forms
in commerce : the one is a thick and almost colourless syrup, the other is
a hard crystalline body, varying in colour from almost white to pale
brown. Glucose is usually made from starch by the action of heating
with dilute sulphuric or oxalic acid. For the purpose, either maize or
rice is usually selected. Invert sugar is produced from cane sugar by
heating with dilute acid. The following are analyses of different types of
commercial glucoses: —

I. Brewer's solid starch glucose (Morris).
II. Confectioner's sirupy glucose (The authors).
III. Brewer's invert sugar (Morris).

I. II. III.

Glucose 57.16 . . 7.50 . . 66.92

Maltose • . . 8.09 . . 60.92 . .

Sucrose . . . . 0.80

Dextrin 16.63 . . 16.20 . .

Proteins 0,97 . . . . 0.59

Mineral matter 1.45 . . 0.18 . . 1.59

Water 15.70 15.20 22.21

100.00 100.00

Un fermentable matter, etc. . . . . . . 7.89

100.00

The glucose in these commercial products is a mixture of dextrose and
laevulose. The sirupy glucoses consist principally of maltose and dextrin.
"Invert sugar" is so called because such sugar rotates the ray of polar-
ised light to the left instead of to the right, as does normal cane sugar.

THE AMYLOINS — Amylo-dextrin, Malto-dextrin.

190. Constitution. — The term "amyloins" was proposed by Arm-
strong as a convenient name for a group of bodies which are compounds
of varying proportions of the amylin or dextrin group, C12H20O10, with
the amylon or maltose molecule, C12H22On. That these bodies are com-
pounds and not mixtures is proved by their being incapable of separation
by the action of alcohol, whereas mixtures of dextrin and maltose in the
same proportions are readily so separated. Further, the amyloins are
unacted on by ordinary yeast, Saccharomyces cerevisice, while the
maltose of a mixture is readily so fermented. They are completely con-
verted by diastase into maltose.

191. Amylo-dextrin, J^12*^22^11 ^ —This body is produced by the

action of dilute acids on starch granules in the cold. After some weeks'
treatment the corpuscles become completely disintegrated, and then con-
sist largely of amylo-dextrin ; this is dissolved in hot water and purified
by precipitation with alcohol. This substance is a definite chemical com-
pound, having the formula above assigned to it as the result of a determi-
nation by Raoult 's method ; and is produced by the hydrolysis of starch.
Amylo-dextrin gives an intense reddish-brown colouration with iodine,
•iind its presence is the cause of the chemical properties hitherto ascribed
to erythro-dextrin.

88 THE TECHNOLOGY OF BREAD-MAKING.

192. Malto-dextrin, )?n IT n"\ ~ When starch is converted by

( V ^12**20^10/ L"

diastase, malto-dextrin is found to a greater or lesser extent in the prod-
ucts, especially when the converting action is not very prolonged. Malto-
dextrin is unfermentable by ordinary yeast, Saccharomyces cerevisiw, by
the action of which it may be distinguished, and separated, from maltose.
Malto-dextrin is, however, slowly fermented by certain secondary yeasts.
Malto-dextrin cannot be separated into its constituents by the action of
alcohol, but diastase completely and readily converts it into maltose.

193. Other Carbohydrates of Cereals. — There are certain other
carbohydrate bodies, of which small quantities are found in wheat and
other grains ; among these are :—

Raffinose, C18H320165H2O, is a sugar somewhat resembling cane sugar
in character, but less easily inverted. Found by O 'Sullivan in barley.

a and (3 Amylan, ttC6H1005, are two bodies having the same empiric
formula, which are found in the mucilaginous portions of grains. They
are almost insoluble in cold water, dissolve in hot water, and gelatinise on
cooling. These substances, when treated with dilute acids, are converted
into glucose without the production of intermediate bodies. Wheat con-
tains from 0.1 to 0.05 per cent, of a amylan, and from 2.0 to 2.5 per cent.
of J3 amylan.

Extractive Matters. — Under this heading are included certain sub-
stances which cannot be readily identified in the same manner as starch,
maltose, and other bodies. This is in consequence of their possessing no
very definite chemical reactions. Lintner has obtained from barley a
white amorphous substance of a gummy nature, to which the name xylan
has been given, and which in composition is represented by the formula,

^nH20010.

EXPERIMENTAL WORK.

194. Cellulose. — Mix in a moderate sized beaker about 5 grams of
wheat meal, with 150 c.c. of water, and 50 c.c. of a 5 per cent, solution of
sulphuric acid ; and set the beaker in a hot water bath for half an hour,
giving its contents an occasional stir. At the end of that time add 50 c.c.
of a 12 per cent, potash solution, and set the beaker in the bath for
another half-hour. Observe that a residue remains; allow this to sub-
side, and wash it by decantation. Finally, transfer it to a filter, and let
it drain. The substance thus obtained consists of the cellulose or woody
fibre of the wheat. Add iodine solution to a portion, and notice that it
produces no blue colouration.

It is assumed that most of the students who go systematically through
this course of experimental work will do so in a regularly appointed
laboratory; they will there find the solutions of sulphuric acid and potash
above referred to ready made up for use. Full directions for their prep-
aration, and also of other special reagents required, are given in the
chapters on analytic work toward the end of the book. Unless he has not
access to such solutions, the student need not at this stage of his work
trouble to specially prepare them.

195. Microscopic Examination of Starches. — Take a small quantity
of either wheat meal or flour and make it into a dough. Tie this up into
a piece of muslin or bolting silk, and knead in a small cup or glass with
water; the starch escapes, giving the water a milky appearance, while
the gluten and bran remain behind in the muslin. Clean an ordinary
microscopic glass slide and cover, shake the starchy water and place a

THE CARBOHYDRATES.

minute drop on the slide, lay on the cover, press it down gently, and soak
up any moisture round its edge with a fragment of blotting paper. Place
the slide on the microscopic stage, and focus the instrument, using first
the inch and then the quarter or eighth objective. The separate starch
cells are then plainly seen. Trace in a few of the cells on paper, with a
camera lucida, and sketch in any points of detail. Measure one or two
of the cells with the eye-piece micrometer, and mark their dimensions on
the drawing.

Take a small quantity of the flours respectively of barley, rye, rice,
and maize, wash out the starch from each, and examine microscopically
in precisely the same manner as with the wheat, making drawings in each
case. A little corn flour, being practically pure maize starch, may be
used instead of maize flour. Cut a potato in halves, and with a sharp
knife scrape off a little pulpy matter from the cut surface, transfer to a
slide, and examine with the microscope.

Notice in each case the relative sizes of the granules, and compare
their shapes. Examine for the hilum and also observe the rings. If the
microscope be fitted with polarising apparatus, study the various starches
under polarised light.

196. Examination of Mixed Starches. — With separate portions of
wheat flour, mix respectively small quantities of rice meal and corn
flour. As before, knead the starch out of each, and examine the milky
fluid for the foreign starches. Notice in the one case the very small rice
starch granules, and in the other the somewhat larger maize starch gran-
ules interspersed among those of the wheat.

197. Gelatinisation of Starch. — Heat separate quantities of one
gram of the starches of wheat, rye, maize, rice, and potato in 50 c.c.
of water; and notice the temperature at which the liquids commence
to thicken through gelatinisation of the starch. The experiment is con-
ducted in the following manner :

Place a moderately large beaker on a piece of wire gauze over a
tripod, as in Fig. 8. Take several small beak-
ers or test tubes, and attach to each a wire
hook, so that they may be hung over the edge
of the large beaker. Fill this large beaker
with water, and use it as a water bath. Put
the starch to be tested, together with the
requisite quantity of water, in one of the small
beakers, and suspend it in the water bath ;
under which place a lighted bunsen. While
the small beaker is thus being heated, stir its
contents with a thermometer, and note the
temperature at which the first appearance of
gelatinisation is detected ; instantly remove
the beaker and plunge it into a vessel of cold
water. When cold, examine a little of the
paste with the microscope, and notice whether
or not many of the granules remain unaltered.
Make a second experiment with the same
starch, arresting the temperature at 2° hotter
or colder, according to the degree of gelatin-
isation revealed by the microscope on the first
trial All the starches specified are to be
tested in the same manner. Gelatinisation of Starch.

90 THE TECHNOLOGY OF BREAD-MAKING.

198. Reactions of Starch Solution. — Gelatinise a little starch by
heating it with water in a test tube or small beaker placed in the hot-
water bath ; then let the solution cool.

Dissolve some iodine in alcohol, and aqueous solution of potassium
iodide, respectively. In each case use sufficient iodine to just give a
sherry tint to the solution. Add some of either of these solutions (that in
alcohol is commonly called a "tincture") to .a small quantity of the
solution of starch; notice the blue colour produced. Heat the solution,
and then allow it to cool; observe the disappearance and gradual re-
appearance of the colour.

Render a portion of the starch solution alkaline by the addition of
caustic soda or potash ; to one portion of this solution add iodine ; notice
that no colouration is produced. To the other, add dilute sulphuric acid
until the solution is slightly acid to litmus paper. Then add some iodine
solution, and observe that the normal blue colour is produced. Add
respectively solution of iodine in potassium iodide, and the tincture of
iodine, to separate small portions of flour; notice the dark blue colour
produced in the first instance, and the sherry tint in the second. To the
second portion add a little water ; the dark blue colour at once appears.
Mount a minute portion of flour on a slide with iodine solution ; examine
under the microscope, and notice the blue colouration of the starch gran-
ules, while other constituents of the flour remain comparatively
uncoloured.

199. Dextrin. — Render some water faintly acid by the addition of a
small quantity of nitric acid ; with this, moisten some starch in a porce-
lain dish, and maintain it at a temperature of 200° C. in a hot-air oven
for about two hours. The hot-air oven is usually made of copper, and is
heated by means of a bunsen placed underneath; through a hole in the
top a thermometer is fixed so as to show the temperature. Before using
the oven, regulate the temperature by turning the bunsen partly on or
off until the thermometer remains steadily within say 10 degrees of 200.
The moistened starch must not rest direct on the bottom of the oven : it
may be placed on a small tripod made by turning down the wires of an
ordinary pipe-clay triangle.

Treat this heated starch with hot water, and filter ; a yellowish-brown
gummy solution is obtained. To a portion, add iodine solution; notice
that no blue colouration is produced, but instead a reddish-brown tint ;
starch, therefore, is absent, The reddish-brown colour is due to the pres-
ence of amylo-dextrin. From another portion of the solution, precipitate
the dextrin by adding strong alcohol ; filter and wash the precipitate with
alcohol, dissolve in a little water and reserve for a future experiment.
Use a little of the solution for fastening together pieces of paper ; notice
that it exhibits the ordinary properties of gum.

200. Maltose and other Sugars. — Take from 5 to 10 grams of ground
malt, and mix with ten times the quantity of water, place the mixture in
a beaker arranged in a hot-water bath, and keep it at a temperature of
60° C. for half an hour : this may be done by turning down the flame, or
altogether removing it from time to time. The temperature may range
from 55 to 65° C., but must not be allowed to go above the latter. At the
end of the half -hour, raise the temperature to the boiling point for five
minutes, and then filter ; the resultant liquid is a solution of maltose and
dextrin, and may be used for experiments on maltose.

Prepare solutions of the following substances, and test them with Feh-
1 ing's solution : (1), starch; (2), the re-dissolved alcoholic precipitate of-

THE CARBOHYDRATES. 91

dextrin; (3), aqueous extract of malt; (4), cane sugar; and (5), commer-
cial glucose.

Set some distilled water boiling in a flask or large beaker for half an
hour. Take 20 c.c. of the mixed Fehling's solution (see Chapter
XXIV.), add an equal quantity of the boiled distilled water, and set in
the boiling hot-water bath for ten minutes; notice that no precipitate is
produced. Heat five separate portions of 20 c.c. of Fehling's solution,
and 20 c.c. of water to the boiling point, and add respectively 20 c.c. of
the starch and other solutions previously prepared. Let them all stand in
the hot- water bath for ten minutes : at the end of that time some of the
solutions will probably be decolourised with the deposition of a copious
red precipitate, while others will remain unchanged. The results should
be as follows : —

Starch — No precipitate.

Dextrin — Very slight precipitate, due partly to the slight reducing
action of dextrin itself, and partly also to the difficulty of
thoroughly washing the dextrin free from maltose.

Maltose — Red precipitate.

Cane sugar — No precipitate.

Glucose — Red precipitate.

CHAPTER VII.
THE PROTEINS.

201. Character of Proteins. — The proteins, while not the most
abundant constituents of wheat and flour, are yet among the most
important. In whatever life exists, and in that physical basis of life, pro-
toplasm, proteins are constantly and invariably present. In matters of
animal origin, such as muscle, blood, milk, the proteins constitute a larger
proportion of the water-free material than in most vegetable bodies, and
much of the work of examining and classifying proteins has been first
done on those derived from animal sources. All animal proteins are,
however, derived either directly, or indirectly through the body of some
other animal, from the proteins of the vegetable kingdom. The name pro-
tein is derived from the Greek word for pre-eminence, and has been
given to these bodies because of their great importance in the animal
economy. Typical among the protein bodies is albumin, the essential con-
stituent of the white of egg ; so much so that the term ' ' albuminous ' ' sub-
stance was often used as a synonym of protein. With a more minute
classification of the proteins, the term albumin was restricted to one par-
ticular protein group ; and the term ' ' albuminoid, ' ' commonly employed
as bearing the same meaning as ' t protein, ' ' was restricted to gelatin and
certain other bodies which are not proteins, but bodies bearing a resem-
blance or relationship to the group of which albumin is the typical
member.

202. Nomenclature of the Proteins. — The proteins were formerly
known as proteids, but in view of the confusion arising from the lack of
understanding as to the exact sense in which the various names applied to
proteins should be used, the Physiological Society and the Chemical
Society conjointly considered the subject through a Committee nominated
by the two Societies. Their final report contained the following recom-
mendations : — •

I. The word Proteid should be abolished.

II. The word Protein is recommended as the general name of the
group of substances under consideration. If used at all, the term Albu-
minoid should be regarded as a synonym of protein. The substances gel-
atin and keratin, which have hitherto been termed albuminoids in the
limited sense in which physiologists have been accustomed to use it,
should be called sclero-proteins (Proc. Chem. Soc., 1907, xxiii, 55).

This restricted use of the term "albuminoid" has not, however, been
universally adopted, as the word is still used as meaning the same as pro-
tein, while in more recent nomenclature the name has been appropriated
to a small sub-group of "simple proteins."

203. Composition of Proteins. — The proteins are distinguished in
composition from the carbohydrates by their containing nitrogen and in
most cases sulphur as essential constituents, in addition to carbon, hydro-
gen, and oxygen. They are substances of extremely complex constitution,
and have very high molecular weights. They are colloid bodies, and for
the most part uncrystallisable. The various proteins differ somewhat in

THE PROTEINS. 93

composition: the following table gives the ranges of variation in per-
centages : —

C H N S 0

From 50.0 6.9 15.0 0.1 20.9
To 55.0 7.3 19.0 2.0 23.5

From these figures various observers have attempted to assign empiric
formulae to the proteins, but in this there is some difficulty, as methods
such as that of Raoult, which was so useful with the carbohydrates, cannot
-be applied to the proteins. Compounds are, however, known of egg
albumin with copper, and of seed globulins with magnesium and other
metals, and from these some idea of the complexity of the protein mole-
cule can be gained. Thus the compound of one atom of copper with egg
albumin has the following formula : CuC204H322N52S2066, while from the
globulin metallic compounds the formula, C292H481N00S2O83, has been sug-
gested for globulin. Plimmer gives C726H1174N194S36214 as the formula of
globin, the basis of haemoglobin.

Within the last ten years Fischer and his co-workers have done much
to make clear the actual constitution of the proteins. Plimmer in his
monograph on the Chemical Constitution of the Proteins remarks that:
"The main results of these [Fischer's] investigations is that the protein
molecule is built up of a series of amino-acids, which form the basis of
their composition, and of which [some eighteen] have been definitely
determined.'/' By the condensation together, or combination with the
elimination of molecules of water, the amino-acids are converted into a
class of products which Fischer terms the "polypeptides." These form
an -essential part of the protein molecule, which may also, however, con-
tain other groups such as phosphoric acid or possibly carbohydrates.

Among the amino-acids which occur in proteins is a thio- or sulpho-
acid, known as cystine, which is di- /?-thio-a-amino-propionic acid), and
may be represented by the formula—

S.CIL.CH (NIL). COOII.

S.CH2.CH(NH2).COOIT.

Recent research has shown that cystine is the only sulphur-containing
compound in the protein molecule, and consequently that the number of
sulphur atoms in such molecule must be two or a multiple of two. As
sulphur is found in all proteins (except the protamines and histones), it
follows that they must all contain cystine as an essential constituent.

204. Reactions of Proteins. — Protein substances are distinguished
by their evolving ammonia on being strongly heated. This is at once
noticed on burning pieces of quill or dried gluten, both of which consist
largely of protein bodies. If the suspected substance be heated to near
the boiling point of concentrated sulphuric acid, to which a little potas-'
shim sulphate has been added, the whole of its nitrogen is converted into
ammonium sulphate, from which free ammonia is obtained by adding
caustic soda in excess, and subjecting the liquid to distillation. This
reaction forms the basis of what is known as Kjeldahl's method for the
determination of nitrogen in organic compounds. In examining sub-
stances for proteins, and especially in discriminating the various proteins
from each other, their following characters are of importance — solubility,
heat coagulation, indiffusibility, action on polarised light, and colour
reactions.

Solubility. — All proteins are insoluble in absolute alcohol and in ether.
Some are soluble in water, others insoluble ; among the latter, many are

94 THE TECHNOLOGY OF BREAD-MAKING.

soluble in weak saline solutions. Some proteins are soluble and others
insoluble in strong or saturated saline solutions.

Mineral and acetic acids, and also caustic alkalies, dissolve all proteins
by the aid of heat, such solution being, however, accompanied by decom-
position. The gastric and pancreatic juices also dissolve proteins, but, in
so doing, change them into a sub-class of proteins, known as peptones.

Heat Coagulation. — This is a very familiar characteristic of some pro-
teins, chief among them being albumin from the white of egg, which on
being plunged into boiling water assumes an insoluble form. Many pro-
teins when dissolved either in water or dilute saline solutions are coagu-
lated by the action of heat. The temperature at which coagulation occurs
affords one method of determining the nature of the particular protein in
the solution. Distinct from heat coagulation is what is known as ferment
coagulation, an instance of which is the coagulation of milk by rennet.

Indiff Visibility. — All the proteins (with the exception of the peptones)
are highly colloid bodies, and when in solution may consequently be sep-
arated from crystalline bodies by dialysis.

Action on Polarised Light. — All proteins turn a ray of polarised light
to the left, or are laevo-rotatory.

Colour Reactions — Xanthoproteic Reaction. — These are very useful
methods of detecting and recognising proteins. The Xaiithoproteic
reaction is obtained in the following manner : Add to the solution under
examination a few drops of strong nitric acid ; a white precipitate may or
may hot be produced, according to the nature and degree of concentra-
tion of the protein. (Peptones and some varieties of albumose give no
precipitate.) Boil; the precipitate or liquid turns yellow, with usually
some solution of any precipitate. Cool and add ammonia; the yellow
liquid or precipitate turns orange. This colouration is the essential part
of the reaction, and is the most delicate test for proteins we possess.

Millon's Reaction. — Dissolve, by the aid of gentle heat, one part by
weight of mercury in two of strong nitric acid ; dilute with twice its vol-
ume of water, and allow the precipitate to settle ; the clear supernatant
liquid is Millon's reagent. On the addition of a few drops of .this to a
solution of protein, a white precipitate forms, which, on being heated,
assumes a brick-red colour. The reaction is prevented by the presence of
sodium chloride. Other substances are precipitated by Millon's reagent,
but the precipitate does not turn red on boiling.

Piotrowski's or "Biuret" Reaction. — Add to the solution of albumin
or similar protein a few drops of dilute solution of copper sulphate; a
precipitate of copper albuminate is formed, except with deutero-albumose
and peptone. Add excess of caustic potash or soda, a violet solution is
produced. Ammonia gives a blue solution.

In the case of albumoses and peptones, the result is, instead, a rose-red
solution with potash, and a reddish-violet with ammonia. Care must be
taken not to add excess of sulphate, as so doing gives a reddish-violet
colour, very difficult to distinguish from this peptone reaction. When
this test is applied in the presence of salt solutions it may be somewhat
modified : thus, magnesium sulphate is precipitated as magnesia by pot-
ash ; before the colour can be observed the precipitate must be allowed to
subside. If ammonium sulphate is present, a large quantity of potash i^
necessary before the colour appears ; sodium chloride does not affect the
reaction.

205. Precipitation of Proteins. — The preceding note on the solubil-
ity of proteins affords some clue to their various modes of precipitation,
the peptones and albumoses being much more soluble than other proteins^

THE PROTEINS. 95

Solutions of the proteins may be precipitated by the following bod-
ies : — Strong mineral acids, especially nitric acid; acetic acid; and also
with excess of sodium sulphate, sodium chloride, or magnesium sulphate.
Salts of the heavy metals, as mercuric chloride or basic lead acetate, also
precipitate proteins ; on suspending the precipitate in water, and passing
a stream of sulphuretted hydrogen, the metal is precipitated and the pro-
tein recovered in an unchanged form. In addition, proteins are precipi-
tated by tannin, or tannin and sodium chloride together; by saturation
with ammonium sulphate ; by picric acid ; and by alcohol in faintly acid
solutions.

Among these the following are convenient methods of removing
proteins from a solution, either as a part of the process for their own
isolation, or as a prior step toward examining the liquid for other sub-
stances : —

1. The solution is mixed with half its volume of a saturated solution
of common salt, tannin is added in slight excess, and the proteins are
entirely separated.

2. The solution is saturated with ammonium sulphate, which precipi-
tates all proteins but peptones.

3. The solution is rendered faintly acid with acetic acid, several
times its volume of absolute alcohol added, and allowed to stand twenty-
four hours. The whole of the proteins are thus precipitated.

4. When proteins of the albumin or globulin group only are present,
simple acidulating and boiling the solution precipitates the proteins.

206. Classification of Proteins. — Proteins are commonly divided into
animal and vegetable proteins, according to their origin. Strictly speak-
ing, the animal proteins have but little to do with the present work, but
as their classification is largely that on which the classification of those
from vegetable bodies is also based, a short account of the animal proteins
is here inserted.

207. Animal Proteins. — These are conveniently arranged in the fol-
lowing groups : —

Class 1. Albumins, soluble in water, in dilute saline solutions, and
saturated solutions of sodium chloride and magnesium sulphate. Precipi-
tated from their solutions by saturation with ammonium sulphate. Co-
agulated by heat, usually about 70°-73° 0.

Members of class — Serum albumin, egg albumin, cell albumin, muscle
albumin, lact-albumin.

Class 2. Globulins, soluble in dilute saline solutions; insoluble in
water, concentrated solutions of sodium chloride, magnesium sulphate,
and ammonium sulphate. Coagulated by heat, temperature varying con-
siderably.

Members of class — Fibrinogeii, serum globulin, crystallin ; vitellin, in
the yolk of egg, not precipitable by sodium chloride.

Class 3. Albuminates, or Derived Albumins, derived from either albu-
mins or globulins by the action of weak acids or alkalies. On heating a
solution of egg albumin to about 40° C. with a few drops of 0.1 per cent,
sulphuric acid or 0.1 per cent, potash solution, the solution loses its prop-
erties and becomes converted into acid-albumin or syntonin, or alkali-
albumin respectively.

Albuminates are soluble in acid or alkaline solutions or in weak saline
solutions ; insoluble in pure water, precipitated like globulins by satura-
tion with sodium chloride, magnesium sulphate, or ammonium sulphate.
Solutions not coagulated by heat.

Caseinogen, the chief protein constituent of milk, is an albuminate.

96 THE TECHNOLOGY OF BREAD-MAKING.

Class 4. Proteases, intermediate products in the hydration of proteins,
formed in the body by the action of the gastric and pancreatic juices, arti-
ficially by heating with water, and more readily by dilute mineral acids.
Are not coagulated by heat, precipitated by alcohol, all give the biuret
reaction. Precipitated by nitric acid, precipitate soluble on heating, and
reappearing as the liquid cools.

The proteoses are subdivided into albumoses, globuloses, etc., accord-
ing to the original protein from which derived, albumin, globulin, etc.
Each group of proteoses may be further subdivided in a similar manner ;
taking albumose, there are two varieties, hemi-albumose and anti-albu-
mose, which on further digestion are converted into hemi-peptone and
anti-peptone respectively. Classified according to their solubilities, they
are divided into —

Proto-albumose, soluble in cold and hot water and in saline solutions ;
precipitated like globulins by saturation with sodium chloride or magne-
sium sulphate.

Hetero -albumose, insoluble in water ; soluble in 0.5-15 per cent, sodium
chloride solution in the cold, but precipitated by heating to 65°. Pre-
cipitated from its solutions by dialysing out the salt, like globulins. Pre-
cipitated by saturation with salts. Proto- and hetero-albumose are often
called primary albumoses, because they are the first products of hydra-
tion of proteins.

Deutero-albumose, soluble in hot and cold water, not precipitated from
its solutions by saturating with sodium chloride or magnesium sulphate,
but precipitated by ammonium sulphate, is an intermediate stage in the
conversion of the primary albumoses into peptone.

Class 5. Peptones are the final product of the hydration of proteins ;
further hydration splits up the peptone into simpler bodies, which are no
longer proteins. The peptones are soluble in water, not coagulated by
heat, and are not precipitated by nitric acid, copper sulphate, ammonium
sulphate, and a number of other precipitants of proteins. Precipitated,
but not coagulated, by alcohol. Precipitated by tannin, picric acid, and
other substances. They give the biuret reaction.

Pure peptone may be separated from all other proteins by ammonium
sulphate : the solution is then subjected to dialysis in order to remove the
sulphate, and the peptone precipitated by alcohol. It may then be dried
by washing with absolute alcohol, ether, and finally standing in desiccator
over sulphuric acid, a vacuum being maintained in the desiccator by a
sprengel or other air-pump. Peptone thus prepared hisses and froths on
being dissolved in water, with evolution of heat.

Peptone is somewhat cheesy in taste, but not unpleasant. Artificially
prepared peptones, as peptonised milk or beef extract, have a bitter taste.
This is due, however, to some bitter substance not yet separated, native
peptones and albumoses being almost tasteless.

Hemi-peptones are split up by the pancreatic juice into simpler prod-
ucts, as leucine and tyrosine. Anti-peptone is not decomposed in this
manner.

Both varieties of peptone are readily dialysable ; albumoses are only
slightly diffusible under similar conditions, while the albumins and glob-
ulins are highly colloid.

Class 6. Coagulated Proteins. — (a] Coagulated by heat, are insoluble
in water, weak acids, and alkalies. Soluble after prolonged boiling in
concentrated mineral acids, also in gastric and pancreatic juice with for-
mation of peptones. (&) Coagulated by ferments, fibrin from blood,
myosin from muscle, casein from milk.

THE PROTEINS. 97

208. Vegetable Proteins. — As previously stated, plants contain a
less proportion of protein matter than animals. They may be found in
solution in the sap or juice of plants, or in the solid state in the proto-
plasm of the plant cells, and in a comparatively dry condition in the ripe
seeds. Protein is often found in granules (aleurone grains). Some of the
vegetable proteins are obtainable in a crystalline form. The classification
adopted for the animal proteins is in the main applied to those of vege-
table derivation.

209. More Recent Official Classification. — In the years 1907 and 1908
committees were appointed by scientific societies in America and England
respectively in order to settle a scheme of classification and nomenclature
of the proteins. The American scheme was of the two the more complete,
inasmuch as it definitely provided for the inclusion of the vegetable pro-
teins. Their classification contained the following groups : —

I. THE SIMPLE PROTEINS.

(a) Albumins.
(6) Globulins.

(d) Alcohol-soluble Proteins (Prolamins) .

(e) Albuminoids.
(/) Histones.
(g) Prot amines.

II. CONJUGATED PROTEINS.

(a) Nucleoproteins.

( b ) Glycoproteins.

(d) Haemoglobins.

(e) Lecithoproteins.

III. DERIVED PROTEINS.

1. Primary Protein Derivatives —
(a) Proteans.

(6) Metaproteins.

2. Secondary Protein Derivatives —
(a) Proteoses.

(&) Peptones.
(c) Peptides.

Although the classification of the vegetable proteins largely follows
that of animal proteins, the special character of those of vegetable origin
necessitates some little modification of the definitions as deduced from
the investigation of the animal compounds.

The following explanations of the various classes are made with spe-
cial reference to the vegetable section, and do not agree in every detail
with the properties already given of the animal groups.

210. Simple Proteins. — Albumins. These have been already defined
as " soluble in water and coagulated by heat," but a more recent classifi-
cation has been based upon the behaviour of albumins and globulins
respectively to a half-saturated solution of ammonium sulphate. The
portion of protein which under these conditions remains in solution is
regarded as albumin. This does not hold good with the vegetable albu-
mins, since some at least are precipitated by this treatment. Again, in

98 THE TECHNOLOGY OF BREAD-MAKING.

the case of the vegetable albumins it is often difficult to say whether such
a body is soluble in pure water, or whether its solubility is due to the
presence of small quantities of mineral salts. One of the best studied
vegetable albumins is the leucosin of wheat, and this is soluble in water
containing merely the slightest traces of mineral matter. The following
are examples of vegetable albumins : —

Leucosin from the seeds of wheat, rye and barley.
Legumelin from the seeds of pea and lentil.

Globulins. — The previous definition of these states them to be "insolu-
ble in water, soluble in dilute saline solutions ' ' ; but among the vegetable
globulins are classed certain bodies which only have the properties of the
globulins when existing as protein salts through combination with small
quantities of acid. On being freed from this acid, they become soluble in
water, and thus no longer conform to the definition of the class. From
their mode of preparation it is nevertheless convenient to include them in
this group.

Globulins were formerly subdivided into two groups according to
whether or not they can be precipitated from a solution by saturation
with sodium chloride. This operation, known technically as "salting-
out," separates the bodies known as myosins from solution. Those re-
maining unchanged were termed vitellins. In the case of the vegetable
globulins, this distinction does not hold good, as certain so-called myosins
are in fact albumins, while some vegetable vitellins are only partly solu-
ble in saturated sodium chloride solution. The body referred to as wheat
myosin is really the albumin leucosin. All vegetable globulins, so far as
has been at present ascertained, are completely precipitated by saturation
with sodium sulphate at a temperature of 33° C. The animal globulins
may all be coagulated by heat, but most of those of seeds are only imper-
fectly coagulated by heating their solutions even to boiling. A character-
istic of a number of the vegetable globulins is that they may be obtained
in a crystalline form, while others can be separated as minute spheroids.
The following are examples of vegetable globulins : —

Legumin from the seeds of pea and lentil.
Tuberin from the tubers of potato.
Unnamed globulin from the seeds of wheat.

The globulin of wheat is mostly if not all contained in the embryo or
germ.

Glutelins. — These consist of proteins which are insoluble in neutral
aqueous solutions, saline solutions, or moderately concentrated alcohol
(about 70 per cent, spirit). The most characteristic and only well ex-
plored member of this group is the glutenin of wheat. Similar proteins
probably exist in other seeds, such as those of rye and barley, and also,
according to Rosenheim and Kajiura, in rice. The rice glutelin has re-
ceived the name oryzenin, and is said to represent the greater portion of
the protein of the seed.

Prolamins. — Certain seed proteins are soluble in alcohol of from 70 to
90 per cent, strength. Representatives of this group have been obtained
from all seeds of cereals except rice ; further, they have never been found
in the seeds of any other family of plants. The suggestion has been made
that these proteins should be called "gliadins," but as that name has
already been appropriated to alcohol-soluble protein of wheat, Osborne
has proposed the group name of * ' prolamins, ' ' because on hydration they

THE PROTEINS. 99

yield considerable quantities of proline and amide nitrogen. The follow-
ing are examples of prolamins : —

Gliadin from the seeds of wheat and rye.

Hordein from the seeds of barley.

Zein from the seeds of maize.

Albuminoids, etc. — The remaining simple proteins, albuminoids, his-
tones, and protamines, are not found to occur in plants.

211. Conjugated Proteins. — Nucleoproteins. These bodies, called also
micleins, occur in the cells of animals and plants. Thus yeast yields a
body represented, according to Miescher, by the formula C29H49N9P3022.
This substance contains phosphorous in considerable quantity (9 per
cent.), and is extremely resistant to the action of pepsin. Nucleoproteins
may be regarded as compounds of nucleic acid with the proteins, which
latter have been shown to have basic properties. Nucleic acid, in turn, is
viewed as a compound of albumin with phosphoric acid. Nucleoproteins
are found in the protein constituents of wheat germ.

Glycoproteins. — These bodies are proteins, containing either a carbo-
hydrate or carbohydrate generating group within their molecule. There
is, however, no definite evidence of the occurrence of glycoproteins in"
plants.

Phosphoproteins. — Egg yolk contains a protein of the globulin type,
of which phosphorus is an essential ingredient, and to which the name of
vitellin has been given. It has been assumed that certain vegetable pro-
teins are also of this class ; but vitellin may be repeatedly redissolved and
re-precipitated without losing its phosphorus, whereas vegetable proteins
containing phosphorus are thereby completely freed from that element.
The conclusion is that the existence of true vegetable phosphoproteins
has not as yet been proved.

Hemoglobins, etc. — It is doubtful whether any haemoglobins have been
obtained from plants, while lecithoproteins are also probably absent from
their constituents.

212. Derived Proteins.— Primary Protein Derivatives. Substantially,
by the action of dilute acids and alkalies, the vegetable proteins undergo
similar changes to those of animal origin when treated in a like manner.
The derived proteins are the bodies already described as Class 3. of ani-
mal proteins.

The proteaus and metaproteins do not need description as a part of
the present work.

Coagulated proteins. — Many of the proteins possess the property of
coagulation by heat, especially in the presence of a small quantity of 'free
acid. This holds good much more with those of animal origin, for the
corresponding seed proteins are in most cases only imperfectly coagulated
by heating their solutions even to boiling. Thus leucosin from wheat,
when obtained in solution by the extraction of wheat flour with water, is
partly coagulated at a temperature of 52° C., but is not entirely so
changed even at the boiling point.

Secondary Protein Derivatives. — Small quantities of proteoses arc
found in seeds, but it is difficult to say whether these existed as such in
the seeds, or have been produced by changes which have occurred during
the processes involved in their separation. Present evidence is not suffi-
cient to exclude the possibility of such changes, and therefore to demon-
strate their existence as original components of the seeds.

The same difficulties exist in the way of deciding whether or not pep-
tones occur in plants. They may be formed from vegetable proteins by

100 THE TECHNOLOGY OF BREAD-MAKING.

boiling with dilute mineral acids, or treatment with gastric or pancreatic
juices. Animal proteins are, as a rule, more easily peptonised than those
of vegetable origin ; thus papain, a vegetable enzyme, converts animal
proteins into peptones, but carries the change of vegetable proteins no
further than proteoses.

213. Albuminoids. — With the proposal, not universally adopted, to
restrict this term to a series of bodies outside the protein group, it will be
well to briefly state the character of albuminoids in this more restricted
sense. The tendons of animals contain a body known as "collagen,"
which is insoluble in water. By the action of dilute acids or boiling
water, collagen is transformed into gelatin : the process is one of hydra-
tion, represented, according to Hofmeister, by the following equation : —

C102H149N31028 + H20 = C10,II151N31028.

Collagen. Water. Gelatin.

The albuminoids, as thus classified, differ from the proteins in that
they contain no sulphur. Gelatin is insoluble in cold water, but dissolves
in hot water, gelatinising, or forming a jelly, on cooling.

214. Proteins of Wheat. — It is a fact too familiar to need experi-
mental demonstration, that the white of egg coagulates on being heated ;
but it will be found on further experiment, as may in fact be gathered
from the preceding description, that if the white of egg be shaken up
with considerable quantities of water and then heated, the albumin sepa-
rates out in coagulated flocks. Similarly on making a cold aqueous in-
fusion of flour, or, still better, of the germ of wheat, and then filtering
the solution until perfectly clear, a liquid is obtained which, on being
raised to the boiling point, throws down abundant flocks of albumin and
globulin. The coagulated protein thus obtained is as white and pure in
appearance as that frem the white of egg, and is closely allied to that of
mixtures of albumin and globulin of animal origin. While the egg albu-
min always occurs in an alkaline liquid, that of vegetables is always
found either in acid or neutral liquids.

Further, every miller and baker knows that flour, on being moistened,
forms a stiff, tenacious paste or dough; he also knows that the flour of
wheat is distinguished in a remarkable manner from other flours by this
character ; for oatmeal, when similarly treated, simply produces a damp
mass, having little or no tenacity. On kneading a mass of wheaten dough,
enclosed within a piece of muslin, with water, until the starch is sepa-
rated, there remains behind a greyish-white sticky elastic mass, to which
the name of "crude gluten" is applied. This substance consists of the in-
soluble proteins of the wheat, together with portions of the ash, carbohy-
drates, and oily matter. Although this gluten, when in the flour, existed
as a powder, yet, on the addition of water, it thus swells up into a tough
mass. Gluten is practically insoluble in water, and without taste; on
being dried by exposure to the heat of the hot-water oven, it changes into
a hard horny mass. Gluten which has been thus moistened with water,
provided it is dried at a low temperature, swells up again on being wet-
ted, although not usually to such a tough mass as when first extracted.
Osborne, with whom has been associated a number of other chemists, has
for some years been engaged in a systematic investigation of the vege-
table proteins ; in 1893 he, in association with Voorhees, communicated to
the American Chemical Journal an article of great importance on "The
Proteids [Proteins] of the Wheat Kernel." This article contains a his-
torical resume of the work previously -done on these compounds, and also

THE PROTEINS. 101

includes the results of their own elaborate investigations on wheat pro-
teins, conducted on the lines of the most recent knowledge of the -constitu-
tion of proteins generally. The following description is very largely
based on Osborne and Voorhees ' article, which is still the most authorita-
tive exposition of the properties of the wheat proteins. It is, in fact, not
too much to say that science generally is indebted to Osborne for most of
the work that has as yet been done on the vegetable proteins.

215. Earlier Researches. — After recounting the' ressiUfc of the "re-
searches of Taddei, Berzelius, Mulder, Gunnsberg, • -and' others, Kitt-
hausen's conclusions are mentioned, in which that'cnemist reco^fii'std -in
1872 that wheat contains five protein bodies, to whish h'e'gave thti liames
of gluten casein, gluten fibrin, plant gelatin or gliadin, mucedin, and
albumin. He expressed a doubt as to the presence of albumin, as what
was viewed as this body might possibly be a mixture of mucedin and
gliadin.

In 1880, Weyl and Bischoff published the view that the protein matter
of wheat is principally a myosin-like globulin, which they call vegetable
myosin, and, if this view be correct, they further assume that it is from
this substance that gluten is derived, other proteins only being present in
small quantity. They extracted flour with a 15 per cent, salt solution,
and found that the residue yielded no gluten ; they consequently assumed
that gluten is formed from myosin as a result of a ferment action simi-
larly to the formation of blood-fibrin from fibrinogen. No ferment pos-
sessing such properties could, however, DC detected. Large quantities of
sodium chloride and other salts prevent the formation of gluten in the
same way as these salts also prevent the formation of fibrin. On first
heating flour with alcohol, they found that subsequently no gluten could
be obtained on washing, and so assumed that the myosin had been coagu-
lated. Also, on warming flour for from 48 to 96 hours, keeping the tem-
perature below 60° C., the coagulation point of myosin, and then adding
a little unwarmed flour and extracting gluten from the mixture, no
gluten is obtained beyond that present in the added flour, showing in
Weyl and Bischoff 's opinion that the gluten-forming substance had suf-
fered coagulation.

Martin in 1886 examined gluten by extraction with alcohol — he found
but one protein substance so extracted. This body is soluble in hot water,
but is insoluble in cold, and so is insoluble phyt-albumose. The residue
insoluble in alcohol is uncoagulated protein, soluble in dilute acids and
alkalies ; this he terms gluten-fibrin. The insoluble phyt-albumose is not
present as such in flour, as direct extraction of the meal with 75 per cent,
alcohol removes no protein. Martin concluded that the insoluble phyt-
albumose is formed from the soluble by the action of water, the gluten-
fibrin being formed by a similar action of water on the globulin, that is,
conversion into an albuminate. The albuminate and insoluble phyt-
albumose together constitute gluten.

Johannsen, 1889, combats the ferment theory of the production of
gluten. He found that a normal dough was obtained by grinding dried
gluten and mixing with starch, and also by mixing moist gluten with
starch.

216. Osborne and Voorhees' Experiments, Wheats used. — One of
these was a Minnesota spring wheat, Scotch Fife, milled under chemical
supervision into "patent" flour from finest and purest middlings, and
"straights" from the coarser middlings. The "shorts" (red-dog?),
chiefly composed of inner portions of the bran, with adhering portions of

102 THE TECHNOLOGY OF BREAD-MAKING.

the endosperm, was also examined. Samples of whole wheat flour were
prepared direct from the wheat by grinding in the laboratory when re-
quired. A variety of winter wheat, known as "Fultz," was also exam-
ined, but only as whole wheat flour. Preliminary investigations showed
that all these different flours yielded protein matter to —

Diluted alcohol,

Water,
„ . 10 per t}e;a&. ;sodium chloride solution,

And after complete and successive extractions with these reagents,
-, / . ; ;- U' dilute 'petash water.

Tlie bodies" extracted by these various reagents will be examined sepa-
rately.

217. Proteins Soluble in Water. — In the course of some preliminary
experiments, 200 grams of spring wheat straight flour were mixed with
800 c.c. of distilled water. No coherent gluten formed, the undissolved
flour settling down as a non-coherent mass. After a few hours' digestion
the solution was filtered ; the filtrate was straw-yellow in colour, becoming
red-brown on standing, and had a very slight acid reaction.

Saturation with ammonium sulphate gave a bulky precipitate, which
contracted on standing, showing the solution to contain but little protein
matter. After 24 hours this precipitate was completely soluble in water,
giving no evidence of the formation of so-called albuminates. Saturation
with sodium chloride gave a small precipitate. Acetic acid in the cold
gave no precipitate until sodium chloride was added.

On slowly heating, the solution gave a turbidity at 48° C., and a floc-
culent coagulation at 52°. After heating to 65° for some time and filter-
ing, the solution became turbid again at 73°, flocks forming in very small
amount at 82°. Heating to boiling caused no further separation ; but the
addition of a little acetic acid and sodium chloride gave a small precipi-
tate. The body coagulating at 52° formed the greater part of the protein
in solution. The complete coagulation of this required a temperature of
65°, but was greatly facilitated by the addition of sodium chloride.

Further experiments showed that extraction of the flour with 10 per
cent, salt (sodium chloride) solution yielded the same proteins, so that
the subsequent examination of the water-soluble substances was confined
to extracts originally made with 10 per cent, salt solution after separation
of the globulins by dialysis.

Again, 4000 grams of straight flour were treated with 8 litres of 10
per cent, brine, allowed to subside over night, and the supernatant liquid
filtered off. Another 2 litres of the brine were added to the residue,
which was stirred up, allowed to settle, and again filtered. The filtrate
was saturated with ammonium sulphate as rapidly as collected. The pre-
cipitate thus procured was filtered and redissolved in 10 per cent, brine,
filtered clear, and dialysed until the chloride had disappeared. This
resulted in the precipitation of a globulin, which was filtered off, and the
solution again dialysed for 14 days, but with no further production of
globulin.

The globulin-free solution was next examined by slowly heating a por-
tion— turbidity occurred at 48°., flocks separating at 55°. After heating
at 65°, the coagulum was filtered off. Further heating resulted in a
minute amount of coagulum being formed at 80° : after filtering, there
was no further precipitate on boiling, and nothing was obtained by add-
ing a little salt and acetic acid. On adding 20 per cent, salt solution and
a little acetic acid to the original solution, a precipitate was caused ;

THE PROTEINS. 103

another portion was first heated to 65°, and a third to 95°, and filtered
before adding the salt solution and acetic acid. The second gave less, and
the third least precipitate. The filtrate from the first of these portions,
when neutralised and boiled, gave no precipitate, showing that, as was to
be expected, the separation of albumin by precipitation with salt and
acid was complete.

This globulin-free solution gave a precipitate on saturation with
sodium chloride, the filtrate became flocculent at 56°, with no further
precipitate on further heating, showing that the higher coagulating pro-
tein had been thus removed. Treatment of the globulin-free solution with
nitric acid yielded a precipitate, a portion of which dissolved on heating,
the rest remaining insoluble : after filtration, the filtrate deposited a pre-
cipitate on cooling, which again dissolved on re-application of heat. The
filtrate from the salt and acid precipitate did not give this reaction,
which is characteristic of certain proteoses, and shows that the salt and
acid precipitate contains a proteose, together with the albumins. Three
distinct protein substances are thus recognised which are soluble in pure
water; two coagulable, one at a higher temperature than the other, and
presumably both albumins and a proteose.

To make sure that the body, which was apparently an albumin, was
not a myosin-like globulin held in solution by the salts naturally present
in river water used for dialysis, a strong aqueous solution of winter wheat
meal was dialysed into distilled water in the outer vessel. The solution
still coagulated at 54°, and contained in 250 c.c. only 0.0008 gram of
mineral matter, proving the substance was an albumin.

218. Albumins. — The remainder of the globulin-free solution, after
making the foregoing tests, was heated to 61°, the precipitate filtered,
washed with water, alcohol, absolute alcohol, and ether, dried over sul-
phuric acid, and heated to 110° ; this was called Preparation 1.

A duplicate lot was prepared in the same way, and yielded 6.4 grams
from 10,000 grams of flour ; this was called Preparation 2.

The filtrate from Preparation 2 was further heated to 75°, and the
small amount of precipitate washed with alcohol and dried as before ; this
was called Preparation 3.

Another preparation was made on the same flour by extracting with
10 per cent, brine, and dialysing at once without precipitation by ammo-
nium sulphate. After the separation of the globulins, the albumins were
precipitated by at once raising the temperature to 90° ; this, after drying,
constituted the Preparation No. 4.

Another preparation was made on the spring wheat "shorts," by ex-
traction with 10 per cent, salt solution, treatment with ammonium sul-
phate, dialysis, coagulating albumin at 65°, and drying; this was Prep-
aration 5.

These substances gave on analysis the following results : —

ANALYSES OF COAGULATED WHEAT ALBUMIN.

1 23 45 Average.

Carbon 53.27 53.06 53.02 52.71 53.02

Hydrogen .. .. 6.83 6.82 6.87 6.85 6.84

Nitrogen 16.95 17.01 16.94 16.26 16.83 16.80

Sulphur .' 1.27 1.30 1.20 1.34 1.28

Oxygen 21.68 21.81 — 22.65 22.27 22.06

100.00 100.00 — 100.00 100.00 100.00

104 THE TECHNOLOGY OF BREAD-MAKING.

These figures agree very closely, except that the nitrogen in No. 4 is
low: as four determinations give concordant results, Osborne and Voor-
hees consider it possible that some of the nitrogen may be lost at the
higher temperature.

219. Proteoses. — As already stated, there are found in the solution
after separating the globulins by dialysis, and the albumins by heating,
small quantities of one or more proteoses which are almost wholly pre-
cipitated by saturation with sodium chloride. On concentrating the fil-
tered solution, after the removal of albumins by heat, a coagulum grad-
ually develops, which must be derived from the proteose-like protein still
remaining in solution before concentration.

This body gave on analysis the following figures :

Carbon 51.86

Hydrogen 6.82

Nitrogen 17.32

Sulphur} . 24.00
Oxygen \

100.00

The small quantity of proteose still remaining after removal of the
coagulum was not separated for analysis. In analyses quoted later, para-
graph 234, the amount of this proteose is seen to be as much or more than
that of the coagulum.

220. Globulin. — The extraction of this body has already been re-
ferred to : in a direct experiment for the preparation of globulin, 10,000
grams of "straight" flour were extracted with 34 litres of 10 per cent,
salt solution, stirred and allowed to stand over night. This was filtered,
precipitated by saturation with ammonium sulphate, filtered and again
dissolved in 10 per cent, brine. The solution produced was exceedingly
viscid, and filtered with extreme difficulty ; this was placed in a dialyser
and left in a stream of running water until the chlorides were removed.
The globulin gradually separated out in minute particles of spheroidal
form. The precipitate was filtered, washed with water, alcohol, and ether,
dried over sulphuric acid and then weighed 5.8 grams. Globulin, thus
prepared, dissolves in 10 per cent, salt solution, from which it is precipi-
tated by the addition of water. Saturation with sodium chloride gives no
precipitate, but saturation with magnesium sulphate, or ammonium sul-
phate, completely precipitates the globulin. The solution in 10 per cent,
brine gives, on slow heating, a very slight turbidity at 87°, which in-
creases slightly up to 99°. Dried at 110°, this globulin constituted
Preparation 8.

A preparation was also made in the same way, except that the pre-
cipitation with ammonium sulphate was omitted. Again the solution was
remarkably viscid, a property possibly due to the presence of gum, for
the pure solution of globulin in 10 per cent, brine showed no trace of it,
neither did an aqueous solution of the flour. On dissolving up the globu-
lin obtained by dialysis in 10 per cent, salt solution, a residue remains,
consisting of an ' ' albuminate " derived from the globulin. This globulin
constituted Preparation 9.

The globulin was also extracted from the "shorts," and its total
quantity amounted to nearly twice as much as was similarly obtained
from a like quantity of flour. This globulin was Preparation 10.

THE PROTEINS. 105
The globulins gave on analysis the following results : —
ANALYSES OF WHEAT GLOBULINS.

8 9 10 Average.

Carbon 51.07 51.01 51.00 51.03

Hydrogen 6.75 6.97 6.83 6.85

Nitrogen 18.27 18.48 18.26 18.39

Sulphur ioq Qi I °-71 °-66 °-69

Oxygen (^'yj (22.83 23.25 23.04

100.00 100.00 100.00 100.00

In contradistinction to the views held by Weyl and Bischoff, and Mar-
tin, Osborne and Voorhees have only found in extracts of wheat meal,
either spring or winter wheat, the one globulin just described ; which in
properties and composition closely resembles those globulins found in
other seeds.

221. Protein Soluble in Dilute Alcohol; Gliadin. — Whether wheat
flour be extracted direct with dilute alcohol, or after treatment with 10
per cent, salt solution, a considerable amount of protein is obtained. The
same is the case if the previously extracted gluten be subjected to alcohol
extraction. Extracts were made by alcohol under all these conditions,
and subjected to repeated fractional precipitations, in order to learn
whether a single protein body or a mixture had been obtained.

222. Direct Alcoholic Extraction. — In direct treatment with alcohol
5000 grams of "straight" flour were extracted with 10 litres of alcohol,
0.90 specific gravity, and allowed to soak over night. The mixture was
then stirred, allowed to settle, and the supernatant liquid poured off.
Three litres more of alcohol of the same strength were added, and pre-
sumably stirred in; after standing, the clear liquid was poured off, and
the residue put in a screw press and squeezed nearly dry. The whole of
the liquid thus obtained was mixed, and constituted "Extract 1." The
residue was again treated with 4 litres of 0.90 alcohol, and once more
pressed nearly dry; this liquid was "Extract 2." The same process was
twice more repeated, and the two extracts mixed, which gave "Extract
3." Each of the three extracts was filtered clear, and concentrated sep-
arately to one-third its volume, and after cooling decanted from the very
glutinous viscid mass which had separated. This precipitated mass was
in each case dissolved in a small amount of hot alcohol, sp. gr. 0.90, and
the solution allowed to cool over night : most of the substance separated
on cooling, and the liquid was decanted from it. The solutions were
treated with a quantity of distilled water and a little sodium chloride
added, the protein was thus precipitated, washed with water, absolute
alcohol, and ether, and dried. The residue was subjected to a series of
fractional precipitations based on the principle of partially dissolving
with alcohol of 0.820 sp. gr., and precipitating from the solution by the
addition of small quantities of sodium chloride solution, which precipitate
was washed, dehydrated with absolute alcohol, digested with ether, and
dried over sulphuric acid. A portion of the principal fraction was again
divided by solution in 250 c.c. of 0.90 alcohol, and partial precipitation by
pouring the solution into 800 c.c. of absolute alcohol ; precipitate and
solution were again treated separately. As the result of a series of frac-
tional precipitations, altogether thirteen fractions were prepared and
then analysed. These constituted Preparations 11 to 23. The results of

106 THE TECHNOLOGY OF BREAD-MAKING.

the whole series are given by Osborne and Voorhees, but five of the frac-
tions are discarded from the final comparison, because of their being'
impure, for obvious reasons. Some, for example, contain fat, while
others have concentrated in them the solid matter which in a series of
filtrations has passed through the filter papers. Subjoined is given the
results of these various analyses, and the weight of each fraction which
was obtained : —

ANALYSES OF " FRACTIONS" OF THE WHEAT PROTEIN OBTAINED BY
DIRECT EXTRACTION WITH DILUTE ALCOHOL.

Carbon

52.52

52.77

52.67

52.55

52.74

52.82

24 25

52.33

52.38

Hydrogen . .

6.78

.78

6.70

6.85

6.77

.81

.91

7.13

Nitrogen . .

17.64

.77

17.66

17.94

17.62

.67

17.69 17

.70

17.82

Sulphur . .
Oxygen . .

1.08
21.98

.26
.42

1.22
21.75

1.21
21.45

1.23
21.64

.11?
.57}

.06

22.67

100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

Weight of]

fraction in I 12.40 8.60 32.26 5.34 17.43 63.0
grams

Nos. 24, 25, 26 are fractional re-precipitations of fraction No. 21.

A study of this series of analyses shows that the whole of the fractions
are in remarkable agreement, and that no fractional separation of the ex-
tracted protein has been effected. For example, Nos. 15 and 16, which
are aqueous solutions, have the same composition as those from solution
in 0.820 alcohol, and also as the residue remaining after treatment with
these reagents. Osborne and Voorhees draw the conclusion that it may
be safely concluded that wheat contains but one protein soluble in dilute
alcohol. The total amount of protein contained in the whole of
these preparations is 207.83 grams, being equal to 4.16 per cent, of
the flour.

223. Alcoholic Extraction after Salt Solution Extraction. — For this
purpose 4000 grams of "straight" flour were taken, extracted with 10
per cent, salt solution so long as anything was removed, and then the
residue squeezed as dry as possible in a screw-press. This residue was
then treated with alcohol of such a strength as to yield with the water
retained in the flour as nearly as possible a solution containing 75 per
cent, of alcohol. Digestion with this solvent was continued for two days ;
the extract was squeezed in a press, and the process repeated three times,
giving altogether four extracts. These wrere concentrated to small bulk,
and the solution decanted from the separated mass, which was washed
with distilled water, re-precipitated by sodium chloride, washed with
absolute alcohol, digested with ether, and dried over sulphuric acid. The
precipitates obtained from the water washings by adding salt were treated
in the same way. The total weight of these preparations was 157.45
grams, equal to 3.94 per cent, of flour, as against 4.16 per cent, obtained
by direct extraction, showing that the dilute alcohol extract is different
and distinct from the proteins soluble in water. These constituted Prep-
arations 27-31. The table on the following page gives the result of their
analyses.

THE PROTEINS. 107

ANALYSES OF * ' FRACTIONS ' ' OF WHEAT PROTEIN OBTAINED BY EXTRACTION
WITH DILUTE ALCOHOL AFTER SODIUM CHLORIDE EXTRACTION.

2V 28 29 30 31

Carbon 52.69 52.72 52.71 52.65

Hydrogen 6.84 6.86 6.81 6.83

Nitrogen 17.73 17.89 17.75 17.08 17.79

Sulphur 1.02 0.95 1.10 1.08

Oxygen 21.72 21.58 21.63 21.65

100.00 100.00 100.00 100.00

Weight of fraction in)
grams }

Nos. 27-30 are the precipitates obtained from the four extracts ; No. 31
is obtained from the water washings of 27 and 28.

The results of these analyses agree very closely among themselves, and
also with the series obtained by direct alcoholic extraction.

224. Extraction of Gluten with Dilute Alcohol. — For the prepara-
tion of gluten, 2000 grams of ' ' straight ' ' flour were made into dough with
distilled water at 20°, and then washed in a stream of river water at 5°
C. When nearly the whole of the starch had thus been removed, the
gluten was chopped fine and digested with alcohol of 0.90 sp. gr. at a tem-
perature of about 20°. This extraction was repeated with fresh portions
of alcohol of the same strength so long as anything was removed. The
extracts were united, filtered clear, and evaporated down to one-fourth
their original volume. This was allowed to stand over night, and the
supernatant liquid decanted from the separated protein. This latter was
then dehydrated with absolute alcohol. The original mother-liquor from
which the protein had separated, and also the absolute alcohol used for
dehydrating, were each precipitated by a small quantity of sodium-
chloride solution. The three products were united, digested with absolute
alcohol, and then with absolute ether. After drying over sulphuric acid,
the Preparation No. 32 weighed 82.0 grams, and formed 4.10 per cent, of
the flour taken. In order to determine whether this substance was a
single protein or a mixture of more than one, the process of fractional
precipitation was again employed. Thirty grams of Preparation 32 were
dissolved in 0.90 alcohol, concentrated to small volume, and then strong
alcohol added till about half the substance taken had been precipitated.
The precipitate was treated with absolute alcohol, dried over sulphuric
acid, and found to weigh 12 grams; this constituted Preparation 33. The
solution was precipitated with water, dehydrated and dried over sul-
phuric acid ; it weighed 16 grams, and was marked Preparation 34. These
substances had the following composition : —

ANALYSES OF "FRACTIONS" OF THE WHEAT PROTEIN OBTAINED BY
EXTRACTION OF GLUTEN WITH DILUTE ALCOHOL.

32 33 34

Carbon 52.58 52.68 52.84

Hydrogen 6.67 6.78 7.18

Nitrogen 17.65 17.65 17.57

Sulphur 1.08 1.09} 99 , ,

'Oxygen 22.02 21.80 \

100.00 100.00 100.00

In this case also the analyses show clearly that no separation into pro-
teins of differing composition had thus been effected.

108 THE TECHNOLOGY OF BREAD-MAKING.

225. Extraction of ''Shorts" with Dilute Alcohol.— In order to
determine whether the "shorts" or bran flour yielded the same body to
dilute alcohol, 2000 grams were taken and subjected to much the same
process of extraction as was flour, except that greater precautions were
necessary in order to remove impurities. Two Preparations, Nos. 36 and
37, were obtained, which had the following composition: —

ANALYSES OF FRACTIONS OF WHEAT PROTEIN OBTAINED BY
EXTRACTION OF " SHORTS" WITH DILUTE ALCOHOL.

36 37

Carbon 52.85 52.74

Hydrogen 6.81 6.87

Nitrogen 17.48 17.67

Sulphur I 99 Q£ 99 79

Oxygen .. .. 22'72

100.00 100.00

A comparison of these figures with those which have preceded shows
that the protein extracted from the bran has a similar composition to that
obtained from the flour.

226. Extraction of Whole Wheat Meal with Dilute Alcohol.— In
view of the fact that Ritthausen, and probably others, employed whole
wheat meal in their investigations of the composition of wheat proteins,
Osborne and Voorhees decided to make some experiments on wheat meals,
in addition to those previously described. Accordingly, 1000 grams of
freshly ground whole spring wheat meal were taken, made into a dough,
and the gluten extracted. This was chopped fine, thoroughly extracted
with 0.90 alcohol, the extract concentrated, and the protein separated by
cooling. This deposit was dissolved as far as possible in dilute alcohol,
and the insoluble substance washed with absolute alcohol, and ether, and
dried over sulphuric acid. This was Preparation 38. The solution was
precipitated with absolute alcohol, dried as usual, and constituted Prep-
aration 39; the filtrate from this was concentrated to small volume,
poured into absolute alcohol, and the precipitate washed and dried as
before, giving Preparation 40.

In a similar manner, Preparations were made from winter wheat
meal; the coagulated protein was labelled 41, and that obtained by
further digestion, 42. These had the following composition : —

ANALYSES OF WHEAT PROTEINS OBTAINED BY EXTRACTION OF WHOLE
WHEAT MEAL WITH DILUTE ALCOHOL.

Spring Wheat. Winter Wheat.

38 39 40 41 42

Carbon 52.90 52.89 53.16 52.82 52.68

Hydrogen 6.99 6.87 6.83 6.88 6.81

Nitrogen 17.52 18.06 17.75 17.55 17.63

Sulphur 1.43 0.92 0.96J 99 ._ 99 ^

Oxygen 21.16 21.26 21.30 J ^''D ^'^

100.00 100.00 100.00 100.00 100.00

Throughout the whole series there is no essential difference in composi-
tion, nor in physical properties ; nor was the protein altered jn composi-
tion by solution in dilute caustic potash, and re-precipitation by an
equivalent quantity of hydrochloric acid; neither, so far as it could be
observed, was its solubility altered.

THE PROTEINS. 109

The composition of this protein, as obtained by averaging the preced-
ing figures, is the following : —

Carbon 52.72

Hydrogen 6.86

Nitrogen . . 17.66

Sulphur . . 1.14

Oxygen 21.62

100.00

227. Properties of Protein extracted by Dilute Alcohol. — If this pro-
tein be dehydrated by absolute alcohol, and thoroughly dried over sul-
phuric acid, it forms a snow-white friable mass easily reduced to pow-
der. When dried from weak alcohol or water, it forms an amorphous
transparent substance, closely resembling pure gelatin in appearance,
being, however, rather more brittle than that body. In the cold, distilled
water turns the substance sticky, and a part dissolves. As the water is
warmed, the degree of solubility increases, and with boiling, a consider-
able quantity goes into solution. A portion of this is re-deposited on cool-
ing. The solution in pure water is instantly precipitated by adding a
very minute amount of sodium chloride. In absolute alcohol this pro-
tein is perfectly insoluble, but dissolves on the addition of water, being
very soluble in 70 to 75 per cent, alcohol. From alcoholic solutions,
minute quantities of salt readily precipitate the protein. Exceedingly
dilute acids and alkalies readily dissolve this protein, which is again pre-
cipitated apparently unchanged in appearance and composition by neu-
tralisation.

This protein has been obtained in a more or less pure form by earlier
observers; Taddei first gave it the name of "gliadin." Ritthausen and
others assumed that it consisted of a mixture of two or more substances,
to which the names of mucin or mucedin, and gliadin or vegetable gelatin,
have been given. Among recent observers, Martin found in gluten only
one protein soluble in dilute alcohol, to which he gave the name of "insol-
uble phyt-albumose, " but, curiously enough, stated that flour extracted
direct with 76 to 80 per cent, alcohol yielded no soluble protein. This is in
direct opposition to the results of Osborne and Voorhees, and also, it may
be added, to those of the authors of the present work, one of whom, prior
to seeing Osborne and Voorhees ' paper, made a series of analyses of vari-
ous flours, in which a direct gliadin estimation by alcohol was included.
Osborne and Voorhees adopt gliadin as the original and appropriate
name for the wheat protein soluble in dilute alcohol. They point out
that gliadin is absolutely distinct in properties and composition from the
other alcohol-soluble proteins, prolamins, obtained from the kernel of oats
and maize.

228. Protein insoluble in Water, Saline Solutions, and Alcohol;
Glutenin. — After treatment with the series of previously described sol-
vents, a protein body remains in wheat flour and gluten, which is
soluble only in dilute acids and alkalies. This protein being especially
characteristic of gluten, Osborne and Voorhees have given it the name
Glutenin.

In the following accounts of extraction of glutenin, it is throughout
understood that the separations are made 011 flour or meal which has pre-
viously been exhausted with one or more of the following solvents:
Water, 10 per cent, salt solution, and dilute alcohol.

110 THE TECHNOLOGY OF BREAD-MAKING.

229. Extraction of Glutenin from "Straight" Flour after Treatment
with Brine and Dilute Alcohol. — After completely exhausting 4000
grams of straight flour successively with 10 per cent, brine and 0.90 sp.
gr. alcohol, the residue was extracted twice with 0.1 per cent, potash solu-
tion. The residual protein was soluble in this, and after standing three
days at a temperature of 5°, with frequent stirring, the extract was fil-
tered off and allowed to stand in a cold room until most of the finer solid
impurities had subsided. The still turbid solution was then decanted and
neutralised with 0.2 per cent, hydrochloric acid, thereby producing a
precipitate which subsided rapidly, leaving a milky filtrate. This pre-
cipitate was redissolved in the dilute potash, allowed to stand in order to
deposit impurities, and again precipitated with 0.2 per cent, hydrochloric
acid. The protein was washed with water, dilute alcohol, absolute alco-
hol, and ether. This preparation was found to be far from pure, and
accordingly a portion of it was again dissolved in 0.2 per cent, potash,
and repeatedly filtered through very dense filter paper till perfectly clear.
As this filtration proceeded very slowly the operation was conducted in
a refrigerator at a temperature near 0° C. Two successive portions of
the filtrate obtained were reprecipitated with 0.2 per cent, hydrochloric
acid, washed with water, alcohol, ether, and dried over sulphuric acid,
and then at 110°. These gave Preparations 45 and 46. It was found
absolutely necessary to filter the potash solution perfectly dear, as other-
wise considerable amounts of non-nitrogenous matter are subsequently
carried down with the precipitate.

230. Extraction of Glutenin after Treatment of Dough with Water
and Exhaustion with Dilute Alcohol. — A dough was made with 2000
grams of spring wheat "straight" flour and distilled water; this was
washed with river water till freed so far as possible from starch. The
gluten was exhausted with 75 per cent, alcohol, and the insoluble residue
dissolved in 0.15 per cent, potash solution, and allowed to stand in a cold
room for 48 hours. The solution was decanted, precipitated with dilute
hydrochloric acid, washed thoroughly with water, absolute alcohol, and
ether. It was then again dissolved in 0.1 per cent, potash, allowed to
stand over night, filtered till perfectly clear, and a part of the filtrate
precipitated by neutralising with 0.2 per cent, hydrochloric acid. This
precipitate was dried as usual, and constituted Preparation 48.

Another lot of gluten was prepared in the same way from 1000 grams
of "straight" flour, extracted with alcohol and then dissolved in potash
water. After standing, this was precipitated by adding acetic acid to
slightly acid reaction. The precipitate was washed with water, alcohol,
and ether, and again dissolved in potash water, reprecipitated with
hydrochloric acid, and again washed and dried as usual over sulphuric
acid. A pure white light mass was obtained, which was marked Prepara-
tion 51.

In order to determine whether the protein lost any nitrogen by pro-
longed solution in potash water, another lot of gluten was similarly
treated, and the potash solution kept in an ice-chest for 20 hours, and
then precipitated and treated in the usual manner. This constituted
Preparation 52, and had evidently lost but exceedingly little nitrogen.

231. Extraction of Glutenin after Direct Exhaustion of Flour with
Alcohol, Water Treatment Omitted. — Another preparation was made by
extracting 200 grams of spring patent flour with large quantities of alco-
hol of 0.90 sp. gr., then washing the flour with absolute alcohol and dry
ing and air-drying. The dry flour was then made into a dough, which

THE PROTEINS. Ill

possessed considerable coherence, showing that the protein insoluble in
alcohol has an important function in dough production. The dough was
washed on a hair-sieve under a stream of water, but yielded no coherent
gluten. The washings were allowed to settle, and the sediment treated
with 0.2 per cent, potash. After standing, the supernatant liquid was
decanted, precipitated with dilute hydrochloric acid, and the precipitate
allowed to settle. It way then again dissolved in dilute potash, filtered
perfectly clear while in the ice-chest, reprecipitated, and washed and
dried in the usual manner. This constituted Preparation 56.

Another experiment was made by direct alcohol treatment, in which
1000 grams of "straight" flour were exhausted with 0.90 alcohol, and the
residue squeezed in a screw-press. This was then extracted with 0.2 per
cent, potash, but filtration was impossible owing to the gummy nature of
the liquid. An equal volume of alcohol, sp. gr. 0.820, was then added,
and after long standing a comparatively clear yellow solution was
syphoned off and filtered clear. This was precipitated with hydrochloric
acid, and the precipitate filtered off and again dissolved in potash, filtered
perfectly clear, reprecipitated, washed with water, dilute and then abso-
lute alcohol, and ether. This yielded Preparation 57, the analysis of
which shows that the same protein is extracted by potash water from the
flour which has not been in contact with water as was obtained in other
experiments.

232, Extraction of Glutenin from Gluten of Whole Wheat Flour.—
A dough was made from 1000 grams of whole spring wheat meal, washed
till free from starch, and the gluten exhausted with dilute alcohol. The
residue was dissolved in dilute potash, allowed to stand, decanted, repre-
cipitated, and the precipitate washed with water, dilute alcohol, absolute
alcohol, and ether, and then re-dissolved in 0.2 per cent, potash water.
This was filtered perfectly clear, and precipitated and treated in the
usual way. The dry protein was Preparation 58.

A preparation was made in the same manner from whole winter wheat
meal, which constituted Preparation 60. In the following table, analyses
are given of the whole of the glutenin preparations which have been
described.

ANALYSES OF PROTEIN OF WHEAT SOLUBLE ONLY IN DILUTE ACIDS
AND ALKALIES — GLUTENIN.

Carbon

..52.29

52.32

,54

52.38

r>6

52.

52.19

52.03

Hydrogen

.. 6.61

6.82

,85

6.81

6.93

6.83

Nitrogen

..17.41

17.33

17.61

17,

,46

17.59

17.20

17.

17.45

17.48

Sulphur
Oxygen

. . 0.94
..22.75

23.25

(22'

,07

,08

1.24

21.98

)

23.

23.43

23.66

100.00 100.00 100.00 100.00 100.00 100.00 100.00

233. Properties of Glutenin. — The characteristic reactions of glu-
tenin, owing to its comparative insolubility, are not numerous. A minute
quantity is dissolved by cold water, and more on slightly warming.
Diluted alcohol also dissolves a small quantity of protein in the cold, and
a larger quantity on boiling, which again precipitates as the liquid cools.
It is just possible that this is due to the presence of traces of gliadin, but
in face of the very careful exhaustion by alcohol previous to preparation
of glutenin, it is more probable that glutenin itself is slightly soluble
both in warm alcohol and warm water.

112 THE TECHNOLOGY OP BREAD-MAKING.

When freshly precipitated and hydrated, glutenin is soluble in 0.1 per
cent, potash solution, and 0.2 per cent, hydrochloric acid. In this condi-
tion it is also soluble in the slightest excess of sodium carbonate solution
or ammonia. After drying over sulphuric acid, it becomes rather less
soluble ill all these reagents. On comparing the analyses of gliadin and
glutenin, a very close agreement is observed. It is well known that many
proteins pass readily into conditions in which their solubility is changed
without any alteration in their composition, capable of detection by
analysis. Osborne and Voorhees therefore concluded that gluten was
made up of two forms of the same protein, one being soluble in cold dilute
alcohol, and the other not soluble. But Osborne, who has since studied
the products of their complete hydrolysis, finds that gliadin differs
sharply from glutenin in yielding no glycine and no lysine ; it also gives
nearly twice as much proline as glutenin (Armstrong, Supplement, Jour.
Board of Agric., June, 1910, p. 48). It can scarcely, therefore, be main-
tained that these proteins have a common origin.

234. Amount of the various Proteins contained in Wheat. — The per-
centage of each protein present in whole-wheat meal was determined by
an analysis of 1000 grams of meal from spring and winter wheats respec-
tively. The following is an outline of the analytic method adopted, which
was the same in each case. To 1000 grams of fine meal were added 4000
c.c. of 10 per cent, salt solution, and the extract filtered ; 2500 c.c. of clear
extract were obtained from the spring meal, and 2600 from the winter
wheat meal. As 100 c.c. of solution were used to each 25 grams of flour,

2500 c.c. = extract from 625 grams spring meal, and
2600 c.c. = „ „ 650 „ winter meal.

The extracts were dialysed for five days, at the end of which time they
were free from chloride. The precipitated globulin was filtered, washed
with distilled water, alcohol, absolute alcohol, and ether, and dried at
110°. The following weights were obtained : —

3.8398 grams = 0.624 per cent, globulin in spring wheat.
3.9265 „ =0:625 „ „ „ winter

The filtrates from the globulin were heated to 65°, and the coagula
formed at that temperature removed by filtration, washed as usual, dried
at 110°, and weighed with the following results : —

1.9714 grams = 0.315 per cent. No. 1 albumin in spring wheat.
1.9614 „ =0.302 „ „ „ winter

The filtrates from these were heated to boiling, and the second coagula
similarly treated. The weights obtained were : —

0.4743 grams = 0.076 per cent. No. 2 albumin in spring wheat.
0.3680 „ =0.057 „ „ „ winter „

The filtrates were evaporated nearly to dryness, and two crops of co-
agulated protein removed, washed, dried, and weighed — together they
amounted to : —

1.6886 grams = 0.269 per cent, coagulum in spring wheat.
1.4516 „ =0.223 „ „ „ winter „

The filtrates from the coagula were next again evaporated to a syrup
and, as no insoluble matter separated, were precipitated by pouring into
strong alcohol, the precipitates were washed, dissolved in water and re-
precipitated, washed with absolute alcohol and ether, and dried at 110°.
They were evidently very impure, and the amount of protein present in

I THE PROTEINS. 113

each was estimated by determining the nitrogen and multiplying by 6.25.
They gave in this way the following results : —

1.3297 grams = 0.213 per cent, proteose and peptone in spring wheat.
2.8063 „ = 0.432 „ „ „ „ winter „

Collecting these figures, the sodium-chloride solution contained the
following amounts of protein matter : —

Spring Wheat. Winter Wheat.

Globulin 0.624 per cent. 0.625 per cent.

Two Albumins together . . 0.391 „ 0.359

Coagulum . . . . . . 0.269 „ • 0.223

Proteose 0.213 0.432

Total . . 1.497 „ 1.639

The remainder of the protein matter constitutes the gluten, and was
determined in the following manner — 200 grams of each meal were made
into a dough and washed free from starch. The wet gluten, freed from
adhering moisture, was then weighed, and exactly one-half dried at 110°
to constant weight.

Spring wheat yielded 12.685 per cent, dry gluten.
Winter „ „ 11.858 „ „' " „

The other half of the gluten was cut up fine, and extracted with alco-
hol of 0.90 sp. gr. The extract was concentrated, and the precipitated
protein extracted with ether and dried at 110°. Reckoned on the whole
meal,

Spring wheat gluten yielded 4.3379 per cent, gliadin.
Winter „ „ 4.2454

The residues, after exhaustion with alcohol, were then dried at 110°
and weighed. Reckoned on the whole meal,

Spring wheat gluten yielded 7.800 per cent, matter insoluble in alcohol.
Winter „ „ „ 7.504

Nitrogen determinations were then made on the following bodies — the
whole meal insoluble alcohol residues, dried gluten, and the sediments of
the water used for washing out gluten, after being washed with strong
alcohol, dried and weighed. The following is the tabulated result of the
various determinations :,—

PROXIMATE ANALYSES OF PROTEINS OF WHEAT.

Spring Wheat. Winter Wheat.

Total nitrogen in the meal . . . . 1.950 per cent. 1,940 per cent.

Total gluten in the meal . . . . 12.685 „ 11.858

Part of gluten insoluble in alcohol . . 7.800 „ 7.504

Per cent, of nitrogen in gluten . . 12.010 „ 12.000 „

Total nitrogen in gluten in per cent.

of flour . . 1.5222 „ 1.4230 „

Total nitrogen in residue of gluten

insoluble in alcohol 0.8245 „ 0.7346

Total nitrogen extracted by alcohol . . 0.6977 „ 0.6884

Gliadin (NX5.68, assuming 17.60 per

cent, of N in gliadin) . . . . 3.9630 „ 3.9100

Gliadin by direct weighing . . . . 4.3379 „ 4.2454

Nitrogen in sediment from washing

gluten 0.2239 „ 0.1552 „

114 THE TECHNOLOGY OF BREAD-MAKING.

— Spring Wheat. — — Winter Wheat. — ,

Nitrogen. - Protein. Nitrogen. Protein.

Glutenin . . . . 0.8245X5.68= 4.683 0.7346X5.68= 4.173

Gliadin . . . . 0.6977X5.68— 3.963 0.6884X5.68= 3.910

Globulin . . . . 0.1148 = 0.624 0.1148 = 0.625

Albumin . . . . 0.6057 = 0.391 0.0603 = 0.359

Coagulum ... . . 0.0453 = 0.269 0.0379 = 0.223

Proteose . . . . 0.0341 - 0.213 0.0791 = 0.432
Prom Water Washings

of Gluten . . 0.2239X5.68= 1.272 0.1552X5.68= 0.881

Total . . . . 2.0050 11.415 1.8703 10.603

Meal 2.10 X5.68=11.93 1.94 X5.68=10.96

Inspection of the above figures shows that the gliadin by direct weigh-
ing agrees fairly well with that estimated from a nitrogen determination.
The residue insoluble in alcohol is, however, very much more than the
true glutenin : thus, in the spring wheat the insoluble residue weighed
7.80 per cent, of the meal, whereas the glutenin calculated from nitrogen
amounted to only 4.683, leaving 3.117 of foreign matter in the residue
insoluble in alcohol. The total protein agrees in each case very closely
with the whole found by direct estimation on the meal. The same figures
as those above given are quoted in a work recently written by Osborne
(1909) as representing the amounts of proteins contained in the grain of
wheat.

235. The Formation of Gluten. — So far as is known, wheat is the
only plant whose seeds contain proteins in such a form as to enable them
to be separated in a coherent mass from the other constituents by wash-
ing with water. Osborne and Voorhees have examined very carefully the
views promulgated on this point by previous observers ; prominent among
these is the "ferment" hypothesis of Weyl and Bischoff, who, as pre-
viously stated, considered the proteins of wheat meal to consist princi-
pally of a globulin very similar in character to myosin, and which they
therefore termed "vegetable myosin." This they regarded as the mother-
substance of gluten, which on the addition of water is changed by a fer-
ment, hitherto unisolated, into gluten, "as other proteins, if present at
all, exist only in small amount" (Weyl and Bischoff). The exhaustive
analyses previously quoted show that globulin and also gliadin form only
about half the total protein of the grain. Osborne and Voorhees point
out that gliadin is extracted in similar quantity from dry flour direct by
alcohol, as is yielded after treatment with 10 per cent, sodium chloride
solution, or by direct extraction of the previously washed out gluten.
Weyl and Bischoff state that with the aid of a 15 per cent, salt solution
the flour was extracted till no protein could be detected in the extract ;
the residue of the meal kneaded with water then gave no gluten. "If the
globulin substance is extracted, no formation of gluten takes place."
Osborne and Voorhees confirm this if the flour is stirred up with a large
quantity of salt solution, and then extracted repeatedly with fresh quan-
tities of the solution. But they say : "If, however, wheat flour is mixed
at first with just sufficient salt solution to make a firm dough, this dough
may then be washed indefinitely with salt solution, and will yield gluten
as well and as much as if washed with water alone. ' '

This statement alone is scarcely a sufficient disproof of Weyl and
Bischoff 's position. In a firm dough made with 15 per cent, salt solution,
the quantity of salt will only amount to 5 per cent, of the dough. As

THE PROTEINS. 115

nothing has been removed in the act of making dough, it may be reason-
ably claimed that this quantity of salt is insufficient to prevent the fer-
ment performing its function, and thus producing gluten ; while further,
the gluten once formed is able to withstand the action of the salt solution
which is unable to decompose it. Osborne and Voorhees go on to state
that ' ' when large quantities of salt solution are applied at once, the flour
fails to unite to a coherent mass, and cannot afterwards be brought to-
gether. " This action of salt solution in large quantities is explained by
subsequent experiments, in which it is shown that such solution mate-
rially modifies the adhesive nature of gliadin.

Weyl and Bischoff's experiment, in which they extracted the flour
with 90 per cent, alcohol, is scarcely conclusive, because according to both
hypotheses this would result in the non-formation of gluten. In the one
case globulin would be coagulated, and in the other gliadin would be
removed, and so according to both reasoners no gluten could be produced.

More recently, Martin has advanced a somewhat similar theory of
gluten formation ; he finds one protein in gluten soluble in alcohol, and in
hot water, but not in cold, which protein he calls an insoluble phyt-albu-
mose. The gluten is termed by him "gluten-fibrin." Martin next in-
quires : Does flour contain gluten-fibrin ? Does it contain insoluble phyt-
albumose ? He states that the first question cannot be answered directly,
and that, if phyt-albuinose originally existed in the flour, it should be ex-
tracted by 76-80 per cent, alcohol, which, however, extracts only fat.
There is here direct conflict of experimental evidence, as the analyses
previously quoted show that considerable quantities of a protein are thus
extracted. Martin next points out that 10 per cent, sodium chloride solu-
tion extracts a large quantity of globulin of the myosin type and of
albumose. Osborne and Voorhees consider that Martin has made the mis-
take of taking albumin for a myosin-like globulin, and, owing to the
voluminous nature of the body when coagulated, has been misled as to its
amount. Martin further looks upon the insoluble albumose as formed
from the soluble, and that the globulin is transformed into gluten-fibrin.
That a body should be obtained from a solution of globulin, which gave
the same reactions as gluten-fibrin, is not surprising, as so-called albumi-
nates, having no characteristic reactions, are derived from nearly all
globulins. Martin tabulates his theory as follows : —

p (Gluten-fibrin —precursor, globulin.

| Insoluble albumose — ,, soluble albumose.

Osborne and Voorhees cannot admit this theory, because it is founded
on two erroneous observations: 1st, that 80 per cent, alcohol does not
extract protein from flour ; 2nd, that at least one-half the protein of the
seed is a myosin-like globulin.

Osborne and Voorhees conclude that no ferment action is involved in
the formation of gluten, and that it contains but two protein substances,
glutenin and gliadin, and that these exist in the wheat kernel in the same
form as in the gluten, except that in the latter they are combined with
about thrice their weight of water. This opinion is based on the follow-
ing reasons : —

1. Alcohol extracts the same gliadin in the same amount, whether
applied directly to the flour, to the gluten, or to the flour previously ex-
tracted with 10 per cent, sodium chloride solution.

116 THE TECHNOLOGY OF BREAD-MAKING.

2. Dilute potash solution extracts glutenin of uniform composition
and properties from flour which has been extracted with alcohol, or with
10 per cent, sodium chloride solution and then with alcohol, as it extracts
from gluten which has been exhausted with alcohol.

Viewed as a refutation of the ferment theory, the weak point of this
statement is that in order to prepare gliadin the flour is in all cases
treated with water, as even the alcohol used contains water to the extent
of 30 per cent, (although extraction with 70 per cent, alcohol is a condi-
tion the reverse of favourable to ferment action). The advocates of the
ferment theory might adduce the fact that small quantities of ferment
substance are capable of changing very large quantities of the body on
which they act, and further might suggest that the small quantity of
globulin which is removed by treatment with sodium chloride solution is
the ferment in question. It is well known that flour contains a diastase
precipitated by alcohol, which presumably belongs to the albumins or
globulins; it is therefore conceivable that among the globulin, albumin,
and indefinite proteoses of wheat, a ferment may exist capable in the
presence of water of producing gliadin from some other pre-existing sub-
stance. It is difficult, however, to prove a negative, and the onus of prov-
ing the existence of ferment action lies rather with those who are
advocates of that hypothesis than with those who view it as unnecessary.
Osborne and Voorhees, without actually absolutely disproving the exist-
ence of a gluten-ferment, account rationally and scientifically for the
production of gluten on the assumption of the pre-existence of its con-
stituents as such in the grain; the balance of evidence is strongly in
favour of the latter hypothesis.

The following experiments are adduced to show that both glutenin
and gliadin are necessary for the production of gluten. A portion of
flour was washed free from gliadin by alcohol of 0.90 sp. gr., and next
with stronger alcohol, and finally with absolute alcohol, and air dried.
The residue made a tolerably coherent dough, but much less tough and
elastic than that obtained from the untreated flour. On washing this
dough most carefully, not a trace of gluten could be obtained.

In another experiment 7.5 grams of finely ground air-dried gliadin
were mixed with 70 grams of starch, and distilled water added. A plastic
dough was formed, but it had no toughness. On adding a little 10 per
cent, sodium chloride solution the dough became tough and elastic. This
was washed with great care with cold water, a little salt solution being
added from time to time ; no gluten was, however, obtained.

The following experiment shows that additional gluten is formed
when glutenin is present, by the adding of gliadin. Two portions of 100
grams each of flour were taken, and to one of them 5 grams of gliadin
added. Both were made into dough with the same quantity of water.
The two doughs exhibited considerable differences, that containing the
extra gliadin being the yellower and tougher of the two. Gluten was ex-
tracted from each by washing, after which each was weighed in the wet
condition; that containing the added gliadin weighed 44.55 grams, and
the other 27.65 grams. On drying at 110° the yield of dry gluten was
respectively 15.41 grams and 9.56 grams ; the difference being 5.85 grams,
which amount more than covers the added gliadin.

On heating finely ground air-dried gliadin with a small quantity of
distilled water, a sticky mass is formed which, on the addition of more
distilled water, forms a turbid solution. But, if to the gliadin moistened
with distilled water a very dilute solution of salt in distilled water is

THE PROTEINS. 117

added, the gliadin is changed into a very coherent viscid mass which
adheres to everything it touches, and can be drawn out into long threads.
Treatment of gliadin with 10 per cent, salt solution, first to moisten it,
and afterward in larger quantity, serves to cause the substance to unite in
a plastic mass which can be drawn out into sheets and strings, but is not
adhesive. This explains the non-success of Weyl and Bischoff's experi-
ment before referred to. The gliadin is the binding material which causes
the particles of flour to adhere together, thus forming a dough. But the
gliadin alone is not sufficient to form gluten, for it yields a soft and fluid
mass which breaks up entirely on washing with water. The insoluble
glutenin is probably essential as affording a nucleus to which the gliadin
adheres, and from which it is not mechanically carried away by the wash
water.

236. Summary. — The following are the properties and composition
of the proteins of the wheat grain : —

1. A globulin, soluble in saline solutions, precipitated therefrom by
dilution, and also by saturation with magnesium sulphate or ammonium
sulphate, but not by saturation with sodium chloride. Partly precipitated
by boiling, but not coagulated at temperatures below 100°. The grain
contains between 0.6 and 0.7 per cent, of globulin.

2. An albumin, coagulating at 52°, which differs from animal albumin
in being precipitated on saturating its solutions with sodium chloride, or
with magnesium sulphate, but not precipitated by completely removing
salts by dialysis in distilled water. The grain contains between 0.3 and
0.4 per cent, of albumin.

3. A proteose, precipitated (after removing globulin by dialysis, arid
the albumin by coagulation) by saturating the solution with sodium chlo-
ride, or by adding 20 per cent, of sodium chloride and acidulating with
acetic acid. Separates as a coagulum on cencentrating the solution, and
thus yields about 0.3 per cent, of the grain.

The solution from this coagulum still contained a proteose-like body
which was not obtainable in a pure state. By indirect methods it is
assumed to amount to from 0.2 to 0.4 per cent, of the grain. Both these
substances, the coagulum and the proteose-like body, are derivatives of
some other protein in the seed, presumably the proteose first mentioned.
As previously explained, it should be borne in mind that the proteoses
may be formed during the processes of extraction by alterations of the
protein matter originally present in the grain.

4. Gliadin, soluble in dilute alcohol, and soluble in distilled water to
opalescent solutions, which are precipitated by adding a little sodium
chloride. Completely insoluble in absolute alcohol, but slightly soluble in
90 per cent, alcohol, and very soluble in 70-80 per cent, alcohol, and is
precipitated from these solutions on adding either much water or strong
alcohol, especially in the presence of much salts; soluble in very dilute
acids and alkalies, precipitated from these solutions by neutralisation,
unchanged in properties and composition. The formation of gluten is
largely dependent on this protein. The grain contains about 4.25 per
cent, of gliadin.

5. Glutenin, a protein insoluble in water, saline solutions, and dilute
alcohol, which forms the remainder of the proteins of the grain. Soluble
in dilute acids and alkalies, and re-precipitated from such solutions by
neutralisation.

118 THE TECHNOLOGY OP BREAD-MAKING.

The following is the composition of these bodies : —
ANALYSES OF PROTEINS OF WHEAT.

Globulin. Albumin. CoaRulum. Gliadin. Glutenin.

Carbon ....... 51.03 53.02 51.86 52.72 52.34

Hydrogen . . . . . . 6.85 6.84 6.82 6.86 6.83

Nitrogen ...... 18.39 16.80 17.32 17.66 17.49

Sulphur ...... 0.69 1.28) 9 . nn (1.14 1.08

22.26

...... . . . .

Sulphur ...... 0.69 1.28) 9 . nn (1.14

Oxygen . . 23.04 22.06 \ (21.62

100.00 100.00 100.00 100.00 100.00

Wheat gluten is composed of gliadin and glutenin, both being neces-
sary for its formation. Gliadin forms with water a sticky medium which,
by the presence of salts, is prevented from becoming wholly soluble. This
medium binds together the particles of flour, rendering the dough and
gluten tough and coherent. Glutenin imparts solidity to the gluten, and
forms the nucleus to which gliadin so adheres that it cannot be washed
away with water. Gliadin and starch form a dough which yields no
gluten, as the gliadin is washed away with the starch. Flour freed from
gliadin gives no gluten, as there is no binding material to hold the par-
ticles together so that they be brought into a coherent mass.

Soluble salts are also necessary in forming gluten, as in distilled water
gliadin is readily soluble. The mineral constituents of the flour are suffi-
cient for this purpose, as gluten can be obtained by washing a dough in
distilled water.

No ferment action occurs in the formation of gluten, for its constitu-
ents are found in the flour having the same composition and properties
as in the gluten, even under those conditions which would be supposed to
completely remove antecedent proteins, or to prevent ferment-action. All
the phenomena which have been attributed to ferment-action are ex-
plained by the properties of the proteins themselves, as they exist in the
seed and in the gluten.

The conclusions of Osborne and'Voorhees agree well with the follow-
ing opinions on a gluten-ferment expressed by one of the present authors
in a previous work on this subject: — "The existence of this body cannot
as yet, however, be recognised as proved. While the formation of gluten
may be due to the intervention of such a body, yet there is nothing re-
markable in considering it to be a simple and direct hydration, by water,
of the gluten compounds existent in the grain. The effect of heating the
flour, and of treatment with salt solution, are fairly accounted for by
their well-known coagulating action on the albuminous matters. So, too,
those wheats whose flours hydrate slowly are grown under conditions
which favour the proteins being in a difficultly soluble condition. ' '

237. Proteins of the Oat-Kernel. — For purposes of comparison the
following statement by Osborne of the composition of the proteins of oats
is given. When oat-meal is extracted with 10 per cent, sodium chloride
solution, two portions of uncoagulated protein were obtained ; after which
alcohol extracted another uncoagulated protein. Two distinct proteins
are thus obtained from oats — that extracted from untreated oats readily
coagulates and becomes insoluble in alcohol, and when wet with absolute
alcohol does not absorb moisture from the air ; whilst that obtained from
oats after treatment with salt solution has no tendency to coagulate, is
freely soluble in cold alcohol of 0.90 sp. gr., and when wet with absolute

THE PROTEINS. H9

alcohol absorbs moisture from the air and becomes gummy. Both sub-
stances, when washed with absolute alcohol and dried, are light yellowish
powders, soluble in dilute acids and alkalies, and reprecipitated on neu-
tralising their solutions (American Chemical Journal).

238. Distribution of Proteins in Wheat. — The proteins of wheat are
not distributed equally throughout the whole seed, there being certain
portions of the wheat grain which are specially rich in soluble proteins ;
the bran and germ are particularly so. Starting from the outside of the
seed, the interior portions become less and less nitrogenous, until the
kernel of the grain is found to consist much more largely of starch.

239. Decomposition of Proteins. — Soluble albumin, or the white of
egg, on being allowed to stand, putrefies, with the evolution of sulphuret-
ted hydrogen and other gases. The odour of sulphuretted hydrogen is
almost invariably described by comparison to that of rotten eggs. Coagu-
lated albumin, when dry, is a fairly stable body ; but, when left in contact
with water, putrefies, yielding valeric and butyric acids, together with
other bodies. The oxygen of the air has no action on albumin.

Dry gluten may be kept indefinitely without change, but if when wet
it is exposed, in masses too large to dry quickly, to air at ordinary tem-
peratures, it gives off a quantity of gas, and at last evolves a strong
putrescent odour. At the same time, the insoluble gluten breaks down
into a thick creamy mass.

240. Nature of Putrefaction. — It is necessary to get accurate ideas
of what putrefaction really is. Every one knows the results of putrefac-
tion in their last or extreme stages ; animal and vegetable substances both
give off gases having most disgusting odours and yield a variety of offen-
sive products. These gases consist of compounds of hydrogen with car-
bon, and also with sulphur; this latter gas, termed by the chemist
sulphuretted hydrogen, is, as just stated, responsible for the odour so
characteristic of rotten eggs. In the earlier stages, however, of putrefac-
tion, the changes do not result in the production of such disagreeable
bodies ; gases are evolved, but these are either inodorous or at most pos-
sess only slight smells. Speaking broadly, putrefaction consists of the
breaking down or degrading of the complex molecules of animal and
vegetable structures into compounds of a more simple character, and
ultimately into inorganic compounds, such as carbon dioxide, water, and
sulphuretted hydrogen ; which latter, in its turn, deposits its sulphur, and
forms water by the action of atmospheric oxygen. Bodies in the first
stage of putrefying absorb more or less oxygen; when this element has
been removed from the supernatant air. a species of fermentation, known
as putrefactive fermentation, proceeds. When dealing with the whole
question of fermentation this change must be viewed more closely. At
present there is one particular point that should, however, be mentioned,
and that is, that by heating any organic liquid, as a solution of hay,
white of egg, or proteins of flour, under pressure at a temperature of
about 266° F. for some time, and then boiling the liquid in a flask whose
neck is loosely plugged with cotton wool until the whole of the air is
expelled, the liquid acquires the property of resisting putrefactive action.
Solutions preserved in this manner may be kept for an indefinite length
of time ; on being once more exposed to the air they again are subject to
putrefaction. It would thus appear that putrefaction is not a process
appertaining exclusively to the grain itself, but is in some way dependent
on the action and presence of air.

120 THE TECHNOLOGY OF BREAD-MAKING.

EXPERIMENTAL WORK.

241. Reactions of Proteins. — Separate a little gluten from flour by
kneading dough, enclosed in muslin, in water. Dry a little of this, and
heat strongly in a test-tube; notice that an odour is evolved similar to
that of burning hair or feathers. Water also condenses in the cooler
parts of the tube : test this water with a strip of red litmus paper, and
notice that it has an alkaline reaction; this alkalinity is caused by the
presence of ammonia. Make a precisely similar experiment with some
white of egg, and observe that the same reactions occur.

Solubility. — Mix some white of egg with about four times its volume
of water. Place a portion of this solution in a test-tube, float it in a
beaker of cold water, and heat gently. Test the temperature at which
coagulation ensues. To successive portions of the albumin solution, add
alcohol, ether, mercuric chloride, and picric acid solutions, and dilute
nitric acid ; notice the formation of a precipitate. To the portions precip-
itated by acid, add caustic soda or potash solution : the precipitates are
re-dissolved.

Colour Reactions. — Test the Xanthoproteic and Millon's colour re-
actions, as described in paragraph 204.

Precipitation. — Precipitate proteins from solutions by the various
methods given in paragraph 205.

Production of Peptones. — Take some of the white of a hard-boiled egg,
and rub it through a fine sieve. Add to it some dilute hydrochloric acid
(0.2 per cent.) and a little prepared pepsin. Gently warm the whole to
a temperature of about 40° C. and notice that the white of egg dissolves.
The albumin has then been converted into peptone.

Soluble Flour Proteins. — Weigh out 50 grams of flour, and mix with
250 c.c. of water in a large flask, shake up thoroughly several times dur-
ing half an hour, and then set aside for a few hours, or even over-night.
Filter the supernatant liquid through a French filter paper until bright.
Heat a portion of this solution in a small beaker placed in a water-bath :
notice the coagulation of vegetable albumin.

242. Gluten and its Constituents. — The separation of gluten will
have been illustrated in the preceding experiments. Moisten flour with
alcohol and fold up in muslin; knead in a small vessel also containing
alcohol ; notice that no gluten is yielded. Make a similar experiment with
a 15 per cent, salt solution : place a sample of flour for the night in the
hot water oven, and treat with ordinary water in the morning : observe
in each case that no gluten is produced.

Place aside some moist gluten and water in an outhouse : notice day
after day the changes which occur in the appearance and physical prop-
erties of the gluten as putrefaction sets in.

Take some carefully washed gluten and grind it up in a mortar with a
little 80 per cent, alcohol. Transfer to a flask and keep at a temperature
of 40° C. for some hours ; filter, and again grind the undissolved residuum
with more alcohol in the mortar. Again digest in the flask, and once
more repeat this treatment. Evaporate down the mixed filtrates over a
water-bath, and notice the transparent yellow gliadin thus obtained.
Carefully dry the insoluble portion, which consists of more or less pure
glutenin.

The extent to which this series of experiments is carried must depend
on the time and opportunities of the student, and also the laboratory
facilities at his disposal.

CHAPTER VIII.
ENZYMES AND DIASTATIC ACTION.

243. Hydrolysis. — It has already been incidentally mentioned that
starch may readily be converted into dextrin and maltose ; with regard
to the carbohydrates generally, one of their special characteristics is, that
the less hydrated members of the series are easily changed to those con-
taining a higher proportion of hydrogen and oxygen. In consequence
of the great importance of these transformations, they will require to be
dealt with fully. The present chapter will, therefore, give particulars of
the nature of these changes, the agents by which they are effected, and
the conditions which are favourable or unfavourable to their occurrence.
As the mutations of the carbohydrates consist of the addition of the ele-
ments of water to the atoms previously present in the molecule, it has been
proposed to include these changes under the general term "hydrolysis."
Hydrolysis is, therefore, denned as a chemical change, consisting of the
assimilation, by the molecule of the substance acted on, of hydrogen
and oxygen in the same proportions as they exist in water ; and result-
ing in the production of a new chemical compound or compounds.
Those bodies capable of producing hydrolysis are termed "hydrolysing
agents" or :<hydrolytics." In order that hydrolysis may occur it is
obviously necessary that water shall be present.

244. Hydrolytic Agents. — These bodies include oxalic and dilute
hydrochloric and sulphuric acids. Commencing with soluble starch, the
acids mentioned possess the power of converting that body first into dex-
trin and maltose, then into glucose. The acid hydrolytics also transform
cane sugar into glucose. It will be noticed that the ultimate products of
hydrolysis of starch are sugars of various descriptions, hence this opera-
tion is frequently termed the " saccharification " of starch.

245. Saccharification of Starch by Acids. — This operation is carried
on as a commercial process for the manufacture of glucose for use in
brewing. The starch is boiled, either in open vessels or under pressure, t
with dilute sulphuric acid. If the operation be stopped as soon as a por-
tion of the solution gives no blue colouration when tested with iodine, it
will be found that dextrin and maltose are the chief products. Contin-
ued boiling results in the transformation of most of the dextrin and
maltose into glucose. The sulphuric or oxalic acid, whichever is used, is
next removed by the addition of calcium carbonate in slight excess. This
reagent forms an insoluble oxalate with the latter acid, and with the
former, calcium sulphate, which is only very slightly soluble. The pre-
cipitate is allowed to subside and the supernatant liquid evaporated
under diminished pressure.

246. Catalysis. — When soluble starch is saccharified by the action of
an acid such as oxalic acid, it is found that the acid itself does not disap-
pear during the reaction. If the necessary precautions be taken, the same
quantity of unaltered acid is found at the termination of the chemical
change as was introduced prior to its commencement. This leads us to
institute a comparison between actions of the type now under considera-
tion and others frequently met with in more general chemistry. Taking

121

122 THE TECHNOLOGY OF BREAD-MAKING.

chemical changes as a whole, they may be resolved into those of two
classes, (1) those in which the reaction is practically immediate on the
mixture of the interacting bodies, as when hydrochloric acid and sodium
hydroxide are. added to each other in solution and at once form the neu-
tral sodium chloride, and (2) those in which the chemical change occupies
an appreciable time. As an illustration of the latter the combination of
sulphur dioxide with oxygen to form sulphur trioxide in the presence of
water may be mentioned. Now in the case of many reactions of the sec-
ond type, there are substances which remarkably accelerate the speed of
the reaction, without themselves undergoing a permanent chemical change.
Thus, if a small quantity of nitrogen oxide, NO, be added to the afore-
said mixture of sulphur dioxide and oxygen, it marvellously increases the
rapidity of combination of these bodies, and that without in itself under-
going permanent alteration. This is, in fact, the method employed in the
manufacture of sulphuric acid, and were there no purely secondary reac-
tions, the nitrogen oxide might be entirely recovered as such at the close
of the chemical process. This process of changing the rate of a slow
chemical action is termed "catalysis," and the active agent therein is
termed a "catalyst." Among the essentials of catalytic action is that
the catalyst does not induce the chemical change but only alters the
rate of one already proceeding ; and further, the catalyst does not com-
bine with any of the products of the reaction.

In the case of many chemical reactions, an important point is that
they only proceed until a certain condition of equilibrium is reached.
Thus if a compound is subjected to such conditions as lead to its dissocia-
tion into the constituent elements, there is a position in which there will
be neither complete combination nor complete dissociation. There will be
simultaneously present free atoms or molecules of the elements and mole-
cules of the compound. If an additional quantity of the compound is
added, dissociation will proceed until the point of equilibrium is again
reached ; or if combining proportions of the elements are added, combina-
tion will ensue till again the position of equilibrium is attained. In a
chemical reaction that is accelerated by the introduction of a catalyst,
and in which there is an intermediate point of equilibrium, the same
catalyst that speeds the reaction to this point will have a reverse action
if added to the substances beyond the equilibrium point. Thus taking the
hydrolysis of cane sugar to glucose, there is in fact a point at which the
action ceases, and on that point being reached, there is present some cane
sugar and also glucose and fructose. If glucose and fructose only be sub-
jected to the action of the same catalyst, a reverse action proceeds until
cane sugar and glucose and fructose are present in equilibrium quantities.
Thus the same catalyst which hydrolyses cane sugar into the simpler
bodies, may also synthesise cane sugar from these substances.

247. Enzymes or Soluble Ferments. — Another most important group
of catalytic agents, which are capable of inducing hydrolysis, consists of
certain soluble bodies of organic origin. Among such substances are
human saliva, filtered aqueous infusions of yeast, flour, bran, and malt.
Chemical research shows that in each case hydrolysis is due to the nitro-
genous constituents of these various agents. In several instances the
active principle has either been isolated or obtained in a .very concen-
trated form; it is not known, however, with certainty whether these
bodies are definite chemical compounds, or whether they are only mix-
tures of certain nitrogenous bodies in a particularly active state.

ENZYMES AND DIASTATIC ACTION.

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These substances form part of a yet larger group of bodies which for-
merly were indiscriminately classed together as "-ferments," that is,
bodies which were capable of inducing fermentation. At present this lat-
ter term, as is explained in a subsequent chapter, is confined to those
chemical actions which are the work of certain micro-organisms ; and the
changes, such as hydrolysis, that are due to active principles which are
not organised or living, form a separate class. These active principles
have been termed soluble-ferments; but, as in order to avoid confusion
with micro-organisms and fermentation, it is well to dissever them
entirely from the idea of fermentation, the term * ' enzyme ' ' has been pro-
posed, and is now generally adopted. It has also been proposed to group
together all the chemical changes due to enzymes under the generic term
of ' ' enzymosis. ' '

A number of chemical reactions are brought about by enzymes, most
of which, however, are instances of hydration of the bodies acted on.
Enzymosis occurs usually most readily at temperatures about 40° C., and
is characterised by the fact that a minute quantity of the enzyme is
capable of causing the characteristic chemical change in a comparatively
enormous quantity of the substance acted on, without itself apparently
undergoing change. In other words, these substances behave as catalysts.
An enzyme may therefore be denned as a substance produced by living
organisms, and capable of acting catalytically on contiguous com-
pounds.

248. Chemical Properties of Enzymes. — These substances can be
extracted from the bodies containing them by the action of water, dilute
alcohol, salt solutions, or glycerin. From these solutions they may be
precipitated by strong alcohol, lead acetate, or saturation with ammonium
sulphate. This precipitate, on being washed with absolute alcohol and
dried in vacuo, yields a friable mass easily reduced to a white powder,
and in composition either protein or closely allied to protein matter. The
enzymes act most vigorously at a temperature of from 40 to 45° C., and
are, in the moist state, destroyed by a temperature of from 50 to 75° C.,
according to the nature of the enzyme. (Certain enzymes when abso-
lutely dry withstand a temperature of as much as 170° C.) The pres-
ence of free acid or alkali, and also small quantities of certain neutral
salts, as ammonium sulphate, are inimical to enzymosis.

249. Classification of Enzymes. — Among the number of enzyniic
actions, comparatively few are of importance in the study of the present
subject; these are placed first in the accompanying table, while others of
less immediate value, but still of interest as illustrative of the whole
scheme of enzymosis, follow.

Osborne and Voorhees' researches rather negative the existence of
Weyl and Bischoff's hypothetical vegetable myosin; but, if the contrary
were the case, the natural place of this enzyme would be as shown in class
6. The fact that there are members of this class which can perform
analogous functions in blood and muscle did much toward paving the
way for the inception of the theory of there being a gluten-forming
enzyme.

250. Cytase. — As early as 1879, Brown and Heron mentioned that
during the germination of grain the cellulose cell-walls, and also the

ENZYMES AND DIASTATIC ACTION. 125

cellulose of the starch granules, are broken down. Brown and Morris
again call attention to the same fact in ttair paper on the "Germination
of some of the Grammese," Jour. Chem.Bc., 1890, p. 458. As germina-
tion proceeds, the pareiichymatous cell-muls of the endosperm are grad-
ually dissolved, and ultimately leav^no sign of separation between the
contents of the contiguous cells. During the progress of these changes
the endosperm is much softened, and attains the condition of "meali-
ness ' ' aimed at by the maljjA in course of the germination of barley in
malt manufacture. Browi^M Morris find that this production of meali-
ness is undoubtedly (fo-terminous with the dissolution of the cell-wall,
and, contrary to what is usually believed, is entirely independent of the
disintegration 0^1® starch-granule. The enzyme, which thus dissolves
the parenchymatous cell-walls of the endosperm, has received the name
Cytase. Cytase is secreted by the embryo during germination, and is
found in considerable quantity in green- or air-dried malt, but is readily
destroyed by the action of heat, and so is found in only very limited
quantity in kiln-dried malt, especially that which has been subjected to a
somewhat high temperature. That cytase is not identical with diastase is
demonstrated by the fact that, whereas a filtered aqueous extract of air-
dried malt dissolves the cell-walls of the endosperm, this power is lost on
subjecting the liquid to a temperature of 60° C., which temperature does
not destroy the vitality of diastase.

251. Diastase*. -*-Since the "mashing" or maceration of malt with
water at about ^temperature of 60° C. has been employed as one of the
operations in thfPbrewing of beer, it has been well known that during this
process the starch of the malt is converted into some form of sugar.
Payen and Persoz, in 1833, stated that the action of an infusion of malt
on starch was due to the presence of a particular transforming agent to
which they gave the name of diastase.

Investigation shows that diastase is secreted by the embryo of such
plants as wheat and barley during germination — in a subsequent chapter
the physiology of its production and action is dealt with somewhat fully.
Diastase is present in large quantity in air-dried malt, and to a lesser but
still considerable extent in the malt after kiln-drying.

For its extraction in a concentrated form, Lintner recommends the
following method : — 1 part of green malt or sifted air-dried malt is ex-
tracted with 2 to 4 parts of 20 per cent, alcohol for 24 hours. At the end
of this time as much as possible of the liquid is filtered off by means of a
press, then filtered through paper until bright. To this filtered extract
2l/2 times its volume of absolute alcohol is added, resulting in the pro-
duction of a precipitate, which is allowed to settle, and washed on a filter
with absolute alcohol. The precipitate is then transferred to a mortar
and rubbed down with absolute alcohol, once more transferred to a filter
and washed with absolute alcohol, and ether. Finally it is dried in vacuo
over sulphuric acid. Prepared in this manner, diastase consists of a yel-
lowish-white powder of great diastatic activity. Its purification is
effected by repeatedly dissolving in water and re-precipitating by alcohol.
Subjecting the aqueous solution to dialysis reduces the quantity of ash
(which consists of normal calcium phosphate) and also increases the per-
centage of nitrogen. A purified diastase gave the following numbers on
analysis calculated on the ash-free substance. Results of analyses of
other enzymes are also given.

126 THE TECHNOLOGY OF BREAD-MAKING.

COMPOSITION OF VARIOUS ENZYMES.

Pancreatic

Diastase. Enzyme. Invertase. Emulsin.

Carbon 46.66 46.57 43.90 43.50

Hydrogen 7.35 7.17 8.40 7.00

Nitrogen 10.42 14.95 9.50 11.60

Sulphur 1.12 0.95 0.60 1.30

Oxygen 34.45 30.36 37.60 36.60

100.00 100.00 100.00 100.00

Authority . . . . . . Lintner. Hiifner. Barth. Bull.

More recently Osborne has prepared diastase from malt in another
manner. The ground malt was first extracted with water and filtered.
To the filtrate ammonium sulphate was added to saturation, and the pro-
teins thus precipitated. The precipitate was suspended in water and
subjected to dialysis, thus removing much of the ammonium sulphate ;
there remained a residue of a globulin character, and this was filtered off.
The filtrate was again saturated with ammonium sulphate, the precipitate
suspended in water, once more dialysed, and filtered, thus getting rid of
most of the globulins. The resulting solution of proteins was next dialysed
into alcohol, with the formation of some precipitate. This was filtered
off, and the solution again dialysed into more alcohol, with the formation
of a further precipitate. The operations of dialysis and filtration were
repeated until altogether five fractions of precipitate had been obtained.
The precipitates were purified by solution in water, filtration, dialysis
first into water, and afterwards into alcohol, and finally re-precipitated
by the addition of absolute alcohol and dried. The fourth fraction was
far higher in diastatic power than any of the others. This preparation
was soluble in water, became turbid at 50° C., and gave a large coagulum
at 56° C. The filtrate from this gave the biuret reaction, thus showing
the presence of proteoses. This preparation had a diastatic power of
600° Lintner and was the most active diastatic substance on record.
Analysis showed it to contain 0.66 per cent, of ash, and allowing for this
it had the following composition : —

Carbon 52.50

Hydrogen 6.72

Nitrogen 16.10

Sulphur 1.90

Oxygen 22.78

100.00

The composition is that of a normal protein, save that the sulphur is
somewhat high, but this may be accounted for by the possible presence of
a little ammonium sulphate.

On further investigation, this substance was found to have the same
coagulating temperature as leucosin (albumin of wheat or barley), and
Osborne regards albumin as being the diastatic body. But the amount
of diastatic action is not proportional to that of albumin, and therefore
Osborne suggests the hypothesis that diastase is a compound of albumin
with possibly proteose, but of this theory there is at present no direct
proof,

ENZYMES AND DIASTATIC ACTION. 127

Some time ago, the Malt-Diastase Company of New York forwarded
to the authors a sample of exceedingly concentrated malt diastase, pre-
pared in their laboratory, which had the following remarkable convert-
ing power : —

(1) One part by weight would convert 150 parts by weight of

starch into dextrin and maltose, within ten minutes at 99° F.

(2) One part would produce from a surplus of starch, 329 parts of

maltose within thirty minutes at 99° F.

(3) Tested according to Lintner's method, this diastase had a

strength of 4,705°.

Diastase gives with tincture of guaiacum and hydrogen peroxide a
blue colouration, which is soluble in ether, benzene, chloroform, and car-
bon disulphide, but not in alcohol. This reaction of diastase is shared by
other enzymes, and is caused by the presence of peroxydase. This latter
substance may be regarded as an enzyme having an oxidising action as
distinct from the hydrolysing actions before described.

Diastase in the pure form does not reduce Fehling's solution, and, as
may be judged from its very nature, is marked by a great capacity for
liquefying starch paste and saccharifying it into dextrin and maltose.
Unlike the acids, diastase, however, is incapable of converting starch fur-
ther than into dextrin and maltose. Diastase readily changes amylo-
dextrin and maltodextrin completely into maltose, but does not under
any circumstances further hydrolyse maltose.

Under favourable circumstances, one part of well-prepared diastase,
such as that of Osborne, is stated to suffice for the conversion of 2000
parts of starch. A dilute solution of diastase is exceedingly unstable,
rapidly becoming acid, and losing its power of starch conversion. This
does not apply to concentrated solutions of diastase in the presence of
sugars such as are obtained by concentrating in vacuo cold-water extracts
of malt to the consistency of a sirup.

252. Diastatic Action or Diastasis. — The action of diastase, being of
such great importance in brewing operations, has been studied closely.
The term "diastase" is occasionally used in a generic sense, and is
then applied to the hydrolysing agents of the cereals generally; thus
cerealin is at times referred to as the "diastase" of bran. Hydrolysis,
when effected by diastase or its congeners, is often termed diastatic
action, for which the shorter term ' ' diastasis ' ' is sometimes used.

253. Measurement of Diastatic Capacity. — The activity of malt
extract, or of the purer forms of diastase, depends on the degree of con-
centration, temperature, and other conditions. Kjeldahl has enunciated

what is known as the law of proportionality. The amount of diastase in
two malt extracts is proportional to the reducing power which they effect,
provided that both act on the same quantity of starch during the same
period of time, and that the cupric oxide reducing power (K) does not
surpass 25-30. If the whole of the starch present were converted into
maltose, K would be 62.5 ; according to this stipulation, therefore, some-
what less than half the starch must undergo conversion into maltose, or,
in other words, starch must be to that extent in excess of the amount
hydrolysed by the diastase. Unless the starch is thus largely in excess,
the diastatic action will not be proportional to the amount of diastase.

Lintner measures the diastatic capacity on soluble starch, prepared as
directed in Chapter VI., paragraph 173, and terms the diastatic activity
of the precipitated diastases as 100, when 3 c.c. of a solution of 0.1 gram
of diastase in 250 c.c. of water, added to 10 c.c. of a 2 per cent, starch

128 THE TECHNOLOGY OF BREAD-MAKING.

solution, produces in one hour, at the ordinary temperature, sufficient
sugar to reduce 5 c.c. of Fehling's solution. These quantities amount to
0.0012 gram of diastase, acting on 0.2 gram of soluble starch, while the
maltose necessary to reduce 5 c.c. of Fehling's solution is 0.0400 gram.
This quantity of maltose produced is approximately equal to 0.05 gram
of starch reduced, and the diastase will have hydrolysed about 41 times
its weight of starch in the time and under the conditions specified. Direc-
tions for the determination of diastase by methods based on this principle
are given in the analytic section of this work. The above is simply a
mode of determining diastatic activity, everything else being equal. The
consideration of how diastatic capacity is affected by changes of tempera-
ture and other conditions is described in detail in subsequent paragraphs.

254. Nature of Diastase. — The effects of diastase on starch have
already been spoken of as including two distinct actions ; first, the lique-
fying of starch paste, converting it, in fact, into soluble starch ; and sec-
ond, the saccharifying of this previously liquefied starch. Certain forms
of diastase possess this latter power only ; but it is usually assumed that
malt diastase possesses the two properties. More recently, the opinion
has been growing that malt diastase consists of two distinct enzymes — the
one a liquefying, and the other a saccharifying agent. More will be said
on this matter when dealing with the diastase of unmalted grain.

There naturally arises, in conjunction with the study of diastase, the
speculation whether diastase is a distinct chemical compound of nature
allied to the proteins, or a property or function certain protein bodies are
capable of exercising under special conditions. Certainly, in the purest
form hitherto isolated, diastase is obtained by processes which secure
soluble proteins in the purest state ; and, practically, any substance called
diastase is unobtainable as distinct and separate from soluble proteins.

Brown and Heron finding that, 011 heating malt extract to a tempera-
ture of about 46° C., the soluble proteins commence to coagulate ; a con-
tinuance of this temperature for some 15 to 20 minutes effects the maxi-
mum amount of coagulation possible at 46° C. On raising the tempera-
ture a few degrees, an additional quantity of proteins coagulate ; this
further increase of coagulation continues, as the temperature rises, up to
about 95° C. The proteins of malt extract may be viewed as being com-
posed of distinct fractions, each of which has a definite coagulating point,
varying from 46° to 95° C. With the coagulation of the proteins, the
diastatic power of the malt extract diminishes ; also, no diminution of
starch converting power has been observed without a coagulation of pro-
teins. Further, at the point at whicli the diastatic power of malt extract
is destroyed (80-81° C.), nearly the whole of the coagulable proteins
have been precipitated. Brown and Heron "are consequently led to con-
clude that the diastatic power is a function of the coagulable proteins
themselves, and is not due, as has been generally supposed, to the pres-
ence of a distinctive transforming agent." They further find that fil-
tration through a porcelain diaphragm results in the production of a
liquid which, on being heated to the boiling point, throws down no pro-
teins. This filtered malt extract they find to be incompetent to produce
diastasis, possessing "absolutely no transforming power." It is there-
fore possible to remove the diastatic agent from the malt extract with-
out the application of heat.

255. Action of Diastase on Starch. — This reaction may first be
summed up briefly by stating that if a cold infusion of malt be made, and
then filtered; it, the infusion, on being added to a solution of starch in
water, at temperatures from 15° to about 70° C., more or less rapidly

ENZYMES AND DIASTATIC ACTION. 129

hydrolyses the starch into a mixture of dextrin and maltose. The longer
the operation is continued, the higher is the proportion of maltose pro-
duced ; but even prolonged action does not result in any further
hydrolysis of the maltose into glucose. The investigation of starch and
its transformation products has for many years occupied the close atten-
tion of what may be called the Burton School of Chemists. Prominent
among these are the names of O 'Sullivan, Brown, Heron, and Morris. By
these and other writers, a number of papers of singular interest and value
have been contributed to the Journal of the Chemical Society. The fol-
lowing paragraphs (256-262) consist largely of a summary of the con-
clusions arrived at and adduced in these papers, after careful collation
with each other, and the work of other investigators.

BROWN, HEROX, AND MORRIS ' RESEARCHES.

256. Malt Extract employed. — It was found that a cold aqueous
infusion of malt was the most convenient diastatic agent to employ, as
diastase when employed in a pure state was liable to considerable varia-
tions in activity. With proper precautions, the aqueous infusion of malt
admitted of any degree of accuracy. The infusion or malt extract was
prepared by mixing 100 grams of finely ground pale malt with 250 c.c. of
distilled water. This mixture was well stirred and then allowed to stand
for from six to twelve hours, and then filtered bright. This extract had
a specific gravity of 1036-1040.

257. Action of Malt Extract on Cane Sugar. — Malt extract is capa-
ble of "inverting" cane sugar, i.e., changing it into glucose. The term
"inverting" is derived from the fact that the resulting mixture of glu-
coses exerts a left handed rotary action on polarised light, while the
original sugar is dextro-rotary. The maximum effect is produced at
about 55° C. ; it is much weaker at 60°, almost destroyed at 66°, and
entirely destroyed by boiling.

258. Action of Malt Extract on Ungelatinised Starch. — According
to Brown and Heron's earlier researches, malt extract is incapable of
acting on unaltered starch ; and even when contact between the two is
maintained for a considerable time, not the slightest action is perceptible
at ordinary temperatures.

Notwithstanding this, it is well known that the starch of seeds is
attacked and dissolved during the natural act of germination ; but this
action they viewed as being inseparable from the living functions of the
vegetable cell.

This statement is at variance with that of Baranet/ky, who avers that
"the starch granules of different kin(ls are acted on with unequal rapid-
ity by the diastatic ferments of plant juices, the strongest ferment of all,
malt diastase, being well known to have no perceptible influence, even
after long exposure, on solid potato-starch granules, while wheat and
buckwheat are dissolved with facility."

In a more recent ] viper on "Germination of some of the Gramineae,"
1890, Brown and Morris refer to Brown and Heron's paper of 1879, and
the conclusion therein expressed is that ungelatinised starch is not acted
on by malt extract, no "pitting" of the granule or disintegration being
produced by artificial means. They also refer to Baranetzky's memoir,
and confirm his statement that solid potato-starch granules (which had
been exclusively used by 0 'Sullivan and themselves in their previous
researches) are highly resistant to diastase. They further find that well-
washed and highly purified barley-starch is in a few days "pitted," dis-
integrated, and dissolved by a cold-water extract of air-dried malt, the

130 THE TECHNOLOGY OF BREAD-MAKING.

action being facilitated, as shown by Baranetzky, by the presence of a
minute quantity of acid. They treated some well-purified ungelatinised
barley -star eh with a solution of precipitated malt diastase, to which
0.0065 per cent, of formic acid had been added. (Acid of this degree of
concentration has no action on barley-starch. ) A trace of chloroform had
also been employed in order to prevent putrefactive changes. The starch
was vigorously attacked, with the production of maltose as the only
optically active substance produced.

At higher temperatures, diastase or malt extract acts on ungelatinised
starch; thus Lovibond ("Brewing with Raw Grain") states that the dif-
fusive action of the diastase through the starch cell-wall is sufficient at
high temperatures, to effect the hydrolysis of the starch granulose. The
temperatures at which he worked were, however, not much below those
given for incipient gelatinisation. The authors also find that on mash-
ing wheat flour with malt extract for some time at temperatures below
the gelatinising point, considerable quantities of starch suffer hydrolysis.

Lintner gives the following table of the quantities of ungelatinised
starch dissolved by treatment with malt extract at various temperatures.
The digestion was allowed to proceed for four hours, but in the case of
the higher temperatures was practically complete in about twenty min-
utes. The results are given in percentages of the total starch taken for
the experiments : —

ACTION OF MALT EXTRACT ON UNGELATINISED STARCH.

50° C. 55° C. 60° C. 65° C.
Per Cent. Per Cent. Per Cent. Per Cent.

Potato Starch . . . . . . 0.13 5.03 52.68 90.34

Rice , . . . . . . 6.58 9.68 19.68 31.14

Wheat , 62.23 91.08 94.58

Maize , 2.70 18.50 54.60

Rye , 25.20 39.70 94.50

Oat , 9.40 48.50 92.50 93.40

Barley , 12.13 53.30 92.81 96.24

Green Malt Starch . . . . 29.70 58.56 92.13 96.26

Kilned „ . . . . 13.07 56.02 91.70 93.62

259. Action of Malt Extract on Bruised Starch. — As the next step in
the investigation, some starch was triturated in a mortar with powdered
glass. This treatment results in cutting the cellulose envelopes of the
granules. The starch granulose is then exposed, and on being treated
with malt extract rapidly undergoes conversion. The product consists
principally of maltose, the actual results obtained in one experiment
being that, after remaining six hours, the clear solution contained—

Maltose 86.3

Dextrin 10.5

Cellulose 3.2

100.0

After twenty-four hours in the cold the maltose had suffered a slight
increase : —

Maltose 91.4

Dextrin 7.0

Cellulose 1.6

100.0

ENZYMES AND DIASTATIC ACTION. 131

It will be noticed that under these circumstances a small quantity of
cellulose becomes dissolved.

260. Action of Malt Extract upon Starch Paste in the Cold.— At
ordinary temperatures malt extract acts upon starch paste (gelatinised
starch) with great rapidity and energy. In 100 c.c. of starch solution,
containing between 3 and 4 per cent, of solid matter, the addition of from
5 to 10 c.c. of the malt extract causes the starch to become perfectly lim-
pid in from one to three minutes. Immediately after arriving at this
point the solution ceases to give a blue colouration with iodine. Amylo'ins
are shown to be present by the brown reaction with iodine, and do not
disappear within some five or six minutes from the commencement of the
experiment. In this case also a small quantity of starch cellulose is dis-
solved, but is slowly re-deposited on the liquid standing. After remain-
ing three hours, three experiments gave a mean of—

Maltose 80.4

Dextrin 19.6

100.0

as the composition of the solution, resulting from hydrolysis by malt
extract.

261. Action of Malt Extract at higher temperatures. — At tempera-
tures of 40° and 50° C., the ultimate products of the action of malt
extract are found to be practically the same as in the cold, but the point
of disappearance of amyloins is reached somewhat less rapidly. At 60° C.
the action is weakened, but still proceeds sufficiently far to produce prac-
tically the same amount of maltose. At still higher temperatures the
transformation of the dextrin, first formed, into maltose goes on much
more slowly. Also, the action of the diastase of the malt extract may be
weakened by the addition to it of dilute alkalies. Such treatment results
in limiting the extent to which he conversion of dextrin into maltose pro-
ceeds. The results may be summed up by stating that, by modifications
of the treatment of starch paste with malt extract, certain fixed points
may be obtained representing several different molecular transformations
of starch.

262. Molecular Constitution of Starch, Dextrin, and Maltose. — The
historical development of the modernly held hypothesis of the molecular
constitution of starch is, in view of the importance of the subject, of con-
siderable interest. Brown and Heron, in their paper on " Starch and its
Transformations," 1879, considered that the most natural conclusion that
can be derived from the varying proportions of dextrin, obtained in
modifications of the hydrolysis of starch paste by malt extract, is that
there are several dextrins, and that these dextrins are polymeric, and not
metameric bodies. Having adopted this view, Brown and Heron 's results
led them to the opinion that the simplest molecular formula for soluble
starch is 10C12H20010, which may also be written C12X10H2GX10010X10. The
first change produced by the addition, of malt extract would, then, be
represented by—

^12X10-"-20X10^30X10 I H2O = ^12X9H2OX9V)10X9 ~\~ ^l2-"-22U11
Soluble Starch. Water. Erythro-dextrin. a. Maltose.

That is, one of the groups of C12H20010 having combined with water to
form maltose, the remaining nine groups constitute the first or most com-
plex dextrin. By the assimilation of another molecule of water, the nine-
group dextrin breaks up into a second molecule of maltose and an eight-
group dextrin. This reaction proceeds through successive stages until

132 THE TECHNOLOGY OF BREAD-MAKING.

finally the one-group dextrin, C]2H.,()0]0, is in its turn transformed into
maltose. There are thus theoretically possible nine polymeric modifica-
tions of dextrin ; the two higher of these are erythro-dextrins ; the remain-
ing seven are achroo-dextrins. The most stable of the whole of these dex-
trins is that resulting from the eighth transformation, having the compo-
sition C12X2H20X2010X2 : the hydrolysis of starch, with the production
of this dextrin, would then be represented by—

Ci2xioH20xi0010xio ~h 8H20 = C12xi2H20x2010X2 -f- SC^H^O.j.

Soluble Starch Acnroo-dextrin£. Maltose.

In the paper by Brown and Morris ("The Non-crystallisable
Products of the Action of Diastase upon Starch," 1885), they
adduce evidence in favour of a third body, maltodextrin, being formed
as an intermediate product during the hydrolysis of starch ; as previously

fC12H22Ou
mentioned, they ascribe to this body the formula, <[C12H20O]0. From

[C12H20010

this it will be seen that maltodextrin is composed of a molecule of mal-
tose united with two of the one-group dextrin. Viewed in the light of
the existence of this intermediate product, they then regarded the fol-
lowing as the simplest molecular formula for starch, capable of account-
ing for the various reactions observed during its hydrolysis —

(C12H20O10)3

(C12H20010)3

(C12H20O10),,

(C12H20010)3

In accordance with this hypothesis, the first step in hydrolysis consists
in the lesion of one of the ternary groups, which is transformed into
maltodextrin by the assimilation of a molecule of water, thus —

TT O

±iu o

One of the five ternary groups Water. Maltodextrin.

constituting the starch molecule.

Malt extract effects the complete conversion of maltodextrin into
maltose —

^12^-22^11 i 9TT n ^P TT O

T TT O ^ ~T~ Z112U 'J^1211221J11-

l2±120U10J2
Maltodextrin. Water. Maltose.

In the change producing maltodextrin, the remaining four ternary
groups of (C12H20010)3 unite to form the most complex of the dextrins.
As the hydrolysis continues, the remaining ternary groups undergo suc-
cessively the same change until one only remains : this is identical with
that before referred to as achroo-dextrin£. The view that the starch
molecule contains fifteen of the C12H.,0O10 group instead of ten, requires
that this, which may be distinguished as "stable dextrin," shall consist
of three groups of C12H.,0010 instead of two: this, of course, makes the
formula the same as that of one of the ternary groups. The reaction for
the production of stable dextrin is then represented by the following
equation : —

f(C12H20010)3

| (C12H2(,0,0)., fC,2H200,0

-|(C12H20010), + 12H20 = = -!C12H200IO + 12C12H220,

|(C12H200IO), IC,2H200IO

l(C12H200,0),,

Soluble Starch. Water. Stable Dextrin. Maltose.

i r

ENZYMES AND DTASTATIC ACTION. 133

Such, very briefly summarised, were the opinions advanced by Brown,
Heron, and Morris, up to 1885, as to the relative molecular constitutions
of starch, dextrin and maltose.

In 1888 and 1889, Brown and Morris contributed to the Chemical
Society's Journal two most important papers 011 "The Molecular Weights
of the Carbohydrates. ' ' To these papers reference has already been made
in the commencement of Chapter VI. By the application of Raoult's
method, the molecular weights of starch and the products of its hydrolysis
were definitely determined. Among these determinations, probably the
most important was that of dextrin. This was made as a preliminary to
the estimation of that of soluble starch. It has been already shown that
these chemists view starch as a compound of five dextrin groups. In
their 1889 paper they say : —

"When the complex molecule of starch is broken down by diastase,
under the conditions most favourable to its complete hydrolysis, we have
shown that a point of equilibrium, or, speaking more strictly, a resting
point in the reaction is reached, when the amount of dextrin produced
corresponds to one-fifth by weight of the amount of starch taken; that is,
when the mixed products have [a] j?J.K6 = 162.6° and K3.86 = 49.3.

"This reaction is represented in the simplest form by

5C12H20010 + 4H20 = C12II,0010 + 4C12H2201i

titarcn. Water. Dextrin. Maltose.

"If the production of maltose and dextrin during hydrolysis is to be
considered as due to a molecular degradation of the starch, and we think
the evidence in favour of this is almost conclusive ; then, no matter what
view we may take of the actual manner in which this degradation takes
place, we cannot escape from the conclusion that the molecule of stable
dextrin of the above equation is one-fifth of the size of the soluble starch
molecule from which it has been derived."

Brown and Heron determined by Raoult's method the molecular
weight of this dextrin, and thus indirectly that of starch. In the next
place they proceeded to consider whether Raoult's method was capable
of throwing any light on the relations of the dextrins to each other, it
being a matter of the highest theoretical importance to determine whether
these bodies constitute a series of polymers, or whether they stand merely
in metameric relation to each other. Accordingly some of the so-called
higher dextrins were prepared ; that is, those which result from starch
hydrolysis arrested at its earlier stages. A comparison of the results
obtained afforded no evidence of there being any difference in the
molecular weights of the higher and lower dextrins. Brown and Morris
summarise their conclusions by saying that there being no differences in
the various dextrins when treated by Raoult's method, "goes, in our
opinion, a long way towards proving that, after all the dextrins are
metameric, and not polymeric. If this is admitted as even probably cor-
rect, it becomes necessary to consider how far our previous views on the
breaking-down of the starch molecule must be modified in order to in-
clude the new facts." Brown and Morris enunciate the following
hypothesis as being more in accord with the facts : —

"We may picture the starch-molecule as consisting of four complex
amylin-groups arranged round a fifth similar group, constituting a
molecular nucleus.

' ' The first action of hydrolysis by diastase is to break up this complex
molecule, and to liberate all the five amylin-groups. Four of these groups
when liberated are capable, by successive hydrolysations through malto-
dextrins, of being rapidly and completely converted into maltose, whilst

134 THE TECHNOLOGY OF BREAD-MAKING.

the central amylin nucleus, by a closing up of the molecule, withstands
the influence of hydrolysing agents, and constitutes the stable dextrin of
the low equation, which, as we know, is so slowly acted upon by subse-
quent treatment with diastase. The four readily hydrolysable amylin-
groups we look upon as of equal value, and in their original state these
constitute the so-called high dextrins, which can never be separated com-
pletely from the low dextrin by any ordinary means of fractionation.

"This hypothesis provides for intermediate maltodextrins or amylo-
dextrins, whose number is only limited by the size of the original amylin-
group.

"Each amylin-group of the five has a formula of (C12H20010)20, and
a molecular weight of 6480; so that the entire starch-molecule, or,
more correctly speaking, that of soluble starch, is represented by
5(C12H20010)20, having a molecular weight of 32,400."

In their Text Book of the Science of Brewing, published in 1891,
Moritz and Morris further explain that probably the outer amylin-groups
cannot exist as such, but immediately on separation from the central
nucleus are partially hydrolysed, yielding amyloins of possibly the very
highest type. These amyloins are gradually hydrolysed, being split up
into smaller aggregations, which constitute the various maltodextrins.

Brown and Millar, in a paper contributed to the Journal of the Chem-
ical Society in 1899, point out that the so-called stable dextrin has a
cupric reducing power of R 5.7-5.9, and therefore must contain a glucose
group. According to this view, the hydrolysis of starch is thus repre-
sented : —

100C12H20010 + 81H20 = 800^0,1 + 39

(^6xi12w6

Starch. Water. Maltose. Stable Dextrin.

263. Effect of Heat on Diastasis. — The rapidity of diastatic action is
considerably influenced by variations of temperature ; extreme cold prac-
tically inhibits it. Starting from ordinary temperatures, diastasis rap-
idly increases as the temperature rises, until, according to Kjeldahl,
54° C. (129° F.) is reached— from that temperature until 63° C. (145°
F.) it remains fairly constant, and then rapidly decreases with any
further rise in temperature, being entirely destroyed at 80-81° C. (176-
177.8° F.). Lintner, working with soluble starch, places the optimum
temperature at 50-55° C. (122-131° F,).

Lintner carefully investigated the effect of heat on diastase itself by
dissolving similar quantities of diastase in water, and then heating the
various solutions to 55° C. (131° F.) for varying periods of time, and
then determining the quantity of each solution requisite to convert the
same amount of starch. He obtained the following results : —
Of the untreated solution 0.55 c.c. was required.

After heating 20 minutes at 55° C., 1.10 c.c. of solution were requisite.
40 „ „ 1.75 c.c.

60 „ „ 2.22 c.c.

By prolonged subjection to this temperature the diastase was much
weakened ; but, where starch and its transformation products are present,
the diastase does not suffer to a like extent on subjection to this tempera-
ture, the strength being reduced by about only half the amount when
heated in water alone. These results should be compared with those of
Brown and Heron, quoted in paragraph 254, on Nature of Diastase.

264. Effect of Time and Concentration on Diastasis. — Other condi-
tions being the same, the time occupied in producing a given amount of
reaction depends on the quantity of diastase present. Concentration

ENZYMES AND DIASTATIC ACTION. 135

within wide limits has little effect on the rapidity of diastatic action:
Kjeldahl states that equal quantities of diastase, acting at the same tem-
perature and for the same period of time, effect the same amount of con-
version in solutions differing widely in degree of concentration.

265. Other Conditions Favourable and Inimical to Diastasis. —
Kjeldahl states that very minute quantities of sulphuric, hydrochloric,
and organic acids accelerate diastasis, but large quantities retard it.
Lintner states that sulphuric acid, to the extent of 0.002 per cent., very
slightly increases the activity of diastase; that 0.01 per cent, retards it,
and 0.10 per cent, exercises a destructive action. He also finds that 0.001
per cent, of ammonia retards diastasis, 0.005 per cent, almost, and 0.2 per
cent, entirely stops the reaction. The influence, not only of these, but, of
course, other substances, depends 011 their degree of concentration.
Speaking generally, acetic and hydrocyanic acids, strychnine, quinine,
and the salts of these bases, very slightly retard the action of diastase.
Alkaline carbonates, dilute caustic alkalies, ammonia, arsenious acid, and
magnesia, exercise a somewhat greater retarding influence, depending on
the amount of these bodies added. The following bodies completely pre-
vent the action of diastase upon starch — nitric, sulphuric, phosphoric,
hydrochloric, oxalic, tartaric, citric, and salicylic acids ; caustic potash,
soda, and lime; copper sulphate and acetate; mercury chloride, silver
nitrate, iron persulphate, alum, and borax. Among antiseptics, formic
aldehyde acts energetically, on many of the enzymes. On the other hand
— alcohol, ether, chloroform, thymol, creosote, essence of turpentine,
cloves, lemon, mustard, etc., exert no retarding influence.

In cases where it is desired to suddenly arrest the action of diastase in
chemical changes, salicylic acid forms a convenient agent. In 100 c.c.
of solution, 0.040 gram of salicylic acid almost destroys the activity of
the diastase in 5 c.c. of 40 per cent, malt extract solution, while 0.050
gram completely arrests all action. In any material containing diastase
and starch, treatment with boiling 80 per cent, alcohol completely para-
lyses any subsequent action of the diastase without gelatinising the starch.

Where it is wished to prevent fermentation or putrefaction without
retarding diastasis, the addition of small quantities of chloroform or
thymol produces the desired effect. Chloroform is conveniently used in
the form of chloroform water, containing 5 c.c. of chloroform to the litre.
Toluene may also be employed for the same purpose, and is very slightly
if at all harmful to enzymes.

266. Ptyalin and Amylopsin. — Ptyalin is found in human saliva, and
at an optimum temperature of 35° C. converts starch paste into dextrin
and maltose ; the reaction being identical with that produced by diastase.
Ptyalin acts best in a neutral medium, but is but little affected by small
amounts of alkali; a very small quantity of acid, however, arrests its
activity, consequently the diastatic action of ptyalin is destroyed on the
mixture of food and saliva encountering the acid gastric juice of the
stomach. Ptyalin is without effect on cellulose, and hence intact starch
granules are not digested by its action.

Amylopsin is an enzyme, very similar to ptyalin, found in the pan-
creatic juice, where it performs important digestive functions on starchy
foods.

267. Raw Grain Diastases. — Earlier observers have pointed out that
barley contains more coagulable proteins than does malt, yet fresh barley
extract exerts but little diastatic action. Experiments, on which these
observations were based, were made with starch-paste, but more recent
investigations in which soluble starch was employed show that in some

136 THE TECHNOLOGY OF BREAD-MAKING.

cases raw barley is more actively diastatic than is the green malt pre-
pared from it. Both from barley and wheat a diastase may be obtained
by the same methods as employed for its extraction from malt, that is, by
treatment with 20 per cent, alcohol, subsequent precipitation of the fil-
tered alcoholic extract with absolute alcohol, and drying in vacuo over
sulphuric acid. Lintner and Eckhardt have examined this enzyme in
order to determine whether or not it is identical with malt diastase. For
this purpose they took quantities of malt and barley extracts respectively,
having the same diastatic value as determined by Lintner 's method, and
subjected soluble starch to their action at varying temperatures. They
found that malt diastase had the greatest activity at 50° C., and the most
favourable period at 50-55°. Raw grain diastase, on the other hand,
showed the greatest activity at 50, and the most favourable period at
45-50°. At 4° the raw grain diastase had as high a reducing power as
was possessed by that of malt at 14.5°. The conclusion is that the two
forms of diastase are distinct from each other.

A more marked and important distinction between these two enzymes
is the inability of that from raw grain to effect liquefaction of starch-
paste, while if by some other means such liquefaction is effected, raw
grain diastase energetically converts the soluble-starch into dextrin and
maltose. Brown and Morris notice that the power to liquefy starch-paste
and to erode the starch-granule go hand in hand : the observed presence
or absence of either property affords safe ground for predicting the
presence or absence of the other of the two. But Baker in a paper com-
municated to the Journal of the Chemical Society in 1902, points out that
he was able to completely liquefy starch-paste by barley diastase, in from
two to three hours at 50° C., with the production of dextrin and maltose.
The raw grain diastase is probably an unused residue of an enzyme pro-
duced during the previous history of the plant.

268. Invertase. — Although diastase is unable to carry the hydrolysis
of starch further than into maltose, yet, as already stated, there is evi-
dence of malt extract containing an enzyme capable of converting cane-
sugar into glucose. Brown and Heron adduce experimental proof of this
point in a contribution to the Journal of the Chemical Society, Vol.
XXXV, 1879, page 609 ; they show that a cane-sugar solution, after being
digested for 16 hours as 55° C. with cold water extract of malt, contained
20.4 per cent, of glucose. If, on the other hand, the malt extract were
previously boiled for 15 minutes, the percentage of invert sugar was
reduced to 0.2 per cent. This enzyme has been termed zymase, but is now
known as invertase, the former name being applied to another enzyme,
which will subsequently be described. For practical purposes the prin-
cipal source of invertase is beer-yeast, from which it may be separated in
a fairly concentrated form. O 'Sullivan and Tompson recommend for this
purpose that sound brewers' yeast be pressed, and then kept at the ordi-
nary temperature for a month or two, during which time it does not
undergo putrefaction, but changes into a heavy yellow liquid. On filter-
ing, this yields a clear solution of high hydrolytic power, containing all
the invertase of the yeast in solution. This liquid has a specific gravity
of about 1080, and is termed "yeast liquor" by O 'Sullivan and Tompson.
This liquor remains for a long time unaltered, except for a darkening of
colour. On adding spirit to yeast liquor till it contains 47 per cent, of
alcohol, the invertase is precipitated, and may be washed with spirit of
the same strength and dried in vacuo, or preserved as a solution by ex-
tracting the precipitate with 20 per cent, alcohol, and filtering, when the
filtrate contains the invertase.

ENZYMES AND DIASTATIO ACTION. 137

Invertase acts rapidly on cane-sugar according to the equation : —
CI2H22On + H20 = C6H1206 + C6H1206.

Cane-sugar. Water. Glucose. Fructose.

The speed of inversion increases rapidly with the temperature until
55-60° is reached. At 65° invertase is slowly, and at 75° immediately
destroyed. Minute quantities of sulphuric acid are exceedingly favour-
able to the action, but a slight increase of acidity beyond the favourable
point is very detrimental. A sample of invertase which had produced
inversion of 100,000 times its own weight of cane-sugar was still active ;
and further, invertase itself is not injured or destroyed by its action on
cane-sugar. There is evidently no limit, therefore, to the amount of
sugar which can be hydrolysed by a given amount of invertase. The
caustic alkalies^ even in very small proportions, are instantly and irre-
trievably destructive of invertase. Invertase is without action on starch,
dextrin, maltose, glucose, fructose and gum.

Osborne has prepared invertase in an exceedingly pure form, and
finds it to give none of the protein reactions, except precipitation by cop-
per sulphate, lead acetate, and phospho-tungstic acid ; though it gave
Millon's, the xanthoprotein, and biuret reactions very faintly. He there-
fore concludes that it is not protein in nature.

269. Maltase. — In addition to invertase, Lintner regards yeast as
containing another and distinct enzyme, to which has been given the name
of maltase. This body possesses the power of changing maltose into
glucose.

270. Intestinal Invertase. — The secretions of the small intestines
contain an enzyme allied to the invertase of beer-yeast, inasmuch as it
inverts cane-sugar into glucose and fructose;- it also inverts maltose into
glucose, thus differing from the invertase of yeast, which has no action on
maltose. Brown and Heron state that it acts on starch, but Halliburton
is of opinion that the bulk of evidence is against the presence of any such
diastatic action.

271. Pepsin, or Peptase, and Trypsin. — Collectively, the fluids of the
stomach are known as gastric juice, and contain an active proteolytic
enzyme termed pepsin. Pepsin may be obtained from the mucous mem-
brane of the stomach by extraction with glycerin, in which pepsin is
poluble. The pepsin is precipitated from its glycerin solution by alcohol,
dissolved in water and freed from salts and peptones by dialysis. Pepsin
is soluble in water to a mucous liquid, but is insoluble in alcohol or ether.
Pepsin has been prepared by Pekelharing in a comparatively pure state ;
he finds it to give the majority of protein reactions, but not to contain
phosphorus, thus negativing any possibility of its belonging to the
nucleo-proteins. In the presence of an acid, preferably hydrochloric,
pepsin attacks and rapidly dissolves insoluble protein substances, as the
white of hard-boiled eggs or lean beef, converting them into peptones.
Pepsin is most active at about 40° C., and loses its power on exposure
to 57-58°. The acid condition is necessary to its action, and is supplied
in the gastric juice by the presence of hydrochloric acid, which in the
gastric juice obtained from the human stomach amounts to 0.02 per cent.,
and in that of the dog to 0.30 per cent. The energy of pepsin is impaired,
and at last arrested by the peptones produced. Dried pepsin may now be
obtained as an article of commerce, being prepared by drying under 100°
F. the fresh mucous lining of the stomach of the pig, sheep, or calf. In
accordance with the scheme of nomenclature in which the names of the
enzymes end in ase, the name of this body is frequently written peptase.

138 THE TECHNOLOGY OF BREAD-MAKING.

Trypsin occurs in the pancreatic juice, and is allied in its general
behaviour to pepsin, possessing like it the power of converting proteins
into peptones. It differs, however, in the fact that it acts best in an
alkaline medium, and less energetically in neutral or slightly acid solu-
tions. The action is arrested by the presence of hydrochloric acid in
excess.

272. Proteolytic Enzyme of Resting and Germinating Seeds. — Seeds
generally appear to contain a proteolytic enzyme in the form of a
zymogen, which during the act of germination becomes converted into an
active enzyme, termed protease. This body converts the proteins of the
seed into peptones, leucin, and tyrosin. Malt extract exerts a marked
physical and chemical effect on the proteins of flour during bread fer-
mentation, a result due to the presence of a proteolytic enzyme, or form
of protease.

273. Zymase. — Researches by Buchner and others, (Berichte
d. Deutsch. chem. Ges., 1897) have shown that when yeast is ground up
with sand and kieselguhr, and then subjected to nitration under hydraulic
pressure, a liquid is obtained which is free from yeast cells, and yet is
capable of converting sugar in solution into alcohol and carbon dioxide.
The chemical action commences in something under an hour and continues
regularly for some days. By treatment with alcohol, an active principle
can be separated from the yeast nitrate. Buchner proposed the name
zymase for this substance, and has proved its action to be due neither to
yeast cells nor to fragments of yeast protoplasm contained in the liquid.
Zymase is, therefore, to be regarded as a definite member of the enzyme
group.

274. Other Enzymes. — Among other enzymes mentioned in the
classified list previously given, a word should be said about those included
in the group of coagulative enzymes. The coagulation of blood on leaving
the body is due to an enzyme ; so also is that of muscle at death, in the
case of the stiffening termed rigor mortis, known in this instance as the
myosin-ferment or enzyme. Interest attaches to this, as the animal
analogue of Weyl and Bischoff's hypothetical myosin, to which they
ascribe the formation of gluten in the doughiiig of wheateii flour.

Space does not permit any further reference to the emulsive and
steatolytic enzymes.

DETAILS OF APPLIED HYDROLYSIS.

275. Empirical Statement of Hydrolysis of Starch. — It will be seen
that the formulae, representing the probable constitution of the molecules,
are much more complex that the empirical formulae respectively of starch
and dextrin. The following empirical equation represents in the simplest
possible manner the above reaction; it must not, however, be viewed
as representing the true nature of the molecular change involved : —

(C6H1005)5 + 2H20 = C6H1005 -f 2C12H22On.

Soluble Starch. Water. Dextrin. Maltose.

276. Hydrolysis of Cane-Sugar. — This operation is slowly effected
by the action of malt extract, or even by prolonged boiling with water,
which effects the same change more or less completely. At ordinary tem-
peratures, dilute sulphuric and hydrochloric acids are capable of slowly
inverting cane-sugar; at temperatures of from 65° to 70° C. the hydro-
lysis occurs with extreme rapidity. For laboratory purposes, complete
inversion is effected by adding to the moderately strong sugar solution
one-tenth its volume of strong hydrochloric acid, and then heating the

ENZYMES AND DIASTATIC ACTION. 139

mixture in a water-bath until the temperature reaches about 68° C. The
change consists of the cane-sugar molecule splitting up into two molecules
of glucose, the one being dextro and the other Ia3vo-rotary—

CI2H220lt + H,0 = C.HU0. + C.HU0.

Cane-Sugar. Water. Dextro-glucose. Ljevo-glucose.

Invertase also effects, this change, and possibly may be employed
commercially for the purpose. 0 'Sullivan recommends its employ-
ment in the laboratory for the hydrolysis of cane-sugar as a step
towards its analytic estimation.

277. Hydrolysis of Dextrin. — By the action of acids, and also of
malt extract, this body may be entirely converted into maltose : the nature
of the chemical change has been described when treating of the hydro-
lysis of starch. Under ordinary conditions, neither invertase nor yeast
itself is capable of effecting the hydrolysis of dextrin.

278. Hydrolysis of Maltodextrin. — This change is readily effected
by the action of malt extract, but not by either invertase or yeast.

279. Hydrolysis of Maltose. — Maltose is a more stable sugar than is
cane-sugar : dilute acids effect its conversion with slowness ; thus a maltose
solution may be boiled for some minutes with dilute sulphuric acid with-
out undergoing change. Complete inversion results from keeping the
solution at a temperature of 100° C. for some six or eight hours. The
principal product of inversion is glucose. As has been previously stated,
malt extract has no hydrolysing action on maltose. Invertase also is
without action on maltose, but maltase effects its hydrolysis.

280. Composition of Malt. — Prior to dealing with the saecharifica-
tion of malt, some information should be given of its composition. Treat-
ment of the general questions of the transformation of barley into malt
must be postponed until the subject of the physiology of grain life is
being discussed. Malts differ from barley in that the protein constituents
show proofs of considerable degradation. Hilger and Van der Becke have
examined barley, barley softened by steeping in water, fresh or green
malt (unkilned), and kiln-dried malt. The following table gives the per-
centage of nitrogen, and of the various nitrogenous constituents : —

NITROGENOUS CONSTITUENTS OF BARLEY AND MALT.

Softened
Barley. Barley. Fresh Malt. Dried Malt.

Total Nitrogen .. .. .. 1.801 1.750 1.751 1.542

Nitrogen of Insoluble constituents 1.6789 1.6853 1.372 1.165

as Albumin (soluble) .. 0.0600 0.0354 0.1571 0.1194
as Peptone . . . . 0.0046 0.0009 0.0058 0.0233

as Ammonium Salts . . 0.0169 0.0290 0.0057

as Amino-acids . . 0.0417 0.0294 0.1417 0.2257

as Amides . . . . 0.0505 0.0029

It will be seen that the insoluble proteins have diminished in quan-
tity, while the albumin has increased ; so also have the products of further
degradation, peptone, amino-acids, and amides.

The starch in barley also suffers considerable diminution ; Brown and
Morris found the quantities of starch in barley before and after germina-
tion to amount to

STARCH IN 1000 CORNS.

Starch in Barley Starch in Barley after

before Germination. Six Days' Germination. Loss of Starch.

Expt. 1 . . . . 20.0552 grams. 15.4398 grams. 4.6154 grams.
2 , 19.9158 15.3636 4.5522

140 THE TECHNOLOGY OF BREAD-MAKING.

Taking the mean of the two experiments, 22.5 per cent, of the starch
has disappeared. A portion of this has been dissipated as carbon dioxide
gas, a portion will have constituted the material from which the new parts
of the plant have been formed, while a third portion will have been
changed into sugars, which remain in the malt at the end of its manufac-
ture. The increase of sugars is well shown in the following table, which
gives in percentages the results of analyses of barley before and after ger-
mination, by 0 'Sullivan.

SUGARS IN BARLEY BEFORE AND AFTER GERMINATION.

— No. 1 Barley— , — No. 2 Barley— -

Before After Before After

Germination. Germination. Germination. Germination.

Sucrose (Cane-Sugar) . . 0.9 4.5 1.39 4.5

Maltose ] [1.2 ] fl.98

Dextrose [ 1.1 .{3.1 J>0.62 <H.57

L*evulose J [0.2 J (0.71

It will be seen that cane-sugar forms a very notable constituent of
malt, and also that the other sugars are present in large quantity.

The percentage of acid considerably increases in grain during malt-
ing; assuming acidity to be due to lactic acid, Belohoubek gives the
following : —

Barley . . . . . . . . 0.338 per cent, as lactic acid.

Green Malt » 0.590

Kilned Malt 0.942

In English malts, however, the percentage of acid is considerably less
than this, being usually about 0.2 per cent. ; so much as 0.4 per cent, is
viewed as an indication of unsoundness. Although the acidity of malt is
usually returned as lactic acid, a considerable amount is due to the pres-
ence of acid phosphates; but, obviously, acidity due to this cause cannot
increase during malting.

The following table gives the approximate composition of malt, based
principally on analyses by 0 'Sullivan < —

APPROXIMATE COMPOSITION OF MALT.

Per Cent. Per Cent.

Starch 44.00 to 50.00

Sugars 9.00 „ 16.00

,, These include Sucrose, from . . 4.501

Maltose, „ .. 1.20 lfif)0

Dextrose, „ .. 1.65 [ "

Laevulose, „ . . 0.20 '

Unfermentable Carbohydrates, not Dextrin 5.00 ,, 7.00

Cellular Matter (Cellulose) 10.00 „ 12.00

Proteins, soluble in cold water . . . . 3.0 ,, 4.50

insoluble „ . . . . 8.00 „ 10.00

- Fat 1.50 „ 2.00

Ash 1.90 „ 2.60

Water 2.50 „ 7.00

Acid reckoned as Lactic Acid . . . . 0.20 „ 0.40

281. Saccharification of Malt during the Mashing Process. — This
process is of interest both from the technical point of view, as being
largely used by the baker, and also scientifically, as representing an
important example of hydrolysis by malt extract. Malt contains the
active hydrolysing principle, diastase, and also from 44 to 50 per cent, of

ENZYMES AND DIASTATIC ACTION. 141

starch. In the operation of malting, the walls of the starch grannies get
more Or less ruptured and fissured ; hence the interior granulose is at the
outset somewhat exposed to the action of the diastase. As a first step
toward the preparation of beer, the brewer treats his ground malt with
water at a temperature of from 65.5° C. (150° F.) to 71.1° C. (160° F.).
This results in the conversion of the starch present into dextrin and
maltose. This operation he terms "mashing." The first change is that
the starch becomes gelatinised, and is then freely susceptible to the
action of diastase. At temperatures below the gelatinising point of
starch, diastasis also proceeds, but somewhat more slowly (comp. Lint-
ner's. table, par. 258). At a temperature of about 60° C. (140° F.)
almost all the starch, and also the amyloms, will have disappeared in
about twenty minutes; this point may be ascertained by taking out a
drop of the liquid and testing it with iodine. An increase of temperature
weakens the action of the diastase ; hence a mashing made at 60° C. (140°
F.) yields in two hours, for the same malt, about 7 per cent, more dextrin
and maltose than when mashed at 76.6° C. (170° F.). Further, as might
be expected from the results already mentioned, the proportion of dex-
trin is much greater in the mashing made at 76.6° C. than at 60° C.
The duration of the mashing operation has also an influence on the amount
of dextrin and maltose produced. With a temperature of 62.7° C. (145°
F.) most of the starch is converted into dextrin and maltose within thirty
minutes, but for some time after, the yield of these continues to slightly
increase. The proportion of maltose to dextrin also becomes higher
with a longer mashing. The following is the result of an experiment by
Graham : —

Length of Percentage of Percentage of Total percentage Ratio of Maltose

Mashing. Maltose. . Dextrin. of Maltose & Dextrin. to Dextrin.

Y-2 hour 48.60 14.61 63.21 3.3 : 1

1 „ 52.35 12.26 64.61 4.2:1

2 hours 53.56 11.39 64.95 4.7 : 1

3 „ 54.60 11.05 64.65 4.9:1
7 „ 61.47 3.53 65.00 17.4:1

It will be seen that by far the greatest proportion of the transforma-
tion is effected within the half-hour, while for all practical purposes the
hydrolysis is completed within two hours at the furthest.

282. Mashing Malt together with Unmalted Grain. — The diastase of
gcod malt is not merely capable of saccharifying its own starch, but is
competent also to hydrolyse in addition considerable quantities of starch
from other sources ; hence, in brewing operations, malt is frequently
mixed with flour from other cereals, either rice or maize being commonly
chosen. The diastase of the malt saccharifies the whole of the starch
present ; but with the proportion of malt unduly low, the ratio of maltose
to dextrin produced is comparatively small.

EXPERIMENTAL WORK.

283 Hydrolysis of Starch. — Mix 10 grams of starch with 200 c.c. of
water, and gelatinise by placing in the hot water-bath. Take 50 c.c. of
this solution and add to them 10 c.c. of five per cent, sulphuric acid.
Maintain at a temperature of 100° C. until a few drops, taken out with a
glass rod or tube, and placed on a porcelain tile, give no blue colouration
on addition of iodine. To the solution add precipitated calcium car-
bonate, or powdered marble, until it ceases to produce effervescence.

142 THE TECHNOLOGY OF BREAD-MAKING.

Allow the precipitate to subside, and filter ; taste the clear solution, notice
its sweetness. Test a portion of this filtered solution with Fehling's solu-
tion, a red precipitate is produced, showing that either maltose or glucose
is present.

To a test tube, containing another portion of the original starch solu-
tion, add some saliva, and stand it in a water-bath at a temperature of
about 40° C. for some time ; notice that the solution becomes more limpid,
and ultimately that it gives no starch reaction, on a few drops being
taken out and treated with iodine. Test now for maltose, by means of
Fehling's solution; a red precipitate is produced. As a complement to
this experiment, boil some corn-flour and water, allow the paste to cool,
place a spoonful in the mouth, retaining it there for some fifty or sixty
seconds, and mixing it with saliva by means of the tongue : notice that the
paste becomes limpid, and acquires a sweet taste.

Take some fresh compressed yeast, mix a little with some of the starch
solution and place in the water-bath at 40° C. Notice that after several
hours the starch remains unaltered, giving a blue colouration with iodine,
and little or no reaction with Fehling's solution. Prepare some "yeast-
water" by shaking up about 50 grams of the compressed yeast with 150
c.c. of cold water ; let this stand for from four to six hours, shaking occa-
sionally, then allow to subside and filter the supernatant liquid. Treat
some starch solution with this yeast-water in the same way as with the
yeast itself : notice that this also causes no alteration in the starch.

Make an aqueous extract of malt, as described in paragraph 256. Take
some sound wheat starch, examine it under the microscope, to see that
none of the granules are fissured or cracked. Add some of the malt ex-
tract to a portion of this starch, and allow it to remain for some hours at
a temperature of 20° C. Maintain another similarly prepared sample at
a temperature of 40° C. for from six to twelve hours. At intervals from
the time of starting the experiment, and at the end of the time, examine
the starch in each case carefully under the microscope, in order to see
whether any of the granules show signs of cracking or pitting. Make a
comparative series of experiments on potato starch. In every experiment,
at the end test the starch granules with iodine, in order to see whether
they still give the starch reaction.

Shake up some starch with water, and' filter: notice that the clear
filtrate gives no reaction with iodine. Rub a little of the starch in a mor-
tar with powdered glass ; this cuts the cellulose envelopes. Shake up
with water, and filter; to the clear filtrate add iodine solution: a blue
colouration shows the presence of soluble starch. To some of the bruised
starch add malt extract, and allow to stand for twenty-four hours at 20°
or 25° C., examine under the microscope, and notice that much of the
interior of the cells is dissolved away. Treat a little with iodine, and
examine under the microscope in order to determine how much unaltered
starch remains. Make some starch paste, as described in paragraph 260 ;
treat it with malt extract as there mentioned, and at intervals of a minute
take out a drop of the solution by means of a glass rod, and test with
iodine on a porcelain tile. Note the time when the starch and the amy-
loins disappear. Make a series of similar experiments with varying tem-
peratures, rising by 10° C. at a time, from 15° C. to the point at which
diastasis ceases. The quantities of solution should be measured; and in
each case, both the starch and the malt extract solutions should be allowed
to stand in the water-bath, regulated to the desired temperature, until
both have acquired that temperature, then mix the two and note the time.

ENZYMES AND DIASTATIC ACTION. 143

If desired, the bath may be regulated for this experiment by means of the
regulator described and figured in Chapter XI. ; in that case it is not ab-
solutely necessary to get the temperature nearer than a degree, but the
exact temperature, as read by a thermometer, should be noted.

Make a cold aqueous infusion of bran or pollard in the same way as
described for malt, and treat starch solution with it, as was done with
the malt extract, both in the cold and at higher temperatures. If sepa-
rated wheat germ is obtainable, make a similar series of experiments with
that substance.

284. Hydrolysis of Cane-sugar. — Mix cane-sugar solution with
strong hydrochloric acid, and heat to 68° or 70° C., as described in para-
graph 276. After hydrolysis, test for reducing sugars by Fehling's solu-
tion. To another portion of the ,cane-sugar solution add some yeast-
water, and maintain for three or four hours at 40° C., after which test
for maltose or glucose by means of Fehling's solution.

285. Mashing of Malt. — Take 100 grams of ground malt, and mix
with 500 c.c. of water at 60° C. in a large beaker ; weigh the beaker and
its contents, and place it in a water-bath at 60° C. Stir occasionally, and
from time to time take out small quantities of the well-stirred liquid on
the end of a glass rod, and test for starch by iodine solution. Note how
long it is before the starch disappears ; as soon as iodine produces no blue
reaction, wipe the outside of the beaker, place it in the balance, and add
distilled water until that lost by evaporation has been replaced : when
this point is reached the beaker weighs just the same as before being
placed in the bath. Then filter the clear solution, cool rapidly to 15° C.,
and take the density by means of a hydrometer. The method of using the
hydrometer, and the conclusions to be drawn from the density of the
wort, are described in the paragraph on ' ' Specific Gravity of Worts ' ' in
Chapter XII. Make similar mashings at the temperatures respectively of
50° and 70° C. ; note in each case the time requisite for saccharification,
and the density of the wort. For the different experiments both the
mashing liquor and the bath must be regulated to the temperature
desired.

286. Substances inimical to Diastasis. — Prepare some starch solution
and malt extract as in paragraph 283. To a portion of the malt extract
add a small quantity of caustic potash, and note the time it takes to sac-
charify the starch, both starch and malt being used in the same propor-
tions as before. Make similar tests with solutions of sulphuric, tartaric
and salicylic acids ; lime, copper sulphate, alum, borax, alcohol, and
essence of turpentine.

CHAPTER IX.
FERMENTATION.

287. Origin of Term. — When a little of the substance called yeast is
added to some wort (i. e., the sweet liquid produced by the infusion of
malt with warm water), at a temperature of about 18° C., it induces a
most remarkable change. The quiescent liquid after a time becomes filled
with bubbles; these rise to the surface and form a scum there; as the
action proceeds these bubbles are produced with increased rapidity.
Their continuous ascension gives the liquid a seething or boiling appear-
ance, and from this has arisen the application of the term " fermenta-
tion" to this peculiar phenomenon; that word being derived from the
Latin ferveo, I boil. Fermentation results in a disappearance of the
maltose present in the wort, together with the production of alcohol and
carbon dioxide gas. The former remains in the liquid ; the latter rises to
the surface and causes the before-mentioned boiling appearance. The car-
bon dioxide bubbles carry with them to the surface a peculiar sticky
"scum"; this substance has received the name of "Yeast," and on being
added to a fresh quantity of wort, is capable of setting up fermentation
therein. During the fermentation of wort, the quantity of this "scum"
produced is many times in excess of that in the first place added to the
wort.

288. History of the Views held of the Nature of Fermentation.— The
earlier researches and published articles on fermentation regard that
change as one of spontaneous decay. Yeast, with which fermentation is
associated, was viewed as a peculiar condition which nitrogenous matter
assumed during one of the phases of its decomposition. That in this state
it was able to set up fermentation in a liquid, which was not at the time
fermenting, was noticed as a remarkable property of yeast, which never-
theless was still considered as only nitrogenous matter in a particular
stage of chemical change. One of these earlier views ascribed alcoholic
fermentation to a vegeto-animal substance which resided in grapes -as well
as in corn. When the grapes were crushed, and the flour moistened, this
fermentative agent commenced to produce active change. The body thus
capable of inducing fermentation was termed a "ferment." The next
step in investigation of this matter was that of Thenard, who observed
that the ferment contained nitrogen, and that in distillation ammonia
was yielded; he therefore ascribed an animal nature to the ferment. (It
should be explained that the older chemists were in the habit of looking
on nitrogenous organic matter as animal, and the non-nitrogenous as
vegetable; no reference is intended to the peculiar organic structure of
the ferment.) Opinion had settled down to the view that yeast was an
immediate principle of plants, when the microscope, which had become
such an important factor in scientific research, was brought to bear on the
construction of yeast. Leuwenhoeck had, as early as 1680, discovered
that yeast consisted of minute granules ; but it was only in 1836 that de
Latour again called attention to its microsopic structure. It was observed
by him that yeast was a mass of little cells, and, further, that these were
capable of reproduction by a process of budding. "Yeast, therefore,"

FERMENTATION. 145

said the discoverer, * ' must be an organism which probably, by some effect
of its growth, effects the decomposition of sugar into alcohol and carbon
dioxide. ' ' This newly discovered form of life was, after some discussion,
placed among the fungi, a new genus being created for it by Meyen, to
which was given the name of Saccharomyces.

This view attracted considerable attention from scientists, and
although the basis of that now almost universally accepted, encountered
most uncompromising opposition. Prominent among its antagonists was
Liebig, who in 1839 argued yeast to be a lifeless albuminous substance,
and held that the cause of fermentation is the internal molecular motion
which a body, in the course of decomposition, communicates to other mat-
ter in which the elements are connected by a very feeble affinity. Said
Liebig, "yeast, and in general all animal and vegetable matter in a state
of putrefaction, will communicate to other bodies the condition of decom-
position in which they are themselves placed; the motion which is given
to their own elements by the disturbance of equilibrium is also communi-
cated to the elements of the bodies which come in contact with them."
Amplifying this theory, Liebig asserted that the protein bodies decom-
posed spontaneously, and the molecular disturbance resulting from this
decomposition effected also the decomposition of such bodies as sugar,
when placed in contact with the decomposing proteins.

For some years, de Latour's, or the vital hypothesis, Liebig 's, or the
mechanical hypothesis, and other views based on catalytic action, were
three contending theories of fermentation.

The next great step was that the whole problem of fermentation re-
ceived a most careful and exhaustive examination at the hands of Pasteur,
who in 1857 gave as his ''most decided opinion" that ''the chemical
action of fermentation is essentially a correlative phenomenon of a vital
act, beginning and ending with it. I think that there is never any
alcoholic fermentation without there being at the same time organisa-
tion, development, multiplication of globules, or the continued consecu-
tive life of globules already formed."

In 1870, Liebig published a long memoir on fermentation, in which
he admitted that yeast was a living organism, but still maintained that
fermentation was a mechanical act, pointing out that the quantity of
sugar decomposed by yeast was out of all proportion to the amount of
carbohydrate (cellulose) which the yeast had assimilated. To quote his
own words — "Yeast consists of vegetable cells which develop and multiply
in a solution containing sugar, and an albumimite, or a substance result-
ing from an albuminate ... It is possible that the physiological process
stands in no other relation to the process of fermentation than that by
means of it a substance is formed in the living cell, which, by an action
peculiar to itself — resembling that of emulsiii on salicin or amygdalin
(enzyme) — determines the decomposition of sugar and other organic
molecules." The admission of the physiological action of yeast being
even indirectly associated with the decomposition of sugars during fer-
mentation was an enormous concession by Liebig. Writing in 1895, one
of the authors summarised the then position in the following terms : —

* ' A study of the action of enzymes shows that Liebig 's position is
partly justified : invertase can be separated from yeast, and after-
wards is fully capable of performing its functions of inverting cane-
sugar, but such study does not lead us to observe a sufficiently close
relationship between enzymic action and alcoholic fermentation as to
prove their identity. Still in many respects there is great similarity.
At present there is the marked distinction that alcoholic fermentation

146 THE TECHNOLOGY OF BREAD-MAKING.

is inseparable from life, while enzymosis occurs in the 'absolute
absence of living organisms. As a result of prolonged research
and investigation the vitalistic theory of fermentation is now prac-
tically universally accepted.

"A careful study of the preceding sentence shows, however, that
the statement of fermentation being a vitalistic act is not an expla-
nation of fermentation. Granted that fermentation is a concomitant
of vitality (i. e., is due in some way to life), there must be some
agent through which life acts in producing the chemical change of
sugar into alcohol and carbon dioxide. In itself, this change is no
more striking than the change of starch, by diastase, into dextrin
and maltose ; yet we know that diastase, although a direct product of
life, is a soluble and absolutely unorganised body. Is there any such
unorganised body through which yeast acts when effecting the de-
composition of sugar ? The answer is — no such substance has as yet
been detected, to say nothing of its isolation.

' * Hoppe-Seyler and Halliburton incline to the hypothesis that the
difference between organised ferment action and that of enzymes is
this : an organised ferment is one which does not leave the living cell
during the progress of the fermentation ; an unorganised ferment, or
enzyme, is one which is shed out from the cells, and then exerts its
activity. Probably the chemical nature of the ferment is in the two
cases the same, or nearly the same.

' ' So far as we are acquainted with the nature of enzymes, they are
either identical with, or closely allied to, the proteins. If fermenta-
tion be due to an enzyme-like body within the living cell, that body
is of the nature of living proteins — like other proteins they are in-
diffusible, and consequently are not discoverable outside the cell wall.
'Like all living things, their properties during life are different
from those after death ; this readily accounts for the fact that, with
a few exceptions, they are not discoverable inside the cell wall after
the cell has been killed by alcohol. The few exceptions are probably
those which are more robust, and withstand the action of alcohol
better.' In this way does Halliburton endeavour to explain the
difference between organised ferments and enzymes. The explana-
tion, unfortunately, does not cover the whole problem. Even the
more robust 'ferments' cannot be said to have life in the ordinary
sense of the term when extracted by dilute alcohol, and obtained in
a state of perfect solution. Independently of any organism, the
enzymes are able to prosecute their functions ; but alcoholic fermen-
tation cannot be induced by any substance contained by the yeast
cell, unless that cell be living. If the protoplasm of yeast be liber-
ated by crushing the cells, such extracted protoplasm does not cause
fermentation. There is little doubt that fermentation does take place
within the cell, and is in some way caused by some property of living
protein, 'but it is an essential that the protein be alive, and a part of
a living organism. This much may be conceded, that probably the
living protein acts in a more or less similar manner to an enzyme.
In view of this it is interesting to note the agreement rather than
the differences between the views promulgated by the illustrious
savants Liebig and Pasteur ; but, after all, there is the broad line of
demarcation — enzymosis is independent of living organisms, while
'fermentation is essentially a correlative phenomenon of a vital act,
beginning and ending with it.' The discussion of the nature of the
vital act producing fermentation does not dispose of the fact of its
being vital. ' '

FERMENTATION. 147

289. Zymase Theory of Fermentation. — In the light of subsequent
researches these views must now be considerably modified. In 1897,
Buchner made the first announcement of the discovery of zymase, which
is referred to and described in paragraph 273. This is an enzymo,
secreted within the yeast cell, but which may be extracted from it and
apart altogether from the living organism can effect the decomposition of
glucose into alcohol and carbon dioxide. Work in this field of investiga-
tion was carried still further by the researches of Buchner, Rapp, Albert,
Harden, and others, the results of which have been published in a series
of papers extending from 1897 to 1905. The net result of such investi-
gation is to confirm the view that zymase is an enzyme, and effects the
decomposition of glucose independently of vital functions of the living
cell. Of this, a striking proof is afforded by some experiments of Albert,
who killed yeast by subjecting it to the action of a mixture of absolute
alcohol and ether. The yeast was then dried and still possessed the power
of exciting alcoholic fermentation. Consequent on the indiffusibility of
the protein contents of the cell, no fermentative enzyme can be extracted
from this unbroken yeast by the action of water. But if the cells be
broken up, an active extract may be obtained. A dried preparation of
zymase has been patented, of which it is said that from 5 to 10 per cent,
of it is capable of raising dough. Zymase has no reproductive action, and
possesses a fermentative power which is only a minute fraction of that
of yeast. It would seem that zymase is destroyed during fermentation
almost immediately as formed, so that no accumulated store of the enzyme
is found in yeast. Harden believes that zymase alone is incapable of
acting on sugar, and that yeast contains in addition another substance
which stimulates the zymase into activity. In his opinion neither of these
alone sets up fermentation in sugar solutions, but the two acting in con-
junction effect the decomposition. In accordance with the zymase theory
of fermentation, sugar finds its way by diffusion into the interior of the
living cell ; it is then changed into glucose by the action of invertase ;
then the decomposition into alcohol and carbon dioxide is effected by the
enzyme zymase secreted by the cell within itself. The zymase is being
continually formed and destroyed in the act of inducing fermentation.
The discovery of zymase is the discovery of the agent by which yeast
effects the decomposition of sugar ; but such discovery leads us very little
beyond the view of Pasteur that "the chemical action of fermentation is
essentially a correlative phenomenon of a vital act,'7 since the zymase is
produced as a function of the life of yeast, and is destroyed in the act of
fermentation.

290. Definition of Fermentation. — The particular action produced
by yeast on wort, and also on the sweet "must," or expressed juice of the
grape, was found on investigation .to be but one of many chemical actions
which are associated with the life, growth, and development of micro-
scopic organisms. Among these may be cited the souring of milk, also of
wine into vinegar, and likewise the changes occurring during putrefac-
tion. Consequently the term fermentation is no longer used in its origi-
nal sense, as signifying a condition resulting in a peculiar seething or
boiling, appearance, but is applied to that group of chemical changes
which are, in Pasteur's words, "correlative phenomena of vital acts."
Subject to the limitations explained in the preceding paragraph, and used
in its extended sense, fermentation may be defined as a generic term
applied to that group of chemical changes which are consequent on the
life and development of certain minute microscopic organisms,

148 THE TECHNOLOGY OF BREAD-MAKING.

In the chapter on the proteins, it was stated that putrefaction is re-
garded as a species of fermentation : equally, with the conversion of mal-
tose into alcohol by yeast, it is a change induced by living organisms.
This of itself is a conclusive answer to Liebig's earlier position, that fer-
mentation is a secondary result of the spontaneous decomposition of pro-
teins, inasmuch as that, in the absence of minute organisms, the decompo-
sition of proteins does not occur : it is consequently not spontaneous, and
therefore fermentation cannot be considered as a process dependent on
spontaneous decomposition.

291. Modern Theory of Fermentation. — The following is a short
statement of this theory. Maltose, proteins, and other fermentable sub-
stances do not decompose of themselves, even when subjected to favour-
able conditions of moisture, warmth, etc., provided that fermenting
organisms and their immediate products are rigorously excluded. These,
on their introduction, thrive and multiply ; taking the nourishment requi-
site for their development from the substance which is fermented.

A special feature characteristic of fermentation is that the amount
of matter consumed and changed into other compounds is excessively
great, compared with the size and weight of the consuming organisms ;
consequently a very few yeast globules decompose very many times their
weight of sugar, and produce a relatively large quantity of alcohol and
carbon dioxide. No very clear reason has as yet been given for this char-
acteristic of fermentation, but one explanation is that the decomposition
of sugar furnishes not only material for the growth and development
of cells, but also the heat necessary for the continuance of yeast life.
It is this double function of sugar in fermentation which causes the
enormous consumption of that compound. Fermentation is thus seen to
be like enzymosis in that a small quantity of the active agents induces
chemical change in much larger quantities of material ; but fermentation
goes further, inasmuch as the quantity of fermenting agent itself also
increases during its continuance.

In alcoholic fermentation then, yeast, in order to obtain heat and
nourishment, attacks glucose or maltose, and excretes or voids carbon
dioxide gas, alcohol, and small quantities of other bodies. The assimila-
tive power of yeast is limited to converting the sugar into these sub-
stances, which then become, so far as it is concerned, waste products.
Other organisms attack the proteins and produce butyric acid and other
compounds. Each particular organism has its special products of fer-
mentation.

292. Experimental Basis of Modern Theory. — It is scarcely within
the scope of the present work to trace step by step the nature of the
various researches which have led to the adoption of the theory just
explained. Briefly stated, the first and most important point is that a
liquid free from ferment organisms, or their germs does not undergo fer-
mentation. In proof of this point, liquids were placed in flasks or tubes,
the necks of which were tightly plugged with cotton wool. The liquids
were then boiled for some time ; the heat destroyed any organisms that
might have been present in the liquids or the wool. As the flasks cooled,
the contained steam condensed ; arid ail1 forced its way through the cotton
wool, which acted as a filter and stopped off any germs that might have
been floating in the air. Hay and beef infusions, must, wort, urine, and
other liquids, on being treated in this manner, may be kept for any length
of time without undergoing fermentation or putrefaction. That the re-
sistance to fermentation is due to the absence of fermenting organisms,
and not to the liquids having been so changed by boiling as to be unfit for

FERMENTATION. 149

fermentation to proceed, is proved, by adding a small quantity of yeast or
other ferment to the sterile liquid, when fermentation sets in and pro-
ceeds vigorously. The chemical changes that are produced depend on the
nature of the ferment that has been added. Yeast effects the decomposi-
tion of sugar into alcohol and carbon dioxide, other ferments cause
putrefaction, and result in the typical bodies characteristic of that
change. While these actions are progressing, the ferment is found to be
developing and multiplying. Further, if the ferment used be pure, one
species only of organism is found in the liquid. Within any possible
limits of observation no transformation of one ferment into another
occurs : each belongs to a distinct and separate race of organisms. This
statement does not deny the possibility of the modification of species by
means of a natural process of evolution. There is, on the contrary, strong
evidence in favour of the gradual evolution of species in course of time.

293. Varieties of Fermentation. — Among the many changes in-
cluded under this term, the following are of importance in the considera-
tion of our present subject: — Alcoholic fermentation, resulting in the
production of alcohol and carbon dioxide ; lactic fermentation, in which
sugar is converted into lactic acid ; acetous fermentation, in which alcohol
is transformed into acetic acid ; viscous or ropy fermentation, resulting in
the production of mannite and different viscous bodies ; and putrefactive
fermentation, in which butyric acid and a variety of offensive products
is formed.

ALCOHOLIC FERMENTATION AND YEAST.

294. The nature of alcoholic fermentation has already been de-
scribed. For the sake of exactness, Pasteur 's definition of it is appended.
"Alcoholic fermentation is that which sugar undergoes under the influ-
ence of the ferment which bears the name of yeast or barm. ' ' When the
word "fermentation" is employed without any qualifying adjective,
alcoholic fermentation is always understood.

295. Substances susceptible of Alcoholic Fermentation. — Pre-emi-
nent among these are the glucoses, which are directly split up into alcohol
and carbon dioxide. Most other sugars may also be fermented; but
usually, as in the case of cane-sugar, require first to be hydrolysed to
glucose. As already explained, this change is effected, when yeast is
added direct to cane-sugar, by the enzyme, invertase ; which latter func-
tions independently of the cell itself, and therefore the inversion of the
sugar is separate and distinct from fermentation proper. Both diastase
and invertase are without action upon maltose ; but maltose undergoes
inversion into glucose before fermentation by the action of maltase.

Pure yeast is incapable of producing fermentation in either starch
paste or dextrin; neither can albuminous bodies, whether of vegetable
or animal origin, be fermented.

296. Fermentation viewed as a Chemical Change. — The conversion
of glucose into alcohol and carbon dioxide may be represented very sim-
ply by the equation—

C6H1206 2C2H5HO + 2C02.

Glucose. Alcohol. Carbon Dioxide.

Taking the action on the glucose as the more simple of the two, the
equation given above does not, however, represent the whole of the
change, for 100 parts of glucose then would yield-
Alcohol 51.11

Carbon Dioxide 48.89

100.00

150

THE TECHNOLOGY OF BREAD-MAKING.

Pasteur carefully collected the whole of the alcohol and carbon dioxide
produced by fermentation of a definite weight of glucose, and found that
he only obtained—

Alcohol . . . . . . . . . . . . 48.51 per cent.

Carbon Dioxide 46.40

100 — 94.91 = 5.09 parts
of glucose not transformed into alcohol and carbon dioxide.

The following bodies- occur as subsidiary products — glycerin, succinic
acid; propyl, butyl, and amyl alcohols; acetic, lactic, and butyric acids.
Of these, the amount of glycerin and succinic acid produced have been
found to be —

Glycerin
Succinic Acid

3.00 per cent.
1.13

4.13

This, therefore, leaves but 0.96 per cent, for the various higher alco-
hols, and the acetic, lactic, and butyric acids ; and also for that portion of
the sugar that goes to help to build up fresh yeast cells.

Buchner and Meissenheimer point out that acetic and lactic acids are
invariably produced in alcoholic fermentation, and under conditions
which negative the possibility of the action of bacteria or oxidation by
the air. They regard the lactic acid as an intermediate product between
the glucose and the alcohol, and suggest the following equation as repre-
senting the change which occurs : —

CHO

HOH

OH
OH

CHOH +

H
H

CHOH OH

COOH

CHOH

CH2H

COOH

CH.OH

HOH

Glucose.

H
H

Water,
4 mols.

Hypothetic

Intermediate

Product 4-

H,0.

COOH
CH.OH
CH3
COOH

CH.OH
CH,

Lactic
Acid
2 mols.

OH
H

Water,
2 mols.

CH9OH

CH?

CH2OH

CH3

Alcohol,
2 mols.

+ C02

+ CO,

Carbon
Dioxide,
2 mols.

Monoyer proposes the following equation as showing the production
of glycerin and succinic acid from glucose —

3H20 = H2C4H4O4 + 6C3H5(HO)3 + 2C02 + 0.

Glycerin. Carbon Oxygen.

4C6H1206

Glucose.

Water.

Succinic Acid.

Carbon
Dioxide.

No free oxygen is, however, detected in fermentation ; any that may
be produced during the decomposition is probably used up by the yeast
cells for purposes of respiration.

Pasteur claims that the glycerin and succinic acid, as well as the alco-
hol and carbon dioxide, are normal products of alcoholic fermentation;
and further, that these bodies are produced from the sugar, and not
from the ferment. He also shows that a portion of the sugar goes to help
to build up the yeast globules. The quantities of glycerin and succinic
acid produced are not constant, but vary with the conditions under

FERMENTATION. 151

which fermentation proceeds; when the action is slow the proportion of
glycerin and succinic acid to alcohol is higher than with brisk and active
fermentation.

Brefeld, however, argues that glycerin and succinic acid are not
products of alcoholic fermentation proper, but rather are pathological
products arising out of the death of the yeast cells. The same view is
advanced in a more modernly expressed opinion that these bodies are
due to the destructive metabolism* of the cells.

A small proportion of the carbohydrate, amounting to about 1 per
cent., is assimilated by the yeast and employed in its constructive meta-
bolism, being transformed into cellulose and fats.

Jorgensen states that during fermentation by the pressed juice of
yeast, i.e. by the separated zymase, glycerin is produced to the extent of
from 3 to 8 per cent, of the fermented sugar, and is derived from the
sugar. On the other hand, no succinic acid is formed. Acetic acid is
produced in minute quantities, but somewhat more than in the fermenta-
tion with the living cell. This is probably due to the action of a special
enzyme. (Micro-organisms and Fermentation, Fourth Edition.)

297. Chemical Composition of Yeast. — When yeast has been washed
carefully so as to free it as far as possible from foreign matters, and then
dried, it is found to have, according to Schlossberger, the following com-
position—

Surface Sedimentary

Yeast. Yeast.

Carbon 48.7 46.4

Hydrogen 6.4 6.2

Nitrogen 11.8 9.5

Oxygen 30.7 34.5

Ash (mineral matter) . . . . . . 2.4 3.4

100.0 100.0

In addition to the above a number of other analyses might be quoted,
showing that yeast is a body of somewhat variable composition; mean-
while attention is directed to the fact that yeast collected from the bottom
of the fermenting liquid contains less nitrogen and carbon than does sur-
face yeast.

Various attempts have been made to separate yeast into its proximate
principles, and estimate these : as a result it may be stated that yeast
contains one or more bodies of the protein type. There are in addition,
also present, cellulose and fatty matters. Payen gives the following as
the result of an analysis of moisture-free yeast : —

Nitrogenous Matter . . . . . . . . . . 62.73

Cellulose (envelopes) . . . . . . . . . . 22.37

Fatty Matters 2.10

Mineral „ 5.80

Naegeli states that the proximate constituents of a sample of yeast
examined by him were as follows. The yeast was a sedimentary one,
containing 8 per cent, of nitrogen : —

Cellulose, Gum, and Cell Membrane . . . . 37 per cent.

Proteins 45 „

Peptones 2 „

Fat 5

Extractives (Leucine, Cholesterin, Dextrin,

Glycerin, Succinic Acid) . . . . . . 4 „

Ash 7

* For an explanation of metabolism refer to Chapter XIII, par. 408.

152 THE TECHNOLOGY OF BREAD-MAKING.

A sample of distiller's compressed yeast examined by one of the
authors gave the following results on analysis: —

Proteins 12.67

Fat 0.80

Mineral Matter 2.05

Water 73.80

Cellulose, etc. (by difference) 10.68

100.00

The mineral matter of yeast is of great importance, and has been
made the subject of careful analysis by Mitscherlich and others. The fol-
lowing table gives the composition of the ash of surface and sedimentary
yeasts by Mitscherlich, and of the surface yeast of pale ale by Bull-
surface Y. Sedimentary Y.

>— — r— — Surface Y. of

Mitscherlich. Pale Ale.

Phosphoric Acid, P00, . . . . 53.9 59.4 54.7

Potash, K20 .. ".. .. .. 39.8 28.3 35.2

Soda, Na.O 0.5

Magnesia, MgO 6.0 8.1 4.1

Lime, CaO 1.0 4.3 4.5

Silica, SiO., traces

Iron Oxide", Fe2O3 0.6

Sulphuric Acid, S03

Hydrochloric Acid, HC1 .... 0.1

Yeast ash is therefore composed principally of phosphoric acid and
potash : attention is directed to the similarity in composition between the
ash of yeast and that of wheat. The above acids and bases probably exist
in combination as the following salts : —

Surf. Y. Sed. Y.

Potassium Phosphates 81.6 67.8

Magnesium Phosphate, Mg3(PO4)2 . . 16.8 22.6

Calcium Phosphate, Ca3(P04) 2 .. .. 2.3 9.7

The potassium phosphate must be looked on as a mixture of the dihydric
phosphate, KH2P04, and the monohydric phosphate, K2HP04. The
former of these phosphates contains 94 by weight of K00 to 142 of P205 ;
the latter contains 188 of K20 to 142 of P205. The weight of K20 in the
surface yeast ash is between that required to produce either of these two
potassium phosphates. The composition of the potassium phosphate of
the sedimentary yeast ash nearly agrees with the formula, KH2P04.

298. Yeast as an Organism. — Viewed as an organism, j^east may be
said to be a plant of an exceedingly elementary structure; it is in fact
one of the simplest plants known. In very minute forms of life it is diffi-
cult to distinguish animals and vegetables from each other, for with
almost any definition that may be selected, one or two species wander over
the border line. One of the most marked differences between the higher
plants and animals is, that the former are able to derive their sustenance
from inorganic compounds, their carbon from carbon dioxide, and their
nitrogen from ammonia. Animals, on the contrary, can make no use of
carbon or nitrogen for the purpose of building up their tissues, unless
these bodies are presented to them in the form of organic compounds.
Hence, in the economy of nature, it will be found that while plants live
and develop, as before stated, by the assimilation of the elements of car-
bon dioxide and ammonia, animals subsist either on vegetable substances,
or on the bodies of other animals. Yeast is unable to assimilate carbon
from inorganic sources, but being able to derive its nitrogenous nutriment

FERMENTATION. 153

from inorganic bodies, is placed in the vegetable kingdom. The chemical
changes produced during the growth of the higher plants result in the
building up of complex compounds from very simple ones : in the animal,
complex bodies are required as nourishment, and are broken down into
simpler bodies. The complexity here referred to is that which may be
measured by the number of atoms in the molecule of the body; thus,
water is a very simple compound, while starch has a most complex mole-
cular structure. The chemical operations of plant-life may be summed
up as consisting of synthesis; those of animal existence as analysis. In
order to effect the synthesis of plant compounds from the substances at
the disposal of vegetables, force is required; this they usually obtain in
the form of heat from the sun. The act of growth of a plant means,
therefore, a continual absorption of heat. On the other hand, animals, in
taking complex bodies and breaking them down into simpler ones, liberate
heat ; consequently, one result of animal life is that heat is continuously
being evolved. Yeast, in this particular, partakes both of the nature of
an animal and of a plant. Its nitrogen may be obtained from inorganic
sources, but is more usually derived from suitable protein matter,
such as peptones. On the other hand, the carbon of yeast is taken
from sugar with the breaking down of that body into simpler compounds,
and the consequent liberation of heat ; therefore during fermentation the
temperature of the liquid rises considerably. Prom a chemical stand-
point, yeast combines in itself the vegetable functions of synthesis with
the animal functions of analysis.

299. Botanic Position of Yeast. — This organism belongs to the
family of Fungi.

Fungi. — The fungi are those plants which are destitute of chlorophyll
(the ordinary green colouring matter of grass, etc.). They reproduce by
buds and spores.

Spores. — Spores are a variety of cell, and in all fungi the spores are
similar in essential points to the yeast cell ; notwithstanding that they
may vary considerably in appearance and details of structure.

Hyphae. — The spore, on being sown in a suitable medium for its
growth, throws out a long delicate stem of tubular structure, termed a
' ' hypha. ' ' A group of these hyphae constitute the fungus.

Mycelium. — One of the best typical examples of a fungus is the com-
mon green mould found on old boots, bread, jam, etc. This has received
the name Penicillium glaucum. On examining a specimen of such mould
from the top of a pot of jam for instance, its base is found to consist of
an interlaced growth of hyphae, forming a more or less compact web or
skin on the jam. This layer of intermingled hyphae is termed the " my-
celium. " From its upper surface a number of hyphae project into the
air, each bearing a quantity of very fine green powder, these are termed
"aerial hyphas. " On the lower surface again, other hyphae grow down
root-like into the liquid, which supports the mould; these are the "sub-
merged hyphae. ' '

Conidia. — Some of the aerial hyphae terminate in short branches, each
of which is divided into a series of rounded spores which are only loosely
attached to the hyphae, and so may easily be shaken off; these spores are
termed "conidia." Each separate conidium, if sown in a suitable liquid,
develops a young fungus, which in its turn rapidly multiplies.

Sporangia. — Some of the fungi, as for instance that known as Mucor
mucedo, have their hyphae terminated in rounded heads; each of these is
called a " sporangium. ' '
F

154 THE TECHNOLOGY OF BREAD-MAKING.

300. Varieties of Yeast. — The yeast fungi constitute the genus
Saccharomyces; they are so named because they mostly live in saccharine
solutions, converting the sugar present into alcohol. The saccharomyces
have no mycelium, and in common with the other fungi reproduce by
buds and spores. The genus saccharomyces comprises several species, a
detailed description of which will subsequently be given.

301. Nature of Yeast Cells. — The yeast organism consists of cells,
mostly round, or slightly oval, from 8 to 9 /A in diameter; the cells may
occur either singly or grouped together as colonies. It is impossible to
obtain any real knowledge of the physical structure of yeast without a
careful and systematic personal examination by the microscope; it has
been thought well, therefore, to arrange the following description in such
a form as to constitute a guide to actual yeast examination.

1. Take either a little brewers' yeast, or bakers' compressed distillers'
yeast, and mix with some water until a milky fluid is produced. By
means of a pointed glass rod, take a small drop of this fluid and place it
on a clean microscopic slide, and gently cover with a cover-glass.
Arrange the microscope in a vertical position, and proceed to examine the
yeast by means of a fairly high power (% objective). Notice that the
yeast consists of cells, of which measure a few by means of the eye-piece

micrometer, and observe that their dimen-
sions agree with those just given. Each
cell consists of a distinct wall or envelope,
containing, within, a mass of more or less
gelatinous matter devoid of organic struc-
ture. The interior substance is named
"protoplasm"; this term being applied to
that ultimate form of organic matter of
which the cells of animals and plants are
composed. The protoplasm of the yeast
cell is not homogeneous, but is always
more or less distinctly granular. Run in
FIG. 9. — Saccharomyces Cerevisice. magenta solution under the cover-glass.

a, a bud colony; b, two spore-form- (This ig readily done by placing a drop of
me cells (arter Lurssen). ,, -, , . -.LI • j £

the solution in contact with one side 01

the cover-glass, and placing a strip of blotting-paper on the other.)
Notice that the sac or envelope remains uncoloured, while the protoplasm
stains comparatively deeply; the-vacuoles are unstained. One or more
circular spots can usually be seen in yeast cells as obtained from a
brewery; these are caused by the gelatinous matter moving toward the
sides of the cell, and leaving a comparatively empty space, containing
only watery cell-sap ; hence these spots are termed vacuoles. A specimen
of yeast is shown in Figure 9.

2. Remove the slide from the microscope, and burst a few of the cells
by placing some folds of blotting-paper on the cover-glass, and then
pressing sharply with the end of a pencil or rounded glass rod. Again
examine under the microscope, note the empty sacs and the extruded
protoplasm, which does not readily mix with the water.

If practicable, try this experiment with yeast of various ages; very
old yeast cells break more easily, and the protoplasm is more fluid, and
takes the colour more readily. By using the magenta stain in a dilute
form, old and dead cells may be differentiated from those which are
healthy and vigorous — the latter remain unstained, or take up the stain
very slightly, while dead cells readily and quickly acquire a magenta hue.

FERMENTATION. 155

3. Take six clean cover-glasses and coat one side of each with a thin
layer of yeast, by painting on the mixture of yeast and water by means
of a camel's hair brush, and set aside until thoroughly dry. The yeast
adheres firmly to the glass, showing that the outside of the cell-walls is
mucilaginous in character.

4. Add a drop of solution of iodine in potassium iodide to one of these
covers, let it stand five minutes, and then wash slightly in water, and
mount the cover-glass, yeast side downward, on a glass slide. The cell-
wall stains slightly, and the protoplasm becomes dark brown ; but no blue
colour is produced; starch therefore is absent. As the cell envelope is
continuous, containing no apertures, the iodine solution must have passed
through its substance.

5. Similarly treat another cover preparation with iodine, and then,
without washing, add one or two drops of 70 per cent, sulphuric acid.
The cell-contents acquire a deeper brown stain, and the cell walls become
brownish yellow, but do not show any blue colouration.

The cellulose of the walls of the cells of most higher plants acquire a
blue colour with this treatment, showing the presence of a cellulose allied
to that of starch, but the cellulose of yeast, and of fungi generally, is
devoid of this property.

6. Treat the yeast on another cover-glass with solution of potash. The
protoplasm is dissolved, leaving nothing to be seen but empty cell-walls.

7. Treat another cover-glass preparation with a solution of osmic acid.
Note that small, sharply defined, dark coloured bodies are seen. Jorgen-
sen regards these as cell-nuclei of the same nature as those generally
observed in the majority of plants without this treatment.

8. Break down a little yeast with water, and focus under the micro-
scope, so as to observe distinctly the small bright granules of fat within
the protoplasm of the cells. Put a piece of blotting-paper on one side
of the cover-glass, and run in at the other a few drops of ether from a fine
pipette — the fat granules dissolve and disappear.

302. Life History. — On examining under a microscope a sample of
skimmed yeast, as obtained from the brewer, it is found to consist either
of single cells, or cells joined together in pairs. Such yeast having
usually remained quiescent for some time, the cells rarely occur in large
groups because, with standing, they tend to separate from each other.
The granulations in the protoplasm, and also the vacuoles, should be vis-
ible. On placing a very small quantity of this yeast in a suitable liquid
for its growth, as malt wort, at a temperature of about 30° C. (86° F.),
the cells, which at first were somewhat shrunken and filled throughout
with granular matter, increase in size from absorption of the liquid in
which they are placed. At the same time the granulations becomes less
distinct, and the whole cell assumes a more transparent and distended
appearance.

To observe this effect, mount a few cells on a microscopic slide with
warm malt wort, and keep under observation with the microscope. After
a time the round yeast cells become slightly elongated through the for-
mation of a small protuberance at one end ; this grows more marked,
until shortly a neck is formed by a contraction of the cell wall. But still,
careful examination shows that there is a distinct opening through this
neck, the contents of the smaller portion being continuous with those of
the cell. As the growth continues, the strangulation at the neck proceeds
until the cell wall completely shuts off the protuberance, which then con-
stitutes a new or daughter cell, attached to the parent. This operation is
known as " budding." The one parent cell is capable of giving off several

156

THE TECHNOLOGY OF BREAD-MAKING.

buds in succession ; but after a time its reproductive energy is exhausted,
and the cell breaks up. These daughter cells in their turn give rise to
other cells, and so the multiplication of yeast globules proceeds with
remarkable rapidity.

Pasteur states that on one occasion he watched two cells for two
hours; during that time they had multiplied by budding into eight,
including the original pair of cells. At this stage, buds of every size may
be seen attached to the parent cells ; some are so small as to be scarcely
visible, while other are nearly as large as the parents.

With the progress of this growth and development, sugar is being
decomposed, the liquid becomes alcoholic, and its specific gravity dimin-
ishes. The brewer terms this change ' ' attenuation, " or a becoming thin-
ner. Another reason for the use of this name is that the liquid becomes
less viscous, from the conversion of the sirupy solution of maltose into the

highly mobile liquid, alcohol.
Simultaneously with the pro-
duction of alcohol, carbon
dioxide gas is evolved; this
rapidly rises to the surface,
and carries up with it the
yeast cells, which float on the
top of the fermenting wort.
Yeast now skimmed off is
found to consist of colonies of
some scores of cells linked to-
gether; the majority of these
are clear and almost transpar
erit. Usually in the middle of
each such group the old or
parent cell can be recognised
by its darker contour and
comparatively exhausted ap-
pearance. As the quantity of
sugar in the liquid becomes
FIG. 10.— Saccharomyces Cerevisice. less, the fermentation slackens,

a, High Yeast, at rest; o, High Yeast, actively bud- -, „ n Tr> ,-, n

ding; cfLow Yeast, at rest; J Low Yeast, actively and finally CCaSCS. If the cells

budding. then be again examined, un-

der the microscope, they will

be found to have a firmer outline, and their contents will be more gran-
ular. In what may be termed old age of the yeast cell, the walls become
abnormally thick, and the granulations very dense. The yeast, on being
removed from the fermenting tun, is usually set aside in store vats; on
standing, it gradually assumes the appearance described as that of the
yeast used for ' ' pitching ' ' or starting the fermentation. The quantity of
yeast thus obtained is considerably in excess of that first added to the
malt wort.

In the moist state, yeast decomposes quickly ; hence if the store be
kept for any length of time, the cells rapidly alter in character. The
walls become soft, thin, and weak, and the interior protoplasm changes
from its normal granular gelatinous condition to a watery consistency.
After a time, if viewed with a high power, a distinct ' ' Brownian ' ' move-
ment is seen of particles suspended in the contents of the cell. The par-
ticles may very possibly consist of minute fragments of cellulose from the
envelopes. After a time the walls also break down and all traces of the

FERMENTATION. 157

yeast organism disappear. The normal bodies produced by the decomposi-
tion of nitrogenous and protein bodies may now be detected in the liquid :
putrefaction rapidly follows, with the production of a most offensive
odour. Such is in broad outlines the life history of a yeast cell, when
sown under normal conditions in malt wort.

Distillers' yeast putrefies much more readily than does that of the
beer brewer : the hops used in the latter act as an antiseptic, and the yeast
putrefies much less rapidly. Evidence of this is afforded in the method
employed for the preparation of invertase from brewers' yeast.

High yeast produces a beer having a special and characteristic flavour,
which distinguishes it at once from beer brewed with low yeast.

303. Influence of Temperature on Yeast Growth. — The temperature
most favourable to the growth of yeast is from 25° C. to 35° C. (77° and
95° F.) Between these points yeast flourishes and grows well; at tem-
peratures lower than 25° growth proceeds, but not so rapidly. At a tem-
perature of about 9° C. (49.6° F.), the action of yeast is arrested; the
vitality, however, of the cell is only suspended, not destroyed, for with
a higher temperature it again acquires the power of inducing fermenta-
tion. Actual freezing does not destroy yeast, provided the cells do not
get mechanically ruptured or injured. Above 35° C., the effect of heat
is to weaken the action of yeast, until at a temperature of about 60° C.
(140° F.), being that at which protein principles begin to coagulate, the
yeast is destroyed. This applies to moist yeast. When dry, the cells are
able to stand higher temperatures than when suffused with water; thus,
dried yeast has been heated to 100° C. without destroying its vitality.

Although a temperature of from 25° to 35° C. conduces to the rapid
growth of yeast, yet there are other circumstances which render it advis-
able to conduct actual brewing operations at a much lower temperature.
In English breweries, a pitching temperature of about from 18° to 19° C.
(65° F.) is commonly employed : during the fermentation the heat rises
to from 21° to 22° C. (72° P.).

Faulkner states that a tun of pale ale, containing 200 barrels of 36
gallons, on being pitched with 600 Ibs. of yeast at 14.5° C. (58.1° F.) had
sufficiently attenuated in 46 hours, during which time the temperature
had risen to 22.2° C. (72° P.).

304. Substances Requisite for the Nutriment of Yeast. — It has sev-
eral times been stated that sugar is required by yeast during its growth :
as yeast cells likewise contain nitrogenous matter, and also certain in-
organic constituents, it is evident that nitrogen in some form, and also the
requisite mineral salts, must be supplied to the growing yeast. Summing
these up, yeast requires for its growth, sugar, nitrogenous compounds,
and appropriate inorganic matter.

305. Saccharine Matters. — These occupy the first and paramount
position, as being absolutely necessary for the production of alcoholic fer-
mentation. Pure yeast sown in a pure sugar solution causes it to fer-
ment; but without the sugar neither alcohol is produced, nor carbon
dioxide evolved. Malt wort, grape juice or "must," and dough, all fer-
ment on the addition of yeast, because they all contain sugar. "It is
necessary indeed that sugar be present; for if we abstracted by some
means or other from the must or douph all the sugar contained in it,
*[and also all substances capable, by the addition of yeast to flour, of
being converted into sugar], without touching the other constituents,
the addition of yeast would produce no gas. Everything would remain

aThe clause in brackets, [ ], is inserted by the authors.

158 THE TECHNOLOGY OF BREAD-MAKING.

quiet until the moment when signs of a more or less advanced putrefac-
tion showed themselves." (Pasteur). It should be mentioned that
yeast is also capable of inducing definite chemical changes in a few other
bodies : among these is malic acid, which is broken up into succinic and
acetic acids, carbon dioxide, and water. It is also stated that yeast
decomposes glycerin into propionic and acetic acids ; this change has been
denied by Roos and Brown. As neither malic acid nor glycerin (in the
free state) occur as constituents of flour, their fermentation lies alto-
gether outside the scope of the present work.

The glucoses, or sugars of the C6H1206 group, are the only sugars
capable of direct fermentation ; of these, glucose or dextrose is more read-
ily decomposed by yeast than is fructose. The two being together in
the same solution, the fructose remains unacted on until the disappear-
ance of the whole of the glucose. Certain other sugars are capable of
indirect fermentation by yeast; among these are cane-sugar, which first,
however, requires to be hydrolysed to glucose by the action of the inver-
tase or soluble diastatic body secreted by the yeast cell. As already
explained, this preliminary diastasis can be effected by yeast water, that
is, water with which yeast has been shaken up, and then filtered in order
to remove the whole of the yeast cells ; such yeast water is, of itself,
incapable of setting up alcoholic fermentation.

Yeast causes certain effects, of which it is difficult to say whether they
are absolutely correlatives of vital acts, as an organism, or merely results
of diastasis. For practical purposes, it matters little to which of these
two classes of chemical action any specific change produced by yeast
belongs; in such cases it is the action of yeast, as a whole, that is of
importance.

Sugar of milk is incapable of fermentation by yeast. Yeast alone is
also unable to ferment either starch paste or dextrin : these bodies require
some more powerful agent for their diastasis, such as malt extract. As
mentioned in Chapter VIII., yeast, indirectly through its action on the
proteins of barley or wheaten flour, transforms starch paste into dextrin
and maltose, after which the yeast induces fermentation. Consequently,
the two, yeast and proteins, in conjunction, are capable of effecting
changes which neither can separately produce.

It almost goes without saying that water is necessary for the develop-
ment of yeast, so requisite is it that saccharine solutions containing over
35 per cent, of sugar are incapable of fermentation. Such a solution, by
outward osmose through the cell wall, deprives the yeast of its normal
proportion of water as a constituent.

306. Nitrogenous Nutriment. — Yeast is capable of utilising, during
its growth, the nitrogen of ammoniacal salts (but not that of the acid
radical of nitrates) ; thus, a solution of pure sugar, mixed with either
ammonium tartrate or nitrate, and certain non-nitrogenous inorganic
salts, permits a healthy development of yeast. With the multiplication of
the yeast cells, the amount of protein matters present increases; there-
fore, by the action of yeast, the ammonium compounds are transformed
into protein bodies. Although yeast thus acts on ammonium salts, organic
nitrogenous compounds form a more suitable nutriment ; among such sub-
stances, the soluble proteins of yeast itself are especially seized on by
yeast. Consequently, always supposing the presence of the inorganic
salts required by yeast, yeast water and sugar form an admirable medium
for its growth and development ; so, too, do natural saccharine juices, as
"must," the juice of apples, pears, etc. In addition to these, malt
infusion must be mentioned,

FERMENTATION. 159

Albumin, whether from the white of egg or vegetable albumin, is
entirely unfit for the nourishment of yeast. This fact is stated with force
by Pasteur, whose opinion is confirmed by that of Mayer, who ascribes
the inactivity of albumin, casein, and other similar bodies, to their highly
colloid nature. The solution molecules of soluble proteins of malt have
such an appreciable volume, that filtration of the solution through a thin
porous earthenware diaphragm under slight pressure is sufficient to pre-
vent these bodies from passing through into the filtrate (Brown and
Heron). It may then be readily understood that yeast cell walls are
impermeable to protein bodies. The compounds produced by digestion of
albumin and its congeners, the peptones, are much more diffusible, and
are "eminently suited for affording the requisite nitrogenous nutriment to
yeast. Pepsin itself forms an admirable yeast food. Schiitzenberger con-
siders it probable that must, malt wort, and yeast water owe their power
of nourishing the cells of yeast, not to the protein bodies, but to certain
of their constituents that are analogous to the peptones, and which have
the property by osmose of passing through the cell walls.

307. Mineral Matters necessary for the Growth of Yeast. — For his

experiments on yeast, Pasteur used yeast ash as the source of his mineral
matter. It is obvious that this substance may be replaced by an artificial
mixture of the salts contained therein. A reference to Mitscherlich 's
analyses of yeast ash shows that the principal ingredient is potassium
phosphate; together with this, there is magnesium phosphate and small
quantities of phosphate of calcium. Pasteur finds, when an unweighable
quantity of yeast is sown in a solution of pure sugar and ammonium tar-
trate, that development of cells and fermentation do not take place; the
addition of yeast ash enables both to occur. Mayer endeavoured further
to ascertain what salts are, in particular, necessary among those present
in the ash. Potassium phosphate is absolutely indispensable; neither
sodium nor calcium phosphates are competent to replace it. Magnesia is
also of great value, if not indispensable, to the development of yeast ; this
base may be supplied either as sulphate or phosphate. Lime seems not to
be absolutely necessary to yeast growth.

308. Insufficiency of either Sugar or Nitrogenous Matter only for
the Nutriment of Yeast. — Yeast is incapable of healthy development in
solutions of sugar alone. A limited growth occurs when the quantity of
yeast added is considerable, because, by a species of cannibalism, the
healthier and stronger cells survive and develop to some extent by feed-
ing on the nitrogenous and mineral matters obtained from the others.
Necessarily, such growth must soon stop. Yeast was stated by Pasteur to
multiply in a nitrogenous liquid, such as yeast water, ' ' even when there
was not a trace of sugar present, provided always that atmospheric oxy-
gen is present in large quantities. ' ' Yeast finds air to be under these con-
ditions an absolute necessity. Without it no development proceeds, nor is
there any but the slightest trace of alcohol found ; carbon dioxide gas is
evolved, being formed by direct carbonisation of oxygen derived from the
air. But, for this change, it must be remembered that air is a necessity.
Assuming the correctness of Pasteur's views as to the growth of yeast by
ihe assimilation of atmospheric oxygen, and expiration of carbon dioxide,
it is necessary to remember that the conversion of oxygen into carbon
dioxide gas results in no change of volume ; this is clearly seen by refer-
ence to the molecular equation —

c + o2 = co2.

• Carbon. Oxygen. Carbon Dioxide.

160 THE TECHNOLOGY OF BREAD-MAKING.

Under ordinary conditions of fermentation, albumin does not evolve alco-
hol or carbon dioxide gas. Neither does pepsin when similarly treated,
although this body is well adapted as a nitrogenous food for yeast. Albu-
min is also unacted on when its solution is first of all mixed with a 2^
per cent, solution of sodium chloride.

309. Behaviour of Free Oxygen on Yeast. — As stated in the preced-
ing paragraph, Pasteur regarded atmospheric oxygen as capable of acting
as a substitute for sugar in the nutriment of yeast, and accordingly he
examined very carefully the general behaviour of free oxygen arid yeast
to each other. In consequence, he developed the following theory of fer-
mentation, which for some time was generally accepted.

Pasteur states, as a result of experiment, that yeast grows better in
shallow than in deep vessels. As a result of some determinations made,
in which one sample of yeast and a saccharine solution were kept in an
air-free flask, and another in a shallow vessel, by which it was freely
exposed to the atmosphere, he finds that the proportion of yeast produced
to the sugar consumed was much greater in the latter than in the former
instance. By dint of most careful experiment he further finds, while a
fermentable liquid may be made to ferment out of contact with air, yet in
order that it shall do so it is essential that young and vigorous yeast cells
shall be employed. With older yeast the fermentation proceeds more
slowly, and with the production of mal-shaped cells, while a yeast stil]
older is absolutely incapable of reproduction in a liquid containing no
free oxygen. This is not due to the yeast being dead, for 011 aerating the
liquid, either with atmospheric air or oxygen, fermentation proceeds
apace. Pasteur therefore concluded that under favourable circumstances
yeast f unctions as a fungus ; that is, it lives by direct absorption of oxy-
gen from the air, and the return of carbon dioxide gas. He consequently
assumed the following relationship between its life in free oxygen and its
life when submerged in a sugar solution — Let some yeast be sown in a
sample of malt wort, containing as much oxygen as it can possibly dis-
solve; the yeast starts active growth, and rapidly removes all the free
oxygen from the liquid, after which it commences to attack the sugar.
During this time, yeast will be living not as a ferment but as a fungus,
namely, by direct absorption of oxygen. Could each yeast cell be sup-
plied with all the oxygen it requires in the free form, it is probable that
it would not exert the slightest fermentative action ; it would, at the same
time, grow and reproduce active healthy cells with great rapidity. As
soon as the whole of the air is exhausted, the yeast attacks the sugar, and
obtains its oxygen by the decomposition of that compound, and ordinary
fermentation proceeds. Consequently, yeast must be viewed as being-
capable of two distinct modes of existence, in free oxygen as a fungus ;
when submerged in a saccharine solution, as a ferment. Of the two the
fungus life is the easiest ; that is, yeast can perform its vital functions
more readily when it obtains its oxygen in the free state .than when it has
for that purpose to effect the decomposition of large quantities of sugar.
If yeast be grown continuously in saccharine solutions, under conditions
which result in the rigid exclusion of air, fermentation becomes more and
more sluggish: the conditions of life are in fact more severe than the
yeast can stand, the struggle for existence is too acute, and its vitality
succumbs. But if a sample of fermenting wort be taken at a time when,
although the sugar is far from exhausted, the fermentation has become
sluggish, and then thoroughly aerated by some means which shall bring it

FERMENTATION. 161

into full contact with air, a remarkable change ensues. At first the fer-
mentation slackens, but the rate of growth of yeast increases ; this is due
to its living as a fungus on the dissolved free oxygen. During this time
it exerts little action as a ferment, but grows and accumulates vital
energy. After a while, the fermentation proceeds much more vigorously
than before the aeration ; this is a necessary result of the renewed energy
and vitality of the yeast cells.

That oxygen is capable of acting in some way as a stimulant to fer-
mentation was known to brewers long before the announcement of this
theory by Pasteur, as they had found that by "rousing" (stirring) tuns
of wort that were fermenting sluggishly, the fermentation was invig-
orated. The agitation following from this rousing aerated the wort.

To borrow his own words, Pasteur summed up his theory of fermenta-
tion in the following terms : — ' ' Fermentation by yeast is the direct conse-
quence of the processes of nutrition, assimilation, and life, when these are
carried on without the agency of free oxygen. . . . Fermentation by
means of yeast appears, therefore, to be essentially connected with the
property possessed by this minute cellular plant of performing its
respiratory functions, somehow or other, with oxygen existing combined
in sugar. Its fermentative power varies considerably between two limits,
fixed by the greatest and least possible access to free oxygen which the
plant has in the process of nutrition. If we supply it with a sufficient
quantity of free oxygen for the necessities of life, nutrition, and respira-
tory combustions, in other words, if we cause it to live after the manner
of a mould, properly so called, it ceases to be a ferment ; that is, the ratio
between the weight of the plant developed and that of the sugar decom-
posed, which forms its principal food, is similar in amount to that in the
case of fungi. On the other hand, if we deprive the yeast of air entirely,
or cause it to develop in a saccharine medium deprived of free oxygen, it
will multiply just as if air were present, although with less activity, and
under these circumstances its fermentative character will be most
marked; under these circumstances, moreover, we shall find the greatest
disproportion, all other conditions being the same, between the weight of
yeast formed and the weight of sugar decomposed. Lastly, if free oxygen
occur in varying quantities, the ferment power of the yeast may pass
through all the degrees comprehended between the two extreme limits of
which we have spoken." According to this view, fermentation is a starva-
tion phenomenon, brought about by the want of free oxygen during the
life of yeast cells in a fermentable liquid.

310. Brown on Influence of Oxygen on Fermentation. — In 1892,
Adrian J. Brown contributed an important paper on this subject to the
Journal of the Chemical Society, which paper necessitates a reconsidera-
tion of the theory of fermentation. In his experiments, Brown employed
the method of counting the yeast cells in his various solutions, by means
of the haematimeter, instead of weighing the yeast, as had been done by
Pasteur in his various researches. This method of working has the advan-
tage that the results are capable of being referred to the amount of effect
being produced by the action of an unit cell.

Brown's first conclusions were that "when any fermentable nutritive
solution, such as malt wort, or a solution of dextrose in yeast water, is
inoculated with a high fermentation yeast, and kept at a temperature
favourable to yeast growth, the cells reproduce themselves rapidly for a
time, and then their reproduction ceases, and that the fermentation of the
solution may still be carried on by the continued life of the cells already

162 THE TECHNOLOGY OF BREAD-MAKING.

formed." Further, he found that with the same liquid, under the same
conditions, the cells increase to about the same maximum, no matter how
the number of cells introduced to start the fermentation may vary. In
support of this view, the following experiment is quoted — Two flasks, A
and B, were taken, and in each 150 c.c. of the same malt wort was placed,
and then a different amount of the same yeast added to each. The con-
tents of the flasks were thoroughly agitated, and the cells counted by the
hasmatimeter. (The standard volume of the instrument employed was
1/4000 of a cubic millimetre, called hereafter ' ' Standard Volume. ") The
flasks A and B contained respectively 0.93 and 7.44 cells per standard
volume. The flasks were kept at 25° C. until fermentation had com-
pletely ceased, when the cells were again counted. In flask A the number
of cells per standard volume had increased from 0.93 to 25.24; whereas in
flask B the increase was from 7.44 to 27.08. The rate of increase differed
widely, but the ultimate number of cells produced was approximately the
same. From these and a number of other similar experiments, the con-
clusion is drawn that in such fermentations the number of yeast cells
increases to some fixed maximum, irrespective of the number originally
added to induce fermentation.

The next point was to experiment by adding more cells than this
maximum number, two similar flasks of malt wort were respectively
seeded with 6.0 and 70.8 cells of yeast per standard volume. Fermenta-
tion was allowed to proceed, and, at its close, in No. 1 flask the cells had
increased from 6.0 to 24.9, while in No. 2 they had decreased from 70.8 to
68.2 cells. In this experiment 24.9 cells may be regarded as the maximum
number that the wort used would grow, consequently with No. 2 flask
there is no increase. Brown regards the actual diminution as due to the
death and disintegration of some of the cells. In the second flask as well
as the first, fermentation proceeded with great rapidity. Other experi-
ments made yielded the same results; therefore, if a nutritive liquid be
seeded with a considerably larger number of yeast cells than the maxi-
mum number it is capable of producing by reproduction, fermentation
proceeds, and a method is afforded of studying fermentation without mul-
tiplication of yeast cells. Having a constant quantity of yeast, through-
out the experiment, evidently eliminates many disturbing factors present
when the quantity of yeast is variable.

Brown in the first place applied this method to the investigation of
the action of oxygen on yeast. A malt wort of 1065 sp. gr. was taken, and
yeast added to the extent of 85 cells per standard volume ; 120 c.c. of this
solution were poured into a flask, A, so as to nearly fill it ; its mouth was
then stopped in such a manner as to permit the escape of carbon dioxide
gas, but to prevent air gaining access to the solution ; 120 c.c. of the same
solution were also placed in another flask, B, of about 1500 c.c. capacity,
so that it simply formed a thin layer on the bottom; this flask was so
arranged as to permit a current of air being drawn through the liquid.
Both flasks were thus similar, except that from the one air was excluded,
while the contents of the other were subjected to abundant aeration. The
fermentation was conducted at 19°, and, after the end of three hours,
arrested by the addition of salicylic acid. The liquids were distilled, and
the amount of alcohol produced estimated from the specific gravity of the
distillate. In A flask, without aeration, 3.35 grams of alcohol had been
formed ; while in B, through which a continuous current of air had been
drawn, the alcohol amounted to 3.56 grams. The number of yeast cells
remained unaltered at the close of the experiment, but slight attempts at

FERMENTATION. 163

abortive budding were observable, particularly in the aerated flask.
Another experiment was tried, in which the fermentable medium was a
solution of glucose in yeast-water, which was seeded with 90 cells per
standard volume. At the end of three hours, fermentation was arrested,
and the residual sugar in the solutions determined polarimetrically. In
A *(unaerated) 1.96 grams of glucose had been fermented; while in B
(aerated) the quantity of fermented glucose was 2.32 grams. In neither
case was there any sign of budding or enlargement of the cells.

In order to meet the objection that the mechanical effect of aeration
might stimulate the action of the cells in the B flasks, the following pairs
of experiments were made in which the A flasks were subjected to the
action of currents of carbon dioxide and hydrogen respectively, and at
about the same rates as the air through the B flasks. The following were
the results : —

"A" flask, with carbon dioxide passed, 3.99 grams of glucose fermented.
Companion B flask, with air passed, 4.28 „ „ „

A" flask, with hydrogen passed, 2.26 ,, „ „

Companion B flask, with air passed, 2.45 „ ,, „

In every case the most work is done in the presence of oxygen.

In all the preceding experiments, as the consequence of the employ-
ment of large quantities of yeast, fermentation proceeded very rapidly ;
in order to watch the results under slower conditions, experiments were
made with fermentation at a low temperature, 7° C. (44.6° F.), and were
continued for 24 hours. Through A flask hydrogen had been passed, and
4.882 grams of glucose had been fermented; while in B flask, through
which air had been passed, the quantity was 5.289 grams. During the 24
hours 190 litres of air had been passed through B flask. In none of the
preceding experiments was there any multiplication of yeast.

These results are in striking contradiction to the views of Pasteur,
who affirms that in the presence of excess of oxygen fermentation prac-
tically ceases. Brown, on the contrary, finds uniformly that in the
presence of oxygen fermentation is more vigorous than in its absence.

As Pasteur's results were obtained by weighing yeast, Brown in one
experiment weighed as well as counted his yeast. At the commencement
there were in each flask 87.6 cells per standard volume, and in 100 c.c.
1.903 grams of filtered, washed, and dried yeast. Fermentation resulted
in the destruction of 6.20 grams of glucose in the hydrogen flask, and 7.38
grams in the air flask. No increase in the number of cells had occurred,
but the weights of yeast, treated as before, were respectively from hydro-
gen flask 2.130 grams, and air flask 2.060 grams. In both cases there is
a slight increase in weight, due probably to assimilation by each individ-
ual cell, but in both cases at the finish of the fermentation we have almost
exactly the same weight of yeast, as well as the same number of cells.
Hence equal amounts of yeast, whether determined by weighing or count-
ing, ferment rather more sugar when supplied with air than when
deprived of it.

Another important experiment proceeded on different lines. The
object was to determine the rate of multiplication of cells, and, at the
same time, the rapidity of fermentation. Six similar flasks of glucose in
yeast water were taken, and each seeded with 0.65 yeast cells per stand-
ard volume. All were allowed to ferment under similar conditions. At
intervals, one of the flasks was taken and the number of yeast cells found,

164

THE TECHNOLOGY OF BREAD-MAKING.

and the quantity
results : —

of alcohol produced determined, with the following

Total

Grams of

Proportion

Number

Mean

grams of

Alcohol

of grams

Time of Commence-

of Cells

number of

Alcohol

found in

of Alcohol

Interval

ment of Experiment,

found in

Cells

found in

each

per 100 c.c.

of time in

and subsequent

each

present

each

interval of

to a

each

Determinations in

Experi-

during

Experiment

Time in

Single Cell

Experiment

Separate Flasks.

ment.

each

in 100 c.c.

100 c.c. of

in each

in Hours.

interval

of the

the

interval of

of Time.

Liquid.

Time.

Jan. 9, 11 p.m. 0.65

„ 10, 11 a.m. 4.87 2.76 0.654 0.654 0.237 12

„ 10, 11 p.m. 12.03 8.45 1.933 1.279 0.151 12

„ 11, 11 a.m. 15.38 13.70 2.975 1.042 0.076 12

„ 12, 11 a.m. 15.88 15.63 4.237 1.262 0.080 24

„ 13, 11 a.m. 15.80 15.80 6.187 1.950 0.123 24

It will be noticed that the number of cells increases rapidly in the
earlier stages of fermentation, and that also the proportion of alcohol pro-
duced by each single cell is greatest during the first twelve hours. This is
contrary to general views that fermentation is slower during the more
rapid multiplication stage of the development of yeast, an effect which
was supposed to be a result of oxygen in the liquid, which, while aiding
the reproduction of the cells, at the same time limited their fermentative
power. Brown's experiments contradict this theory.

In a further paper communicated to the Chemical Society in 1894,
A. J. Brown devotes himself to a critical examination of Pasteur's the-
ory; of which criticism the following is a brief outline: — Pasteur, as
previously explained, compared the fermentative power of yeast cells
under varying conditions of aeration, and arrived at the conclusion that
when aeration is perfect, fermentative power ceases, and when aeration is
reduced, fermentative power increases. The type of experiment used for
this purpose was that of determining, under varying conditions of aera-
tion, the proportion of the weight of the yeast formed to the weight of
sugar fermented. This ratio of yeast to sugar is, Pasteur considers, an
expression of fermentative power. If, as Pasteur argued, the amount of
yeast formed during fermentation were in direct proportion to the sugar
fermented, the ratio of yeast to sugar would remain constant, however
much or little sugar were available. Brown contends that his experi-
ments show conclusively that such is not the case, there being no direct
proportion between weight of yeast formed and sugar fermented. In
order to show that the total fermentative power of yeast has not been
measured in Pasteur's experiments, a fermentation was carried on under
aerobic conditions, until the sugar originally present was decomposed.
Afterwards, using the principle of overcrowding as a means of prevent-
ing reproduction, the crowded cells were fed with more sugar. Feeding
was carried on at intervals until three times the original weight of sugar
had been thus fermented, but no increase in the weight of yeast had
occurred. In Brown's opinion, Pasteur's apparent deficiency in fermenta-
tive power was due to the employment of a limited amount of sugar in
the experiment. Brown objects to Pasteur's aerobic experiments in shal-
low dishes, because they were allowed to continue but a limited time, and
therefore a time factor is introduced : further, cane-sugar was used as the
fermentable material, and consequently the results were complicated by
the hydrolytic functions of the yeast having to precede fermentation.
Pasteur's measure of fermentative power in the experiments referred to
is an expression of the action of the inversion and fermentative functions

FERMENTATION. 165

in a limited time. Brown concludes by submitting, in place of Pasteur's
theory that fermentation is "life without air," the hypothesis that
"yeast cells can use oxygen in the manner of ordinary aerobic fungi,
ami probably require it for the full completion of their life-history ; but
the exhibition of their fermentative functions is independent of their
environment with regard to free oxygen." Nothing in the results of
any of Pasteur's experiments are contradictory to such a hypothesis.

311. Buchner's Views on the Action of Oxygen. — Mention has al-
ready been made of Buchner 's researches on zymase as the agent through
which* yeast effects alcoholic fermentation. That investigator, together
with Rapp, pointed out in 1898 that Pasteur's views of fermentation were
biologically correct, inasmuch as yeast has obtained the power of acquir-
ing its oxygen by means of fermentation instead of by the more usual
course of the direct assimilation of oxygen. They show further that
oxygen stimulates the multiplication of yeast cells. So thoroughly, how-
ever, has yeast acquired the fermentation habit, that even in the presence
of oxygen, yeast is far more active as a fermentative agent, than as a
mere respiratory organism.

312. Mai-Nutrition of Yeast. — When yeast is deprived of a normal
proportion of each of the necessary constituents for its healthy life, the
vitality of the cells is thereby lessened. One result of this is that the cells
tend to assume abnormal forms. Thus, in the case of prolonged growth,
without access of free oxygen, yeast cells elongate, and at times are
observed to be several times as long as broad (sausage-shaped). The same
peculiarity of outline may be noticed in yeast that has been grown in
sweetened water. The reason may be that, with a deficient supply of
nutriment, each cell stretches itself out, as it were, in order to expose as
great a surface as possible to the medium. It is well known that the area
of surface of a sphere is less in proportion to its cubical contents than is
that of a cylinder or of any other solid body. By offering a greater sur-
face to the liquid in which it is growing, the yeast cell presumably is
enabled to absorb a greater amount of nutriment. In breweries where
sugar is largely used as a substitute for malt the yeast suffers from the
low percentage of nitrogenous matters contained in the wort : the result
is that such yeast has little vitality and is soon exhausted.

Large quantities of mineral salts also affect the shape of the yeast cell ;
thus, the yeast of Burton ale is oval (egg-shaped) in outline: the Burton
water is extremely hard, containing calcium sulphate in large quantities.

Badly nourished yeast, on examination, is usually found to have ab-
normally thin and fragile cell walls, these being broken by the slightest
pressure ; the contents of the cells are also thin and watery, instead of
full of healthy granulations of gelatinous protoplasm.

313. Sporular Reproduction of Yeast. — In addition to the budding
process already described, yeast also reproduces, when deprived of all
nourishment, by the formation of spores within the cell. To observe this
effect, prepare first a block of plaster of Paris by taking some of the pow-
der, rapidly making it into a thin paste, and then pouring same into a
cardboard mould. Let it set, and then strip away the cardboard. Smear
on the smooth surface of the plaster a little pressed yeast which has been
previously washed in distilled water. Place the block with yeast face up-
wards in a shallow dish, and pour in water until its surface is just a little
below that of the yeast. Cover it over with a glass shade to keep out dust,
etc., and stand in a warm place (about 20-25° C.). Each day remove a
little and examine under the microscope; after a few days some of the
cells will show denser masses of protoplasm aggregated around from two

166 THE TECHNOLOGY OF BREAD-MAKING.

to four points. These gradually grow, and at last occupy the whole of the
interior of the cell. They become coated with cell envelopes, and then
constitute ascospores. The walls of the ascus or mother-cell after a time
disappear, and the liberated spores perform the functions of yeast, induc-
ing fermentation, and reproducing by the ordinary mode of budding.

Among the conditions necessary for spore
formation are young and vigorous cells,
comparative absence of nutriment, and a
fairly warm temperature. The speed of
spore formation is greatly influenced by
the latter condition ; within certain limits
increase of temperature quickens the for-
mation of spores. This is also termed
FIG. 11. — Ascospores. multiplication by endogenous division.

Cells containing ascospores are shown in

Fig. 11, which represents the first stages of development of the spores of
8. Cerevisice I., after Hansen: a, 1), c, d, e contain rudiments of spores,
with the walls not yet distinct; /, g, ~k, i, j are completely developed
spores with distinct walls.

314. Substances inimical to Alcoholic Fermentation. — Dumas has
carefully investigated the action of foreign substances on alcoholic fer-
mentation ; Schiitzenberger quotes largely from his results ; the following
data obtained by Dumas are taken from the English translation of Schiit-
zenberger 's work. In the first place, a series may be given of those bodies
which retard, and when in sufficient quantity absolutely arrest, fermen-
tation. These include the mineral acids and alkalies (phosphoric acid
excepted), soluble silver, iron, copper, and lead salts; free chlorine, bro-
mine and iodine, alkaline sulphites, and bisulphites of the alkaline earths,
manganese peroxide ; essences of mustard, lemon, and turpentine ; tannin,
carbolic acid (phenol), creosote, salicylic acid; sugar in excess, alcohol
when its strength is over 20 per cent. ; and hydrocyanic and oxalic acids,
even in small quantities. Phosphoric and arsenious acids are inactive.
Sulphur has no effect on fermentation, but the carbon dioxide gas evolved
contains from one to two per cent, of sulphuretted hydrogen.

As may be gathered from the statement of the chemical changes pro-
duced by yeast, that substance gives always a more or less acid reaction.
Dumas states that this acidity requires, for its neutralisation, alkali,
equivalent to 0.003 grams of normal sulphuric acid per gram of yeast. In
his experiments he added various acids to yeast in proportions of from
one to a hundred times the normal acid of the yeast. In this manner was
determined the retarding or other action of the various acids on fermen-
tation. Similar experiments were made with bases, and also salts; with
the latter, saturated solutions were first made ; the yeast was allowed to
soak in these for three days, and then its fermenting power tested by its
action on pure sugar. Dumas divided the salts into four groups. First,
those under whose influence the fermentation of the sugar is entire, and
more or less rapid ; second, those which permit partial but more or less
retarded fermentation ; third, those which permit the sugar to be more or
less changed, but without fermentation ; fourth, those that prevent both
change and fermentation. Alum is placed in the first of these classes,
borax in the second, and sodium chloride (salt) in the third. Strychnine
has no effect on the properties of yeast. For a detailed account of Dumas '
results the student is referred to Schiitzenberger 's work.

315. Isolation of Yeast and other Organisms. — As a preliminary to
the study of varieties of yeast, it is absolutely necessary to have some

FERMENTATION. 167

means of separating and growing each variety in a state of absolute
purity. Pasteur did an enormous amount of work in this direction ; but
the crucial point in all such investigations as these is the purity or other-
wise of the yeast used to commence the experiment ; in all Pasteur 's re-
searches he used an apparatus which afforded most excellent means for
the prevention of the incursion of foreign germs
during his growth ; but he does not give us an
absolutely certain method of obtaining a per-
fectly pure yeast to start with. In flasks of spe-
cial construction, well known as "Pasteur's
Flasks" (Fig. 12), Pasteur introduces wort, then
sterilises the same by boiling it, and afterwards
sows therein a small quantity of the yeast he
wishes to cultivate in the pure state. The Pas-
teur's Flasks have a long narrow neck, which, as
shown in the illustration, is bent twice on itself,
the end being stopped with a plug of cotton
wool. In addition, there is a side tubulure,
stopped with india rubber tubing and a glass
plug. The wort is introduced through the side
tube, and when boiled the steam escapes through
the bent tube. On cooling, the air which enters
is sterilised by nitration through the cotton FIG. 12.— "Pasteur's Flask."
wool. The yeast is sown during a momentary

removal of the glass plug. On the completion of this fermentation,
a little of the new growth of yeast is taken and transferred with all
due precautions to a second Pasteur's Flask of sterilised wort, and
there again fermented. The yeast was grown in this way again and
again, until the experimenter was of opinion that the preponderating
growth of the yeast would have crowded out of existence any foreign
germs. To further aid in accomplishing this object, Pasteur also intro-
duced in his growth-flasks some substances inimical to the organisms he
wished to exclude, or else worked at a temperature specially favourable
to the particular organism whose growth he desired to favour. The yeast
obtained in this manner he terms pure yeast; undoubtedly this may be
possible, and in many experiments was probably the case ; but it is never-
theless only a possibility we have to deal with, for the germs of foreign
organisms may not be really dead, but only present in smaller quantity
and in a weaker condition. More recent investigators have described
methods by which it is possible to cultivate and develop the growth of
yeast from one single isolated cell ; in this manner giving the surest guar-
antee of the actual purity of the yeast produced.

A first step in this direction is the adoption of what is known as
"Nffigeli's Dilution Method," which is based on diluting down the liquid
under examination until a single drop will, on the average, contain but
one organism. This may be accomplished in the case of yeast by taking
a drop of the mixture of yeast and water, diluting it down considerably
with water previously sterilised by boiling, until the number of cells pres-
ent in a drop can be counted under the microscope. If these are esti-
mated, for instance, to be about one hundred, then this liquid is further
diluted to a hundred times its volume. Every precaution must be taken
to sterilise all vessels and liquids used in the operation. Each drop of
this ultimate dilution of yeast should contain one cell only. Ten drops
are then placed in 20 c.c. of sterilised water, and thoroughly agitated.
One c.c. is then placed in each of 20 separate flasks containing culture

168 THE TECHNOLOGY OF BREAD-MAKING.

fluid, which may, for example, be sterilised wort. The probability is that
ten out of the twenty flasks will contain but one organism only, the others
remaining unimpregnated. But here again it is only a balance of proba-
bilities, and no certain inferences may be drawn. Hansen proceeded a
step further by showing that, if the inoculated flasks are vigorously
shaken, and then allowed to stand, the yeast cells will sink to the bottom
and attach themselves to the sides of the flask. If more than one cell be
present, the probabilities are that they will lie on the bottom some dis-
tance apart. After some days the flask is raised carefully, and each yeast
cell will be the centre of a small white speck visible to the naked eye, and
consisting of a colony of yeast. In only one such speck be found, the
flask contains a pure culture from one cell only. Subsequent cultivation
may proceed on the lines laid down by Pasteur.

Koch, in his experiments on Bacteria (certain minute organisms to be
hereafter described), used specially prepared gelatin as a cultivating
medium. The material was mixed with water until it acquired such a
consistency as to set, when cold, into a jelly, which became fluid at a tem-
perature of 35° C. For a cultivation experiment some of the gelatin is
melted, a few of the bacteria are taken out on the point of a needle and
added to the gelatin. They are then diffused by shaking up the mixture,
which is next poured out upon a flat surface properly protected. After
some hours, a separate and pure culture is obtained from each single
bacterium present. On taking a minute particle from one of these
little culture spots, and again sowing it in gelatin, a single species of
bacterium was obtained. It was by experiments based on this principle,
but carried out with most special precautions, that Koch isolated and
exhaustively studied the " Comma Bacillus" of cholera, so inseparably
associated with his name.

Hansen modified this method for yeast culture, using, instead of
Koch's nutrient gelatin (which consisted usually of meat broth and gela-
tin), a mixture of hopped wort and gelatin. In a bright hopped wort of
about 1058 gravity is dissolved from 5-10 per cent, of gelatin, the quan-
tity being regulated so as to cause the mixture to "set" at 30-35° C.,
being solid below, and liquid above those temperatures. This mixture
must, of course, be thoroughly sterilised. Some of the yeast which it is
desired to cultivate is first diluted down by the Naegeli method until of a
convenient degree of dilution. This must be ascertained by experiment : a
drop of this solution is next taken by means of a sterilised piece of plati-
num wire, and transferred, wire and all, to a flask containing some of the
treated gelatin preparation. This is agitated, so as to secure thorough
mixture, but at the same time the production of froth must be avoided. A
drop of this gelatin is taken out and examined microscopically to deter-
mine whether a sufficient number of yeast cells are present. Should they
be too crowded, the contents of the flask are diluted with more gelatin ; if
too few are present, some more must be taken from the yeast-containing
flask by means of another piece of platinum wire. To cultivate the yeast,
a modification of Koch's glass-plate known as Bottcher's moist chamber,
is employed.

The chamber consists of a microscope slide, on which is cemented the
glass ring, c, the upper surface of which is ground flat. In use, a small
quantity of the gelatin and yeast, as prepared above, is placed on the
under side of the cover-glass. The upper edge of the glass ring is smeared
with vaseline, and a few drops of water placed in the bottom of the cham-
ber. The cover-glass and gelatin is placed on the ring and gently pressed

FERMENTATION. 169

down, when the vaseline makes a tight joint between it and the chamber.
Each yeast cell embedded in the gelatin can now be subjected to micro-
scopic examination, and any particular one kept under observation. To
do this, any of the devices in common use as finders for any particular
part of a microscopic object may be employed, but a very convenient one
is Klonne and Miiller's marker, which consists of an appliance that can
be screwed concentrically into the screw of the microscope which carries
the objective. The desired cell is brought into the centre of the field : the
objective is removed and the marker substituted for it. By means of the
focussing screw it is lowered gently on to the cover, on which it marks a
small ring encircling the cell required to be kept under observation. The

FIG. 13.— Bottcher's Moist Chamber.

a, Thin Cover-glass; b, Layer of Nutritive Material; c, Glass Ring; d, Layer of Sterilised
Water.

cell is allowed to develop until a visible colony is formed. By means of a
sterilised piece of platinum wire it is now picked off, and used to seed a
prepared culture solution in a Pasteur 's or other flask. This operation of
transference may be conducted in a dust-free room in the open air, but
preferably in. a small cupboard kept for the purpose, the walls of which
have been moistened with glycerin, so as to maintain the interior as a
germ-free space. The apparatus, and the hands of the operator, are
introduced through a door just sufficiently large to provide for their
admission. Large cultures are made, as before, by successive transfer-
ences to larger flasks.

Hansen's experiments on the effect on brewing, of specific varieties of
yeast, were made with cultures obtained in this manner from single cells.

316. Classification of Yeasts. — In classifying yeasts as a genus of the
fungi, they have received the following definition, based upon that of
Rees.

CLASSIFICATION OF THE GENUS SACCHAROMYCES.

Budding Fungi, mostly without a mycelium, the individual species of
which occur with cells of different form and size. Under certain treat-
ment, and sometimes also without any previous treatment, cell-nuclei are
seen. Under certain conditions the cells develop endogenous spores; the
germinating spores of most species grow to budding cells ; in exceptional
cases a promycelium is first formed. Number of spores 1 to 10, most fre-
quently 1 to 4. Under favourable conditions the cells secrete a gelatinous
network, in which they lie embedded.

The greater number of the species induce fermentation.

The following is a list of the more important species : —

Saccharomyces cerevisiae . . • • ] T 1 xr ea

Minor . . . . . . Ferment of Leaven.

Ellipsoideus . . . . Ferment of Wine.

Pastorianus.

170 THE TECHNOLOGY OF BREAD-MAKING.

317. Saccharomyces Cerevisse, or Ordinary Yeast. — At least two dis-
tinct varieties of ordinary yeast are known, to which the names of
"High" and "Low" yeast have been given. The former of these is the
common yeast of English ale fermentation; the other, that of the well-
known "lager" beer of continental production. Saccharomyces minor, a
species of yeast found in leaven, is also possibly a sub-variety of S. cere-
visice; so, too, is the distillers' yeast made in this country, and also im-
ported from Holland and France, and sold as compressed yeast.

318. High Yeast. — This variety is so-called because of its ascending
to the top of the fermenting liquid during fermentation. It consists of
cells mostly round or slightly oval, from 8 to 9 ^ in diameter, and answer-
ing generally to the description of yeast given in paragraphs 301 and 302.
Illustrations of Brewers' High Yeast, Distillers' Yeast, and Bakers' Pat-
ent Yeast are given in Plate II., to which reference is also made in
Chapter XII.

319. Low Yeast. — Sedimentary yeast, or the "low" variety of Sac-
charomyces cerevisiae, is that used in the manufacture of lager beer. In
general properties it much resembles the high yeast which has already
been studied. In form the cells are somewhat smaller, and also rather
more oval than those of normal high yeast ; but differ very little in shape
from high yeast when grown, as at Burton, in very hard waters. Fig. 9,
paragraph 301, gives illustrations of low yeast.

320. Distinctions between High and Low Yeast. — Whereas high
yeast rises to the surface of the liquid during fermentation, "low" yeast
always falls to the bottom, and forms a sediment there ; hence the name
"sedimentary" yeast. Brewing with low yeast is performed at much
lower temperatures than with high ; thus, whereas with the latter pitching
temperatures of 20° or 21° C. (68° or 70° F.) are employed, the lager
beer brewer starts his fermentation at as low as 8° C. (47° F.), or even
6° C. (43° F.). ' Working with this low temperature, fermentation pro-
ceeds much less rapidly than with high yeast ; growth and reproduction
proceed more slowly, and the budding gives rise to less extensive colonies
of cells. As Pasteur aptly describes it, low yeast when growing has a
much less ramified appearance. (See Fig. 10.) It is doubtful whether
the term "low," as applied to this yeast, has been given from the lowness
of the temperature employed for fermentation, or because the yeast
always drops to the bottom of the fermenting vat ; both are characteristics
of this variety. This yeast is further distinguished by its producing a
different type of beer to the celebrated product by high fermentation of
English and Scotch breweries.

It may be well to mention that the low yeast of lager beer is not that
which is being imported from the continent, and sold so largely for bread-
making purposes. As a matter of fact, lager beer yeast is very badly
suited for the fermentation of bread ; its action is extremely slow, and
results in the production of a heavy, sodden, and frequently sour, loaf.

321. Convertibility of High and Low Yeasts. — This has been for
many years a much-discussed problem both by brewers and scientists, and
is typical of the discussions which arise on the general question of the im-
mutability or otherwise of the different yeast species and varieties. Stu-
dents who approach this subject with a previous knowledge of the laws
of the origin of species as a result of evolution, as enunciated and dem-
onstrated by Darwin, will be prepared to expect from the general evi-
dence of biology that not only high and low yeasts, but also all forms and
species of Saccharomyces, have had one common origin, their diversities

FERMENTATION. 17]

PLATE II.

Con ifi/cs sect ID i&tiUe+~3

VARIOUS COMMERCIAL YEASTS

172 THE TECHNOLOGY OF BREAD-MAKING.

having been produced by differences in environment extending over num-
berless generations. When discussing, however, whether or not low and
high yeast are convertible, and really therefore of the same species, it is
understood that the question refers to convertibility during small amounts
of time, not such lengthy periods as are requisite for an actual evolution
of distinct species. Pasteur, at an earlier period of his researches, con-
sidered the two yeasts to be convertible, but as the result of later investi-
gations, affirmed the two yeasts to be distinct. This belief is founded on
experiments in which high yeast is grown repeatedly at the lowest possible
temperature, and low yeast at the temperature employed for high fer-
mentation. Supposing the yeasts to be pure at the commencement of
such an experiment, he asserts that no transformation of the one variety
into the other is effected. In this opinion he differs from many brewers,
who state that under such conditions the one yeast is converted into the
other. Pasteur gives the following explanation of the observed change : if
the high yeast had in it a few cells of low yeast as impurity, on being
sown and caused to reproduce at a low temperature, the low yeast cells
present would thrive well/ while the high yeast would languish. The
minute quantity of low yeast cells, finding the conditions favourable to
their growth, develop ; and the others, through the conditions being un-
favourable, are after a time outnumbered and disappear. The change of
low into high yeast is explained as being just the converse of that now
described. An authoritative dictum on this subject is that of
Jorgensen, who, in 1893, asserts that, "in spite of many assertions to the
contrary, it has not hitherto been possible to bring about an actual con-
version of top-yeast into bottom-yeast, or vice versa. The investigations
of Hansen and Kiihle show that it is certainly possible for a bottom-fer-
mentation yeast to produce transitory top-fermentation phenomena;
these, however, quickly disappear with the progressive development of the
yeast/'

322. Distillers' Yeast. — The yeasts employed by distillers for the
purpose of fermenting their worts differ in some most important charac-
teristics from ordinary brewers' yeast. They are, in the first place, grown
in un-hopped worts, as against the hopped worts of the brewer. In
appearance they resemble low yeast more closely than the normal brewers'
high yeast, averaging slightly smaller in size, and forming less extensive
colonies. The yeast is less mucilaginous than that of the brewer, and so
does not form so sticky a mass. The distillers ' yeasts are ordinarily high
yeasts, but see the subsequent account of compressed yeast manufacture,
Chapter XII. They are sharply separated from the brewers' yeast by
their capacity for inducing a vigorous fermentation in dilute mixtures of
flour and water. If equal weights of brewers' and distillers' yeast be
sown in a solution of sugar in water, and fermented under the same con-
ditions, the brewers' yeast will usually cause a slightly more rapid evolu-
tion of gas; but if, instead, a mixture of flour and water be used, the
distillers' yeast will cause many times more gas to be evolved than does
that from the brewer. This difference is not owing to the absence of sugar,
for if to the flour and water sugar be added in the same proportion as
in the pure sugar solution, there is still little or no more fermentation
caused by the brewers' yeast. The probable reason is the actual toxic
effect of certain constituents of flour on brewers' yeast. (See paragraph
377.)

Jorgensen states that distillery yeasts exhibit marked differences in
their sedimentary forms, and in ascospore formation, to brewers' yeasts.
Microscopic examination of compressed yeast, according to Belohoubek,
indicates, in the following manner, alterations in the appearance of the

FERMENTATION.

173

cells. As decomposition sets in, the protoplasm becomes darker in colour
and more liquid; the vacuoles become larger, and the sharp outline be-
tween them and the plasma gradually disappears: the plasma shrinks
from the cell-wall, and finally collects in irregular masses in the cell-fluid.
At times cells appear in pressed yeast, which suddenly, develop a number
of small vacuoles ; these abnormal vacuolar cells speedily perish.

323. Saccharomyces Minor. — This is a form of yeast described by
Engel as being obtained by him from leaven (a name given to old dough) .
To obtain the ferment he washes a piece of leaven in the same way as
described in a previous chapter for the separation of the gluten of flour
from its starch. The yeast cells pass through, and may be detected by
microscopic examination of the liquid after the larger starch cells have
settled to the bottom. The cells of Saccharomyces minor are globular,
occurring either isolated or in pairs or groups of three. They are about
6 mkms. in diameter, and have an indistinct vacuole. In Pasteur's fiuid
they reproduce but slowly, and form new cells of the same dimensions as
were the original. They easily reproduce by sporulation, the spores
being about 3 mkms. in diameter, and are united in twos or threes. They,
on the whole, closely resemble the yeast of beer. Although Engel treats
saccharomyces minor as a distinct variety, the balance of evidence is in
favour of its identity with S. cerevisiae. Grove considers it to be but a
form of that ferment. The lesser size and activity may be attributed to
its having continually reproduced itself in an unfavourable medium, such
as dough; hence its stunted appearance and slow growth, as compared
with the more favourably environed yeast of beer.

Engel views this form of yeast as being the active ferment in the fer-
mentation of bread. In this, of course, he is referring to continental
black bread, in the fermentation of which leaven is employed, this being
made by kneading together flour, bran, and water, and allowing the mass
to undergo spontaneous fermentation.

White bread fermented with either brewers' or distillers' yeast belongs
to a totally different category.

Saccharomyces minor and other yeast varieties are illustrated in Plate
III. The numbers following the multiplying sign give the magnification
in diameters.

324. Saccharomyces Ellipsoideus. — This is the ordinary ferment of
vinous fermentation, that is, that

by which ' t must, ' ' or the expressed
juice of the grape, is converted into
wine. The cells of this variety of
yeast are oval, and about 6 mkms.
long; they reproduce both by bud-
ding and spores. When grown in
malt wort, they produce a beer of a
decided vinous flavour, which is
sometimes made and sold as " bar-
ley wine."

325. Saccharomyces Pastorianus.
—The cells of this variety of yeast
vary considerably in size ; they are
cylindrical in shape, with oval
ends, and appear when seen in colo-
nies somewhat like strings of
sausages. Budding occurs at the
joints, where groups of smaller

FIG. 14. — Saccharomyces Pastorianus.

a, The same more highly magnified (after
Pasteur).

174 THE TECHNOLOGY OF BREAD-MAKING.

daughter cells may be observed; these are first either round or. slightly
oval. The elongated cells are from 18 to 22 mkms. long, and about 4
mkms. in diameter; the daughter cells are about 5 to 6 mkms. in length.
S. Past or i anus occurs in the after fermentation of wine and beer, and
also in bakers' "patent" yeasts. As it is found in English beers which have
been kept for some time in store, cells of it are probably more or less
present in all commercial English yeasts. Being a less active variety than
8. cerevisiae, it remains dormant while the first or principal fermentation
proceeds ; but when the most of the sugar has disappeared, the 8. pasto-
rianus, being able to live and develop in a less nutritious medium, grows
and reproduces. Brown and Morris point out that the amyloins cannot
be either fermented or hydrolysed by ordinary yeast ; but that 8. pasto-
rianus is capable of hydrolysing maltodextrin for itself, thus giving rise
to an apparent direct fermentation of that body. This will explain how
this latter ferment thrives and reproduces in a medium so deficient of
sugar as not to permit the growth of Saccharomyces cerevisice.

326. Saccharomyces Mycoderma, or Mycoderma Vini. — Closely
allied to the saccharomyces already described under the name of yeast is
this species, which belongs to the fungus family proper. Saccharomyces
mycoderma requires for its growth and development free oxygen, and be-
longs to Pasteur's division of "aerobian" plants. Although the fungi
proper luxuriate rapidly when growing with free access to air, yet they

are speedily destroyed by enforced
submergence below the surface of a
Liquid. Saccharomyces mycoderma
occurs on the surface of wine, beer,
and bakers' yeasts, on their being
exposed for some days to the air, form-
ing after a time a thick wrinkled skin
or mycelium ; in which state it is said
to be "mothery. " The mycoderma is
known as that of wine (vini), or of
beer (cerevisiae) according to the
liquid on which it appears. Viewed
under the microscope, the mycelium is

_ found to consist of extending branches

FIG. 15.-Mycoderma cerevisioe. of elongated cells closely felted or

From Copenhagen Breweries. intertwined together. See illustration

on Plate III, and Fig. 15 of Myco-
derma cerevisice. The individual cells are either oval or cylindrical, with
rounded ends. They are about 6-7 mkms. long, and 2-3 mkms. in diame-
ter. The Mycoderma vini reproduces either by budding or by spores.
The spore forming cells attain a length of as much as 20 mkms. Particu-
larly in summer time, the growth of this fungus proceeds with extreme
celerity, the mycelium first formed being thrown into folds by its rapid
development; at the same time considerable heat is produced. Micro-
scopic examination shows that Mycoderma vini is very like yeast in
appearance ; for a long time it was supposed that the two were identical,
and that the mouldiness of beer was produced by the yeast cells ascend-
ing to the surface, and there developing as a fungoid growth. The two
organisms are, however, distinct species, and have not been transformed
one into the other. Mycoderma vini during its growth seizes oxygen with
great avidity, entirely preventing, during the period of its actual life,
the development of other organisms also requiring oxygen, but endowed
with less vital energy. Pasteur states that on submerging this mould

FERMENTATION.

175

PLATE ffl.

Mycoderma. V,ni * 3OO
LH Aesobiasi form. R H Subtneryed form.

( after MaaxhjOHs & Latb)

VARIOUS "FOREIGN" YEASTS.

176 THE TECHNOLOGY OF BREAD-MAKING.

during its actual growth into malt wort, or other saccharine liquid, it
for a short time causes fermentation, with the production of small quan-
tities of alcohol ; but this action soon ceases with the early death of the
fungus. In addition to this limited fermentative action, Mycoderma vini
acts on wines and beers as a somewhat powerful oxidising agent ; it
conveys the oxygen of the air tp the alcohol of the liquid, causing its
complete slow combustion into carbon dioxide and water, and conse-
quently rapidly lessening the alcoholic strength of the medium. Although
wines and beers become sour simultaneously with the development of
Mycoderma vini, the souring is not due to this organism, but to another
distinct growth.

The limited alcoholic fermentation produced by Mycoderma vini leads
to its being classed among the saccharomyces.

327. Hansen on Analysis of Yeasts. — It is principally due to the re-
searches of Hansen that we are able to classify yeasts into species and
races with such accuracy as is now possible. The results of his work have
had such important effects on the brewing industry, and indirectly on
that of bread-making, that the present book would not be complete with-
out some reference to these classical investigations.

Hansen 's fundamental idea was that the shape, relative size, and
appearance of yeast cells, taken by themselves, were not sufficient to char-
acterise a species, since the same species under different external condi-
tions could assume very different forms. Further, although, for example,
a microscopic field of pure S. cerevisiae could be distinguished by its
appearance from pure 8. pastorianus, yet in a mixture of the two it is
not possible to distinguish individual cells of the one from those of the
other. 8. cerevisiae forms at times sausage-shaped cells, while 8. pasto-
rianus occurs to a certain extent as round or oval cells. Some other
method, then, than microscopic examination is necessary for their differ-
entiation.

328. Formation of Ascospores. — By investigation of the conditions
under which different races of yeast formed ascospores, Hansen was en-
abled to arrive at a mode of analysis of yeasts. A description of the mode
of procedure by which ascospores are obtained has already been given,
but Hansen ascertained with more exactitude the precise conditions nec-
essary, and thus sums up his conclusions : — The cells must be kept moist
and have a plentiful supply of air ; further, to form spores they must be
young and vigorous. For most species a temperature of 25° C. is the
most favourable; for all species this temperature favours their develop-
ment.

Hansen found the process of spore-formation to vary in different
species. 8. S. cerevisiae, pastorianus, and ellipsoideus germinate into
spores in essentially the same way. 8. ludwigii and 8. anomalus have
each a separate and distinct mode of spore growth. ,»

While all species form spores at 25°, Hansen set himself to determine
whether with different species there was any difference in their behaviour
under varying conditions of temperature. In making observations, he
registered the time when the cells first showed distinct indications of
spore formation. The limits of temperature for all species are between
from 0.5 to 3°C. and 37.5°C. At the highest temperature all species de-
velop first indications in about 30 hours, and show very little difference
in time at 25°C. ; but with lower temperatures very evident differences
occurred. Hansen also found that there were differences in anatomical
structure of spores that could be utilised for analytic purposes. In the
so-called cultivated yeasts, 8. cerevisice employed for brewing, the spores

FERMENTATION.

177

PLATE IV.

FormaLt/ioji of Ascoepores

1 . Saucctv cereriffvoe I. 2, . Saucchf . Pcusturvcmue I .

3. Scuxfa PoArtortcurvajs II . &. ScLcchi . PcustzrriarvaG JH.

5 . Sauoch. eltipsoidbvcus 1 6 . Scucch>. eLUpsovdeue II .
(after Hanserv » 1000 . )

178 THE TECHNOLOGY OF BREAD-MAKING.

have a distinct membrane, with non-homogeneous granular contents and
a definite vacuole. In the case of the so-called wild yeasts, the spore
wall is frequently indistinct, the cell contents homogeneous, and the vac-
uole absent.

Hansen. investigated very closely the following six species of yeast,
particulars of which are furnished.

Illustrations of the formation of ascospores are given in Plate IV.

Saccharomyces cerevisiae I., English top-fermentation yeast. Fer-
ments glucose and maltose very vigorously. Spores strongly refractive to
light, walls very distinct ; size 2.5-6 p.

8. pastorianus I., Bottom-fermentation yeasts; frequently occurs in
the air of fermenting rooms; imparts to beer a disagreeable bitter taste
and unpleasant odour; can also produce turbidity and interfere with
clarification in fermenting vat. Size of spores, 1.5-5 p.

8. pastorianus II., Feeble top-fermentation yeast; found in air of
breweries; apparently does not cause diseases in beer. Size of spores,
2-5 f,.

8. pastorianus III., Top-fermentation yeast, one of the species which
produce yeast -turbidity in beer; but in certain cases clarify opalescent
worts. Size of spores, 2-5 /x.

8. ellipsoideus I., Bottom-fermentation yeast ; occurs on ripe grapes.
Size of spores, 2-4 /*.

S. ellipsoideus II., Usually bottom-fermentation yeast; causes yeast
turbidity, more dangerous than 8. pastorianus HI. ; also imparts a sweet-
ish, disagreeable, aromatic taste to beer, and a bitter, astringent after-
taste. Size of spores, 2-5 /x.

It will be noticed that Hansen sub-divides both 8. pastorianus and
ellipsoideus. He also sub-divides other species into different races or
varieties. The leading points of connection between temperature and
spore formation are given in the following table : —

TEMPERATURE AND SPORE-FORMATION OF YEASTS.

Sacch. Sacch. Sacch. Sacch. Sacch. Sacch.
Cerev. I. Past. I. Past. II. Past.III. Ellip.I. Ellip.II.

Highest limit of development.

Temperature of .. .. 37.5° 31.5° 29° 29° 32.5° 35°
Most rapid development.

Temperature of . . . . 30° 27.5° 25° 25° 25° 29°
Most rapid development.

Time, in hours, of appear-
ance of first indication of

spores 20 24 25 28 21 22

Time, in hours, of appearance

of first indications at 15°C. 110 50 48 48 45 62
Lowest limit of development.

Temperature of . . . . 9° 0.5° 0.5° 4° 4° 4°

It will be seen that considerable differences exist between the various
yeasts in the particulars given. In addition, Hansen has* also in-
vestigated the conditions of film formation and other properties which
aid in the task of yeast differentiation.

329. Detection of "Wild" Yeasts.— In utilising spore formation,
cultures are made at temperatures of 25° and 15° respectively, the latter
being examined after three days — 72 hours. All the wild yeasts will have
commenced to show indications, while the cultivated yeast will be free
from them. When used practically for technical purposes, this method

FERMENTATION. 179

is capable of detecting with certainty an admixture of 0.5 per cent, of a
wild yeast in an otherwise pure culture. For this and other tests applied
to yeast by Hansen's methods, it is essential that the preliminary trials
of the yeast be uniform, so as to make the tests comparative.

330. Varieties of Cultivated Yeast. — Not only have distinctions been
drawn between cultivated and wild yeasts by the methods just described,
but also well-marked and distinct varieties of cultivated yeast have been
grown. Each of these possesses distinct characteristics, and is valued for
certain kinds of beer. Thus, Jorgensen, for practical purposes, classifies
different races of yeast prepared by pure culture methods in his labora-
tory into the following groups : —

A. — BOTTOM-FERMENTATION SPECIES.

1. Species which clarify very quickly and give a feeble fermenta-
tion in the fermenting vessel ; the beer holds a strong head. The beer, if
kept long, is liable to yeast-turbidity. Such yeasts are only suitable for
draught-beer.

2. Species which clarify fairly quickly and do not give a vigorous
fermentation ; the beer holds a strong head ; high foam ; yeast settles to a
firm layer in the fermenting vessel. Beer, not particularly stable as re-
gards yeast-turbidity. Yeasts are suitable for draught-beer, and partly
for lager beer.

3. Species which clarify slowly and attenuate more strongly; the
beer has a good taste and odour ; the yeast deposit is less firm in the fer-
menting vessel. Beer is very stable against yeast-turbidity. These yeasts
are suitable for lager beer, and especially for export beers which are not
pasteurised or treated with antiseptics.

B. — TOP-FERMENTATION SPECIES.

1. Species which attenuate slightly and clarify quickly. The beer
has a sweet taste.

2. Species which attenuate strongly and clarify quickly. Taste of
beer more pronounced.

3. Species which attenuate strongly, clarify slowly, and give a nor-
mal after-fermentation. The beer is stable against yeast-turbidity.

Hansen has isolated two yeast races from ordinary yeast, both of
which are employed in the Carlsberg breweries ; these are known as Carls-
berg No. 1. and Carlsberg No. II. Each has distinct properties of its
own; thus, No. I. gives a beer well adapted for bottling, containing less
carbon dioxide than No. II., and possessing a lower degree of attenua-
tion ; well adapted for home use. No. II. is principally cultivated for
export, giving a good draught-beer containing more carbon dioxide.

Passing for the moment the work of different investigators in review,
Pasteur freed yeasts from weeds or foreign vegetable growths of the
bacteria group. Hansen first eliminated wild yeasts as a fruit grower
might eliminate crab-apples and other wild fruits from his orchard.
Lastly, he has devoted his attention to the growth of distinct breeds of
cultivated yeast, each specialised for a particular type of beer. Jorgen-
sen 's experiments carry the analogy a step further. He -finds that
among the progeny of a single yeast-cell, cells can be selected which may
show important differences in respect of the taste, smell, and other prop-
erties of the fermented liquid. Such cells may, in fact, differ from each
other as do children of the same parents,

180 THE TECHNOLOGY OF BREAD-MAKING.

In yeast factories much the same is being done for the bakers. Yeasts
are selected for their vigour and capacity for fermentation, and these are
cultivated to the exclusion of types incapable of yielding such excellent
results. Thus Lindner has introduced. a variety of pure culture yeast in
most of the distilleries of Germany, under the name of Race II. The
results have been good. A further development on the same lines is the
employment of pure cultures of the bacillus of lactic acid in distilleries.
As subsequently described, this serves to inhibit excessive development
of lactic acid itself, and butyric acid fermentation. Race V. has been
specially recommended for this purpose.

EXPERIMENTAL WORK.

331. Substances produced by Alcoholic Fermentation, — Prepare
some ten or twelve ounces of malt wort, by mashing ground malt in five
times its weight in water : and take its density by a hydrometer. To the
wort add a small quantity of either brewer's or compressed yeast, place
it in a flask arranged with a cork and leading tube, and set it in a warm
place (30-35° C.). Attach the leading tube to a flask containing lime-
water, so that any gas evolved by the yeast has to bubble through the
liquid. Notice that after a time fermentation sets in, and that the yeast
rises to the top ; gas bubbles through the lime-water and turns it milky,
thus showing that carbon dioxide is being evolved. When the liquid
becomes quiescent through the cessation of fermentation, again take its
density with the hydrometer, notice that it is less than before ; return the
liquid to the flask, and connect to a Liebig's condenser and distil; notice
that the first drops of the distillate have the appearance of tears, as
described in paragraph 101, Chapter III. Cease distilling when about
one-tenth of the liquid has distilled over ; notice that the distillate has
an alcoholic or spirituous odour. Test it for alcohol by the iodoform
reaction.

332. Microscopic Study. — Proceed with this on the lines of para-
graph 301.

Mount a trace of the yeast in a little warm malt wort, arid examine
carefully: notice alteration in appearance of the yeast cells as they set
up fermentation : keep the microscope with slide in focus for some time
in a warm place, and observe from time to time the changes as they pro-
ceed. Watch specially for the development of budding, and as soon as
any signs are detected watch the cell at short intervals until the bud has
become completely detached from the parent cell.

Sow a little yeast in a beaker in a small quantity of wort ; take out a
little and examine under the microscope a few hours later : examine again
on each successive day until some three or four days have elapsed since
the fermentation has ceased. Note during the height of the fermentation
the colonies of cells, sketch some of these : observe the clear outlines and
transparent protoplasm of the new cells as compared with the shrunken
appearance of the parent cells. As time proceeds, notice the gradual
alteration in appearance of the yeast, until at last the new cells are sim-
ilar in appearance to those originally sown.

Study sporular reproduction as directed in paragraph 313.

CHAPTER X.

BACTERIAL AND PUTREFACTIVE FERMENTATIONS.

MOULDS.

333. Schizomycetes. — Grove defines the Schizomycetes or "splitting
fungi" (Spaltpilze) as being unicellular plants, which multiply by re-
peated subdivision, and also frequently reproduce themselves by spores,
which are formed endogenously. They live, either isolated or combined
in various ways, in fluids and in living or dead organisms, in which they
produce decompositions and fermentations, but not alcoholic fermenta-
tion.

Among these organisms are included bacteria, bacilli, vibrios, etc., but
comparatively few of these have an immediate bearing on the present
subject, and so the great majority need not here be described.

^^feta

<&M£<K

mi-'SS^i *3<s yjfv

FlG. 16. — Growth-forms of Bacteria.

a. Cocci; b, Diplococci and Sarcina; c, Streptococci; d, Zooglcea; e, Bacteria and
Bacilli; /, Clostridium ; g. Pseudo-filament, Leptothrix, Cladothrix; h. Vibrio, Spirillum
Spirochaete, and Spirulina; i, Involution-forms; £, Bacilli and Spirilla, with cilia or flagella;
/, Spore-forming Bacteria; m, Germination of the Spore.

The difficulty of classifying the Schizomycetes increases with a more
minute acquaintance with these organisms, as investigation shows that
one and the same organism occurs in varying forms under different con-
.ditions. Some of the various growth-forms are illustrated in Fig. 16.
If, on the other hand, grouped according to the chemical changes they
produce, then in many instances more than one organism is found cap-
able of inducing the same chemical reaction. For the purposes of the
present work, it will be more convenient to accept provisionally a classi-
fication according to chemical effects produced.

181

182 THE TECHNOLOGY OF BREAD-MAKING.

The Schizomycetes possess the property of surrounding- themselves
with a gelatinous substance, in which large colonies of them may be seen
imbedded. They are then said to be in the "Zoogloea" stage.

334. Bacteria. — These organisms consist of small cells, commonly
cylindrical in shape; they increase by transverse divisions of cells, and
reproduce by sporulation. Bacteria have a spontaneous power of move-
ment.

ORGANISMS OF PUTREFACTION.

335. Bacterium Termo. — This is essentially the ferment of putrefac-
tion. It is present in air, and also in waters contaminated with sewage.
Hay, meat, or flour infusions, malt wort and other liquids, on being ex-
posed to the atmosphere, become turbid, and are then found on micro-
scopic examination to be densely crowded with bacteria. The cells are
oval in shape and about 1.5 to 2 mkms. in length : they are constricted in
the middle, giving them a sort of hour-glass appearance; at each end is
an extremely fine filament, termed a " flagellum," and sometimes a
"cilium." This is probably the organ by which the bacterium exerts its
motile or moving power. For illustrations of this and other forms of
bacteria see Plate V.

This definite movement of the bacterium must not be confounded with
the simple oscillatory movement of small particles of matter when sus-
pended in a fluid. This latter may be observed by rubbing up a little
gamboge in water, and microscopically examining a drop of the liquid;
the small solid particles are seen to be in a continual state of motion.
This latter is termed the ' ' Brownian ' ' movement.

The spores of the bacteria, in common with most other of those of the
schizomycetes, are extremely tenacious of life. They may be dried up
and exist in a dormant state for an indefinite time without losing their
vitality ; for immediately on being again moistened and placed in a suit-
able medium, they commence an active existence and cause putrefaction.
The dry spores are not destro}7ed by even boiling them for so long as a
quarter of an hour ; they are also not affected by weak acids.

336. Bacilli. — The word bacillus literally means a stick or rod, and
is applied to the organisms of this genus because of their rod-like shape.
The cells are long and cylindrical and occur attached to each other, thus
forming rod-like filaments of considerable length. There is little or no
constriction at the joints, which with low microscopic powers are scarcely
observable. They increase by splitting transversely, and reproduce by
spores. Bacteria and bacilli are closely allied genera, some species of the
one closely resembling species of the other. In the very long cells of
bacteria the transverse divisions may be detected, while in the equally
long cells of bacilli no traces of division can be seen. Bacilli are some-
times motile, but after a time pass into a condition of rest, or zooglcea
stage. The long threads of bacilli often assume a zig-zag or bent form ;
and unless subjected to very careful examination, appear to be con-
tinuous. Pasteur's filaments of turned beer "consist of bacilli."

337. Bacillus Subtilis. — This organism is also termed "Vibrio sub-
tilis," and is largely present in air. Owing to its being the predominant
organism produced when an aqueous infusion of hay is exposed to the
air, it is frequently referred to as the bacillus of hay. The cells are
cylindrical, and grow to about 6 mkms. in length, and are provided with
a flagellum at either end. They usually occur adherent to each other,
forming long filaments, as shown in Plate V.

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 183

PLATE V

Fig. 1 Fig: 2 .

actti (Baaisen) x 400(dbouX}.)
Fig: 5 .

. Cohru. c, DaZ&rujcrJ *6SG& x 4000
Fig: 6

Bacillus STjubt&C* (Cohn/) x 650. CLostridvafn/ Invtyricvurnj (Praffrnawi,'\x/) x

VARIOUS DISEASE FERMENTS.

184 THE TECHNOLOGY OF BREAD-MAKING.

The term " vibrio," applied to certain forms of schizomycetes, is
derived from their appearing to have a wriggling or undulatory motion ;
this effect is illusory, being actually caused by their rotating on their
long axis.

FIG. 17.— Bacillus subtilis X 4000 (after Dallinger).

Ah enlarged illustration of B. subtilis is given in the following figure,
17. They increase by transverse division, and reproduce by spores. As
the spore formation of B. subtilis has been most carefully observed, a
description of its mode of reproduction will be of service as a type of
that of the sckizomycetes generally. In spore formation the protoplasmic
contents of the cell accumulate at the one end, causing an enlargement
there; the rest of the cell after a time drops off and dies; the mature
spore may then live for even years without losing its vitality ; and being
of extreme minuteness, these spores permeate the atmosphere, and are
ever ready to germinate on finding a suitable medium. In the act of
germination the spore splits its membrane open, and a new rod grows
and projects through the opening. The dry spores are extremely tena-
cious of life, and withstand boiling for an hour in water without losing
their vitality. Some three or four consecutive boilings in a flask plugged
with cotton-wool, with a few hours7 interval between, are necessary to
ensure sterilisation from this organism.

Various writers impute different specific fermentative actions to B.
subtilis, but it is doubtful whether the production of any particular
chemical compound should be associated with it. It is essentially the
organism of putrefaction, and effects the decomposition both of nitro-
genous and carbonaceous bodies with the evolution of mal-odorous gases.
Both it and B. termo are stated to possess the power of peptonising pro-
teins, this operation being a preliminary to their further conversion into
leucin, tyrosin, and allied bodies.

338. Diastatic Action of Bacteria. — This latter action is a conse-
quence of the property possessed by the bacteria of attacking protein
bodies and converting them into peptones. Wortmann has devoted con-
siderable attention to the investigation of the problem whether or not
bacteria have any action on starch : whether or not, by the secretion of a
starch-transforming substance similar to diastase, or in any other but not
clearly defined way, they are capable of transforming starch into soluble
and diffusible compounds. In order if possible to obtain a solution of
this problem, Wortmann experimented in the following manner: —

To about 20 or 25 c.c. of water a mixture of inorganic salts (sodium
chloride, magnesium sulphate, potassium nitrate, and acid ammonium
phosphate, in equal proportions) was added to the extent of 1 per cent.
The same quantity of solid wheat-starch was next added, and the liquid
then inoculated with one or two drops of a strongly bacterial solution;
shaken, corked, and allowed to remain .in a room at a temperature of 18°
to 22° C. (Bacterium termo was the predominating organism in the
inoculating fluids employed.) In from five to seven days, the first signs
of commencing corrosion of the starch granules had become visible, the
larger grains being first attacked, and much later, when these had almost
completely disappeared, those of lesser size.

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 185

In a second series of experiments, soluble starch was substituted for
the solid form, the progress of the reaction being watched by the aid of
iodine. Samples taken from time to time exhibited at first the blue
colour, then violet or dark red, passing to wine red, and finally, when
the starch had disappeared, underwent no change.

Wheat-starch grains are found to be by far the most readily attacked
by 'bacteria when compared with other varieties, in several experiments
having even completely disappeared before other sorts of starch were
affected. Of a number of starches, that of potatoes alone entirely re-
sisted attack. When wheat-starch in the solid state was mixed with
starch solution or with starch paste, the solution became entirely (and the
paste in greater part) changed before any action occurred on the solid
granules.

With regard to this unequal power of resistance shown by different
kinds of starch, Wortmann concludes from his further observations that
the difference of rapidity with which a given kind is attacked and dis-
solved by a ferment is inversely proportional to its density, provided
always that the granules in question are entire and uninjured by cracks
or fissures. In the same way are explained the differences in point of
time in which granules of the same kind are sometimes observed to
undergo change accordingly as they are intact or otherwise.

The cause of potato-starch, or of bean-starch, and even under certain
conditions, wheaten starch, resisting attack, in spite of the abundant
pressure of bacteria, is apparently to be sought for in the fact that other
more easily accessible sources of carbon nutriment were also present,
certain protein constituents of the potato slices, or of the beans employed
affording this more readily than the starch granules; just as in the ex-
periments above cited, with wheaten starch solution and solid wheaten
starch, the former was preferentially attacked ; only after all, or at least
the chief portion, of the proteins present had been used up, was the starch
in these cases attacked.

Another point was also established in the course of these experiments
— that if air is excluded, no appearance of corrosion or solution of the
starch granules is manifested.

That the starch in the process became changed in part to glucose was
easily ascertained by testing with Fehling's solution, and a detailed series
of experiments, made with a view to eliminating if possible the ferment
itself, yielded evidence showing that bacteria possess the remarkable
property of producing a starch-transforming ferment, only when no
source of carbon other than starch is at their disposal, and this ferment
is incapable of changing albumin into peptone, just as in the case of
diastase. The results of Wortmann 's researches may be briefly recapi-
tulated—

1. Bacteria are capable of acting on starch, whether in the solid
state, as paste, or in solution, in a manner analogous to diastase.

2. As in the case of diastase, different kinds of starch are attacked
by bacteria with different degrees of rapidity.

3. The action of bacteria on starch is manifested only in the absence
of other sources of carbon nutriment, and when access of air is not pre-
vented.

4. The action of bacteria on starch is effected by a substance secreted
by them, and which, like diastase, is soluble in water, but precipitable
by alcohol.

5. This substance acts precisely as diastase in changing starch into
a sugar capable of reducing cupric oxide, but is not possessed of pep-
tonising properties.

186 THE TECHNOLOGY OP BREAD-MAKING.

These results* of Wortmann's are quoted at some length because of
their bearing' on the action of bacteria in dough. One most important
point is, that the diastatic action of bacteria, or their secretions, only
occurs in the absence of protein matter, which is the substance most
specially suited for the development of these organisms; consequently,
with the exception of the transformation of sugar more or less into lactic
acid, the carbohydrates are unattacked by the schizomycetes during nor-
mal dough fermentation. The bacteria cause more or less change in pro-
teins, but exert no diastatic action. These protein changes are, by the
way, unaccompanied by any appreciable evolution of gas.

It will be noticed that Wortmann expressly states that the bacteria
have no peptonising action ; while it is also as expressly stated that they
readily attack the proteins. He does not state what substances he finds
produced by this action. The opinion is, nevertheless, very generally
held that peptones are produced during changes which occur during the
fermentation of dough, and it has been supposed that the bacteria were
the active agents. Thus, Peters describes a bacillus which he found
among the organisms of leaven which possesses a peptonising power.

339. Putrefactive Fermentation. — Putrefaction is that change by
which most organic bodies containing nitrogen in a protein form are first
resolved into substances having a most putrid odour, and ultimately into
inorganic products of oxidation. Bacterium termo and B. subtilis have
already been mentioned as the principal organisms of putrefaction.
Pasteur divides the act of putrefaction into two distinct stages, which it
will be well here to describe. On exposing a putrescible liquid to the air,
there forms on the surface a film composed of bacteria, etc. ; these com-
pletely exclude any oxygen from the liquid, by themselves rapidly ab-
sorbing that gas. Beneath, other more active organisms, which Pasteur
groups together under the name of "vibrios," act as ferments on the
protein matters of the liquid, and decompose them into simpler products ;
these simpler products are in their turn oxidised still further by the
surface bacteria. Pacteur practically defines putrefaction, or putrid
fermentation, as fermentation without oxygen.

340. Action of Oxygen on Bacterial and Putrefactive Ferments.—
Pasteur draws a hard and fast line between certain bacteria which he
affirms live in oxygen, and absolutely require it, and others to which
oxygen acts as a poison; to which latter class he states that the vibrios
belong. This name is used by him seemingly to refer to those micro-
organisms which are in active motion. Of the bacteria of the first type,
he mentions that if a drop full of these organisms be placed on a glass
slide, and examined with a microscope, there is soon a cessation of mo-
tion in the centre of the drop, while those bacteria nearest the edges of
the cover-glass remain in active movement in consequence of the supply
of air. On the other hand, if a drop of liquid containing the vibrios of
putrefactive fermentation be studied in a similar way, motion at once
ceases at the edge of the cover-glass; and, gradually, from the circum-
ference to the centre, the penetration of atmospheric oxygen arrests the
vitality of the vibrios. Pasteur thus divides the bacteria into an aerobian
and an anaerobian variety ; the former require oxygen, the latter find it
a poison, and live and thrive best in its total absence. In proof of this
view he describes experiments of a most careful character made by him.

341. Conditions Inimical to Putrefaction. — First and foremost
among these is the keeping out of the germs of putrefactive ferments
from the substance. Meat and protein bodies, generally, have come to be
ordinarily viewed as very changeable substances, whereas in the absence

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 187

of germ life they are very stable bodies. Putrefaction is the concomitant,
not of death but of life. If animal fluids are drawn off into sterilised
vessels without access of air, they keep for an indefinite length of time.
Or the germs may be destroyed by heat, when putrescible substances also
remain unchanged. This latter is the basis of Appert's methods for the
preservation of animal substances. These methods consist of exposing
the substances to a sufficiently high temperature in hermetically sealed
vessels ; or they may be heated in vessels so arranged that air may escape,
but that any re-entering shall be freed from bacterial germs either by
passing through a red-hot tube, or by being filtered through a thick layer
of cotton-wool.

Tinned meats, milk, etc., are preserved on this principle of Appert's.

Putrefaction may be arrested by intense cold, although even freezing
bacteria does not destroy their power of inducing putrefaction when
again warmed. As a consequence of this action of cold, meat when thor-
oughly frozen may be preserved almost indefinitely. The absence of
water is another preventative of putrefaction. Vegetables and meat, if
thoroughly desiccated, show, on keeping, no signs of putrefying. In the
same way, yeast, although in the moist state one of the most putrescible
substances known, may, by being carefully dried, be kept for months, not
merely without putrefying, but also without destroying the life of the
cell.

342. Products of Putrefaction. — These are exceedingly numerous
and complex, among them may be found volatile fatty acids, butyric, and
others of the series ; ammonia, and some of the compound or substitution
ammonias; ethylamine, trimethylamine, propylamine, et<?~: carbon diox-
ide, sulphuretted hydrogen, hydrogen, and nitrogen.

LACTIC AND OTHER FERMENTATIONS.

343. Lactic Fermentation. — This is primarily the fermentation by
means of which milk becomes sour. The chemical change is a very simple
one. Milk contains the variety of sugar known as lactose or sugar of
milk, C12H22On. By hydrolysis, this splits up into two molecules of a
glucose called lactose, galactose, or lacto-glucose, C6H1206. When sub-
jected to the influence of the lactic ferment, lacto-glucose is decomposed
according to the following equation : —

C6H1206 = 2HC3H503.

Lacto Glucose. Lactic Acid.

Ordinary glucose, and also cane-sugar and maltose, are susceptible of the
same transformation. From numerous recent researches, there is evi-
dence of a number of organisms which possess the power of producing
lactic acid by the conversion of glucose. One or more of these is always
found present in greater or less quantity in commercial yeasts, also 011
the surface of malt ; in the latter case it may be detected by washing a
few of the grains in water, and then
examining the liquid under the micro-
scope. Its shape, according to Lister,
when developed in milk, is shown in
the accompanying illustration. When
% viewed with a lower power in a field
of yeast, the lactic ferment appears as

small elongated cells somewhat con- Fic/l&^/fcd^l^ X 1140
stricted in the middle, generally de- (after Lister),

tached, but occurring sometimes in twos and threes ; their length is about
half that of an ordinary yeast cell. When single they exhibit the
Brownian movement.

188 THE TECHNOLOGY OF BREAD-MAKING.

Lactic fermentation proceeds most favourably at a temperature of
about 35° C., and is retarded and practically arrested at a temperature
which still permits the growth and development of the yeast organism,
and consequent alcoholic fermentation. For this reason brewers always
take care to ferment their worts at a low temperature, thus preventing
the lactic ferment, which is always more or less present, from any rapid
development. The other bacterial and allied ferments are also affected
in a similar manner by temperature. Dilute solutions of carbolic and
salicylic acids (and also hydrofluoric acid) greatly retard lactic fermen-
tation, while in such very weak solutions they have but little action on
the yeast organism ; hence yeast is sometimes purified by being repeatedly
grown in worts, to which small quantities of these acids have been added.
The most favourable medium for lactic fermentation is a saccharine solu-
tion rather more dilute than that used for cultivating yeast, and contain-
ing proteins in an incipient stage of decomposition. The analogy between
this fermentation and the alcoholic is close, because the two may proceed
side by side in the same liquid. The presence of acid is inimical to lactic
fermentation; hence the fermentation arrests itself after a time by the
development of lactic acid; provided this is neutralised from time to
time by the addition of carbonate of lime or magnesia, the fermentation
proceeds until the whole of the sugar has disappeared. In a slightly acid
liquid, as for instance the juice of the grape, alcoholic fermentation pro-
ceeds almost alone; but with wort, which is much more nearly neutral
(if made with good malt), lactic fermentation sets in with readiness, and
consequently has to be specially guarded against. Some varieties of the
lactic acid ferment require air for their growth and development, while
others are anaerobic in their character.

In addition to its specific action on glucose, converting it into lactic
acid, the lactic ferment has other functions of importance in commercial
operations ; thus, the presence of lactic ferment germs on malt result in
the formation of a little lactic acid during the mashing; in distillers'
mashes this is found to be somewhat valuable, and is encouraged, as it
apparently helps to effect a more complete saccharification of the malt,
and consequently increases the yield of alcohol. It also peptonises the
proteins, bringing them into a condition more adapted for the nutrition
of yeast. Distillers, therefore, frequently allow their malts to develop
considerable acidity before using them, and give new mash tuns a coat-
ing of sour milk before bringing them into use. In bread-making, by the
Scotch system, the presence of the lactic ferment is deemed to make bet-
ter bread : either the ferment, or the lactic acid produced, softens and
renders the gluten of the flour more elastic.

Hansen's methods have been applied to the preparation of pure cul-
tivations of lactic ferments, with the view of securing a more satisfactory
acidification of cream preparatory to its being made into butter. Two
distinct species have been isolated, which give particularly favourable
results in butter-making ; one of these is stated by Storch to give a pure
and mild slightly sour taste, imparting at the same time a very pure
aroma to the cream and butter made therefrom. There are other lactic
acid-forming bacteria, which, on the contrary, produce diseases in milk ;
thus, one species causes the milk to become viscous at the same time as it
undergoes lactic fermentation. Further, certain bacteria induce a tallow-
like flavour in butter. Not only may we have a fermentation produc-
ing lactic acid as distinct from other acids, but also there are differentia-
tions in the character of the secondary products formed at the same time

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 189

as the lactic acid, and which secondary products affect most vitally the
success or otherwise of the particular process from its manufacturing
standpoint. It is more than possible that these variations in the nature of
lactic fermentation itself may have a direct bearing on the success of
bread-making operations.

344. Butyric Fermentation. — At the close of the lactic fermentation
of milk, the lactic acid or lactic salts, as the case may be, seem to be acted
on by ferment organisms and converted into butyric acid with the evolu-
tion of carbon dioxide and hydrogen—

2HC3H503 = HC4H702 + 2C02 + 2H2.

Lactic Acid Butyric Acid Carbon Dioxide. Hydrogen.

Several species of bacteria are capable of inducing butyric acid fer-
mentation. The most carefully examined among these is Clostridium
butyricum, known also as Vibrio butyricus, which occurs in the form of
short or long rods, and is in shape and general appearance very similar
to B. subtilis, differing, however, from that organism in that it contains
starch. In breweries and pressed yeast factories, butyric fermentation
is often caused by organisms of altogether different type to C. butyricirm.
This particular organism is anaerobic in character, but others of the
species producing butyric acid are distinctly tolerant of oxygen. The
general conditions of butyric fermentation are similar to those of lactic
fermentation. A temperature of about 40° C. (104° F.) is specially suit-
able ; the presence of acids is to be avoided ; or where butyric fermenta-
tion is not wished, its prevention is more or less attained by working at a
lower temperature and with a slightly acid liquid. However, with the
fully developed organism, a slight acidity is unable to prevent butyric
fermentation. Although butyric fermentation is usually preceded by
lactic fermentation, the butyric ferment is also capable of acting directly
on sugar itself, and also on starch, dextrin, and even cellulose.

Tannin has a markedly prejudicial effect on the growth and develop-
ment of bacterial life, hence the addition of this substance, or any com-
pound containing it, to a fermenting liquid, exercises great preventive
action on the development of lactic and butyric fermentation. Hops
contain tannin as one of their constituents, and also the bitter principles
of the hop cause a hopped wort to be much less liable to lactic fermenta-
tion than one unhopped. For a similar reason, bakers add hops to their
patent yeast worts.

345. Acetic Fermentation. — Certain organisms effect the change of
wine and beer into vinegar. The reaction is one of oxidation of the
alcohol present: in the first place, aldehyde is formed, and then this body
is oxidised into acetic acid, according to the following equations : —

2C2H5HO + O2 = 2CJI40 + 2HaO.

Alcohol. Oxygen. Aldehyde. Water.

2C2H40 4- 02 = 2HC2H302.

Aldehyde. Oxygen. Acetic Acid.

Pasteur described under the name of Mycoderma aceti an organism
through whose agency alcohol is oxidised into acetic acid. Hansen has
detected two distinct species under this name, distinguished by the one
staining yellow, and the other blue, with iodine solution. Both possess
the same chemical properties, and in order to develop vigorously require
a plentiful supply of oxygen. They are, in fact, strictly aerobic. A tem-
perature of about 33° C. is the most favourable to the production of
acetic fermentation. Bacterium, aceti also converts propyl alcohol into
propionic acid, but is without action on either butyl alcohol or the amyl
alcohol of fermentation.

190 THE TECHNOLOGY OF BREAD-MAKING.

Bacterium, aceti forms a mycelium on the surface of liquids, posses-
sing1 a certain amount of tenacity : viewed under the microscope, this
mycelium is seen to consist of chains of cells, as shown in Plate V.

In the substance known as ' ' mother of vinegar ' ' or the vinegar plant,
long supposed to be identical with B. aceti, A. J. Brown discovered a
separate organism, which, in addition to producing acetic acid, is also
marked by the property of causing the formation of cellulose ; to this he
has given the name of Bacterium xylinum.

Peters has discovered in extremely old and sour leaven an acetic acid
bacterium, distinct from those just described. The individuals are about
1.6 />i long, and 0.8 ^ broad, truncated at one end, and tapering at the
other. Interest attaches to the isolation of this specific organism, inas-
much as a small proportion of the acidity of bread is due to acetic acid.

A temperature below 18° C. is almost inhibitory to the action of the
acetic acid ferment, while most antiseptics, and especially sulphur diox-
ide, are exceedingly inimical to acetous fermentation.

Jorgensen remarks that ''an important advance was made in our
knowledge of acetic bacteria when Buchner and Meisenheimer, as well as
Herzog, proved that this remarkable fermentation is brought about by
the activity of an enzyme. The cells may be killed with acetone, and then
treated in the same way as the alcohol yeasts (see Chapter IX., paragraph
289), and it can then be shown that, after evaporating the liquid, the
residue can bring, about the acetic fermentation, although it contains no
living cells. By this discovery the real nature of the fermentation be-
comes clear. Like the alcoholic fermentation, it is caused by an enzyme,
which may react independently of the living cell that brought it into
existence." (Micro-organisms and Fermentation, Fourth English Edi-
tion.}

346. Viscous Fermentation. — Viscous fermentation is that variety
which causes * ' ropy beer. ' ' Pasteur supposed this to be due to an organ-
ism consisting of globular cells of from 1.2 to 1.4 /* in diameter, adhering
together in long chains. Moritz and Morris, who have devoted particular
attention to this subject, disagree with Pasteur's views, and ascribe ropi-
ness principally to a ferment known as Pediococcus cerevisice. This organ-
ism occurs either in pairs of cells or tetrads (i.e., four cells arranged in
the corners of a square), diameter of each cell being 0.9 — 1.5 /x. These
organisms are similar in appearance to those marked &, Fig. 16. Beer,
after having undergone this fermentation, runs from the tap in a thick
stream ; and in very bad cases, a little, when placed between the fingers,
pulls out into strings.

A somewhat similar condition sometimes holds in bread, which then
is termed ropy bread ; this is discussed very fully in Chapter XVII.

347. Disease Ferments. — The ferments of lactic, viscous, and other
than alcoholic fermentation, are frequently called "disease ferments,"
from their producing unhealthy or diseased fermentations in beer.

348. Spontaneous Fermentation. — In this country, alcoholic fermen-
tation is usually started by the addition of more or less yeast from a
previous brewing ; it was formerly the custom to allow the fermentation
to start of itself. This is said still to be practised in some parts of Bel-
gium in the manufacture of a variety of beer, known as ' ' Faro ' ' beer. In
manufacturing such beers, the vats of wort are allowed to remain exposed
to the air, and fermentation is excited by any germs of yeast that may
find their way therein. It is possible that under such circumstances a
wort may only be impregnated by yeast germs, in which case pure alco-
holic fermentation alone will be set up. It is far more likely, however,

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 191

that germs of lactic ferment and other organisms will also get into the
wort ; consequently the beer will be hard or sour, and also likely to speed-
ily become unsound. On the other hand, grape juice is always allowed to
ferment spontaneously, but then this liquid is distinctly acid, through the
presence of potassium bitartrate; and acidity retards or prevents bac-
terial fermentation.

Bakers' barms or patent yeasts are at times allowed to ferment spon-
taneously; they are then found to contain a large proportion of foreign
organisms, principally the lactic ferment. Except where very special
precautions are adopted, they are liable to be uncertain in their action,
and often produce sour bread.

But in all cases of so-called "spontaneous" fermentation it must be
remembered that the fermentation is due to the presence in the wort of
yeast cells or spores that either have been introduced along with the malt
and hops without being destroyed, or else have found their way into the
wort from some external source, such as germs floating in the air. It is
also frequently possible that a sufficient quantity of yeast remains about
the fermenting vessel from the last brewing to again start fermentation.

MOULDS AND FUNGOID GROWTHS.

349. The nature of these has been already referred to in Chapter
IX. and the mould of beer, Mycoderma cerevisicc, described and its prop-
erties explained. The moulds are all of them members of the fungus fam-
ily. A few other varieties, because of their having more or less connec-
tion with the subject of this work, require description.

350. Penicillium Glaucum. — This is the ordinary green mould of
bread, jam, etc. The base of this consists of a mycelium bearing both sub-
merged and aerial hyphae. The upper ends of the aerial hyphae terminate
in a string of conidia or spores, which break off on the slightest touch ;
these constitute the green powder which gives this mould its character-
istic appearance. One of these spores, on being sown in an appropriate
medium, as hay infusion or Pasteur's fluid, germinates and produces a
young penicillium. The conidia retain their vitality for a long time, and
from their extreme minuteness are readily carried about by the air ; hence
substances that offer a suitable medium for the growth and devlopment of
moulds, become impregnated on being exposed to the atmosphere.

Under favourable circumstances penicillium developes with extreme
rapidity ; some few years since the barrack bread at Paris was attacked
by this fungus, a few hours was sufficient for its development, and the
mould was in active growth almost before the bread was cold. It is stated
that the spores of this species are capable of withstanding the heat of boil-
ing water, so that the act of baking an infested flour would not neces-
sarily destroy the spores.

351. Aspergillus Glaucus. — This is another mould very similar to
penicillium in appearance and colour, but having at the ends of its hyphae
small globose bodies containing the spores; these bodies being termed
sporangia.

352. Mucor Mucedo. — This mould develops well on the surface of
fresh horse dung ; this substance, if kept warm, will be found after two or
three days covered with white filaments, these being the hyphag, and ter-
minating in rounded heads or sporangia. In form M . mucedo somewhat
resembles A. glaucus, but is distinguished from it by having a whitish
aspect, A. glaucus being of a greenish colour.

192 THE TECPINOLOGY OP BREAD-MAKING.

353. Micrococcus Prodigiosus. — This or-
ganism consists of round or oval cells, from
0.1 to 1 mkm. diameter. These are at first
colourless, but gradually assume a blood-red
tint : they grow on wheat-bread, starch paste,
etc. M. prodigiosus is the cause of the appear-
ance known as blood-rain occasionally seen on
bread : at times the growths proceed so far as
FIG. ]9.-MicrococcUS prodigious, to produce dripping blood-red patches on the

Cohn X 1200 (from nature). , ^ -,

354. Red Spots in Bread. — A phenomenon sometimes confused with
the effect of M . prodigiosus, but nevertheless quite distinct therefrom, is
that of intensely red-coloured spots in freshly baked bread. These are so
bright as to lead to the suspicion that concentrated tincture of cochineal
or other powerful dye had by accident got on to the dough and been
baked with it. Fortunately for the baker, the occurrence of these spots is
rare, and consequently there are few opportunities of minutely investi-
gating them. So far as the authors' experience goes, the spots occur most
frequently in bread made from flour of the very highest class, such as
Hungarian patents : they have also seen them in bread containing a large
admixture of Oregon flours. The spots in bread do not increase in size
as the bread grows old, nor are they apparently associated with any
change in its constituents : there are no signs, in fact, of the colouration
being due to the presence of any living and multiplying organism. It is
exceedingly difficult to obtain specimens of the colour spots in unbaked
dough, and only on one occasion has such a specimen come into the
hands of one of the authors. In that case a small batch of dough was sent
him while absent from home, and was only examined by him on his return
after two days. The dough had then got a slight dry skin on, but there
were no signs of any growth or spreading in the dough ; so far, therefore,
as any conclusion may be drawn from this, it is against the source of
colour being any organism developing in the dough. Careful microscopic
examination of coloured portions of the bread show in the fainter spots
that while the starch is uncoloured, there is a red dyeing of the gluten.
In the larger and darker spots there may be sometimes seen by the naked
eye a nucleus, which is so dark in colour as to be almost black. On break-
ing down a little of this nucleus with water, and examining microscopic-
ally, the author has invariably found fragments of the outer integument
of the grain. Among these have been detected portions of the outside
layer of bran, showing its characteristic markings, and also hairs of the
beard of the wheat, all of which are intensely coloured. In one sample,
only cursorily examined some years ago, a number of filaments somewhat
similar to cotton-wool were observed, but not identified ; these, too, were
coloured to a very deep red. No signs of fungus spores or other special
organisms were observable, but spores might possibly be crushed in the
breaking down with water. The lack of material for purposes of further
examination has prevented the author from carrying these investigations
beyond this point, and such tests as are here recorded were made a num-
ber of years ago. The most probable cause of the colour is its deposit on
the outside of the grain after its removal from the husk and prior to its
being milled. It is suggested as its possible source either some insect of
the cochineal species, or an intensely coloured microscopic vegetable
growth, such as a mould. These minute particles of outer bran carrying
the colour on the surface are sufficiently fine to pass through the dressing
silks, and so get into the flour. They would be so small as to be perfectly

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 193

invisible in any ordinary examination by the naked eye. On being wetted
the colour spreads and stains the surrounding gluten, hence the colour in
the dough, which remains also and is seen most distinctly in the baked
bread.

355. Musty and Mouldy Bread. — Mouldincss may be very often
noticed in bread which has been kept for a few days : at times a loaf of
one day's production will remain quite sound, while another will rapidly
become mouldy. The Analyst, October, 1885, contains an article by Percy
Smith, giving an account of some experiments made by him 011 musty
bread. The bread when new had no disagreeable taste, but on the second
day had become uneatable. Smith made a series of experiments, among
which were the following :—

(a) Musty bread, one day old, soaked in water, enclosed between

watch glasses.

(b) Flour from which the bread was made, similarly treated.

In six days a had begun to turn yellow, emitted a disagreeable odour,
and began to assume a moist cheesy consistency and appearance. This
portion was found to be swarming with bacteria. On b, mucor mucedo
grew in abundance ; the flour ultimately dried up without further change.

Aspergillus glaucus appears, but no mucor, neither does the bread
become cheesy nor evolve odour of musty bread. The following are
Smith's conclusions based on these and other experiments.

"Ordinary bread turns mouldy owing to the growth of A. glaucus.
Musty bread, on the other hand, yields both A. glaucus and M. mucedo,
and then undergoes putrefactive decomposition, becoming the home of
vibriones and bacteria. These organisms, of course, can have nothing to
do with the mustiness ; they only flourish because there is a suitable nidus
for their growth. It is, however, curious that the musty bread should
decay while the sweet bread should not, whilst the only apparent differ-
ence between them is in the growth of M. mucedo. The suspected flour
produces an abundant crop of mucor, but does not decay. This is no
doubt due to the fact that starch is not so suitable a nidus as is dextrin
for bacteria. Perfectly pure flour failed to decompose when kept between
watch glasses, but when placed in a damp cellar readily became musty,
and produced a crop of M. mucedo." He further concludes that this
fungus is the cause of the mustiness in the cases cited, although other
species may possess similar properties. When the flour was baked into
bread, the assimilation of moisture regenerated the fungus, thus causing
the bread to become musty, for which result it is not necessary for the
plant to arrive at maturity ; the disagreeable taste being: developed as soon
as flocci are visible under the microscope. Mucor has apparently a specific
chemical action on bread that is not possessed by Aspergillus glaucus.

Hebebrand has recently published the results of some investigations
on mouldy bread. He infected some samples of rye bread from mouldy
bread, the organisms being chiefly Penicillium glaucum and Mucor
mucedo. These were kept for periods of seven and fourteen days, and
'similar samples at once dried for analysis. The results showed that the
mould caused a considerable loss of substance, carbohydrate being con-
verted into water and carbon dioxide. There was only a slight loss of
proteins, but the loss of carbohydrates caused the percentage of proteins
to appear much higher in the dry substance of the mouldy bread. The

194 THE TECHNOLOGY OF BREAD-MAKING.

decomposed protein was converted into amides. The following numbers
show the percentage composition (1) of dried fresh bread, and (2) of the
dried mouldy bread : —

No. 1. No. 2.

Protein, Insoluble . . . . 9.75 per cent. 9.77 per cent.
Soluble . . . . 1.92 „ 5.15

Maltose 1.54 „ 0.50

Dextrin 8.02 „ 11.86

Starch 76.75 „ 63.52

Fat 0.26 „ 2.11 „ (?)

Ash 1.44 „ 2.41

Crude Fibre . . 0.05 2.47

356. Diseases of Cereals. — Certain diseases to which the cereal
plants are subject are due to parasitic fungoid growths. Among these
are mildew, smut, bunt, and ergot. Their nature may briefly be consid-
ered at this stage of our work.

357. Mildew. — To the farmer this blight is unhappily too familiar ;
if a wheat field be examined in May or June, a greater or less number of
the plants will appear as though some of the lower leaves had become
rusty ; at the same time the leaves are sickly and atrophied. As the dis-
ease develops the number of rusty leaves increases ; the "rust'' itself will
be found on examination to consist of the spores of a fungus, known as
the Puccinia gramims or corn mildew. The mycelium penetrates the tis-
sues of the leaves, occupying the intercellular spaces, and thus gradually
destroys them, with the effect of seriously injuring and reducing the corn
crop.

Shutt collected by hand on the same day in the same field samples of
rust-free and rust-attacked wheat. The former have a normal ear both
as to size and colour, and a plump, well-filled grain. The straw of the
latter showed many spots of infection, while the ears were smaller than
normal and the grains light and much shrivelled. The following are the
results of analysis of the two samples of wheat : —

Rust-free. Rusted.

Weight of 100 grains in grams . . . . 3.0504 1.4944

Water per cent 12.26 10.66

Crude Protein „ 10.50 13.69

Crude Fat „ 2.56 2.35

Carbohydrates „ 70.55 68.03

Fibre ' „ 2.29 3.03

Mineral Matter „ 1.84 2.24

The protein is considerably higher in the rusted grain, a result prob-
ably due to the fact that protein is first lodged in the grain during the
processes of metabolism, and afterward the carbohydrates. A result of
rust attack is that the maturation of the grain is retarded, and the lodg-
ment of starch is incomplete. But though the total protein is high, the
wheat will probably be found to be lacking in strength (Jour. Amer.
Chem. Soc., 1905, 366).

358. Smut. — This disease is also known as "dust brand," "chimney
sweeper," and by other names all referring to the black appearance of
ears of grain infested by it. When the grain is nearly ripe, there will be
noticed here and there in a wheat field shrivelled looking ears, which look
as though covered with soot. Smut is due to a fungus which has received
the name of Ustilago segetum. The fungus develops within the seeds,
destroying the contents of the grain, and replacing them by a mass of
spores which appear as a fine brownish black powder. Smut is a very

BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 195

destructive parasite, and attacks barley, oats, and rye, and also, although
to a somewhat lesser extent, wheat. Viewed microscopically, the spores
of U. segetum are found to be spherical, and to have a diameter of about
8 mkms. ; their appearance is shown in the following figure.

FlG. 20. — a, Smut, fc, Bunt X 400 diameters.

359. Bunt or Stinking Rust. — Unlike smut, bunt produces no exter-
nal signs of its presence in a wheat field : there is no sooty appearance of
the ear, nor any rust above the leaves. It is not until the wheat is
threshed from the straw that the bunted grains are discovered in the
sample. Externally, these grains are plumper than those which are
sound ; but on their being broken, the interior, instead of being white and
flour-like, is found to be filled with a black powder, having a greasy feel
when rubbed between the fingers, and a most foetid and unpleasant odour.
This dust consists of the spores of a fungus termed Tilletea caries, mixed
with portions of its mycelium. The spores are much larger than those of
smut, and, viewed under the microscope, appear as shown in Fig. 20 : they
are about 17 mkms. in diameter.

The presence of bunt is said not to affect the wholesomeness of flour ;
it is stated that bunted flour is at times made up into gingerbread; the
other condiments used masking its colour and odour. With the extreme
care manifested in modern systems of milling, it is improbable that bunt
often finds its way into the flour.

360. Ergot. — This disease is almost exclusively confined to rye ; like
bunt and smut, ergot is due to a fungus which develops within the grain,
filling its interior with a compact mass of mycelium and spores, and alter-
ing the starch cells by replacing the amylose with a peculiar oily matter.
This fungus is termed Oidium abortifaciens. The ergotised grains are
violet-brown or black in colour, moderately brittle ; and when in quantity
evolve a peculiar nauseous fishy odour, due to the presence of trimethyla-

> mine. Ergot possesses powerful medicinal effects, and when taken in
anything over medicinal doses, acts as a violent poison. The presence of
ergot in flour is therefore extremely dangerous.

Chemical tests for the detection of ergot and moulds will be given in
the analytic section of this work.

196 THE TECHNOLOGY OP BREAD-MAKING.

EXPERIMENTAL WORK.

361. Prepare some malt wort; filter and allow the liquid to remain
for some days in an open flask. In about 24 hours the liquid becomes
turbid; examine a drop under the microscope with the highest power at
disposal. Bacteria will be seen in abundance; notice that they have a
distinct migratory movement. Examine a sample each day, and observe
that the bacteria grow less active, and ultimately become motionless ; they
have then assumed the zoogloea stage. Carefully search the liquid for
other organisms ; 'bacilli should be detected, being recognised by their fila-
mentous appearance. Vibrios should also be observed ; they appear very
like 'bacilli, except that they have bent joints. When actively moving
they exhibit an undulatory movement, depending on their rotation on
their long axis.

Examine microscopically some of the sediment of "turned" beer;
large quantities of bacilli can usually be observed. These organisms are
also commonly found in bakers' patent yeasts.

Place some fresh clear wort in a flask and plug the neck moderately
tightly with cotton-wool ; boil the liquid for 5 minutes and allow to cool :
notice that the contents of the flask remain clear. At the end of a week,
remove the plug and examine a drop of the liquid under the microscope,
bacteria and other organisms are absent. The wort is still sweet and free
from putrefactive odour. Let the flask now stand freely open to the
atmosphere : organic germs gain entrance, and putrefactive or other
changes rapidly occur. On the next and succeeding days, examine micro-
scopically.

Procure a small quantity of milk and allow it to become sour ; examine
microscopically for Bacterium lactis. Also, wash a few grains of malt in
a very little water, and examine the washings for this organism.

Prepare two samples of wort, strongly hop the one by adding hops in,
the proportion of one-tenth the malt used : boil the two samples, filter and
set aside under precisely the same conditions. Observe the relative rate
of growth and development of bacterial life in the two.

CHAPTER XI.
TECHNICAL RESEARCHES ON FERMENTATION.

362. In this chapter are contained the results of certain technical
researches made by the authors and others on matters having a more or
less direct bearing on bread-fermentation.

363. Strength of Yeast. — To the baker, the first consideration about
yeast is its strength or gas-yielding power : there are other effects which
it also produces, but its all-round activity may be fairly measured by the
quantity of gas it evolves from a suitable saccharine medium. The term
"strength" is therefore used in this sense; it follows that the strongest
yeast will also raise bread better, because the rising of the dough is due
to the gas evolved by the yeast from the saccharine constituents of the
flour. Different modes have been adopted from time to time for the pur-
pose of testing the strength of yeast. The essential principle of these has
been to ferment a definite quantity -of some saccharine fluid with a con-
stant weight of yeast, at a constant temperature, and to then determine
the volume of gas evolved in a given time.

The reader is already aware that water is capable of dissolving carbon
dioxide gas to the extent of its own volume ; this, therefore, is an obstacle
to the employment of water for its collection. One of the authors, never-
theless, made the experiment, and found that on collecting the gas
evolved by the yeast during fermentation, in the ordinary manner in a
graduated gas jar over water, most interesting results could be obtained.
These were of course not absolutely correct, because a certain quantity of
the gas was absorbed by the water ; still, duplicate experiments gave cor-
responding quantities of gas, while most important information was
gained as to the general character of different yeasts when examined in
this manner. Results obtained in this way may therefore be viewed as
comparable with each other.

364. Yeast Testing Apparatus.— In the next place a series of experi-
ments were made in which the gas was admitted to the graduated jar
through the top, and so did not bubble through the water at all. When
collected in this way the amount of absorption was small and very uni-
form. Two jars were two-thirds filled in this manner with washed carbon
dioxide gas prepared from marble and hydrochloric acid. They were
then allowed to stand, and the amount of absorption observed hourly.
The rate of absorption, with the particular jars used, was as nearly as
possible a cubic inch per hour. Subsequent trials with jars of one hun-
dred cubic inch capacity gave an outside rate of absorption of two cubic
inches per hour. A still better plan is to use instead of water an aqueous
solution of calcium chloride of a degree of concentration giving a specific
gravity of 1.4. With this solution there is practically no absorption of
carbon dioxide. A saturated solution of common salt (brine) may be
used instead of the calcium chloride, with only slightly more absorption.
As a result of numerous experiments, the authors employ one or other of
the forms of apparatus shown on the following page.

198

THE TECHNOLOGY OF BREAD-MAKING.

FlG. 21. — Yeast-Testing Apparatus.

The glass bottle, marked a in the figure, is of about 12 ounces
capacity, and is fitted with india-rubber cork and leading tube, h. The
sugar or other saccharine mixture to be fermented is raised to the desired
temperature, and then placed in this bottle. The yeast is weighed out,
and then also added ; they are then thoroughly mixed by gentle agitation.
By means of an india-rubber tubing joint at c, the generating bottle is
connected to the leading tube, e, of the glass jar, /. This leading tube is
provided at d with a branch tube, which may be opened or closed by
means of a stopper of glass rod and piece of india-rubber tubing. The
jar,- /, is graduated, as shown, into cubic centimetres commencing immedi-
ately below the shoulder with 0, and ending near the bottom with 1000.
This constitutes the apparatus proper ; in use the generating bottle, a, is
placed in a water-bath, g g. This bath is fixed on a tripod over a bunsen
burner, and is provided with an iron grid, h, in order to prevent the gen-
erating bottle coming in absolute contact with the bottom of the bath.
By means of an automatic regulator the bath is maintained at any
desired temperature. The gas jar, /, stands in a pneumatic trough, i i.

As a rule, more than one test is made at a time, the water-bath should
therefore be sufficiently large to take four or six bottles at once : two
pneumatic troughs are then employed, and either two or three of the gas
jars, /, arranged in each. While for strictly accurate experiments it is
essential that the yeast bottles b.e kept as nearly as possible at a definite
temperature, yet results of interest may be obtained without the employ-
ment of a water-bath. The whole apparatus should, under those circum-
stances, be placed in some situation where, as nearly as possible, a con-
stant temperature is maintained.

At the start of the experiment the air is exhausted through d, which
is again closed with the stopper. As the fermentation goes on the gas
evolved is collected in /, and its volume read off, from the surface of the
water, at the end of each half-hour or hour. Full and detailed particu-
lars are given at the end of this chapter as to the exact mode of procedure
in using this apparatus.

TECHNICAL RESEARCHES ON FERMENTATION. 199

When the requisite allowance is made for the absorption of the gas
by water, the corrected reading very nearly corresponds with the absolute
amount of gas which has been evolved. It is far better, however, to use
brine and so prevent any absorption of the gas. There are slight varia-
tions due to alterations of barometric pressure and of temperature ; these
can, if wished, be calculated out and allowed for — that is not, however,
for ordinary purposes necessary. Gases are usually measured at a stand-
ard pressure of 760 millimetres, or very nearly 30 inches of mercury, that
is with the barometer standing at 30. A rise or fall of the barometer
through half an inch only makes a difference of one-sixtieth on the total
reading, and this may as a rule be neglected. In case the estimation is
being made in either the laboratory or a bakehouse, the temperature is,
as a rule, fairly constant. Supposing it be taken at 70° F., then it will
be found that a difference of 5° either way only causes a variation in the
volume of the gas of one hundredth the total amount. Barometric and
thermometric variations may, therefore, for most practical purposes, be
neglected. Further, whatever variations there may be either in tempera-
ture or pressure, all the tests made at the same time are made under pre-
cisely similar conditions.

In all the experiments quoted, except the later ones, the gas was col-
lected over water. No corrections were, however, made for absorption,
because it is evident that at the outset the carbon dioxide remains as a
layer of gas within the bottle, simply displacing air over into /; during
this time no absorption can take place. It should, however, be remem-
bered that, when the gas remains stationary for any length of time, a
quantity must have been evolved about equal to that being absorbed.

In the alternative apparatus, the generating bottle, a, and leading
tube, &, are the same as before. At c1, a glass stop-cock is fixed in the
leading tube which is attached by means of india-rubber tubing to d1, the
further end of which just passes through an india rubber cork fixed in
the glass bottle, e1, having a capacity of 600 c.c. or thereabouts. Another
tube, /*, leads from the bottom of e1, and has its lower end open. Under
this is placed a graduated measuring jar, 01, of 500 c.c. capacity. In use
the yeast and fermenting medium are placed as before in the generating
bottle, a. The bottle e1 is filled with brine, and the apparatus fixed to-
gether and arranged in position as shown in the figure. As gas is gener-
ated in the bottle, a, it displaces an equivalent amount of brine in e1, the
liquid passing over and being collected in the measuring jar, gl. Read-
ings of the volume of brine thus displaced may be made hourly, and thus
results obtained of a similar character to those with the other apparatus.
When the collecting jar is filled to the 500 c.c. mark, the stop-cock, c1 may
be closed and the brine in r/1 returns to e1, and the collection and meas-
urement of gas again commenced on reopening the stop-cock, c1. This
second form of apparatus can be the more readily fixed up from appli-
ances found in the laboratory, while both are practically identical in their
working. In the first form, the gas within is under diminished pressure,
any leakage therefore will increase the apparent amount of gas evolved.
In the second arrangement, the gas is under increased pressure, and
consequently any leakage will result in loss of gas.

365. Degree of Accuracy of Method. — This is a matter of great
importance, because unless fairly constant and accurate results are

200

THE TECHNOLOGY OF BREAD-MAKING.

obtainable, little or no confidence can be placed in them, or any deduc-
tions based thereon. A number of duplicate experiments were therefore
first made in order to test the accuracy of the estimations ; the results are
appended. They serve also to show how the results may be entered up in
the laboratory note-book. For the composition of "Yeast mixture," see
paragraph 367 : —

No. 1, Brewer's Yeast, y2 oz. ; Yeast Mixture, J/£ oz. ; Water, 6 oz. at

30° C.

No. 2. Duplicate of No. 1.
No. 3. French Compressed Yeast, *4 oz- 5 Yeast Mixture, y2 oz. ;

Water, 6 oz. at 30° C.
No. 4. Duplicate of No. 3.

TIME.

GAS EVOLVED IN CUBIC INCHES.

Tempera-
ture.

No. 1.

No. 2.

No. 3.

No. 4.

0.0^

vy.w i

0.0

0.0^

29.7

i 0.7

0.5

• 3.1

\ 2.5

\ hour

0.7

0.5

3.1

2.5

30.0

• 5.8

5.5

16.1

15.2

1 „

6.5

6.0

19.2

17.7

30.0

• 7.7

• 7.8

•21.8

21.4

\\ hours. . .

14.2

13.8

41.0

39.1

29.8

• 7.8

- 8.2

•21.0

20.7

2 „ ....

22.0

62.0

59.8

28.9

8.0

• 7.7

20.0

20.4

2J „ ....

30.0

29.7

82.0<

80.2

29.5

11.0

11.3

21.5

21.0

3 „ ....

41.0

103.5<

101.2

30.0

6.0

> 5.7

22.3

23.2

3i „ ....

47.0

46.7

125.8

124.4

30.25

7.5

8.0

17.8

20.4

4 „ ....

54.5

53.7

143.6

144.8

30.25

14.9

15.9

4J „ ....

—

158.5

160.7'

30.0

9.5

9.3

5 „ ....

—

170.0'

30.0

, 7.0

5.0

5J „ ....

—

175.0

175.0<

30.0

2.8

0.8

6 „ ....

—

177.8J

175.8J

29.9

The figures placed opposite the brackets represent the volume of gas
given off in each successive half -hour. A thermometer was placed in the
water-bath and the temperature observed at the time of each reading,
and registered in the last column. The temperature in this experiment
shows considerably greater variations than that in those made later. It
will be noticed that both pairs of duplicates agree very closely throughout
the entire fermentation.

TECHNICAL RESEARCHES ON FERMENTATION. 201

It may here be mentioned that a half-ounce of sugar yields, on the
supposition that the whole is transformed into carbon dioxide and alco-
hol, the following quantities: —

1/2 oz. of sugar = 14.2 grams, and yields 7.30 grams of C02 =
3.705 litres = 226 cubic inches at 0° C. ==

242 „ 20°C.

(One cubic inch == 16.4 c.c.)

It will be remembered that actually only about 95 per cent, of the
sugar is thus converted into carbon dioxide and alcohol ; these quantities
in strictness, therefore, require to be reduced about 5 per cent.

As in the experiments to be now described the same brand or kind of
yeast was used on different days, it was necessary, as a preliminary, to
ascertain the degree of constancy of strength of the same yeast. Deter-
minations were made on one brand of compressed yeast with the follow-
ing results : —

No. 1.— April 27, 1885, ]

No. 2.— May 7, 1885, • Yeast, l/$ oz. ; Yeast Mixture, y2 oz. ;

No. 3.— June 30, 1885, Water, 6 oz. at 30° C.

GA?

EVOLVED IN

CUBIC INCK

ES.

TIME.

No.

0.0

0.0,

1 hour
2 hours
3

21.7
63.0-
96.0

21.7
41.3
33.0

24.5
60.9
104.0

24.5
>36.4
43.1

28.7'
60.6-
104.2

>28.7
31.9
43.6

4 „
5

130.3
154.5

34.3
24.2

136.0
158.5

32.0
22.5

145.0
175.0

40.8
30.0

170.2

15.7

175.0

17.5

177.8^

> 2.8

Although these results do not agree with that closeness observable in
the duplicates, yet it will be seen that the yeast is throughout fairly simi-
lar in behaviour ; still, it must be remembered that in experiments made
on different days the results are not always strictly comparable, because
the yeast is sure to be not absolutely the same in each case.

366. Effect of Different Media on Yeast Growth.— That certain sub-
stances are eminently fitted for aiding the growth and development of
yeast, while others are not so suited,. has already been stated. In order
to measure quantitatively the effect of sowing yeast in different solutions,
the following determinations were made.

367. Comparison between Sugar, " Yeast Mixture," Pepsin, and
Albumin. — The "yeast mixture" referred to is based on the fluid in
which Pasteur cultivated a yeast, and which is known as "Pasteur's
Fluid." Pasteur employed a solution of sugar and ammonium tartrate

202

THE TECHNOLOGY OF BREAD-MAKING.

to supply saccharine matter and nitrogen; to this he added some yeast
ash as a source of mineral constituents. This fluid may be closely
imitated by use of the following formula —

Potassium Phosphate
Calcium Phosphate
Magnesium Sulphate
Ammonium Tartrate
Purest Cane Sugar
Water

20 parts

2 „

; ; loo ;;

.. 1500 „

.. 8376 „

10,000 parts

As this solution keeps badly, the yeast mixture consists of Pasteur's
Fluid, minus the water. The salts are first powdered and dried, and then
mixed until thoroughly incorporated. This mixture has the great advan-
tage that while dry it can be kept any length of time without change.

Date, April 26, 1885.
No. 1 Pure sugar, l/2 oz. (14.2 grams1) ; compressed yeast, Va °z- (3.5

grams) ; water, 6 oz. (170 grams) at 30° C.
No. 2. Yeast mixture, */2 oz. ; compressed yeast, % oz. ; water, 6 oz. at

30° C.
No. 3. Pure sugar, l/2 oz. ; pepsin, 1.5 grams ; compressed yeast, !/tt

oz. ; water, 6 oz. at 30° C.

No. 4. Yeast mixture, l/2 oz. ; pepsin, 1.5 grams; compressed yeast,
l/H oz. ; water, 6 oz. at 30° C.

At the expiration of seven hours, the following quantities of gas had
been evolved : —

No. 1. . . 51.3 cubic inches.
No. 2. 132.0

No. 3 . . 112.0 cubic inches.
No. 4 181.5

Experiments were also made with pepsin and albumin by themselves,
but neither of these gave practically any evolution of gas.

From these experiments the following conclusions are derived : —

Pure sugar undergoes a regular but somewhat slow fermentation.

Sugar mixed with about ten per cent, of pepsin ferments at first
more slowly, but afterwards much more rapidly.

''Yeast mixture," consisting of sugar, ammonium tartrate, and
inorganic salts, ferments from the commencement still more rapidly.

Yeast mixture, with about 10 per cent, of pepsin, undergoes still
more rapid fermentation.

Nitrogenous bodies alone, as pepsin, albumin, in water, or 2^ per
cent, salt solution, evolve practically no gas.

Pepsin and other nitrogenous bodies must therefore be considered,
not as the substances from which yeast causes the evolution of gas, but
as stimulating nitrogenous yeast foods.

1 In these experiments an anomaly will be noticed in the systems of weights
employed. In deference to the fact that many of the readers of this book will
be much more familiar with the English than the metric weights and measures,
the authors have, where practicable, used the former system.

The relation between grams and fractions of an ounce may be understood by
remembering once for all that

1 ounce or 16 drams = 28.35 grams.
^ „ „ 8 „ = 14.2
J4 „ • „ 4 „ = 7.1

/8 )) ,, ^ ,, O.O ..

TECHNICAL RESEARCHES ON FERMENTATION. 203

368. Comparison between Filtered Flour Infusion, Wort, and Yeast
Mixture Solution. — Pursuing the same line of investigation, experi-
ments were next made for the purpose of examining and comparing flour
infusion, wort, and yeast mixture, as fermentable substances. An in-
fusion of flour was made by taking 400 grams of flour, and 1000 c.c. of
water ; these were shaken thoroughly in a flask, from time to time, for
half an hour, and then allowed to subside : the clear liquid was filtered,
and its specific gravity taken ; this amounted to 1007.2. Meantime, some
malt wort had been prepared ; this was divided into two portions, the one
of which was boiled, the other allowed to remain at the mashing heat.
These were next cooled, and each diluted down until the specific gravity
coincided with that of the flour infusion. A solution of yeast mixture of
the same density was also prepared. Fermentation was started in each
of these with the results given in the following table : —

Date, May 8, 1885.
No. 1. 40 per cent, filtered flour infusion, Sp. G. 1007.2, 6 oz. at

30° C. ; compressed yeast, ]/\ oz.
No. 2. Unboiled malt wort, Sp. G. 1007.2, 6 oz. at 30° C. ; compressed

yeast, ^ oz.
No. 3. Boiled wort, Sp. G. 1007.2, 6 oz. at 30C C. ; compressed yeast,

y4oz.

No. 4. Yeast mixture and water, Sp. G. 1007.2, 6 oz. at 30° C. ; com-
pressed yeast, ]/\ oz.

At the end of five hours, the following quantities of gas had been
evolved : —

No. 1 . . 8.3 cubic inches. No. 3 . . 18.2 cubic inches.
No. 2 . . 17.1 „ ! No. 4 24.3

The flour infusion evolved gas but slowly, and toward the end of five
hours, over which the experiment lasted, had fallen off considerably. The
two malt infusions yielded carbon dioxide at about double the speed ; that
in the boiled wort being the higher. The greater quantity of gas in the
latter instance is due to the fact that boiling coagulates some of the pro-
teins of the wort, and so leaves a greater percentage of sugar in the liquid,
when both are diluted to the same density. This is an interesting
instance of the removal of proteins resulting in a more copious and rapid
evolution of gas. The yeast mixture causes the carbon dioxide to be
evolved with still greater rapidity. Summing up the results :—

In solutions of the same density,

Flour infusion, on fermentation, yields gas somewhat slowly ;

Unboiled wort, at about double the speed ;

Boiled wort, slightly more rapidly than the unboiled; and

Yeast mixture solution, at about three times the rate of the flour
infusion.

The soluble extract of flour is thereby shown to be capable of only
a slow fermentation ; this is due to its containing a comparatively low
proportion of sugar, and much of that of a kind which requires to be
inverted before it can be fermented.

369. Comparison between Flour and its Various Constituents fer-
mented separately. — From the baker's point of view, it is of very great
importance that he should know which of the several constituents of
flour it is that affords, during fermentation, the gas by which. his dough
is distended. The following experiments were made for the purpose of
obtaining definite information on this subject — No. 1 requires no further

204 THE TECHNOLOGY OF BREAD-MAKING.

explanation. In No. 2, 34 grams of flour were mixed with 6 oz. (=170
c.c.) of water, being equivalent to 20 per cent, of flour in the water. In
No. 3, the flour was agitated several times with large quantities of water,
and allowed to subside between each washing, the supernatant liquid
being poured off, and only the insoluble residue retained. In this man-
ner, the washed insoluble residue is obtained comparatively free from the
other constituents. Of these three samples, No. 2 represents the whole of
the flour, No. 1 the soluble, and No. 3 the insoluble portion. No. 4 con-
sisted of 20 per cent, flour infusion, with gelatinised starch added; the
whole being subjected to a temperature of 30° C. for 12 hours before fer-
mentation : this method was adopted in order to determine what diastatic
effect was produced by the flour infusion on the gelatinised starch, it
being assumed that whatever starch was converted into sugar would,
under the influence of the yeast, be decomposed with the evolution of car-
bon dioxide gas. No. 5 was a somewhat similar experiment, made with
gluten; some flour was doughed, and then the gluten washed as well as
practicable in a stream of water. In order to get as large a surface as
possible, this gluten was next rubbed in a mortar with clean sand ; it was
in this way cut up into a ragged mass. The gluten was mixed with water
and kept at 30° C. for 12 hours, in order to permit any degrading action,
that warm water is capable of exerting on gluten during that time to
assert itself. In Nos. 4 and 5, yeast was added at the end of 12 hours.
No. 6 was a repetition of No. 4, except that the gelatinised starch and
flour infusion were mixed immediately before fermentation. In No. 7 the
starch was simply added to the flour infusion without previous gelatinisa-
tion. No. 8 consisted of wheat-starch and water only, to which yeast was
added. The starch used for these experiments was specially prepared in
the laboratory from the best ' Hungarian flour by washing the dough,
enclosed in muslin, thus separating the gluten. The starch was allowed
to settle, and the supernatant liquid poured off; the starch was then
stirred up with some more water, and again allowed to subside. These
washings were repeated daily for about a fortnight, at the end of which
time the starch was air-dried. On being tested with Fehling's solution
the starch gave no trace of precipitate: its purity was therefore assured.
This series of fermentation tests altogether extended over a period of
three days.

Date, May 11, 1885.

No. 1. 20 per cent, filtered infusion of flour, 6 oz. at 30° C., com-
pressed yeast, *4 °z-

No. 2. 34 grams flour ; water, 6 oz. at 30° C. ; compressed yeast, % oz.
No. 3. Washed insoluble residue from 34 grams of flour : water, 6 oz.
at 30° C. ; compressed yeast, l/[ oz.

Date, May 12, 1885.

No. 4. 20 per cent, filtered flour infusion, 6 oz. at 30° C. ; wheat
starch, 5 grams taken and gelatinised, cooled, then added to
flour infusion. Mixture placed in bottle and maintained at
30° C. for 12 hours ; then ^ oz. compressed yeast added and
fermentation commenced.

No. 5. Moist thoroughly washed gluten, 5 grams, triturated in mortar
with sand in order to expose large surface : gluten with 6 oz.
of water at 30° C. placed in bottle and maintained at 30° C.
for 12 hours; then l/\. oz. compressed yeast added and fer-
mentation commenced.

TECHNICAL RESEARCHES ON FERMENTATION. 205

Date, May 13, 1885.
No. 6. 20 per cent, filtered flour infusion,. 6 oz. at 30° C. ; wheat

starch, 5 grams, gelatinised ; compressed yeast, ^4 °z-
No. 7. 20 per cent, filtered flour infusion, 6 oz. at 30° C. ; wheat

starch, 5 grams, ungelatinised ; compressed yeast, *4 oz.

Date, May 11, 1885.

No. 8. Wheat starch, 5 grams, gelatinised, water 6 oz. at 30° C. ; com-
pressed yeast, %. oz.

At the expiration of six Hours, the following quantities of gas had
been evolved : —

No. 1 . . 2.5 cubic inches.
No. 2 17.5 .

No. 5 . . 1.3 cubic inches.
No. 6 33.7

No. 3 . . 3.0 „ No. 7 . . 8.2

No. 4 . . 37.5 „ | No. 8 . . 0.9

No. 1, consisting of 20 per cent, flour infusion, gave off very little gas,
the quantity amounting to only 2.5 cubic inches in six hours ; this is very
much less than that obtained in the previous series of experiments in
which a 40 per cent, infusion was employed ; the latter gave off 8.3 cubic
inches in five hours. No. 2, containing the whole of the flour, gave off gas
much more copiously, in six hours there being 17.5 cubic inches of gas
evolved. After the second hour, the evolution fell off slowly but regu-
larly.1 The washed residue gave off just the same amount of gas as did
the filtered infusion ; in fact, at the end of the fifth hour, No. 3 gave the
higher reading. It will be noticed that the whole of the flour gives off
three times as much gas as do the filtered infusion and the washed residue
together. The reason is that, when flour is shaken with water and then
filtered, the substances which under the action of yeast evolve gas are not
all removed in the filtrate : they are only separated from the insoluble
residue with great difficulty, and several washings do not so thoroughly
remove fermentable matter as to leave the residue completely unfer-
mentable. That the fermentation in No. 3 is not due to the insoluble
residue is proved by the result of experiment No. 5 ; for with well washed
and kneaded gluten, but very little gas is evolved, the total amount in
nine hours being only 1.5 cubic inches, and this although the gluten for
twelve hours previous to fermentation was digested with water at 30° C.
Much of the fermentable matter of flour belongs to what may be called
the semi-soluble portion, that is, 'the part of the flour which is retained by
an ordinary filter paper, but on kneading is readily separated By the
mechanical action from the gluten. In Nos. 4 and 6 the quantities used
are the same, but the former of the two samples affords evidence of
diastasis having been occasioned during the twelve hours for which the
gelatinised starch was subjected to the action of the flour infusion. No. 6
at first proceeded somewhat the more rapidly, but evolved very little gas
during the second hour; during the third hour, however, it recovered
itself and proceeded regularly, until at the expiration of six hours the
evolution of gas ceased, with a total of 33.7 inches. In No. 4 the fermen-
tation proceeds rapidly and regularly, falling off towards the end, and
finishing at five hours with 37.5 cubic inches. As a result of the previous
diastasis, a larger quantity of gas is evolved, but in each instance the
greater part of the starch remained behind, as if 5 grams of starch were

1 In all these tests, readings were made either every hour or half -hour, but
usually the result of one reading only is here given. When of special interest,
however, the explanatory remarks contain also references to other readings.

206 THE TECHNOLOGY OF BREAD-MAKING.

completely changed into sugar, and then by fermentation into carbon
dioxide and alcohol, the yield of gas would roughly be about 85 cubic
inches at 20° C. The diastatic action of the flour infusion will have more
or less effected the hydrolysis of the starch into dextrin and maltose ; the
latter will have undergone fermentation, while the former is unferment-
able. Experiment No. 8 shows that the diastasis of the starch is effected
by the flour infusion, and not by the yeast, for where pure gelatinised
starch and yeast alone are employed, exceedingly little gas is evolved;
during eight hours, but 1.2 cubic inches only having accumulated. This
experiment was allowed to proceed overnight, and at the end of twenty-
one hours, 7.0 cubic inches had been evolved. Another reading was taken
at the end of the twenty-second hour, and showed that 0.8 cubic inches
had been evolved during the hour. It would seem that the diastatic
action of yeast on pure starch increases somewhat after some hours ; but
within a limit of eight hours, which covers the time that flour is in most
instances subjected to fermentation, little or no action has occurred. The
greater evolution of gas after twenty-one hours may possibly be due to
sugar formed by the action of bacteria on the starch. Very striking in
connection with this is the result obtained in experiment No. 7, for when
the ungelatinised starch was mixed with flour infusion and subjected to
fermentation, 8.5 cubic inches of gas were obtained in eight hours. The
flour infusion must under these circumstances have succeeded in
hydrolysing some of the starch ; for although starch is washed most care-
fully, there will always be a certain number of cells whose walls are suf-
ficiently thin to permit diastasis to occur; and as stated in a previous
chapter, some investigators are of opinion that even unbroken wheat
starch cells are comparatively readily attacked by hydrolysing agents.
(Refer to Chapter VIII., paragraph 258.) Summing up the results
obtained in these experiments, it is found that-
Filtered flour infusion supports fermentation slowly.

The frequently washed residue of flour supports fermentation at
about the same rate.

The entire flour, mixed with water, evolves about six times as much
gas as either the filtered infusion or the washed residue from the same
weight.

Kneaded and washed gluten evolves practically no gas.

Flour infusion and gelatinised starch together evolve gas in consid-
erable quantity.

The quantity of gas is increased when the infusion and the gelatin-
ised starch remain together some time before fermentation ; which re-
sult is due to diastasis by the proteins of the infusion.

Ungelatinised starch, under the influence of yeast and flour infusion,
evolves a moderately large quantity of gas.

Gelatinised starch alone undergoes little or no fermentation during
a period of eight hours, but ferments slowly after standing some twenty
hours.

370. Further Investigation of Fermentation of Flour Infusion. — In
order to further determine the source of gas during the fermentation of
flour infusion, the following experiments were made : — A forty per cent,
filtered infusion of stone milled flour, from English wheat, was prepared
by taking 600 grams of flour, and 1500 c.c. of distilled water : these were
several times shaken together during half an hour, and then allowed to
subside. The upper layer of liquid was next poured off and filtered
through washed calico: this was subsequently again filtered in the ordi-
nary manner through paper until perfectly clear. On testing with iodine

TECHNICAL RESEARCHES ON FERMENTATION. 207

no colour was produced, thus showing the absence of both starch and
amyloins. The specific gravity of the infusion was 1008.5, being some-
what higher than that of the forty per cent, infusion used in a previous
experiment. A portion of the infusion was tested for sugar, before and
after inversion, and also for proteins. Six ounces of the infusion were
then fermented at 25° C., with a quarter-ounce of compressed yeast. The
experiment was continued for twenty-two hours, at the end of which time
fermentation had entirely ceased. The clear liquid was then decanted off
from the layer of yeast at the bottom, and tested for sugar and proteins
as was done in the separate portion of the original infusion. To the yeast
remaining in the bottle there was at once added a half-ounce of sugar and
six ounces of water at 25° C., and the testing apparatus set up, and the
quantity of gas evolved measured.

The sugar was estimated by Fehling's process in the following man-
ner:— A weighed quantity of the flour infusion was raised to the boiling
point, and maintained at that temperature for about five minutes, in
order to coagulate proteins ; the loss by evaporation was then made up by
the addition of distilled water, and the solution filtered.

Quantities taken= 25 c.c. Fehling's Solution.
50 c.c. Water.
20 c.c. Forty per cent. Flour Infusion.

Weight of cuprous oxide, Cu2O, yielded — 0.1531 gram. Assuming
this precipitate to be due to maltose, then

0.1531X0-7758 = 0.1187 gram of maltose in 20 c.c. of the flour
infusion == 1.48 per cent, of maltose in the flour.

In the next place, 50 c.c. of the flour infusion were taken, 5 c.c. of
fuming hydrochloric acid added, and the solution inverted by being
raised to 68° C. The acid was then neutralised by solid sodium carbonate,
and the solution made up to 100 c.c. with water. This produced a twenty
per cent, inverted solution.

Quantities taken = 25 c.c. Fehling's Solution.
50 c.c. Water.
20 c.c. Twenty per cent, inverted Flour Infusion.

Weight of cuprous oxide, Cu20, yielded — 0.1860 gram.

In 20 c.c. of a forty per cent, solution there would be double this
quantity = 0.1860 X 2 = 0.3720 gram. From this must be deducted the
amount of precipitate due to the maltose present.

0.3720 — 0.1531 = 0.2189 gram of Cu,O due to a reducing sugar pro-
duced by inversion. Assuming this sugar to be cane-sugar, or at least
to have the same reducing power, then

0.2189X0.4791 = 0.1048 gram of cane-sugar in 20 c.c. of the forty
per cent, infusion == 1.31 per cent: of cane-sugar in the flour.

The total sugar in the flour would thus be 2.79 per cent.

After fermentation, the upper liquid from the yeast bottle was also
tested for sugars, after filtration and coagulation of proteins as before.
The uninverted solution gave no precipitate whatever with Fehling's
solution. A portion was next inverted with acid in the manner already
described; 20 c.c. of this solution gave a slight trace of precipitate with
Fehling's solution, which was too little to weigh. So far, the practical
result may be summed up in the statement that filtered aqueous flour
infusion contains two or more varieties of sugar; these during the act
of fermentation entirely disappear.

208 THE TECHNOLOGY OF BREAD-MAKING.

The infusion was tested for proteins by distillation with alkaline per-
manganate solution, with the following results, calculated to the percent-
age present in the flour —

In the infusion before fermentation — 0.76 per cent.

after „ 0.78

Compared with analyses of other flours, these quantities are low ; this is
probably accounted for by a forty per cent, infusion being made, whereas
a ten per cent, infusion is used in most analyses ; the more dilute solution
extracts the somewhat viscous proteins with greater readiness. The only
deduction from these determinations is, that the amount of proteins in
a filtered flour infusion is practically unchanged by the act of fermen-
tation, there being no disappearance whatever of these bodies.

The following are the results of the fermentation experiments —

No. 1. Flour Infusion, 6 oz. ; compressed Yeast, y\ oz. ; Temperature,
25° C.

No. 2. Yeast from previous experiment after cessation of fermenta-
tion : Sugar, ]/, oz. ; Water, 6 oz., at 25° C.

At the expiration of six hours, the following quantities of gas had
been evolved : —

No. 1 . . 9.6 cubic inches. | No. 2 . . 73.5 cubic inches.

As six ounces of the forty per cent, flour infusion would contain the
soluble matter of 68 grams of flour, it follows that there would be present,
according to the analysis, 1.89 grams of sugar. This quantity, if entirely
converted during fermentation into carbon dioxide and alcohol, would
yield about 32 cubic inches of gas at 20° C. By the method adopted for
testing, 15 cubic inches were registered at the end of twenty-two hours ;
to this would have to be added a correction for the amount lost by ab-
sorption by the water, in order to obtain a correct estimate. It is difficult,
when the total quantity of gas evolved is small, to determine with
accuracy the loss by absorption, because the gas in the apparatus consists
of a mixture in which air is predominant, consequently the rate of
absorption is less than with pure carbon dioxide gas. If it were desired to
accurately estimate the quantity of gas, collection over mercury would
have to be adopted. This is of little importance in the present experi-
ment, because the total measured comes well within the amount of gas
that the sugar would theoretically yield. In other words, there is no need
to go outside the sugar to find a source from which the carbon dioxide is
obtained, as the whole of the sugar disappears, and in the act of fermen-
tation is capable of yielding more gas than that observed to be evolved.
That the cessation of fermentation is not due to the exhaustion of the
yeast is proved by experiment No. 2, in which the same yeast has more
sugar added to it, when a vigorous fermentation was immediately set up.
That the cessation of fermentation is due to the exhaustion of the sugar
is proved by that compound being absent on analysis of the infusion after
fermentation. Summing up the whole of the results —

FLOUR INFUSION.

Before Fermentation.
Sugar, 1.89 grams in the six ounces

of infusion.
Proteins, 0.517 gram present.

After Fermentation.

Sugar, absent.

Proteins, 0.530 gram present.
When Fermentation had ceased,
15 cubic inches of gas had been
evolved, and the yeast was still
unexhausted, and capable of in-
ducing fermentation in fresh
sugar solution.

TECHNICAL RESEARCHES ON FERMENTATION. 209

Reasoning on these results, together with those obtained in the series
of experiments on flour and its various constituents taken separately, the
only logical conclusion is that the fermentation of dough is essentially a
saccharine fermentation.

It may be demurred that the circumstances are different in an aqueous
infusion to those which hold in a tough elastic mass such as dough. But
it is inconceivable that the fermentation actually immediately depends on
the conversion of any but soluble constituents of the flour into gas ; there-
fore, if those proteins, so soluble as to pass through filter paper, are not
capable of yielding gas as a result of fermentation by yeast, it follows that
the more insoluble protein compounds likewise will not yield gas. The
fact that washed gluten yields no gas affords corroborative proof of this
point. (The small quantity actually obtained by experiment may be
accounted for by the well-known difficulty of perfectly freeing gluten
from all starchy and soluble matters. ) That the fermentation of the flour
itself yields several times more gas than does the filtered infusion, lends
no support to the theory that it is the protein matter that is evolving gas,
because it has been shown that pure ungelatinised starch causes a marked
evolution of gas, being doubtless first converted into dextrin and maltose
by diastasis. The fermentability of the washed residue is also accounted
for by its containing starch. Supposing even that in dough', after fer-
mentation had ceased, sugar as such existed and could be removed and
detected by analytic methods, that of itself would be no proof of the evo-
lution of gas being at the expense of the proteins, or peptones derived
therefrom (for the argument equally applies to these latter bodies),
because simultaneously with the fermentation produced by the yeast there
is a production of sugar by diastasis of the starch. Fermentation of
sugar in a stiff dough is rough work for yeast cells, and it may well be
that after a few hours they are thoroughly exhausted, and disappear
through disruption of their cell walls : the continuance of diastasis would
still cause the slow production of more or less sugar. Further, the dias-
tasis of the starch must throughout fermentation precede its subsequent
conversion into carbon dioxide and alcohol; and so, if the reaction be
stopped at any point, more or less sugar would as a rule be found. Again
drawing a conclusion, the fermentation of dough is in part due to the
fermentation of the sugar present, in part to the diastasis of a portion
of the starch of the flour and its subsequent fermentation; these
sources are sufficient, and more than sufficient, for the production of all
the gas evolved; these statements admit of experimental proof. There
is no satisfactory evidence in favour of the gas evolved being in any
sensible degree derived from the protein constituents of dough. It
should be noticed that no assertion is made that no gas whatever is de-
rived from the protein constituents of flour ; it is possible that in extreme
cases gas is produced from protein matters as a result of butyric and
putrefactive fermentations ; but in ordinary bread-making, as it holds in
America and the United Kingdom, the amount of gas derived from this
source is of no importance compared with that from sugar, and indirectly
from starch. Whatever amount of gas there is that is thus obtained from
proteins is the result, not of the action of yeast, but of bacteria. Further,
the statement that protein bodies do not themselves evolve gas during panary
fermentation must not be construed into meaning that they do not affect
the quantity evolved. In their capacity as nitrogenous yeast-foods, they aid
the yeast in its development, and consequently in its production of gas by
decomposition of saccharine bodies.

210 THE TECHNOLOGY OP BREAD-MAKING.

371. Effect of Salt on the Fermentation of Flour. — Most bakers are
familiar with the general statement that salt retards fermentation : in
order to determine the amount of such retardation the following experi-
ments were made. In the first, flour and water alone were fermented ;
the others consisted of flour mixed with salt solutions of various strengths.
The appended table contains the results : —

Date, May 27, 1885.
No. 1. Flour, 34 grams; water, 6 oz. at 30° C. ; compressed yeast,

% oz.
No. 2. Flour, 34 grams ; water, 6 oz. at 30° C. ; compressed yeast,

l/4 oz. ; salt, 2.5 grams — 1.4 per cent, salt solution.
No. 3. Flour, 34 grams ; water, 6 oz. at 30° C. ; compressed yeast,

l/± oz. ; salt, 5.0 grams = 2.9 per cent, salt solution.
No. 4. Flour, 34 grams; water, 6 oz. at 30° C. ; compressed yeast,

l/4 oz. ; salt, 8.5 grams = 5.0 per cent, salt solution.
At the termination of six hours, the following quantities of gas had
been evolved : —

No. 1 . . 18.2 cubic inches.
No. 2 . . 15.2

No. 3 . . 15.1 cubic inches.
No. 4 . . 13.3

In the first test, 19.2 cubic inches of gas were evolved in seven hours,
while with 1.4 per cent, of salt present in the solution (No. 2) the gas
was diminished to 15.8 cubic inches. Summing up the conclusions de-
rived from this series of experiments —

The use of a 1.4 per cent, solution of salt instead of water produced
a marked diminution in the evolution of gas.

Increasing the amount of salt to 2.9 per cent, made very little differ-
ence on the speed of fermentation.

With 5.0 per cent, of salt, gas was evolved still more slowly.
372. Effect on the Fermentation of Sugar of the addition of Flour
and Potatoes. — In order to throw light on this point, the experiments
recorded in the following table were performed.

Date, May 21, 1885.
No. 1. Sugar, ]/2 oz. ; compressed yeast, *4 oz. ; water, 6 oz. at 30° C. ;

raw flour, 5 grams.

No. 2. Sugar, l/2 oz. ; compressed yeast, *4 oz. ; water, 6 oz. at 30° C. ;
flour, 5 grams, gelatinised in small quantity of water and
allowed to cool.
Date, May 18, 1885.
No. 3. Sugar, l/2 oz. ; compressed yeast, ^ oz. ; water, 6 oz. at 30° C. ;

potato, 5 grams, boiled.

No. 4. Sugar, l/2 oz. ; compressed yeast, l/^ oz. ; potato, 5 grams, in
small pieces, boiled ; clear filtered water employed for boiling
them, made up to 6 oz. at 30° C., and used instead of ordi-
nary water.
Quantities of gas evolved in six hours : —

No. 1 . . 84.3 cubic inches.
No. 2 . . 135.0

No. 3 . . 138.1 cubic inches.
No. 4 . . 133.6

In the first experiment, with raw flour, the quantity of gas evolved
keeps very close to that evolved from the sugar solution and yeast only,
until three hours have elapsed. After that time the speed of evolution of
gas falls off sharply, until in nine hours the quantity of gas evolved is
only just as much as the sugar alone had evolved in six hours. The
actual diminution of speed of the evolution of gas, as a result of the
presence of flour, is noticeable in several experiments. With gelatinised

TECHNICAL RESEARCHES ON FERMENTATION. 211

flour, on the other hand, the fermentation proceeds more rapidly, and
to a greater extent than with sugar only. The result of No. 3 with
boiled potato is almost similar to No. 2. No. 4, containing boiled
potato water, ferments at almost exactly the same rate as did No. 3
with the whole of the potato. Summing up,
The addition to sugar of —

Raw flour retarded the fermentation in the latter part of the

experiment.
Gelatinised flour, boiled potato, and boiled potato water, each

stimulated and increased the amount of fermentation to about

the same degree.

373. Effect of Temperature on Fermentation. — In order to measure
quantitatively the effect of variations of temperature on the production
of gas by fermentation, the following experiments were made :^Two
different brands of compressed yeast were employed, one of which is
designated yeast "A," the other yeast "B"; the same quantity of yeast
was employed throughout the experiment. The series included tests by
each yeast on sugar, yeast mixture and flour, at the respective tei^pera-
tures of 20°, 25°, 30°, and 35° C. == (68°, 77°, 86°, and 95° F.).
The following are the results of one set of tests : —
Date, July 3, 1885. — The complete series at 20° C. made this day.
„ July 2,1885.- „ „ 25° C.

„ June 30, 1885.— „ „ 30° C.

„ June 29, 1885.— „ „ 35° C.

No. 1. Yeast mixture, ^ oz. ; compressed yeast, A, *4 oz- ; water, 6 oz.

at 20° C.
No. 2. Yeast mixture, y^ oz. ; compressed yeast, A, J4 oz- 5 water, 6 oz.

at 25° C.
No. 3. Yeast mixture, y* oz. ; compressed yeast, A, y± oz. ; water, 6 oz.

at 30° C.
No. 4. Yeast mixture, y2 oz. ; compressed yeast, A, ^ oz. ; water, 6 oz.

at 35° C.
Gas evolved at the end of six hours : —

No. 1 . . 83.8 cubic inches.
No. 2 . . 113.3

No. 3 . . 177.8 cubic inches.
No. 4 . . 175.0

(At the end of three hours, Nos. 3 and 4 had evolved 104.2 and 128.0
cubic inches respectively.)

Considering first the series consisting of yeast A with yeast mixture,
a temperature of 25° C. increases the total quantity of gas considerably
over that evolved at 20° C. ; a further increase to 30° more than doubles
the average speed of evolution of gas. Beyond 30° the amount of gas
evolved is not materially increased with the rise in temperature, thus at
35° C. there is very little more gas evolved than at 30° C. In the series
where sugar is substituted for yeast mixture, the production of gas is less,
but the same general relation exists between the various members of the
series.

With flour, on the other hand, there is a more equal increase, as shown
by the following table, still there is a greater increase between Nos. 2 and
3 than the others : —

No. 1. Flour, 34 grams; compressed yeast, A, ^4 oz- '•> water, 6 oz. at
20° C.

No. 2. Flour, 34 grams ; compressed yeast, A, l/^ oz. ; water, 6 oz. at
25° C.

212 THE TECHNOLOGY OF BREAD-MAKING.

No. 3. Flour, 34 grams ; compressed yeast, A, *4 oz- ; water, 6 oz. at

30° C.
No. 4. Flour, 34 grams ; compressed yeast, A, ]/$ oz- ; water, 6 oz. at

35° C.
Gas evolved at the end of six hours : —

No. 1 . . 14.6 cubic inches.
No. 2 . . 18.2

No. 3 . . 24.4 cubic inches.
No. 4 . . 28.3

Another precisely similar series of experiments was made with B
yeast, which, being the stronger yeast of the two, gave off in every case
more gas than did yeast A in the corresponding experiment. This differ-
ence was not so striking when yeast mixture was used, because its stimu-
lating effect helped the weak yeast proportionally the more. But in sugar
each yeast has to depend more fully on its own vitality in producing fer-
mentation. Consequently the stronger yeast B causes the evolution of a
proportionately higher quantity of gas than does the yeast A.

Summarising the results obtained—

In the three media employed, the rapidity of production of gas in-
creases with the temperature ; this increase is more marked between 25°
and 80° than between 30° and 35° C.

374. Behaviour of Yeasts at High Temperatures. — In view of the
fact that, in baking, some of the work of the yeast is done in the oven, it
becomes of interest to ascertain how different yeasts behave as fermenting
agents at high temperatures. For this purpose the following experiments
were made in 1895 : —

EXPERIMENT ON YEAST AT 77° F. (25° C.)

Quantities taken — yeast, ^ oz- ; flour, 2.4 oz. ; water, 6 oz.
No. 1. — Compressed distillers' yeast.

„ 2. — Compressed brewers' yeast, ordinary.

„ 3.— „ „ „ special.

„ 4. — Thin brewers' yeast.

GAS EVOLVED IN CUBIC INCHES.

Time. No. 1. No. 2. No. 3. No. 4.

1 hour 4.0 2.0 7.0

2 hours 6.0 15.0

3 „ 15.0 10.0 18.5 4.0

4 „ 13.0 22.5 6.5

5 „ 8.0

5/2 „ 21.0

7 „ 22.0

Yeasts Nos. 1 and 4 were next tested in precisely the same manner,
except that the temperature was raised to 122° F. (50° C.) The follow-
ing were the results : —

GAS EVOLVED IN CUBIC INCHES.

Time. No. 1. No. 4.

1 hour 13.0 1.0

2 hours 22.75

2/ „ 23.15

3 Stop 1.5

Notice how completely No. 4 ceases work at this higher temperature ;

while No. 1 for a time is even more energetic in action.

In the next place a series of tests were made at 131° F. (55° C.) . The
quantities taken were not precisely the same as in the previous tests, but
are given in detail.

1.0

1.25

—

2.0

4.0

5.0

—

2.75

3.0

6.25

7.75

2.75

3.0

3.5

6.5

8.75

4.0

3.5

5.5

7.0

10.0

5.75

—

TECHNICAL RESEARCHES ON FERMENTATION. 213

No. 1. Compressed distillers' yeast, *4 oz. ; flour, 1.2 oz. ; water, 6 oz.

No. la. Yeast as No. 1 ; sugar, ^ oz. ; water, 6 oz.

[No. 4. Thin brewers' yeast did not work with flour at 122° F.]

No. 4a. Thin brewers' yeast, ^ oz. ; sugar, l/4 oz. ; water, 6 oz.

No. 5. Another sample compressed distillers' yeast, ^ oz. ; flour, 1.2

oz. ; water, 6 oz.

No. 5&. Yeast as No. 5 ; sugar, l/± oz. ; water, 6 oz.

GAS EVOLVED IN CUBIC INCHES.

Time. No. 1. No. la. No. 4a. No. 5. No. 5a.

15 minutes
30 „

1 hour

2 hours

3 „

4 „ . . . . Stop 10.75 Stop 4.0 7.5

Comparing the two samples of distillers' yeast; No. 1, it will be
noticed, works more vigorously, both in flour and in sugar, than No. 5.
The thin brewers ' yeast, No. 4, works at this temperature in sugar ;
although inactive in flour and water, at a temperature lower by nine
degrees. At a temperature of 140° F., neither Nos. 1 nor 4 evolved any
gas in a sugar solution. These results agree broadly with the general
behaviour of the yeasts during baking. They were first published by one
of the authors in The Science and Art of Bread-making, 1895, and estab-
lish the fact that at high temperatures, distillers ' yeast retains its activity
to a much higher point than does English brewers' yeast.

375. Comparative Fermentative Tests with Brewers' and Distillers'
Yeasts in Flour and Sugar Solutions. — The following experiments were
made with the view of comparing the fermentative capacity of brewers'
and distillers' yeasts in flour and sugar solutions respectively: —

No. 1. Sugar, */2 oz. ; water, 6 oz. at 25° C. ; distillers' compressed
yeast, % oz.

No. 2. Flour, 68 grams; water, 6 oz. at 25° C. ; distillers' compressed
yeast, % °z-

No. 3. Sugar, l/2 oz. ; water, 6 oz. at 25° C. ; compressed English brew-
ers' yeast, l/4 oz.

No. 4. Flour, 68 grams ; water, 6 oz. at 25° C. ; compressed English
brewers' yeast, y\ oz.

The following were the quantities of gas evolved in six hours : —

No. 1 . . 40.8 cubic inches.
No. 2 . . 32.3

No. 3 . . 80.0 cubic inches.
No. 4 . 1.9

No. 1 calls for no special remark, being similar in character to many
tests previously made. The quantity of flour in No. 2 is double that used
in previous experiments, the object being to get a mixture which should
be a nearer assimilation to dough, while still possessing sufficient fluidity
to permit the escape of the produced gas. As might be expected, the
amount of gas evolved is higher than in tests where 34 grams were used.
No. 3 was a test with the compressed brewers' yeast — there is a more
rapid evolution of gas than in the corresponding test with the distillers'
yeast; so far, the verdict would be in favour of the brewers' yeast as
being a stronger yeast. This verdict is borne out by the results of com-
mercial use of the yeast for brewing purposes. Next comes test No. 4, the
results of which are most remarkable ; the English brewers ' yeast, which

214 THE TECHNOLOGY OF BREAD-MAKING.

had been by far the stronger in sugar solution, causes practically no evo-
lution of gas whatever from the flour mixture. On the next day the
experiments were repeated, with similar results.

376. Brewers' Yeast and Ferments. — When brewers' yeast is em-
ployed for bread-making purposes it is usual first to allow the yeast to
develop in a "ferment," generally composed of boiled potatoes rubbed
down through a sieve into water, and a little raw flour added. In order
to ascertain the effect of different substances as constituents of a "fer-
ment, ' ' the following experiments were made : —

Water. Brewers' Yeast.

No. 1. Sugar, 1 gram . . . . . . 200 c.c. 2 grams.

No. 2. Boiled potatoes, 5 grams . . . . „

No. 3. Filtered potato juice, 10 grams . . ,,

No. 4. Malt extract, 2.5 grams . . . . „

No. 5. Diastatic malt extract, 2.5 grams „

No. 6. „ „ ,, killed, 2. 5 grams „

. No. 6 was precisely similar to No. 5, except that the solution had been
raised to the boiling point, with the view of destroying the diastase
present.

The following were the quantities of gas evolved after six and a half
hours' fermentation at 30° C. : —

No. 1 . . 125 cubic centimetres.
No. 2 . . 25
No. 3 . 16

No. 4 . . 160 cubic centimetres.
No. 5 . . 76
No. 6 . 74

After fermentation had ceased, and about twenty hours from the com-
mencement of the experiment, 50 grams of flour were added to each * ' fer-
ment," and the bottle again immersed in the bath at 30° C., and readings
taken of the quantities of gas evolved. At the end of six hours, these
were : —

No. 1 . . 23 cubic centimetres.
No. 2 . . 11
No. 3 . . 31

No. 4 . . 43 cubic centimetres.
No. 5 . . 15
No. 6 . . 30

As a ferment constituent potato juice causes the evolution of less gas
than do potatoes, while as a stimulant on the yeast 's after-power of induc-
ing fermentation in flour the juice is far the more efficacious. While the
gas evolved in the two diastatic malt extract solutions is practically the
same, that in which the diastase had been destroyed acted in this case as
the more energetic after-stimulant of flour fermentation. Possibly a con-
centrated solution of diastase may exert some retarding influence on the
energy of yeast. In an experiment conducted in this fashion the action of
the yeast in the mixture of flour and water is less in all cases, except No.
4, than when the yeast and flour mixture are fermented direct (36 cubic
centimetres). During the working of the "ferment," the operation was
carried on without access of air, a condition which may have had a
retarding action on the energy of the yeast (Science and Art of Bread-
making, Jago, 1895, p. 223, et seq.).

377. Toxicity of Flour to Yeast. — In view of recent investigations
on the toxic behaviour of flour towards yeast, the experiments described
serve to show that flour retards the fermentative action on sugar of brew-
ers' yeast. (Distillers' yeast is also similarly affected, but only to a much
less extent.) In this relation it is interesting to note the work that has
been done on what are called " toxalbumins. " In investigations carried
out on the proteins of the seed of Ricinus, it has been shown that its
toxic property belongs to the protein, and is closely related to the propor-
tion of coagulable albumin contained in various fractions of the seed

TECHNICAL RESEARCHES ON FERMENTATION. 215

protein. It seems, therefore, almost certain that true toxalbumins occur
in seeds (The Vegetable Proteins, Osborne, 1909, p. 96). Michaelis has
also pointed out that foreign protein matter is under all circumstances
a deadly poison for yeast, and that this is rendered innocuous by the
proteolytic enzyme present. It is probably therefore the protein of flour
which exerts a retarding action on fermentation.

Baker and Hulton have recently (1909, 1910) reinvestigated this mat-
ter, and have confirmed the just quoted conclusions of one of the authors,
viz., that the presence of flour inhibits the fermentation of a solution of
sugar by brewers' yeast. Independently, Lange, in the course of a series
of investigations, conducted in 1904 and 1905, re-discovered that the flour
of wheat and certain other grains exercised a poisonous action on yeast,
and especially brewers' types of yeast. The following is a synopsis of the
work and conclusions of Lange, Henneberg, Hayduck, Wendel, Baker,
and Hulton on this and closely allied subjects. The authors are indebted
to the Treatise on Brewing by Sykes and Ling for a resume of a lecture
by Delbriick before the London section of the Institute of Brewing in
1906, from which many of the conclusions of the above named German
authorities are gleaned. The lecture is reported more fully in Journ.
Inst. Brewing, 1906, 642. From Hayduck 's researches, the lecturer, Del-
briick, derived the laws that in the production of yeast, the fermenting
power is in inverse ratio to the multiplication of the yeast-cells. Moderate
multiplication produced a yeast rich in protein ; a rapid multiplication,
on the other hand, produced a yeast poor in protein. Therefore every-
thing which hindered multiplication, such as a low temperature, the shut-
ting off of air, lack of movement, fermentation under carbon dioxide
pressure, conduced to the yielding of a yeast which was rich in protein
and in fermenting power. Obviously, therefore, these are among the
matters to be considered in the manufacture of a vigorous yeast. It is
also evident that such treatment must not be carried to extremes, since
an undue restriction of multiplication would seriously lessen the output
of yeast. In yeast manufacture the conditions must be so balanced as to
obtain the maximum of vigour combined with a fair production of yeast.

Delbriick also dealt with an inquiry which is so frequently made,
what important physiological significance has the peculiar dynamic ef-
fect of the splitting up of sugai into alcohol and carbon dioxide"? To this
he replies that it is easy to say that a sort of subtle respiration process was
going on here — that the cleavage was a hidden source of heat; but the
significance of this activity was, particularly from a zymo-technological
point of view, far more comprehensive. It was known that the most
powerful defensive agencies of the yeast against the attacks of foreign
organisms lay in its fermentation energy. Delbriick had always looked
upon the fermentative effect of the yeast in this light, and had demon-
strated that its organism, in sending out carbon dioxide and alcohol,
thus protected itself against all the organisms for which these substances
were poisonous. The effect of the carbon dioxide is ten times as deadly
as that of the alcohol. Delbriick therefore arrives at the conclusion that
zymase (the yeast enzyme which decomposes sugar into alcohol and car-
bon dioxide) is not only a respiration enzyme, but also a fighting enzyme.
He also regards the proteolytic enzyme of yeast, as a part of its fighting
organisation, inasmuch as it attacks all inimical organisms, dissolving and
killing them. As already mentioned, foreign protein matter is a poison to
yeast, and this is rendered innocuous by the action of the proteolytic

216 THE TECHNOLOGY OF BREAD-MAKING.

enzyme by which it is degraded. The law that in the struggle for exist-
ence, those organisms which specialised in the production of fighting sub-
stances and in the cultivation of fighting enzymes, would be the strongest,
applies especially to the micro-organisms. Lactic acid bacteria possessed
means of defence in the lactic acid enzyme, while the butyric acid bacteria
were similarly protected by the production of butyric acid, a substance
which is pernicious in its effects on other organisms. It was in the course
of these researches that Lange independently re-discovered that bruised
grain (or bran) or meal, or even an aqueous extract of them, had a
poisonous effect on yeast. He further found that different kinds of yeast
varied in susceptibility to this poisonous action. Thus the distillers' yeast
races were capable of offering resistance, but such power was less marked
in brewers' top-fermentation yeast, and still less so in the bottom-fermen-
tation type of brewers' yeast. As to the nature of these poisonous sub-
stances, there was some probability that they belonged to the proteins and
to the enzymes produced by them, since the injurious action could be
neutralised by heating the grain or its aqueous extract. The following
are some of the more important conclusions of the German authorities.
The toxic action only becomes manifest when the yeast and cereals are
present together in distilled water. Rye, wheat, and barley, in the form
of grits or flour, placed with bottom-fermentation beer-yeast in a solution
of saccharose, will kill up to 99 per cent, of the yeast in a few minutes.
Maize and oats do not show this toxic action. By agitation with distilled
water, the flours of rye and wheat furnish extracts that are also toxic
toward beer-yeast, but to a far less extent than the corresponding solid
substances. The protein sludge separating from the coarser particles
when rye grits are shaken up with water is specially poisonous. The
same effect is produced by the glutinous mass obtained by kneading
wheaten flour under water. It is probable that the toxic substance must
be sought among the proteins, or may be produced therefrom by the
action of the yeast. All these toxic effects are completely obviated by the
addition of a small quantity of inorganic salts to the solution, lime salts
being the most effective, and next to them magnesia salts. A partial or
complete removal of the toxic action can be effected even by replacing
distilled water by tap-water. Among other substances exerting a strongly
poisonous action on low-fermentation beer-yeast is egg-albumin. Wheaten
flour seems also to exert a toxic action. on high-fermentation distillers'
yeast, but this requires confirmation (Treatise on Brewing, Sykes and
Ling).

These conclusions, it will be noticed, apply to bottom-fermentation
beer-yeast, whereas in the experiments previously described as having
been made by one of the authors top-fermentation beer-yeast was em-
ployed. This, though admittedly less susceptible to the inhibitory action
of the active cereals, is nevertheless similarly affected. Further, in these
experiments, no definite retarding action was caused by the addition of
egg-albumin. It is possible that the low temperature evaporation of this
body to dryness in the preparation of the desiccated product may have
modified its inhibitive action.

378. Baker and Hulton's Researches. — In 1909, these writers com-
municated to the Society of Chemical Industry the results of some re-
sear,ches on the action of wheaten flour on brewers' yeast. This was fol-
lowed by a paper on the "Toxins in Cereals," which appeared in the
Journal of the Institute of Brewing in 1910. The experimental work con-
firms that previously described, and among other things goes to show
that with mixtures of flour and water, tap-water enables a greater amount

TECHNICAL RESEARCHES ON FERMENTATION. 217

of gas to be evolved than does distilled water. Thus with 20 grams of
Hungarian flour, 50 c.c. of water, and 1 gram of unwashed pressed brew-
ers' yeast, fermented at 110° F., the following results were obtained at
the end of four hours : —

Carbon Dioxide Evolved.

Brewers' Yeast and Distilled Water . . . . 10 c.c.

Distillers' „ „ „ .... 287 „

Brewers' Yeast and Tap-water . . . . . . 35 „

Distillers' „ „ .. 287 „

The tap-water contained in grains per gallon :—

Total Solids 21.42

Solids after ignition 19.74

Silica . 0.28

Lime . . . . . . . . . . . . . . 7.60

Magnesia . . . . . . . . . . . . 0.71

Sulphuric Acid (S03) 2.69

Potash 0.42

Soda 1.26

Chlorine 1.40

Nitric Acid (N20fl) °-31

Using the tap-water it will be noticed that the activity of the brewers'
yeast is much increased. On examination of the results caused by the
additiojT of various inorganic salts to tap-water, it was found that potas-
sium sulphate, calcium chloride, sodium chloride, and many other salts act
as accelerants. Baker and Hulton regard potassium sulphate as the most
favourable of these, and find that a solution containing 0.6 gram per 100
c.c. exerts a very decided accelerating action. They make the following
suggestion as to the reason of the difference between the two yeasts
(distillers' and brewers') —

In a distillery wash, before the yeast is introduced, there are present
large quantities of raw cereals, such as barley and rye, containing toxins,
and since the distiller pitches his yeast into unboiled wort and therefore
one with this cereal poison still active, only those yeast cells which can
survive and are immune to such toxic substances and can reproduce in
this environment will carry on the race, giving rise to cells inheriting this
advantageous variation. There will thus be obtained in a few generations
by natural selection what is to all intents a new species bearing this char-
acter of immunity to cereal poison. When such yeast is used for bread-
making, where it is again exposed to the action of the toxic substance in
wheaten flour, the high gas yield at once shows that it is now immune,
while brewers' yeast which has always been grown in a boiled, and there-
fore non-poisonous wort, is readily susceptible. The accelerating influence
of potassium sulphate, sodium chloride, etc., on the fermentation of flour
with brewers' yeast is thus seen to be correlated with the protective func-
tion these salts exert on the yeast by negativing the toxic effect of the
flour, while distillery yeast which is already immune to these toxins, from
having been grown in their presence, needs no such protection, and is, in
fact, not activated by these salts (Journ. Inst. Chem., July, 1909).

Baker and Hulton do not attribute the protective action of potassium
sulphate to any ' ' salting out ' ' of proteins, but conceive that it may lie
in some kind of physiological stimulation of the yeast, whereby it is ren-
dered more resistant to an unsuitable environment. They further point
out that brewers' yeast, which was formerly used for bread-making, is
now practically useless, the reason being possibly due to the fact that

218 THE TECHNOLOGY OP BREAD-MAKING.

modern flours being better milled contain a smaller proportion of fibre,
husk, etc., than formerly. The husk probably has a protective action
towards brewers' yeast similar to that of salts ("Toxins in Cereals,"
Journ. Inst. Brewing, xvi, April, 1910).

In making this suggestion the writers have apparently overlooked the
fact that when brewers ' yeast was so largely employed for bread-making,
it was the custom to use a ferment consisting of boiled potatoes with their
skins on, the water in which they were boiled, and raw flour. The yeast
was allowed to work and multiply in this mixture before being intro-
duced into the sponge (earlier dough stage). The stimulating effect of
potatoes as an agent in fermentation has been already described in para-
graph 372.

EXPERIMENTAL WORK.

379. The student who has the opportunity will do well to perform
for himself most of the experiments described in this chapter, and com-
pare the results he obtains with those here recorded. He should com-
mence by making duplicate tests with the same yeasts, in order to gain the
requisite accuracy and practice in working. The experiments described
in the 365th and following paragraphs, or as many of them as practicable,
should be performed. It is recommended that 25° C. be adopted as the
standard temperature throughout the experiments, instead of 30° C.
Practical directions follow.

380. Apparatus requisite. — Water-bath to hold yeast bottles, sets of
yeast testing apparatus, pneumatic troughs, bunsen burner and automatic
temperature regulator, thermometer, etc.

The water-bath may conveniently consist of a large iron saucepan (or
Scotch "goblet") ; to this should be attached a side-tube, by means of
which the height of the water in the bath may be regulated : for descrip-
tion of this very useful device see "The Hot-Water Oven," Chapter
XXI. Adjust the height of the water in the bath, so that the yeast
bottles, when charged, shall be on the verge of floating, the surface of the
liquid in the bottle will then be about an inch below that of the water in
the bath. During very hot weather, and particularly when working at
the lower temperatures, it is advisable to have a stream of cold water
running through the bath. For this purpose, lead the end of a piece of
bent tube, connected with a water tap, into the bath over the top, on the
opposite side to side-tube before referred to : turn on a small stream of
water through this bent tube, scarcely more than what would cause rapid
dropping from its end. Water will then be continually finding its way
in through this tube, and making its exit through the side-tube : thus
lowering the temperature when necessary. Do not let the stream from
this cold water tube impinge directly on either of the yeast bottles.

The construction and arrangement of the yeast testing apparatus and
pneumatic troughs have already been sufficiently fully described.

381. Automatic Temperature Regulator. — The bath is warmed by
means of a bunsen burner arranged underneath, and, in order to main-
tain the temperature at any desired point, an automatic regulator is em-
ployed. As an unvarying temperature is necessary for several other
chemical operations, a detailed description of such an automatic regulator
is given. There are several of these instruments made and sold under
various names; but for general purposes the following modification, de-
signed by one of the authors, and shown in Fig. 22, is simple and not
likely to get out of order. An improved form of this instrument is now
made by Baird and Tatlpck Ltd.; of London.

TECHNICAL RESEARCHES ON FERMENTATION. 219

The instrument consists of a bulb, a, about 4 inches long, and 24 incn
in diameter ; to this is attached a stem, b b, about a ^4 inch diameter, and
6 inches long. This stem bends over at the top, and is
connected with a U-tube, c d e, l/^ inch diameter, in
which are blown 2 bulbs as figured, / /, about 24 incn
diameter. The one end, c, of this U-tube is closed with
a stopper, g, which is ground in with extreme accu-
racy. From the centre of the bottom of this stopper,
a hole is bored upwards for a short distance, which
hole joins another bored inwards through the side of
the stopper ; this hole, therefore, affords a passage up
through the bottom of the stopper and out through
its side. A corresponding hole is bored through the
side of the neck, c, of the U-tube, so that if the stopper
be turned so that these two holes coincide, a passage is
provided from the U-tube to the exterior; this exit
may be closed at will by slightly turning this stop-
per, g. To the other end, e, of the U-tube, c d e, is
sealed a bent tube, h i j; below the point, e, this tube,
h i j, is made much finer, having its smaller end, j,
3/32 inch in diameter, and ground obliquely as shown
in the figure. Below the joint, e, but as near to it as
possible, an outlet tube, k I, is sealed into the U-tube,
c d c. This completes the regulator; the method of
using the instrument, and its principle, may be con-
veniently described together.

By means of a screw-clamp carried on a retort- '
stand, or any other suitable holder, fix the regulator
upright, and so that the bulb, a, shall be wholly im-
mersed in the water of the bath, and the ends of the
tubes, h and Z, projecting over its side. The regulator
should be perfectly rigid when fixed; the clamp is
best screwed on to the stem, b b. Connect up h by d

india-rubber tubing with the gas tap, and join up I to
the bunsen burner. Partly fill the U-tube, c d e, with
carefully cleaned mercury through c. Turn on the
gas and light the bunsen burner, then continue the
filling of c d e with mercury until the level rises suf-
ficiently high in the limb, d e, to very nearly close the
end of jet j. The quantity of mercury added should
be sufficient to just begin to shut off the supply of gas
to the bunsen; it is evident that then a very slight
rise in level of the mercury would either considerably
diminish or entirely shut off the gas from the burner.
Next heat a little india-rubber sufficiently to liquefy it ;
smear the stopper, g, and its neck with this liquid, taking care to preserve
a clear passage through the hole in the stopper. Then pour some of the
strongest alcohol obtainable, which has been recently boiled, through c,
until the bulb, a, its stem, b 5, and the part of c are completely filled with
"alcohol. Insert the stopper, </, so that the hole through it is open ; the
excess of spirit escapes. It sometimes happens, in filling the instrument
with spirits, that the level of the mercury in the U-tube is disturbed, the
spirits floating on its surface at c, forcing up the level in e sufficiently far
to entirely close the jet, j. Should this happen, the mercury must again

FlG. 22. — Automatic

Temperature

Regulator.

220 THE TECHNOLOGY OF BREAD-MAKING.

be adjusted by removing a small drop by means of a fine pipette. Hav-
ing made these adjustments, the instrument may be regulated for any
desired temperature. Place a thermometer in the bath, so that the height
of the mercury can be easily read and that its bulb does not touch the bot-
tom. Suppose it is wished to maintain the bath at 25° C., turn the
stopper, g, so that the hole is open, and light up the burner. The gas
finds its way through the tubes, h i j k I, in the directions of the arrows.
As the temperature of the water in the bath increases, so does that of the
spirits in a. With a rise in temperature the alcohol expands, and a small
portion finds its way out through the hole in the stopper, g. Watch the
thermometer carefully, and when the temperature stands at about one-
tenth of a degree below 25° C., turn the stopper, g, so as to close the hole
through it. The spirit, in expanding, now finds no means of escape, and
therefore drives down the mercury in c d, causing a corresponding rise in
d e: the consequence is that the jet, j, is either wholly or partly closed,
and the gas either completely or partly shut off from the burner. The
bunsen used should have a cap of fine wire gauze fastened on to it, so as
to prevent its lighting at the bottom when the flame is turned very low.
A small pin-hole burner should be fixed to the bunsen, and fed from an
independent supply, so as to re-light it should the regulator turn it com-
pletely out ; this "pilot" burner must be turned down so as to only give a
flame about % inch high, and should not be able to appreciably warm
the bath. The regulator will at first most likely shut off the gas com-
pletely ; the bath will then cool slightly, and as the alcohol in a contracts,
the level of the mercury in d e will fall, and so the jet, j, will once more
be opened, and a passage of gas to the burner permitted. With this regu-
lator properly set, the temperature keeps between two extremes that after
a short time closely approach each other ; in fact, the mercury so adjusts
itself as to partly close the aperture j, allowing just sufficient gas to pass
to keep the bath at a constant temperature. The end of ,; is cut obliquely
in order to prevent the mercury sticking to it, and so acting irregularly.
Alcohol is used in a instead of air, because it is not affected by changes
of atmospheric pressure ; when temperatures above the boiling point of
alcohol are required, the instrument must be used with air, or else some
liquid having a sufficiently high boiling point. Alcohol is preferable to
water, because it has a much higher co-efficient of expansion, that is, for
an equal rise in temperature it expands much more. With the instru-
ment set as described, it should maintain the temperature closely at 25°
C. ; if it should be found to be somewhat higher, the instrument may be
made more delicate by adding a very little more mercury, or it may be
shut off somewhat earlier ; thus, if it be found to give a constant tempera-
ture 0.4° over that at which the stopper, g, is shut off, then all that is
necessary is to always shut off at 0.4° below any temperature that may be
required. Should the temperature be too low, it may be raised slightly
by carefully turning the stopper, g, momentarily, until the slightest drop
of spirits oozes out; if the temperature is too high, the bath must be
cooled down, and again regulated on the rising temperature. If the bath
is required to be used for several days at the same temperature, all that
is requisite is to turn off the gas when the day's work is done ; as the bath
cools, the mercury rises in c d through contraction of the alcohol ; the
bulbs, / /, are provided in order to allow of this rise without its altering
the regulator. When the bath is next required, simply turn on the gas, and
the regulator, without any attention, will maintain the temperature at the
point for which it was adjusted. The advantage of this form of regu-
lator is that it keeps perfectly constant for a very long time, as there are
no parts to shift, or places from which leakage may occur ; the stopper,

TECHNICAL RESEARCHES ON FERMENTATION. 221

g, smeared with melted india-rubber, is perfectly air-tight. Grease will
not answer as well as the india-rubber, as it is dissolved by the alcohol.

382. Method of Testing. — To make one or more experiments pro-
ceed in the following manner : — First, carefully enter in the notebook the
particulars of each experiment, and number them : place corresponding
numbers on the bottles. Regulate the water-bath at the desired tempera-
ture, and place in it a flask containing sufficient water for the experi-
ments that are to be made. Having cleaned the whole apparatus, arrange
in order the generating bottles required, and weigh out and introduce
into them the yeast mixture or other substance to be fermented. Next
weigh the yeast, taking care that a good representative sample is ob-
tained. With pressed yeast cut a thin slice off the middle of the slab,
avoiding dry and crumbling fragments. Brewers' yeast must first be
well stirred, and then weighed out in a counterpoised dish. Break up
the pressed yeast carefully in a small evaporating basin, with some of the
water which has been raised to the right temperature ; for this purpose an
india-rubber finger stall placed on the finger is useful. Pour the yeast
and water into the bottle ; rinse the basin with the remainder of the six
ounces of water. As rapidly as possible introduce each sample of yeast,
to be tested, in its respective bottle in precisely the same manner. Hav-
ing introduced the yeast, yeast mixture, or other substance, and water,
into the respective bottles, gently shake each bottle so as to thoroughly
mix the ingredients; then tightly cork each bottle, and arrange the ap-
paratus as shown in Fig. 21, given at the commencement of the chapter.
Remove the glass stopper at d, and suck out the air from the apparatus
until the water or brine rises in the jar, /, somewhat above the zero, then
again insert the glass stopper. Pinch the india-rubber tubing on one side
of d so as to make a slight opening, and thus permit air to enter ; in this
way lower the liquid in / until its level exactly coincides with the zero.
Perform this operation as rapidly as possible with all the apparatus being
used, and note the exact time in the notebook. As the fermentation pro-
ceeds, the surface of the liquid in the jars will become lower, and in this
way a measure of the amount of gas yielded is obtained. At the end of
every half-hour or hour from the commencement, read off the volume of
gas, and enter the same in the notebook. When the jars are nearly full of
gas watch them carefully, and as soon as the 100 cubic inches, or 500 c.c.,
mark is reached, withdraw the plug at d, blow into the jar for a few sec-
onds so as to displace carbon dioxide through the bottom, and then suck
out the air until the liquid again rises to the top of jar, re-insert the plug,
and rapidly adjust the surface of the liquid to the zero. This operation
should last only a very short time, and does not practically affect the
results that are being obtained. The readings may be taken for from,
say, two to six hours ; or, if wished, until the action ceases. These direc-
tions apply equally to the ordinary use of the apparatus for testing the
strength of yeasts. With the alternative displacement apparatus, the
earlier part of the procedure is the same. The difference in the mode of
collecting and measuring the evolved gas has been already sufficiently
explained.

383. Preparation of Yeast Mixture. — Tt is essential that the sub-
stances composing this mixture be thoroughly mixed. The following is
'the best mode of procedure. First, dry the substances at a gentle heat

(100^ C.). In the laboratory this is done by placing them in a hot-water
oven ; then finely powder each in a mortar, and weigh out the right quan-
tities. Then thoroughly mix the first four ingredients; afterwards add
the fifth, and again mix ; then add the sugar little by little, mixing be-
tween each addition. In this way an equal composition of the mixture

THE TECHNOLOGY OF BREAD-MAKING.

throughout is assured. Coarse crystalline coffee sugar is almost chem-
ically pure ; failing this, the best loaf sugar may be used.

The pepsin necessary for the experiments may be obtained from the
chemist.

The malt wort may be prepared by infusing coarsely ground malt
with ten times its weight of water for two hours at 65° C. : it is then
nltered and diluted down with water until at the right density.

In experiments with flour, the flour and part of the water should first
be placed in the generating bottle, and thoroughly shaken before the
addition of yeast.

The starch is gelatinised by allowing it to stand in a small beaker,
with some water, for about five minutes in the hot water-bath, stirring
thoroughly meanwhile.

The experiments on flour infusion, in which the sugar is determined
before and after the fermentation, are very important, but had better be
postponed until the student has proceeded with his studies of analysis.

In the temperature experiments the tests at the same temperature
should be made on the same day, and the complete series with as little
interval as possible between.

In addition to the experiments described in this chapter, many others
will suggest themselves to the practical baker : these he may arrange for
himself, and use the yeast apparatus as a means of measuring the evolu-
tion of gas, under any conditions that may be of interest to him. The
student will do well, in addition, to perform the following series of tests.

384. Keeping Properties of Different Yeasts. — Procure samples as
fresh as possible of different pressed, brewers', and patent yeasts. Test
immediately after procuring them ; then store in a cool cellar, and test
each sample on successive days until they are capable of setting up little
or no fermentation. To ensure perfect accuracy it is well to keep each
sample of yeast in a weighed vessel ; any loss by evaporation may then in
the case of the liquid yeasts be made up each day by the addition of dis-
tilled water. The pressed yeast may be kept in a stoppered bottle, or,
preferably, the portion for each estimation should be taken from the in-
terior of the mass ; as a check, moisture should then be estimated in the
yeast each day.

385. Use of Testing Apparatus without Temperature Regulator. — In

the foregoing descriptions given it has been directed that the yeast bottle
stand in a water-bath regulated by an automatic temperature regulator.
While such an arrangement is extremely useful, it is not absolutely neces-
sary. For actual bakehouse use the following plan answers well. Select
a place somewhere near the oven where the temperature is pretty con-
stant, and, if possible, between 70° and 80° F. Arrange on a shelf,
clamped to the wall, a saucepan sufficiently large to take the yeast bottles,
and fix the trough for the graduated jar in position. The saucepan will
have to be raised sufficiently high by means of blocking ; this should be
properly done at the outset, as the apparatus should remain there per-
manently. When about to use the apparatus, first of all fill the saucepan
with water at the desired temperature F., and then make the estimation.
A warm place being chosen, the water in the saucepan will not fall very
much in temperature during the time necessary for carrying out the ex-
periment. This method of using the apparatus applies more particularly
to yeast testing than to the more delicate experiments described in the
preceding pages.

CHAPTER XII.
MANUFACTURE OF YEASTS.

386. For baking purposes three commercial varieties of yeast are
employed, namely, Brewers', Distillers' Compressed, and "Patent"
yeasts. These latter may again be subdivided into malt and hop yeasts as
used in England, and the Scotch flour barms. The superior quality of
the distillers ' compressed yeast has led to its now being used to the almost
entire exclusion of the other kinds. Still there are districts where dis-
tillers' yeast cannot be obtained, and therefore bakers still have to manu-
facture their own "patent" yeast. Descriptions follow of how these dif-
ferent types of yeast are manufactured.

BREWERS' YEAST.

387. In the chapter on Fermentation an account is given of the ap-
pearance of an actively fermenting tun of brewers' wort. The brewer
first treats his malt with water at a temperature of about 65° C. for about
two hours, more or less; during that time the starch of the malt is con-
verted into dextrin and maltose. The liquor is then allowed to drain
from the grains, or husks of malt, and is transferred to a copper in which
it is boiled with hops : the hops are removed and the wort rapidly cooled,
either by being exposed to the air in shallow open coolers, or poured over
a specially arranged apparatus, consisting of a series of pipes through
which cold water is passing, and which is termed a refrigerator. This
cooling must be done as rapidly as possible, as a temperature of about
30° C. is particularly suited to the rapid growth and development of
disease ferments. On the wort being cooled to 18 or 19° C. (65° F.),
about one one-hundred and fiftieth part of its weight of yeast from a
previous brewing is added. Fermentation sets in, and after a time yeast
rises to the surface, and is skimmed off. The first is rejected because any
lactic ferments or other bacteria that may be present are, from their
small size, floated up to the surface with the yeast on its first ascent. At
the time when the fermentation is most active and vigorous, the best
yeast is being produced. As fermentation slackens, cells are thrown to
the surface which have been grown in a comparatively exhausted me-
dium. Such yeast is weak, and possesses less vitality. For their own
pitching purposes, the brewers reserve the middle yeast. Bakers who use
brewers' yeast should be supplied with that equal in quality to what the
brewer himself uses for starting fermentation. The yeast, when skimmed,
should be stored in shallow vats, so as to admit of free access of atmos-
pheric oxygen,

In some breweries the beer is allowed to finish its fermentation in
large casks, arranged so that the bung-hole is very slightly on one side :
the yeast slowly works out of the bung-hole and flows in a shallow stream
down the outside of the cask until it reaches the bottom, when it drops
in a gutter arranged to receive it. A number of these casks are usually
arranged side by side, and connected together by a pipe at the bottom;

224 THE TECHNOLOGY OP BREAD-MAKING.

they are consequently technically termed "unions." The one gutter re-
ceives the yeast from the series of unions and conveys it to the proper
receptacle. The yeast from these unions is found to make far better
bread than that skimmed from large fermenting1 tuns. The reason is that
the yeast gets thoroughly aerated during its flow down the side of the
cask. For baking purposes, the thorough aeration of yeast is essential.

388. Employment of Brewers' Yeast. — Brewers' yeast is used in the
production of what is called ' ' farmhouse ' ' bread : it is supposed to pro-
duce a sweeter flavoured loaf than do other varieties. On the other hand,
brewers' yeasts darken the colour of bread. For reasons explained in the
preceding chapter, for bakers' purposes, brewers' yeast is weak, and if
used alone must be employed in considerable quantity. Almost invari-
ably a potato ferment, or some substitute therefor, is employed together
with brewers' yeast. It is apt when freely used to impart a bitter taste
to the bread : this may be in part obviated by washing the yeast, but even
then it is exceedingly difficult to remove the bitter taste. Particularly
in summer time brewers' yeast is found to be very unreliable and un-
certain in its actions. Even those bakers who prefer brewers' yeast,
when they can procure it good, find themselves compelled to resort to
compressed yeast during the hot summer months.

In selecting a brewers' yeast for bakers' purposes, those breweries
should be avoided where large quantities of sugar or other malt substi-
tutes are used instead of malt itself. Such brewing mixtures contain a
deficiency of appropriate nitrogenous matters, and, although the result-
ant beer is sounder, and better meets the present requirements of the
public, the yeast produced is, from the bakers' standpoint, weak and im-
poverished through ill nourishment.

389. Microscopic Examination of Yeast.— This operation requires a
fair amount of experience before a trustworthy judgment can be formed.
For the examination of yeast under the microscope, it should be diluted
with water until so weak as simply to give a milky appearance to the
water. A minute drop is then put on a slide, over which a cover is gently
placed. In microscopically examining yeast, there are two distinct points
to be observed : first, the presence or absence of disease ferments, bacteria,
etc. ; second, the appearance of the yeast cells themselves. For satisfac-
tory work, a power of six vor eight hundred diameters is necessary : the
objective must be a good one, giving not only magnification, but also clear
and accurate definition. It is a good plan to use a microscope in which
several objectives are fastened to one "nose-piece," so that the powers
may be changed instantaneously, without the trouble of unscrewing the
one objective and then replacing it by another. Working with such an
instrument the yeast may first be examined with a magnification of
about 440 diameters, and then, having seen the aspect of a fairly large
field, a few typical cells may be observed more closely with a magnify-
ing power of about 1000 diameters.

First, with regard to the presence or absence of foreign ferments. The
fewer of these the better the yeast. A yeast for bakers' purposes needs
to be judged by a somewhat different standard to that adopted by the
brewer. To the latter, the presence of lactic or butyric ferments or other
disease organisms means that, during the period the beer is stored before
it is all consumed, there is ample time for changes to go on which will

MANUFACTURE OF YEASTS, 225

result in either a marked deterioration or spoiling of the beer. But if
this change does not make itself perceptible until, say, two or three weeks
have elapsed, it follows, as bread is fermented, baked and eaten within
about three days, that under ordinary circumstances such changes can-
not take place in bread. This explanation is necessary, because it is well
known as a matter of fact that many bakers do succeed in producing
very good bread, who use a yeast in which there is frequently an abund-
ance of foreign organisms. It will in such cases, however, be found that
they take special precautions which serve to prevent an injurious action
of these during fermentation. Summing up, yeasts may be used by
bakers which could not possibly be employed by the brewer, because the
fermenting process of the former is so much shorter; nevertheless an
excess of disease ferments may set up injurious action even during the
time of panary fermentation unless special precautions are taken. It is
consequently safely laid down that the fewer of these foreign organisms
the better. The presence or absence of disease ferments affords a valuable
indication as to the previous history of the yeast, apart from their own
specific action on the dough. A yeast largely contaminated with foreign
organisms has been badly made: unsound malt will very likely have been
used for its manufacture, and the whole process of fermentation con-
ducted in dirty vessels. As in a brewers' yeast the presence of disease
ferments tells us this of its previous history, the yeast should be con-
demned, because, when carelessly produced under such unfavourable
conditions, the yeast itself is likely to be unsound, or at least very un-
certain in its quality.

Secondly, with reference to the yeast cells themselves, the actual
shape of the cells will vary with its origin. Ordinary English brewers'
yeast consists of round cells, but Burton yeast is oval ; so also is that in
other districts where very hard water is used. With any yeast the cells
should be about equal in size; not irregular, with some very large and
others small. The cells should be isolated, or at most only attached in
pairs : where they occur in large colonies, the yeast is too young, and has
not had time to thoroughly mature. The cells should appear plump and
not shrunken. The cell-walls should be of moderate thickness: if very
thin the yeast is too young and has not attained maturity; on the other
hand, very thick integuments denote an old, worked out yeast. Thin
cell-walls may also be due not only to very young yeast, but also to the
yeast being over kept long enough for the breaking down of the walls to
have commenced : under these circumstances the protoplasm of the in-
terior of the cells is seen to be broken down and frequently exhibits a
"Brownian" movement. If in this condition, the yeast is far gone, and
will be found weak and exhausted for bread-making. As in this opera-
tion yeast does not bud or reproduce, but does its work in virtue of the
energy and vitality of the original cells introduced, it is in the highest
degree important that these cells should be strong, healthy, and, as far
as is possible, in full maturity; when in this condition, the contents of the
cells should show slight granulations. Each cell should have one, or at
most two, vacuoles ; but when placed in a drop of clear beer wort on the
slide, the fluid should rapidly penetrate the cell-walls, causing the con-
tents to become lighter, and the vacuoles to disappear. These changes
occur but slowly in old cells that have been worked for a long time.

In Plate II., Chapter IX., illustrations have already been given of
different varieties of yeast employed by the baker. The drawings of

226 THE TECHNOLOGY OF BREAD-MAKING.

brewers' yeast for this plate were made in the summer, and represent
samples of brewers' yeast during practically the hottest weather of the
year. The specimens marked a and b were taken from two London
samples of yeast, as sold to London bakers by yeast merchants. A con-
siderable number of disease ferments are present in both, marking them
as being in an unhealthy condition. It is to be feared that often suffi-
cient care is not taken for the storage and preservation of yeast, espe-
cialy during the hot weather, by those who collect brewers' yeast for
redistribution among bakers. For purposes of comparison, some yeast was
obtained from a Brighton brewery: this is figured in section c. It was
found to be far away purer than either of the London samples; one or
two bacteria are shown in the sketch, but there were several microscopic
fields that contained no foreign ferments whatever. In general aspect,
the cells of yeast c were firmer in outline, the walls being thicker while
the interior matter showed more distinct and darker granulations. It
should be added that in these drawings the estimated magnification is
only approximate. In every case where it is wished to ascertain exact
dimensions, the eye-piece micrometer should be called into requisition.

MANUFACTURE OF COMPRESSED YEASTS.

390. These yeasts are now so widely and successfully used that an
account of their origin and mode of manufacture claims a place in this
work. They are not, as has been stated, low or bottom yeasts of lager
beer fermentation, but are distillers' yeasts, and are formed as the
principal product in the manufacture of spirits from malt and raw
grain ; the spirits being used in the manufacture and treatment of
liqueurs, perfumes, wine, and brandy. The manufacture can only be
successfully conducted on a very large scale, and cannot be imitated by
the baker who simply wishes to make yeast for his own consumption.

Being desirous of giving as accurate an account as possible of some
of the most advanced and scientific methods of manufacturing com-
pressed distillers' yeast for bakers' purposes, the authors put them-
selve's in communication with the directors of the Netherlands Yeast
and Spirit Manufactory of Delft, Holland. In response they received
an invitation to visit the factory and personally inspect the processes of
manufacture. The following description is compiled from information
thus gained, supplemented by data furnished for the purpose by the
directors of. the factory.

The operations of yeast manufacture resolve themselves into four
groups which may be classified under the following heads : —

1. Treatment of the raw grain, including the malting of barley.

2. Mashing and preparation of the wort.

3. Fermentation.

4. Collection and packing of the yeast.

(1) Treatment of the raw grain. The grain required is brought by
barge and directly discharged by elevators into granaries provided for
that purpose. For yeast and spirit manufacture, there must be a suffi-
ciency of appropriate protein matter, and also of carbohydrates. Brew-
ing sugars are inadmissible, because by unduly reducing the proportion

MANUFACTURE OF YEASTS, 227

of protein matter, they would cause the production of an unhealthy and
weak yeast. The cereals most commonly used are barley, rye, and maize.
Rice is not well fitted for yeast production, because of its comparatively
non-nitrogenous character. The grain on arrival is first subjected to such
cleaning operations as may be necessary, including gravity separations of
lighter and heavier foreign matter, and then a thorough washing. The
cleaned grain is next conveyed to the mill, where the rye and maize are
reduced to a moderately fine meal by roller mills. The barley is first
converted into malt. In order to effect this object, two separate systems
are in use.

Ordinary Malting System. On this, known also as the old system,
the barley is first soaked in water of a suitable temperature in large
tanks. When sufficiently moistened, which operation may take from fifty
to sixty hours, the grain is transferred to the malting floors and there
allowed to germinate or sprout. As previously explained, this treatment
destroys the parenchymatous cell- walls, and thus renders the interior of
the grain more readily amenable to diastatic action. At the same time
diastase itself is developed, and the nitrogenous matter rendered more
soluble. When germination has proceeded sufficiently far, the malt is
dried in kilns. The malt kilns are conical buildings in which the grain is
laid on perforated plates. At the base the source of heat is fixed and con-
sists of a species of grate in which the fuel is consumed. By means of a
fan placed at the top of the kiln, a current of air is continually drawn
through the grain, which is thus effectually dried.

Pneumatic Maltings. On this system the malt floors are replaced by
revolving drums, which are charged with barley. Air saturated with
water is led into the drums and thus moistens the grain. Germination
proceeds under efficient control, and when it has proceeded sufficiently
far, the malt is conveyed to kiln-drums and there dried by means of
heated air.

Whether prepared by the old or floor-system, or pneumatically, the
finished malt is ground to meal.

(2) Mashing and preparation of the Wort. The meal of the raw
grains, maize and rye, is treated by boiling with water in large boilers by
the action of high pressure steam. When thoroughly cooked the mixture
of grain and water is cooled and passed into the saccharification tuns,
where the malt is added. Mashing then proceeds until the hydrolysis of
the whole of the carbohydrates to maltose is as complete as possible.
While the brewer finds it advantageous to retain dextrin and some
amount of malto-dextrins in his wort, the distiller has practically no use
for anything except the maltose, and so pushes the enzymic action to its
utmost limit. At the close of the mashing the wort requires to be reduced
to the fermenting temperature. It is important that this be effected as
rapidly as possible, as the intermediate cooling stage is one at which the
wort is most susceptible to disease fermentation. For this purpose, re-
frigerators are employed, of which there are several patterns. One of
the most convenient is that originally devised by Lawrence, in which a
copper pipe is bent again and again on itself so as to form a vertical rack,
with connected horizontal pipes in a series one over the other. Cold
water passes through the pipe, and the wort is allowed to flow over the
outer surface, thus being rapidly cooled and at the same time aerated.
The cooled wort is then conveyed to the fermentation vats, where it
awaits the next stage in the process of manufacture.

228 THE TECHNOLOGY OP BREAD-MAKING.

(3) Fermentation. Of late years, the necessity of starting fermenta-
tion with a pure yeast culture has been more and more fully recognised.
As explained in a previous chapter, paragraph 330, certain races of yeast
are specially adapted for dough fermentation. For the preparation of
these a specially equipped chemical and biological laboratory is provided.
By appropriate methods, such yeasts are cultivated from a single cell
until an appreciable quantity is obtained. In larger apparatus con-
structed on the principle of the Pasteur flask, a more abundant growth of
the pure yeast is obtained, and this is used in starting the fermentation
of the wort. The finished yeast is similarly controlled by tests as to pur-
ity and strength made in the laboratory ; and as occasion arises, the pitch-
ing yeasts are reinforced by addition or substitution of new pure culture
yeast. The firm employs two distinct methods of fermentation, known
respectively as the "Vienna7' and the "Aerating" systems.

Vienna System. The first step in this system is the preparation of
what, in the bakers ' phraseology, may be termed a ' ' ferment, ' ' that is, a
preliminary fermentation of a relatively small proportion of the grain.
Malt and rye are taken together for this purpose, and mashed at a con-
venient temperature, so as to obtain as complete a transformation as pos-
sible of the starch into maltose. The mash thus produced is allowed to
stand in the tubs at a temperature most suitable for the production of
lactic acid, that is, about 35° C. The lactic acid germs on the skin of the
malt rapidly develop, and a marked acidulatioii ensues. This is a most
interesting step in the fermentation, and while the immediate result is
the production of lactic acid, yet its ultimate effect is the prevention of
development of the lactic acid ferment. This organism is peculiarly
sensitive to the effect of its own product, and as little as 0.15 per cent, of
lactic acid added to a mash is sufficient to prevent lactic fermentation
taking place, although, on the contrary, if lactic fermentation be once
started, it will proceed until something like 1.5 per cent, of lactic acid has
been formed. The reason of this inhibitory effect is that the addition of
lactic acid is a deterrent not only to lactic fermentation, but also to the
multiplication of lactic acid bacteria, so that, by its addition in the earlier
stage, any reproduction of these organisms, and consequently any but the
smallest possible production of lactic acid, is prevented. This first de-
velopment of lactic acid, then, in what may be for convenience called the
"ferment," serves to check undue development of acidity in the main
fermentation. It also further serves the useful purpose of peptonising
and otherwise breaking down the nitrogenous matter of the grains in the
mash, so as to render them available as yeast foods.

The unfiltered wort, containing the "grains" or husks of the malt
and the raw grains, is treated at the desired temperature with pitching
yeast in the form of the ferment already described. Air is driven through
the wort by mechanical means in order to secure thorough aeration, and
this operation is repeated from time to time as fermentation proceeds, as
found necessary. The grains contained in the mash rise to the surface
and there act as a non-conductor of heat. In from three to four hours
after pitching, the carbon dioxide forces itself up in a sort of cauliflower
head through the grains and "breaks." The grains are removed by a
skimming operation, and fermentation is allowed to continue for from
ten till twelve hours from the commencement, and then the process of
skimming off the yeast is commenced. The skimming is effected by means
of a long arm which sweeps right round the vat and collects the yeast

MANUFACTURE OF YEASTS.

229

from the top into an inverted cone, which from its shape is called a para-
chute. The alcohol from the fermentation remains in the wort, which
liquid is distilled, and the alcohol thus obtained in a concentrated form.
The residual liquid, together with insoluble matter consisting principally
of fibre from the grains, is prepared for, and used as, cattle-food. The
following figure, No. 23, shows diagrammatically the "Vienna" method
of yeast manufacture.

Barge
lo

| Rye, Maize

V. J

Bar

Malt

ley !
ings

Mill

Wort

Ferme

ntation

Yeast,
cleansed,
washed,
pressed.

Spirit
by
distillation.

Wash
(cattle-
food).

Carbon
dioxide
in air.

FlG. 23. — Vienna System of Yeast-Making.

Aerating System. By this method, the wort is filtered from the grains
before fermentation. The pitching or starting yeast is added to the clear
wort, through which a strong current of air is forced. The yeast as pro-
duced does not rise to the surface of the fermenting wort, but sinks and
forms a deposit on the bottom of the vats or tuns. At the close of the
fermentation, the supernatant clear liquid contains the alcohol, and is
removed for purposes of distillation. The residual liquid, together with
the filtered grains, is prepared for use as cattle-food. The course of the
various operations of the "aerated" system is shown diagrammatically
in Fig. 24.

Wort

I
Filtration

Residue

Deposit

of
yeast.

Fermentation of filtered
wort with supply of air

Clear liquid from

which through

distillation

Carbon
dioxide
in air.

Alcohol.

-Wash (cattle-food).

Clear liquid
wash

FlG. 24. — Aerated System of Yeast-Making.

230 THE TECHNOLOGY OP BREAD-MAKING.

(4) Collection of the Yeast. The yeast, whether skimmed on the old
system or deposited on the new, has to be cleansed. For this purpose it
is mixed with water and passed through a series of sieves (20 holes to the
square millimetre). The sieves retain any grains and allow the yeast to
pass through. The yeast is then washed by decantation, and allowed to
settle. Any minute particles which have passed through with the yeast,
being lighter than water, rise to the surface and are thus separated. The
deposited yeast, still containing much water, is passed through centri-
fugal machines by which much of the water is removed. The thick yeasty
liquid is next pumped into filtering presses and thus obtained in the
familiar dry state. The yeast is now ready to be packed, and for the
British market is filled into jute bags, which are mechanically pressed
into block shape and finally branded with the name and description of the
manufacturers. As thus prepared "N.G. and S.F." yeast consists of
pure yeast cells of a specially selected type. It is practically free from
foreign or "wild" yeast and also from bacteria.

The secrets of successful yeast manufacture are raw materials of the
highest quality, absolute cleanliness during the whole process of manu-
facture, and finally eternal vigilance. This last is the invariable price
of excellence in yeast. Cleanliness of vessels is ensured by washing and
scalding with live steam. As an additional precaution, all vats and tuns
are periodically treated either with sulphurous acid or bisulphite of lime,
both of which are absolutely harmless and most efficient antiseptics. All
floors are kept clean by continual rinsings with water, the pathways con-
sisting of raised planks, under which the water passes freely. In the
yeast-cleansing rooms, where, being in the quiescent stage, the risk of
contamination is greatest, the floors and walls are continually treated
with solution of chloride of lime, thus most effectively destroying all dis-
ease germs. Such is in outline the process of manufacture employed in
the production of one of the most widely used and highest character
yeasts imported from the continent into the United Kingdom.

391. Characteristics of Compressed Yeasts. — A good sample of com-
pressed yeast has the following characteristics — it should be only very
slightly moist, not sloppy to the touch ; the colour should be a creamy
white ; when broken it should show a fine fracture ; when placed on the
tongue it should melt readily in the mouth; it should have an odour of
apples, not like that of cheese ; neither should it have an acid odour or
taste. Any cheesy odour shows that the yeast is stale, and that incipient
decomposition has set in.

Viewed under the microscope, compressed yeast consists of somewhat
smaller and more oval cells than those of brewers' yeast. In the best
varieties are found no, or only traces of, foreign ferments ; other brands
contain them in large numbers. The yeast cells themselves should pos-
sess the same characteristics as have already been described while treat-
ing brewers' yeast. A drawing of compressed yeast is given in Plate II.
The cells were found, on measurement, to have the following dimen-
sions—

Longer diameter . . . . 10 mkms. = 0.0004 inch.

Shorter diameter .. .. 7.6 mkms. = 0.0003 "

Diameter of round cells . . 7.6 mkms. = 0.0003 "

The sample in question was remarkably free from disease ferments,
one only being seen in the field sketched, while several fields showed no
foreign organisms whatever. The granulations show very distinctly. The
yeast in question was a very pure one, and yielded exceedingly good re-
sults when subjected to strength tests.

MANUFACTURE OF YEASTS, 231

In general character, the compressed yeasts are steady and trust-
worthy in their action; they produce sweet, well-flavoured breads, to
which, when in good condition, they do not impart any yeasty taste.
Their good qualities stand out most distinctly in summer time, when
other yeasts so frequently fail entirely to produce a satisfactory loaf of
bread. Their being produced in such large quantity causes their manu-
facture to be entrusted to men who bring the highest skill that practical
experience and science can furnish to bear on every detail of manufactur-
ing processes. The many good properties of distillers' compressed yeast
have led to its almost universal employment where obtainable, in place
of other kinds of yeast.

"PATENT," OR BAKERS' HOME-MADE YEASTS.

392. As already explained, these are now largely replaced by com-
pressed yeast. But there are still districts where this is unobtainable,
and where bakers must perforce prepare their own yeast. It is hoped
that these will find the following paragraphs of service. Bakers' home-
made yeasts may be divided into two varieties — malt and hop yeasts as
used in England, and flour barms as employed in Scotland.

393. Bakers' Malt and Hop Yeasts. — These consist essentially of
small mashes of malt and hops, fermented either by the addition of some
yeast from a previous brewing, or allowed to ferment spontaneously : the
latter is known as "virgin" yeast. The hops present tend to prevent
disease fermentations, as their bitter principle is inimical to bacterial
growth and development. In virgin yeasts, particularly, it is necessary
to use hops largely, and also plenty of malt ; as lactic and other foreign
ferments flourish far better in a dilute saccharine medium than in a
stronger one. The reader will already be familiar with the general out-
lines of the fermentation of a hopped wort : as an introductory to direc-
tions for the preparation of patent yeast a careful study of the following
experiment, made by one of the authors, will be of service. The student
will do well to repeat the experiment for himself : sufficiently full direc-
tions are therefore given to enable him to do so.

Take two quarts of water and half an ounce of good hops; set these
to boil in a large glass flask or other clean vessel ; boil for half an hour, and
then cool down to 65° C. (149° F.). Scald out a large glass beaker, or
failing this, a vessel of copper or enamelled ware ; wood will not answer
well. Weigh out 12 ounces of ground malt and mix with the hops and
water in the beaker. Maintain the whole at a temperature of from 65°
to- 70° C. (149° to 158° F.) for two hours; this may be done by standing
the beaker in a hot water-bath. By the end of this time the saccharifica-
tion of the malt should be complete. Have ready another glass vessel per-
fectly clean and scalded. Strain the wort, from the grains, through
calico into this second clean vessel ; cool down as rapidly as possible to
25° C. (77° F.). In the meantime have ready a large water-bath, care-
fully regulated at a temperature of 25° C. by means of an automatic
temperature regulator. Also thoroughly clean and scald six glass beakers
of about 16 ounces capacity, and have ready glass covers for each beaker.
Pour the filtered wort into these beakers, placing about an equal quan-
tity in each. Label both beakers and covers with numbers from 1 to 6.
Let No. 1 remain in the condition of plain wort; to No. 2 add 1 gram
(15 grains) of good brewers' yeast; to No. 3 add 0.7 gram (10 grains)
of good compressed yeast. Prepare Nos. 4, 5, and 6 in exactly the same
manner, so as to form a corresponding set. Cover each beaker with its
glass cover and stand the whole in the water-bath. Let the first series

232 THE TECHNOLOGY OF BREAD-MAKING.

remain undisturbed, but aerate those of the second by, some five or six
times a day, pouring* the contents of each beaker into a clean empty
beaker, and then back again several times. After each aeration replace
the covers and stand the beakers again in the bath.

After about 24 hours examine each sample under the microscope. In
the authors' experiment, No. 1 at that time, and also after three days,
contained no yeast, while the whole liquid was swarming with bacteria ;
a slight froth had formed on the top. A portion of this wort was then
sown in Pasteur's Fluid (Yeast Mixture), and again examined at the
end of three hours, being maintained for that time at 26.6° C. (80° F.) ;
it still contained no yeast. The student is recommended to employ a
fermenting temperature of 25° C. This result was obtained not merely
once, but also in a complete duplicate series of experiments. The mode
of procedure is the same as that employed by those bakers who are in
the habit of allowing their yeast to ferment spontaneously — except that
chemically clean vessels are employed throughout. Another interesting
point is that although yeast was being used in the room at the time, and
even beakers, containing actively fermenting worts, were standing side
by side in the same water-bath, yet the loosely fitting glass covers were
sufficient to prevent the entrance of yeast cells or spores into beaker No.
1 from external sources.

Within twenty-four hours after being pitched, each sample was thus
examined under the microscope. Nos. 2, 3, 5, and 6 were in a state of
vigorous fermentation.

At the end of three days the yeasts were again examined, having been
maintained at a temperature of 26.6° C. (80° F.) for this period.

After this lapse of time the fermentation had very nearly ceased. In-
stead of observing a field covered with perfectly new cells, the majority
of which were actively budding, the aspect of the yeast is far more
quiescent. Here and there an old cell is still to be seen. The new cells,
however, have begun to assume somewhat the same appearance. In some
of them vacuoles are to be seen, but only in a few. All the cells are more
or less filled with faint, but distinct, granulations.

There is at the end of this time a marked difference in appearance be-
tween the pressed as compared with the brewers' yeast. The vacuoles
show much more distinctly, so also the interiors of the cells are much
darker.

Particular attention is drawn to the fact that whereas samples Nos. 1
and 4, which were allowed to ferment spontaneously, swarmed, after
three days, with bacteria; the whole of the other four specimens which
had been sown with yeast showed, on observation, no foreign ferments
whatever. It is possible that some may have been discovered by careful
and systematic examination, but the main point is that, compared with
Nos. 1 and 4, they were to all intents absent. Now, save by the addition
of yeast, all the samples were exposed to precisely the same conditions ;
the only conclusion to be drawn is that the presence of yeast growth is
more or less inimical to that of foreign or disease ferments. The practical
lesson to be learned from this is that bakers who prepare their own malt
and hop yeasts, by sowing them with small quantities of pure yeast, not
only induce a healthy growth of pure yeast ferments, but also retard the
growth and development of disease ferments. The most probable ex-
planation of this lies in the fact that, under the conditions of the experi-
ment, there is a more or less acute struggle for existence between the two
organisms, and yeast, being the more vigorous and hardy, grows and
developes at the expense of the bacteria. (Compare with the views ad-
vanced in paragraph 377.)

MANUFACTURE OF YEASTS, 233

After standing some time the vessels of yeast were covered with a film
of Mycoderma cerevisice; a growth which has been described in Chapter
IX., and illustrated in Fig. 15.

Nothing has as yet been said about the difference between the series
of beakers that were allowed to remain undisturbed, and those which
were aerated from time to time. Before doing so it would be well to
describe the results of determining the amounts of gas evolved by the
respective samples on being tested in the yeast apparatus. At the time
these experiments were made, the older form of apparatus was employed,
in which the gas bubbled up through the water.

After standing three days these samples of yeast were tested by being
inserted in the testing apparatus. Half an ounce of yeast mixture was
taken, to this was added six ounces of the thoroughly stirred yeast. At
the end of three hours the following quantities of gas were found to have
been evolved from each : —

Cubic Inches.

No. 1. Spontaneous ferment, undisturbed . . . . 3.1

No. 2. Pitched with brewers' yeast, undisturbed . . 16.8

No. 3. Pitched with pressed yeast, undisturbed . . 35.6

No. 4. Spontaneous ferment, agitated . . . . 3.7

No. 5. Pitched with brewers' yeast, agitated . . 18.6

No. 6. Pitched with pressed yeast, agitated . . . . 42.8

The experiment shows very clearly that the agitation has resulted in
the yeast being in every instance more vigorous in action. In the case
of the spontaneous ferment there was a distinct, though slow, evolution
of gas. The samples pitched with the pressed yeast had, by the by, more
than twice the capacity for causing the evolution of gas than had those
which were pitched with brewers' yeast. It is plain that agitation in
some way increases the vigour of yeast. Those students who have care-
fully read the section of Chapter IX. dealing with the influence of
oxygen on fermentation, will clearly understand the cause of such in-
crease in fermentative power. •

When yeast is being made by bakers from malt and hops, although
fermentation goes on, it is not the fermentation, as such, that is wanted.
The change required is not the production of beer, but the growth and
development of yeast; hence the operation should be so conducted as to
induce the greatest yield of yeast in the most active and vigorous form.
Aeration, or "rousing," as it is often termed, is, as will now be well
understood, of considerable service. In brewing large quantities of yeast,
it would obviously be difficult to aerate by pouring from vessel to vessel ;
the same object may be served by from time to time thoroughly stirring
the fermenting yeast. This free access of air not only stimulates the
growth of yeast, but in addition is inimical to the development of disease
ferments ; so much so, that by careful working with plenty of air a yeast
can be made to give moderately good results, that would be absolutely
unusable if fermentation were conducted in closed vessels. It follows
that yeast is better brewed in comparatively shallow and open tubs than
in deep and closed ones.

The careful performance throughout of this experiment will not only
be an instructive exercise on fermentation, but will also afford good prac-
tice with the microscope.

394. Formula for Manufacture of Malt and Hops Patent Yeast.—
The following formula for the manufacture of patent yeast is taken from
"The Miller," — 40 gallons of water and 2 Ibs. of sound hops are boiled

234 THE TECHNOLOGY OF BREAD-MAKING.

together for half an hour in a copper, and then passed over a refrig-
erator, and thus cooled to a temperature of 71° C. (160° P.). The liquor
passes from the refrigerator to a stout tub; \l/2 bushels (about 63 Ibs.)
of crushed malt are then added, and the mixture thoroughly stirred. The
mash is allowed to stand at that temperature for \l/2 hours, filtered from
the grains, and then rapidly cooled to 21° C. (70° P.). The passage over
the refrigerator serves also to thoroughly aerate the wort. Spontaneous
fermentation is then allowed to set in, and the yeast is usually ready for
use in 24 hours, but is in better condition at the end of two days. All
fermenting tubs, and other vessels and implements used, are kept clean
by being from time to time thoroughly scalded out with live steam. The
result is the production of a yeast of very high quality. Or fermentation
may be started by the addition of a small quantity of good yeast.

395. Suggestions on Yeast Brewing ; what to do, and what to avoid.
—The quantities given above are larger than those required by many
bakers, but the formula may be adopted for smaller brewings by taking a
half, or quarter, or some other proportion of each ingredient. In con-
nection with brewing, the first consideration is the room ; this should not
be in the same part of the bakehouse as the ovens. Select, if possible, a
room having an equable temperature of from 65 to 70° P. Stout tubs
of appropriate size should be used for brewing ; these should be about the
same width as depth. Before commencing, clean all tubs and implements
with boiling water. The hops are better boiled in a copper ; iron vessels
are apt to discolour them, especially if the vessels are in the slightest de-
gree rusty. Let the hop liquor cool down to the temperature given,
before adding the malt, as a temperature much higher than from 65 to
70° C. destroys the diastatic power. On no account 'boil the malt : some
bakers place malt and hops together, and boil the two, under a mistaken
idea that they get more extract from the malt. The result is that dias-
tasis is arrested long before the whole of the starch is converted into
dextrin and maltose. For the same reason, fifteen minutes is too short a
time for the mashing to be continued. The baker not only requires to
saccharify his malt, but it is also necessary for him to convert as large a
proportion as possible of his dextrin into maltose. This is hindered either
by using too high a temperature, or mashing for too short a time. Start-
ing with a mashing liquor at 65 to 70° C., and mashing for from \l/2 to 2
hours, gives about the best results. The cooling after removal from the
grains, which may be washed or " sparged" with a small quantity more
water, must be done quickly, so as to have the wort for as short a time
as possible at a temperature of from 35 to 40° C., as at that temperature
bacterial fermentations proceed most vigorously. The wort at 21.5° C. (70°
F.) may either be pitched with a small quantity of yeast reserved from
the last brewing, or by the addition of a small quantity of good fresh
compressed yeast. If wished, the fermentation may be allowed to set in
spontaneously, as suggested in the preceding paragraph, in which case a
"virgin" yeast is produced. It is doubtful, however, whether this is to
be recommended in most cases. The risk of spoiled yeast is greater, and
at times alcoholic fermentation does not set in at all, or too late to pre-
vent its being preceded by excessive lactic and other foreign fermenta-
tions. The temperature should not be allowed to rise, during fermenta-
tion, much above 21 to 22° C. In summer time there is a great tendency
for a rapid rise to set in ; this may be controlled by placing an attempe-
rator in the wort, and passing a stream of cold water through. An at-
temperator consists of a properly arranged series of pipes, through which
hot or cold water at will may be passed. Temperatures must in all cases

MANUFACTURE OF YEASTS, 235

be got right by actual use of the thermometer. From time to time, stir
the fermenting wort so as to rouse or aerate it. When the yeast is made,
keep it freely exposed to air. In making patent yeast it is very poor
economy to stint either malt or hops : a weak wort produces a much less
healthy and vigorous yeast than does a strong one, besides being much
more subject to disease fermentation, and consequent acidity. And, when
made, the dilute yeast shows no saving, because so much more of it has
to be taken in order to do the same work.

396. Specific Gravity of Worts, and Attenuation. — In addition to
taking the temperature of his worts, the brewer also tests the density or
specific gravity of each sample. This is done as a means of estimating
the amount of soluble extract obtained from the malt. The maltose and
other soluble carbohydrates, yielded on mashing, increase the specific
gravity of the wort. Taking the density of water as 1000, each gram of
carbohydrate in 100 c.c., or, what amounts to the same thing, each Ib.
of carbohydrate in 10 gallons of the wort increases the density of the
solution by 3.85. Thus, suppose that a wort is found at 15.5° C. (60° F.)
to have a specific gravity of 1011.5, then

1011.5 — 1000

— = 3 = weight in Ibs. of

sugar and other solid matter in 10 gallons of the clear wort. As the
density of a liquid varies with its temperature, all densities are best taken
at the uniform temperature of 15.5° C.

The Inland Revenue Act of 1880 assumes that 2 bushels of average
malt, weighing 84 Ibs., will produce a barrel (36 gallons) of wort having
a density of 1057. Accepting this estimate as correct, and assuming that
the 40 gallons of water employed in the previously given recipe, together
with the small extra quantity used in sparging or washing the grains,
yield after loss through evaporation 40 gallons of wort; then the wort
produced ought to have a density of 1038.3, which is equal to almost
exactly 10 Ibs. of solid extract per 10 gallons of wort. Working with
comparatively imperfect methods, and in small quantities, the baker can
not expect his malt to yield the full extract, but as a matter of practice he
ought at any rate to get nothing less than a density of 1030. One of the
most important sources of loss arises from imperfect sparging of the
grains ; these should be washed once, and may then with economy be pur
into a small press and squeezed dry. Of course, if with extra washing
water the volume of the wort is increased, then the density will naturally
fall. Testing the density of his wort is not only of importance to the
baker, as a measure of the degree of efficiency with which he is extracting
the valuable matters of his malt, but is also a test, of the highest value, of
the regularity of his work. If one day a wort of comparatively high
density is being attained, and on another one of low density, something
is wrong, and must be righted. The baker should always endeavour to
have his worts at the same density when ready for pitching : 1030 may be
taken as a very good standard to work at. If it is found in practice that
the densities fall below this, mash with comparatively less water ; if the
densities run too high, dilute the wort with water until of the right
density before pitching. The necessary quantity of water to add may be
easily calculated, on remembering that the volume of the wort is in
inverse proportion to the density, less 1000. Thus, supposing that the
40 gallons of wort are found to have a density of 1035, then

as 30 : 35 : : 40 : 46 gallons.
The wort will have to be made up to 46 gallons, therefore 6 gallons of

236 THE TECHNOLOGY OP BREAD-MAKING.

water must be added. The quantity of wort produced should always be
measured; to do this, determine once for all the capacity of the ferment-
ing tubs in the following1 manner : — Prepare a staff about an inch square ;
pour water into the tub, gallon by gallon, and at each addition put in the
staff and mark on it the height of the water. This operation once com-
pleted, the quantity of wort made can at any time be determined simply
by plunging the staff into the tub and reading off the number of gallons
as marked on it.

For practical purposes, the density of a wort is best determined by a
hydrometer; this instrument is made either of brass or glass. It has a
weighted bulb at the bottom, and a long graduated stem ; accompanying
the hydrometer is a tall glass jar, knqwn as a hydrometer jar. Fill this
jar with wort at the right temperature, and place in the hydrometer;
as soon as it comes to rest, read off the graduation which coincides with
the level of the liquid ; the number gives the density. For the baker, the
most convenient hydrometer is one graduated in single degrees, from 1000
to 1040. The hydrometer is also sometimes known as a saccharometer.

As fermentation proceeds, the density of the liquid becomes less, and
at the same time it loses its sirupy consistency — hence the brewer states
it to have become * ' attenuated. ' '

397. Microscopic Sketches of Patent Yeast. — In Plate II. are given
microscopic sketches made of patent yeasts collected in the South of
England.

The sketches marked respectively a and 1) were drawn from samples
of patent yeast, both obtained in the same town, but from different
bakers, during the summer. The sample marked a was evidently pre-
pared in a strong wort ; in fact, at the time of examination the yeast was
still sweet through presence of maltose in considerable quantity, and had
a high density. The yeast was not free from disease ferments, but still
compared remarkably favourably in this respect with all other samples
examined. One specially noticeable point about the sample was the
elongated shape of the cells ; some were not merely ovoid, but even de-
cidedly pear-shaped. One sketched shows this peculiarity in a very
marked manner. This yeast was at the time yielding very good results ;
the bread was sweet and of good flavour. One is in doubt with regard to
sample b, whether it should be viewed as an example of alcoholic or bac-
terial fermentation; certainly the latter ferments are about as plentiful
as yeast cells. The yeast contained very little either of maltose or hops ;
in fact, it had evidently been brewed with as little as possible of these
ingredients employed. Readers will probably not be surprised that yeast
a produced a far superior loaf of bread than did yeast &. The sample c
is likewise of considerable interest ; it was also taken during the summer.
The baker was in the habit of, at the close of his yeast brewing, setting-
aside a portion for the purpose of pitching his next lot of wort. This
pitching yeast was stored in a corked bottle. This also was a yeast brewed
in a poor wort, although not so bad as sample &. Notice particularly, in
c, the chain of elongated cells ; these are often noticed in yeast grown
without sufficient aliment, and the sketch shows a striking example.

SCOTCH FLOUR BARMS.

398. Parisian Barm, Montgomerie. — Mr. J. Montgomerie, of Glas-
gow, has furnished the authors with the following account of the manu-
facture of Parisian barm as now conducted in Scotland.

MANUFACTURE OF YEASTS. 237

"Sixteen Scotch pints (of two Imperial quarts each) of water at
164° F. are mashed with 24 Ibs. of crushed malt for from 3l/2 to 4 hours,
standing1 in a warm place so as to ensure as little loss of temperature as
possible. It is then transferred to a malt press, and the wort drawn off.
The wort, with the exception of 3 pints, is put in the tub, and 3 pints of
water added at a temperature to bring it up to 120° F. (You have 13
pints of wort and 3 pints of water, making lJ/2 Ibs. malt to the pint of
water). Put in 112 Ibs. flour. A good barm flour is a blend of flour
obtained from spring and winter wheats in about equal proportions. The
wort and flour are then stirred into a batter. Forty pints of boiling
water are then stirred in, 4 pints at a time. The starch in the flour will
gelatinise at the thirty-second pint. The last 8 pints are added when it
begins to liquefy. The 3 pints of wort are then added.

To take off a scald with a

4 pint mash, the temperature of the wort is 140 degrees F.
6 „ „ „ 134 „

132

10 „ „ „ 130

„ 130

12 „ „ „ 126

Ml 94
77 77 ?7 -L^T ,,

16 „ „ „ 120

20 „ „ „ 120

24 „ „ 120

30 „ „ „ 116 „

35 „ „ „ 110

40 „ 100

The last is the biggest taken off in any factory.

"The scald is then cooled until the temperature drops to between 80
and 90° F. in winter, and 60 and 70° F. in summer. If the Barm Cellar
is kept at a constant temperature of, say, 56°F., then 80° F. is a very
good temperature to scald at.

"Storing the Scald. Take the temperature of the scald and add 13
pints of matured barm as a store, i.e., 1 pint of barm to 4 pints of scald.
(As may be gathered from the preceding description, the "store" is a
portion of old barm added for the purpose of pitching, or starting fer-
mentation.) Allow it to lie for 3 or 4 hours, then divide into two or three
suitable vessels and remove to the Barm Cellar, which should be large and
airy, to ferment. The barm will come up its height in 18 hours, and then
gradually settle down with a clear round bell on the top on the second
day of fermenting. On the third day it will begin to clear off, and on the
fourth will be cleared off. The barm is now ready for using, but most
bakers prefer to allow it to mature to the fifth day, as it gives a better
flavoured loaf, and the fermentation of the dough is more easily con-
trolled. In the event of the barm showing signs of hardness, decrease the
quantity of malt used at mashing, and if of greenness, increase the
quantity of malt.

"To keep barm right, it is essential that everything should be kept
scrupulously clean, with a plentiful supply of fresh air, and that the
barm be stored and kept at a constant temperature. ' '

399. Scottish Barms, Meikle. — Mr. J. Meikle, the well-known baker
and writer on bread-making, has supplied the following information on
Scottish barms, for which the authors express their acknowledgments

238 THE TECHNOLOGY OF BREAD-MAKING.

and thanks. The various data were submitted by Mr. Meikle to a
number of bakers in Scotland, and may therefore be taken as thoroughly
reliable in every way.

COMPOUND BARM.

40 Ibs. Water.
10 Ibs. Malt.

4 Ibs. Store.

4 oz. Hops.

2 oz. Salt.
Mash 3 hours.

" Compound Barm is not now used to the extent it was at one time,
but many of the older bakers agree that it is the barm for flavour in
bread. Take 10 Ibs. of water and mix in the hops, bring the water to the
boil and allow to simmer for a few minutes. Transfer this to a 5 gallon
tub and add 30 Ibs. of water at 180° F. to make up to 40 Ibs. Throw a
flour bag over the tub and allow the liquor to cool to 164° F., then stir in
the malt, cover up the tub well, and keep it in a warm corner for about
three hours. At the end of that time run the 'mash' into a barm press
and press out all the liquor. Cool this as quickly as possible to 72° F.,
stir in the store and the salt, then set the whole to ferment for 36 hours.
At the end of that time the gas should all be gone ; it should in fact have
ceased to hiss : if hissing still goes on the barm must not be used as it is
not ready. Some Scotch bakers will not touch this barm until hissing
ceases, but a good rousing stir will help matters considerably.

' ' I have used pounds in connection with liquor, and will use this sys-
tem in what follows for the reason that the Scotch 'pint' does not always
mean a definite quantity. It generally means half an Imperial gallon,
but often it means a real old Scotch pint, which is equal to about 3
Imperial pints or almost 4 Ibs. avoirdupois. An Imperial gallon of water
weighs 10 Ibs. avoirdupois, so that the figures given divided by 5 give the
number of Scotch pints (half gallons) as generally in use, and divided by
4 give old Scotch pints.

VIRGIN BARM.

20 Ibs. Water at 125° F.
32 Ibs. Flour.
45 Ibs. Water at 212° F.
10 Ibs. Store.

"To lie 12 hours before 'Storing,' or till it falls to 80° F. ; 60 hours
afterwards it will be ready.

"Mix the water at 125° F. with the flour into a stiff paste by hand,
making sure that boiling water is immediately afterwards available.
Scrape down the batter in the inside of the tub, then, add boiling water 2
pints at a time (a gallon) stirring vigorously between each addition with
a stick of the nature of a broom handle. The mixture will be easy to stir
at first, but when the starch cells begin to burst it will 'grip,' and care
must be taken, first, to keep clear of lumps, second, not to add too much
water. The strength of the final barm depends on the solids, not upon the
amount of water added. The scald must now lie for about 12 hours, when
it will have not only become cool, but also thin, and slightly tart (acid).
Now add the store and a handful of flour, stir well and allow to ferment

MANUFACTURE OF YEASTS. 239

for 56 hours. Foaming will start at the sides and will gradually cover
the top : if a ring still remains in the centre when the barm is to be used
the baker must make up his mind for weak fermentation. Real Virgin
Barm is not stored at all, but I have never seen such barm worked. Vir-
gin, so called, has been gradually displaced by Parisian, but I have seen
it used many years and have seen much good bread made from it.

PARISIAN BARM.

15 Ibs. Water {
33/4 Ibs. Malt {mash at 160° F.

22 Ibs. Flour.

35 Ibs. Water at 212° F.

10 Ibs. Store.

"To lie 12 hours before storing or until it reaches 76° F. ; ready 50
hours afterwards.

"This is the barm of Scotland today and is made as follows: Mash
the malt and water as for compound barm ; that is, measure the water in
a clean tub at a temperature of about 180° F., cover this up and allow
the temperature to fall to 162° F., then add the malt. The reason for
using water at 180° F. is to ensure the tub being thoroughly warmed up :
by well covering up after mashing the proper temperature is kept up for
a longer period — the subsequent barm will be no good unless care is exer-
cised at the very start. In two and a half hours wring off the liquor and
add sufficient water at 150° F. to bring up the total to 15 Ibs. and the
temperature to 128° F., stir in the flour by hand, and afterwards add the
boiling water, and stir vigorously as already described for Virgin barm.
The scald should not be so stiff as for Virgin, and should taste sweet when
newly made. It begins to thin almost immediately, and as it lies gets a
little sharper in taste; it should not, however, be cooled artificially.
When storing stir vigorously and well. Parisian barm while fermenting
behaves like a thin ferment made with distillers ' yeast, sugar and a hand-
ful of flour, only the bells or gas bubbles are larger and brighter. The
barm has the strength, without the "rampness," of compound, and the
mildness without the weakness of Virgin. Of suitable barm flours more
further on. In the making of scalds in large places machinery has been
utilised. The stirring machine is used with success in making large scalds
in the factories, such scalds being afterwards divided amongst several
tubs for fermenting purposes." (Personal Communication, October,
1910).

CHAPTER XIII.

PHYSICAL STRUCTURE AND PHYSIOLOGY
OF THE WHEAT GRAIN.

400. Functions of the Wheat Grain. — The wheat grain is that part
of the plant on which falls the task of performing the functions of repro-
duction, hence all its parts are specially adapted to that purpose. The
germ, or embryo, of wheat, really the true seed, is that portion of the
grain which ultimately develops into the future plant. The main body,
composed principally of starchy matter, is termed the "endosperm": its
function is to supply the germ with food during the first stages of its
growth. Besides these there are the various outer and other coverings,
destined for the adequate protection of the seed, which together consti-
tute the bran. The physical structure of the wheat grain requires for its
systematic study the use of the microscope : the descriptions following
therefore include practical directions for microscopic observation. The
arrangement adopted is that most easily followed by the student in a
course of actual microscopic work. For earlier studies it is well to obtain
from the dealer ready-mounted longitudinal and vertical sections of a
grain of wheat. In every case, practise sketching what is seen : as before
stated, the accompanying figures are facsimiles of those which the student
should himself make.

401. Longitudinal Section of Whole Grain. — -In the first place, ex-
amine the longitudinal section of the grain of wheat with the 3-inch
objective ; the whole of the grain will then be in the field. Try,- in the
next place, to make a sketch of it. For this purpose the student should
use a camera lucida if he should possess one. Trace in the outline and
other principal lines with a hard pencil ; then go over them with a litho-
graphic pen and liquid Indian ink. It will be impossible to get in all the
details ; the effort should be rather to show what is essential ; thus the
object of the sketch with the low objective is to get an idea of the gen-
eral shape and arrangement of the different constituent parts of the
grain. When the drawing is complete, mark underneath the number of
diameters to which it has been magnified.

In Plate VI. is given a section through the crease of the grain, which
is shown in elevation by shading on the left-hand side of the figure. The
whole of the figure has been obtained by careful tracing in the authors'
laboratory from typical slides, and is throughout a faithful representa-
tion of the grain. The germ is seen at the lower end of the figure, and a
fair idea of its size, compared with that of the endosperm, which consti-
tutes the remainder of the grain, may be obtained. Enclosing both germ
and endosperm is the bran. With the low power, which the student has
been directed to use, the square cells of the bran lining the interior, and
known as aleurone cells, are just visible. The name commonly given to
these is, by the by, a misnomer; they are not "gluten" cells, for the
reason that they contain no gluten. The more minute examination of the
grain is best made by the aid of the higher powers, and shows more of the
details drawn in Plate VI., to which reference is made in the paragraphs
which follow.

The various parts of the grain are fully indicated on the plate itself.

240

STRUCTURE AND PHYSIOLOGY OP THE WHEAT GRAIN. 241

PLATE VI.

Cuticle. \

, I

'* / BRAN.

Lvtarch,G>ll -filled
I u 'ith yrcuu 'te.s •

E. Endosperm.
G. Germ.

LONGITUDINAL SECTION THROUGH A GRAIN OF WHEAT.

CbbtJLlt £

242

THE TECHNOLOGY OP BREAD-MAKING.

402. Transverse Section of Wheat Grain. — Examine next a trans-
verse section of a grain of wheat; the section, below figured, Fig. 25, was
cut from a grain of Kubaiika wheat, and passes through the germ.

FlG. 25. — Transverse Section of Grain of Wheat, magnified 13 diameters.

On examining carefully such a section as that shown, the pigment-
containing celare seen in a line passing completely round the grain, and
spot of colour in the crease. Notice that the aleurone
i do not continue round the germ. Observe also as much
e structure of the germ itself, and the relative dimensions
germ and endosperm.

e same section in the next place with the 1-inch objective
outer skins of the bran are here seen more plainly; the

forming a t
cells gj the
as poa&ble o

FIG. 26. — View of Crease in Grain of Wheat, as shown in a transverse section, magnified 110

diameters.

square aleurone or cerealin cells are also plainly visible. Notice that near
the bottom of the crease, the cells, instead of being in single line, are in
double, becoming more numerous and irregularly arranged as the bottom
is approached. The crease distinctly bifurcates at the bottom; the pig-
ment layer of the grain becomes considerably enlarged, and its section is
seen at the middle of the fork as a dark yellow spot of considerable size.
With this power the starch granules also become visible.

STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 243

403. Section Cutting and Mounting. — It has been assumed that, for
the purposes of making these studies and sketches, the student has had in
his possession sections that he has purchased ready mounted. He will
probably at this stage of his work wish to prepare and mount sections of
his own. Wheat in its ordinary state is too brittle to permit of its being
cut in thin sections. In the first place, therefore, soak a few grains in
water for about twenty-four hours ; the water may be luke-warm, say at

. a temperature of 80° to 90° F. When the grains have become moderately
soft, sections may be cut from one of them. For this purpose a very
sharp razor, which has been ground flat on one side, is generally used.
Take one of the grains between the thumb and finger, cut off one end, and
then proceed to slice off sections as thin as possible. Some little practice
will be necessary before they can be successfully cut of the requisite thin-
ness.

This operation is rendered easier by the use of a section cutting table.
This little piece of apparatus consists of a plate of brass, the surface of
which has been turned perfectly plane ; in the centre is fixed a tube con-
taining a piston, which may be raised by means of a screw. The object
whose section it is wished to procure is first cast into a block of either
cocoa butter or solid paraffin. In either case the temperature of these
must only just be raised to the melting point. This block of solid paraffin
or other substance is next trimmed down so as to go into the tube of the
section cutting table. Adjust the screw at the bottom so that the grain
is in about the right position, then draw the razor across the top of the
tube and cut off the upper part of the grain ; screw up the piston at the
bottom of the tube very slightly, and cut off a section by again drawing
the razor across the plane surface of the table. In this manner thin sec-,
tions may be cut with comparative ease. Having thus obtained the sec-
tions, wash them in a little spirits of wine and transfer to a slide. If it
is only wished to examine them without this being preserved, they may
be mounted in a mixture of water and glycerin in equal volumes, pro-
tected with a cover slip, and at once placed under the microscope. When,
however, it is wished to make a permanent mount, they may be embedded
in glycerin jelly (Deane's medium). Having washed and prepared a
section, and also the slip and cover, place a very little of the glycerin jelly
on the slide, warm very gently, and the jelly becomes liquid. Place the
section carefully in the liquid medium, taking care that it is thoroughly
immersed. Remove all air bubbles, place on the cover as carefully as
possible, gently squeeze out any superfluous medium, and allow to cool.
The jelly will then again become solid. Clean the edge of the cover glass,
and coat round with asphalt varnish.

404. The Germ. — The appearance and general characteristics of the
germ itself should now be carefully studied; for this purpose use the
1-inch objective.

In Plate VI. the germ is shown very distinctly, and the whole of its
parts named and indicated by reference marks. This should be carefully
studied. Notice that the aleurone cells of the bran terminate at the
junction of the endosperm and germ, and only the "testa" or envelope of
the true seed encloses the embryo. The "plumule" is that part of the
young plant which penetrates to the surface during growth, and then con-
stitutes the growing stem and leaves of the plant. It consists of four
rudimentary leaves enclosed within the plumule sheath. The radicle, or
rootlet, on commencing its growth, forces its way downward into the
earth. The germ constitutes about 2.0 per cent, of the whole grain, while
its enclosing membrane is stated by Mege Mouries to amount to as much
as 3.0 per cent.

244 . THE TECHNOLOGY OF BREAD-MAKING.

The nature of the other portions of the germ had best be described
when dealing with their functions in connexion with the act of germina-
tion (paragraph 410).

405. Endosperm and Bran. — Attention must next be directed to the
structure of the endosperm and the branny coatings by which it is envel-
oped. For this purpose a very thin section should be selected and then
examined under the %-inch objective.

The bran of wheat is divided into the outer envelopes of the grain and
those of the seed proper. Following these in the order of the letters given
in Fig. 27 :—

a — is the outer " epidermis, " or "cuticle." According to Mege
Mouries this constitutes 0.5 per cent, by weight of the whole grain.

& — is the "epicarp," and amounts to about 1.0 per cent, of the grain.

c — is the last of the outer series of the envelopes of the grain, and is
known as the "endocarp." It is remarkable for the well-defined round
cells of which it is composed. The endocarp amounts to 1.5 per cent, of
the grain.

d — is the first of the envelopes of the seed proper ; it is that to which
reference has already been made as the "testa"; it has also received the
name of "episperm." The colouring matter of the bran occurs princi-
pally in the episperm.

e — is a thin membrane lying underneath the testa, and enveloping the
aleurone cells. This membrane and the testa together form 2 per cent, of
the grain.

/ — is the layer of "aleurone" cells, so called from the protein of that
name which they contain. As may be seen from the figure, the cells are

Fie. 27. — Longitudinal Section through Bran and Portion of Endosperm of Grain of Wheat,

magnified 440 diameters.

almost square in outline ; one is at times replaced by two lesser ones, as
occurs immediately above the cell /. Notice particularly that this layer
does not envelop the germ, but only encloses the endosperm.

STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 245

(j — represents the layer of parenchymatous cellulose by which the in-
terior of the endosperm is divided up into a number of cells of compara-
tively large size, these in turn being filled with starch granules, and
embedded in gluten.

h — shows the "hilum" of an individual starch' granule.

In order to complete the investigations of the appearance, when
viewed under the microscope, of the various coatings of the wheat grain,
it is not only necessary to examine these skins in section, but also, so far
as possible, as seen on the flat. The bran of wheat can be split up with
comparative ease into three layers, which can be successively peeled off
from the endosperm. The first of these consists of the epidermis, or
cuticle, and also epicarp. Following these are the endocarp and episperm,
which usually peel off together. The inner and last skin consists of that
containing the cerealin cells.

Take a few grains of soft red wheat and soak them for a few hours in
warm water ; when they are sufficiently softened, take one, and with a fine
pair of forceps strip off the outer skin and place it in a watch glass.
When the whole of the outer skin has thus been removed, carefully strip
off the middle layer in the same manner, and also reserve it for examina-
tion. The division of the inner layer from the endosperm is often only
accomplished with difficulty; in case they do not separate well, let the
grain soak some time longer.

Next proceed to examine these several coatings. Mount each on a
slide in a drop of water (or preferably, when wished to examine the
mount for some time, in a drop of glycerin), so that it is practically freed
from bubbles, and lying flat and without creases. Put on a glass cover
and press gently down. Examine with either a quarter or eighth-of-an-
inch objective.

FIG. 28. — Outer Layer of the Bran of Wheat, magnified 150 diameters.

Observe in the outer layer that it consists of a series of cells, some
four to six times long as broad, and arranged longitudinally in the direc-
tion of the length of the grain. A portion of the outer layer is shown in
Fig. 28. Notice at the one end (of the actual section, not the figure) the
beard of the grain, and note particularly the attachment of each hair to
the skin (the root). Observe also the canal extending about half the
length of the hair, Fig. 29 is a drawing of such hairs.

246

THE TECHNOLOGY OF BREAD-MAKING.

FlG. 29.— Beard of Grain of Wheat.

Next observe the appearance of the second layer of skin that has been
detached ; this is shown in Fig. 30.

FlG. 30. — Middle Layer of the Bran of Wheat, magnified 250 diameters.

In this will be seen two layers of cells that are not both in focus at the
same time, the one layer being, in fact, underneath the other. There are
in the first place a series of long cells arranged transversely to the longi-
tudinal section of bran shown in Fig. 27, where they are marked c.

FlG, 31. — Inner or Aleurone Layer of the Bran of Wheat, magnified 440 diameters.

STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 247

Because they are thus arranged around the grain of wheat they are fre-
quently termed "girdle" cells. The great difference between looking at
the same thing in one direction and then in another is strongly exempli-
fied in this study of these particular cells in plan and in section. An
instructive lesson may be gained by comparing the section illustrated in
Fig. 27 with a similar section cut transversely instead of longitudinally.
Such a section is given later in the series. The colour-containing cells
underlie those to which reference has just been made.

In the next place examine the inner, or aleurone cell, layer of the bran.

The aleurone or cerealin cells of the bran are often referred to as
being cubical ; that this, however, is not the fact is well shown in Fig. 31.
They certainly have a square or rectangular outline when seen in section,
whether longitudinal or transverse, but the skin, viewed on the flat sur-
face, shows that the cells are irregular in outline, each accommodating its
contour to that of those surrounding.

There follows a sketch of 'the transverse section through the bran of
wheat; this should be carefully compared with the longitudinal section,
Fig. 27.

FlG. 32. — Transverse Section through Bran of Wheat, magnified 250 diameters.

The actual section from which this drawing has been made is not so good
a one as the longitudinal section, from which Fig. 27 was drawn. Viewed
with a moderately high power it is difficult to get very much of the thick-
ness of the section in focus at the same time. ; still sufficient is. noticed, on
careful observation, to show the general structure of the bran. The out-
line of the aleurone cells is more irregular than was the case in the longi-
tudinal section ; they are also noticed to be, in several instances, overlap-
ping each other. Looking at the cells of the middle skin of the bran, they
are seen to be of considerable length, justifying the remarks made about
them when studying their appearance as seen on the flat. While, how-
ever, these middle cells are seen lengthwise, it follows of necessity that
the ends of the cells of the outer skin much be presented to the eye. This
sketch, taken with the others, gives a tolerably complete idea of the
microscopical structure of a grain of wheat.

A careful study of these sections of the wheat grain and of the vari-
ous layers into which the bran can be divided should give the miller in
particular a clearer and more real idea than he can otherwise have of the
nature of these outer integuments of the wheat grain, which it should be
his object to remove. The study should not merely be confined to the
drawings given in this work, but should extend to the actual slides them-
selves under the microscope.

406. Bran Cellulose. — The bran of wheat consists largely, as is well-
known, of cellulose or woody fibre, together with a considerable propor-
tion of soluble albuminous matter. Cellulose may be obtained in a fairly

248 THE TECHNOLOGY OF BKE AD-MAKING.

pure state by alternate treatment with hot dilute solutions of acid and
alkali. The actual structure of the cellulose of the different layers of the
bran possesses considerable interest, and may be studied in the following
manner : Strip off the different layers of skin as before directed, put
pieces of each in a separate test-tube, and first digest for an hour with
dilute sulphuric acid ; pour off the acid, and digest with caustic soda solu-
tion for another hour. Make up solutions of 1 part respectively of acid
and alkali, and 20 parts of water. Wash the resulting cellulose, and
mount carefully on a glass slide ; examine under the microscope.

Reviewing the whole three layers, one finds that the outer one is
largely composed of cellulose, and consequently is condemned as an arti-
cle of human food. The middle layer contains less cellulose, but contains
a higher proportion of colouring matter. The proportion of cellulose in
the inner layer is still less, but the amount of protein is high. This pro-
tein body is injurious to the flour, inasmuch as it exerts considerable
action on broken starch granules. There are therefore cogent reasons
for the non-admission of any part of the bran into the flour.

407. Cellulose of Endosperm. — On taking a grain of wheat and care-
fully cutting off the bran so as to have a piece of the endosperm only, and
treating this interior portion of the grain with acid and alkali, a trace of
cellulose is obtained which shows no distinctive organisation under the
microscope. The student will do well to verify this fact for himself. Let
him also treat small quantities of different varieties of flour in a similar
fashion, and examine the remaining cellulose. Such an inspection is cal-
culated to teach much concerning the success of the operation of milling.
He will be able to see whether or not the number of small particles of
bran in the flour is large. He will also learn whether or not the bran
itself is intact, or whether portions of one or other of the surfaces have
been removed and ground up into the flour.

PHYSIOLOGY OF GRAIN LIFE.

408. Protoplasm. —In explaining the nature of yeast, Chapter IX.,
reference has already been made to the fact that the interior of the cells is
filled with " protoplasm, " and that this material is the "ultimate form of
organic matter of which the cells of plants and animals are composed."
Protoplasm has also been defined as the "physical basis of life," and for
that reason merits in this place some little examination. Yeast may be
viewed as an unicellular plant, whereas wheat and the higher plants gen-
erally are multicellular in nature, so that yeast serves as an introduction
to their study. From what has been already described of the life-history
of yeast, the following conclusions as to the nature of its protoplasm may
be drawn : First, that protoplasm is the seat of those chemical changes
which are inseparable from the life of the organism. Such chemical
changes, collectively, are termed the metabolism of the organism.
Those processes which go to the building up of more complex chemical
compounds are termed constructive metabolic processes, while those in
which complex compounds are broken down into simpler compounds or
elements are termed destructive metabolic processes. In the most
recent nomenclature, the term metabolism is sometimes restricted to the
constructive processes, while the changes of destruction or degeneration
are referred to as processes of katabolism. Vines classifies the funda-
mental properties of the protoplasm of the yeast plant. as follows :

"1. it is absorptive, in that it is capable of taking up into itself the
substances which constitute its food.

STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 249

"2. It is metabolic, in that it is capable of building up from the rela-
tively simple chemical molecules of its food the complex chem-
ical molecules of the organic substances present in the cell ; and
in that it is capable of decomposing the complex molecules of
these substances into others of simpler composition.

"3. It is excretory, in that it gives off certain of the products of its
destructive metabolism.

"4. It is reproductive, in that portions of it can become separate from
the remainder, and lead an independent existence as distinct
individuals. ' '

The protoplasm of certain more highly organised unicellular plants
have, in addition, other distinct properties, such as contractibility, irri-
tability, etc. In the lower multicellular plants all the cells appear to be
exactly alike, but in most the constituent cells vary and have special
functions allotted to them : such groups or arrangements of cells constitute
what is known as an organ. Thus, certain cells are absorptive in their
nature, while others are excretory: others, again, are charged with the
functions of reproduction, and these are known as the reproductory
organs. The seed or grain of wheat is one of the most important among
these latter, and it is only such other functions of the plant as are
directly associated with seed life that can be touched on in this place.

Like other parts of plants, the seed is built up of parenchymatous cells
containing modified protoplasm, which consists of a series of meshes or
network enclosing within them, in the ripe seed, grains of starch. The
network portion is composed of proteins, and of these an exhaustive
description has already been given. The insoluble proteins constitute
what Reinke named the plastin of the cell, while the more soluble portions
are the globulins and peptones; of which latter, seeds usually contain con-
siderable quantities. The plastin is probably the organised protoplasm of
the cell, while the globulins and peptones are unorganised or dead proto-
plasm. The higher plants, such as the cereals, contain in certain of their
cells differentiated protoplasmic bodies, which may contain colouring
matter, in which case they are known as chlorophyll- or etiolin-corpuscles ;
or they may be colourless, in which case they are starch-forming
corpuscles or amyloplasts.

409. Constructive Metabolism of Plants. — The roots serve as the ab-
sorbing medium through which the plant obtains water and substances
which may be in solution in water. From the atmosphere plants absorb
carbon dioxide. Much of the oxygen of this carbon dioxide is returned to
the atmosphere in the free state, the carbon being used in the constructive
metabolism of the plant. In addition to the carbon dioxide and water,
the plant has at its disposal for metabolic purposes salts containing nitro-
gen and sulphur.

A most important point in the study of metabolism is that the assimi-
lation of carbon from carbon dioxide is confined to those portions of
plants which contain green colouring matter (or closely allied matter to
be subsequently described). Further, the decomposition of carbon
dioxide can only take place in the presence of light. On treating green
leaves of plants with alcohol, the green colouring matter is dissolved out,
and has received the name of chlorophyll. Within the leaves this chloro-
*phyll exists in cells or corpuscles known as chlorophyll-corpuscles, the
chlorophyll itself having apparently a similar composition to other proto-
plasm. Etiolated plants — that is, plants grown in the absence of light —
contain corpuscles in which the colouring matter is yellow, not green ; this
matter has received the name of etiolin, and is doubtless closely allied to

250 THE TECHNOLOGY OF BREAD-MAKING.

chlorophyll in properties. Oil exposure to light, the etiolin corpuscles
absorb carbon dioxide and exhale oxygen, the etiolin being converted into
chlorophyll. Investigation of a most careful and exhaustive nature dem-
onstrates that the absorption of carbon dioxide and exhalation of oxy-
gen, with the formation de novo of organic matter in plants, is essen-
tially a function of chlorophyll (including etiolin), and cannot occur
in its absence.

But little can be stated positively as to the exact nature of the chem-
ical changes induced by chlorophyll, but they may be summed up in the
statement that it produces, by synthesis, protein matter. The first step
is probably the formation, from carbon, hydrogen, and oxygen, of com-
paratively simple substances, such, perhaps, as formic aldehyde, CH20
(the simplest possible carbohydrate), and its polymers. (Glucose and
other of the higher carbohydrates may be viewed as polymers of formic
aldehyde, thus 6CH2O — C6H1206, glucose.) The next upward step
might be the production of nitrogenous substances of the amide type
(asparagin, etc.), and finally, by further synthesis, the still more complex
protein. Differences of opinions exist as to the manner in which starch
is formed by the plant — there is first the observed fact that the chloro
phyll-corpuscles of a growing plant exposed to light contain starch grains,
and that these disappear during darkness. Vines is of opinion that * ' the
starch which makes its appearance in the chlorophyll-corpuscles, when
constructive metabolism is in active operation, is not the first product of
the synthetic processes, but only an indirect product : protoplasm is the
substance which is formed in the chlorophyll-corpuscles, and it is only in
consequence of the decomposition of the protoplasm formed that starch is
produced." In a paper contributed to the Journal of the Chemical
Society, in 1893, by Brown and Morris, these chemists advance the view
that cane sugar is first formed as an up-grade product of constructive
metabolism, and that the starch is formed within the chlorophyll-
corpuscles from this compound. There is proof that protein matter is
capable of being so decomposed as to result in the splitting off of a carbo-
hydrate molecule from its substance, as in the production, for example, of
the cellulose cell-wall of yeast from its protoplasm.1 On the other hand,
Brown and Morris have shown that the chloroplasts of the leaf can form
starch when fed directly with cane-sugar solution, and claim that "both
under the natural conditions of assimilation and the artificial conditions
of nutrition with sugar solutions, the chloro-plasts form their included
starch from antecedent sugar." However, in whatever manner formed,
chlorophyll causes, in the presence of light, the production both of pro-
teins and carbohydrates, including starch, within the leaf. The final
process of constructive metabolism is the conversion of dead protein mat-
ter into living organised protoplasm ; but our knowledge of the difference
between these is very slight. Vines points out "that the primordial
utricle of dead cells readily allows of the passage into it and through it of
substances, which could not enter or pass through it in life. This is in
accordance with the well-known fact that it is impossible to stain living
protoplasm; it is when protoplasm is dead that colouring matters can
penetrate into it."

Having traced the synthesis of protoplasm and other organic matter
in the leaf, the next problem is the mode of their translocation or trans-
ference to other parts of the plant. Brown and Morris have proved the

1 Pavy, in some investigations of the chemical pathology of diabetes, shows
that glucose may be formed from proteins during human digestion.

STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 251

existence in leaves of a diastase, which they term leaf diastase, or " trans-
location diastase," from its functions as an agent in the translocation of
the chlorophyll products. They show that by the agency of this diastase
the starch (which during darkness disappears from the chlorophyll
corpuscles of the leaves) is converted into maltose. They further are of
opinion that the cane-sugar which the leaves may contain is converted
into dextrose and laevulose. Probably also the proteins are changed by
analogous processes into peptones, and from these into amides, in which
form the nitrogenous organic substances are most likely distributed
through the plant. The diastase and proteolytic enzymes, then, pour into
the various vessels of the plant a solution of maltose, dextrose, lasvulose,
and peptones and amides. These are carried to the new parts of plants
for the purpose of forming buds, roots, etc., and to the seed portion, there
to be stored up as provision for the young plant during its first stages of
growth, and before able to obtain nutriment by the action of its own
chlorophyll.

The physical structure of the wheat seed or grain has been already
described, the embryo of the plant being at the lower end, near where the
seed is attached to the ear, and the upper portion being the endosperm,
the whole being enclosed within the cuticle known as bran. Of the forma-
tion of the seed as the plant grows, we cannot here speak ; but assuming
the seed to have formed its outer envelope, it before ripening is found, on
examination, to be full of a milky looking fluid, which consists of the sap
which is being supplied by the vessels of the plant.

Within the seed a synthetical process proceeds, by which is caused the
formation of protein matter from the sugar and amides supplied by the
sap. From this is derived the starch of starchy seeds, while the residuum
of the protein forms what are known as aleur one-grains. Vines points
out that comparatively little is known of the manner in which starch is
formed in seeds, but it is assumed that it is produced in the same way as
in other parts of the plant.

After the separation of the starch, there remains behind in the seed a
small proportion of sugar ; part of which consists of sucrose, and is prob-
ably an up-grade sugar, and the remainder of glucose or allied sugar pro-
duced by the subsequent degradation of the cane sugar. In some seeds
the non-nitrogenous matter is stored up as oil instead of starch — com-
paratively little fatty matter is present, however, in wheat, except in the
embryo itself.

The residual matter of the protoplasm, after the separation of starch,
is stored up in the form of small granules, known as aleur one-grains.
These form the matrix in which the starch grains are embedded, and con-
stitute the protein matter of the endosperm. The series of cuboidal cells
forming the interior layer of the bran are also filled with aleurone, and
have the name aleur one-layer.

During the growth of the seed from the milky stage before referred to,
the sap continues to bring supplies of maltose and nitrogenous matters,
which undergo the constructive metabolic process just described; while
under the influence of a ripening sun the water is evaporated. Gradually
the contents of the seed acquire a firmer consistency, until at last the solid
ripened grain of wheat is produced. In this condition the seed is in a
resting stage, and may without injury be subjected to desiccation and
extremes of temperature, which would be fatal were it in its active state.
Under the influence of moisture and warmth, active changes are set up in
the resting seed, and the development of the new plant commences.

252 THE TECHNOLOGY OF BREAD-MAKING.

410. Germination of Wheat and Barley. — In order to understand the
phenomena of germination, reference should at this stage be made to the
section of the wheat germ given in Plate VI. Although in the resting
stage the wheat germ contains no starch, yet within twenty-four hours of
the seed being kept in a moist state, starch is found in abundance within
the germ, although no alteration has occurred in the endosperm, being
doubtless produced by dissociation of the protoplasm of the embryo. This
is followed by an elongation of the radicle, which at this stage contains
starch, as do also the leaves of the plumule. The plumule, with its
further growth, first bursts through the envelope, and finds itself in con-
tact with the " pericarp," or outer skin of the grain (enveloping the
testa). The pericarp is next ruptured, and the growth of the plumule
proceeds outside the grain. On looking at the figure of the germ (or, still
better, an actual section under the microscope), there will be noticed a
series of elongated cells, constituting what is known as the scutellum :
between this and the endosperm is a series of cells of another type,
arranged with their longest diameters directed toward the endosperm;
these latter form what is called the absorptive and secretive epithelium.
At the time when the radicle breaks through its sheath, the cells of the
scutellum lying next the epithelium begin to show starch granules, which
gradually pervade the tissue of the germ : these may be taken as the first
indication of the passage of reserve material from the endosperm to the
germ, while the epithelium is regarded as the absorptive contrivance by
which the germ thus derives sustenance from the endosperm. The first
visible effect on the endosperm is the breaking down of the paren-
chymatous cell-walls, and following on this we have the starch corpuscles
attacked. There are, in the first place, minute pittings on the surface of
the grains of starch, which increase both in size and number until the
whole granule is completely dissolved, with the formation of maltose.
The dissolution and assimilation of the starch of the endosperm proceeds
gradually, the more remote parts being last to suffer attack. The protein
matter of the endosperm is at the same time converted into peptone, and
probably amides, by a proteolytic enzyme. By means of the epithelium,
these are transferred to the growing plant. The aleurone cells of the
bran show no signs of change until the reserve starch is nearly exhausted,
when they begin to suffer attack, the cell-walls undergoing dissolution.
Doubtless the function of the aleurone cells is to provide protein nutri-
ment for the plant at a comparatively late stage of its growth, hence the
highly resistant cell-walls. In their researches on the Germination of the
Gramince, Brown and Morris demonstrate that the epithelium of the
germ secretes diastase during germination, and this is the agent of trans-
formation of the contents of the endosperm. They also, as has been pre-
viously mentioned, have shown that the diastase of germinating grain is
cyto-hydrolytic (cellulose dissolving) as well as amylo-hydrolytic. They
consider the former action to be due to a distinct and separate enzyme
from diastase proper, and that it also is secreted by the epithelium.

Two varieties of diastase have been described in the chapter on En-
zymes, that from raw grain, and ordinary or malt diastase — the former is
probably identical with the diastase of translocation, by which the starch
of the chloroplasts is converted into sugar ; while the latter is essentially a
diastase of germination, and is only secreted by the epithelium of the
scutellum. The power to liquefy starch-paste and to erode starch-gran-
ules always accompany each other, and, in fact, are never separable, being
in each case functions of germination diastase, or diastase of secretion.
Raw grain diastase is produced during the production of the embryo in

STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 253

the growing and unripe seed, and probably then acts as translocation
diastase for the purpose of preparing nutritive matter for the developing
embryo. The portion of such diastase remaining unused in the ripe seed
constitutes the diastase of raw or ungerminated grain.

The changes just described are those which wheat undergoes during
germination, and occur in an incipient form in sprouted or "growy"
wheat, in which the diastase of secretion, together with cytase, will have
more or less broken down the parenchymatous cell-walls, and also possibly
have eroded some of the starch. A useful test for growy wheat is to
examine the germ for starch; if any such granules are found within a
section when viewed under the microscope, it may safely be concluded
that the wheat is unsound. The changes to which malt owes its properties
are practically the same ; when germination has proceeded sufficiently far,
its further course is arrested in malting by kiln-drying the grain.

EXPERIMENTAL WORK.

411. The experimental work undertaken in connexion with the sub-
ject-matter of this chapter should consist in following its detailed direc-
tions for microscopic examination of wheat.

CHAPTER XIV.
CHEMICAL COMPOSITION OF WHEAT.

412. Principal Constituents of Cereals. — Proximate analysis of the
cereal grains shows that they contain as their principal constituents — fat,
starch, cellulose, dextrin, sucrose, raffinose, and possibly other sugars,
soluble protein bodies, consisting of albumin, globulin, and proteose ; in-
soluble protein bodies, consisting of glutenin and gliadin, which together
constitute gluten; mineral matters, consisting principally of potassium
phosphate and water.

In a table recently compiled by Hutchison, the general composition of
the cereals is given as follows : —

Constituents.

Fat

Wheat.

1.7

Barley.

1.9

Oats,
Hulled.

8.1

Maize.

5.4

Rye.

2.3

Rice,
no Husk.

2.0

Millet.

3.9

Buck-
wheat.

2.2

Carbohydrates. .
Cellulose

71.2
2.2

69.5

3.8

68.6
1.3

68.9
2.0

72.3
2.1

76.8
1.0

68.3
2.9

-61.3
11.1

Proteins

11.0

10.1

13.0

9.7

10.2

7.2

10.4

10.2

Mineral matter

1.9

2.4

2.1

1.5

2.1

1.0

2.2

Water

12.0

12.3

6.9

12.5

11.0

12.0

12,3

13.0

413. Average Composition of American Wheats. — Herewith is given
the average composition of American wheats, according to Richardson,
Chemist to the United States Department of Agriculture. The carbohy-
drates consist of the starch, dextrin, and sugar. The total quantities of
proteins are given, being derived from the percentage of nitrogen found.

254

CHEMICAL COMPOSITION OF WHEAT.

255

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256 THE TECHNOLOGY OP BREAD-MAKING.

414. Composition of Wheats, Fleurent. — Fleurent gives the follow-
ing as the composition of certain hard wheats examined by him, viz., Rus-
sian, Algerian, and Canadian wheat. (The last, however, contained from
25 to 30 per cent, of soft wheat.) The relative weight of endosperm,
embryo, and husk, is of interest : —

Russian Algerian Canadian Goose

Wheat. Wheat. Wheat,

Average weight of a grain in grams 0.030 0.048 0.037

Constitution, per cent : —

Endosperm 84.95 84.99 84.94

Embryo 2.00 1.50 2.05

Husk .. .. .. 13.05 13.51 13.01

COMPOSITION OF THE ENTIRE WHEAT.

Water . . 11.42 11.34 11.36

Nitrogenous matters : —

Gluten 14.76 11.00 10.88

Soluble (Diastases, etc.) . . 2.25 1.82 1.67

Ligneous, of husk . . . . 1.92 1.90 1.91

Starch 50.15 55.05 54.55

Fatty Matters 1.18 1.93 2.70

Soluble Carbohydrates : —

Sugars 2.14 2.68 2.18

Galactose 0.65 0.46 0.75

Of husk 1.76 2.19 1.90

Cellulose 9.73 9.40 9.21

Mineral Matters 1.56 1.42 1.35

Undetermined and loss 2.48 0.81 1.54

100.00 100.00 100.00

The gluten of the Russian wheat was found to contain : gliadin, 46.45 ;
glutenin, 37.89 ; congluten, 15.66 per cent. To the congluten, Fleurent
ascribes the tenacity and want of elasticity of the flour of these hard
wheats, which make inferior bread (Comptes Rend. 133, 944).

415. Durum Wheat, Norton. — This variety of wheat, Triticum
durum, is largely grown near the Mediterranean, and in Southern Russia,
for the manufacture of macaroni. Of recent years it has been somewhat
extensively grown in America, and used in the manufacture of bread
flours. In consequence, durum wheat has attracted considerable atten-
tion, not only in America, but also from European importers of American
flours. An extensive investigation of its properties was carried out at the
South Dakota Agricultural Experiment Station, U. S. A., by Norton, with
the following results. Samples of the wheat were grown at the station
and compared with European durum wheat, and also other American
varieties of wheat.

The Grain. The durum wheats have a very large kernel, being nearly
twice as large as that of ordinary bread wheats. The grains are hard, of
an amber colour, and appear almost translucent.

Composition of the Wheat. In order to compare the general composi-
tion of durum wheats with the bread wheats, a proximate analysis of Ku-
banka, one of the best Russian durum wheats, and one of the best Amer-
ican bread wheats (Blue Stem, Minnesota), was made. The results of
these analyses, together with the mean of American wheats as published

CHEMICAL COMPOSITION OF WHEAT. 257

by the Bureau of Chemistry of the Department of Agriculture, U. S. A.,
are given in the following table :

Kubanka Minnesota Mean of

Durum Bread American

Constituents. Wheat. Wheat. Wheats.

Water 9.32 6.00 10.62

Mineral Matter 1.71 2.46 1.82

Fat 2.34 2.49 1.77

Crude Fibre 2.52 3.35 2.36

Crude Protein, N X 5.7 14.46 13.21 12.23

Carbohydrates other than Crude Fibre . . 69.65 72.49 71.18

Sugar 3.26 1.42

Dextrin 1.25

Invert Sugar, Soluble Starch . . . . Nil Nil

This wheat was found to be remarkably sweet, and hence the sugar
was determined with, as shown, a very high percentage. The dextrin is
also extremely high as compared with quoted analyses by Stone, in which
0.27 and 0.41 per cent, respectively of dextrin were found in whole
wheats. In the case of the flours, as a result of indirect indications, maca-
roni or durum flours are estimated to contain from 1 to 2 per cent, of
sucrose as against 0.18 and 0.20 per cent, in two samples analysed by
Stone.

Protein Content of American Crops. In American durum wheat
crops, there is an increase in protein matter as against original imported
seed. The following are some results calculated to the water-free basis : —

Number of Protein, N y 5.7
Analyses. Per Cent.

Imported seed 7 15.73

Crop of 1901 31 18.13

1902 32 14.57

1903 45 17.34

The year 1902 was a very unfavourable one for durum wheat.
Durum Flour. A straight flour was prepared from durum wheats,

apparently of the 1903 crop, and various determinations made thereon.

Colour. The durum wheats possess a yellow colouring principle which

is also found in the flour, which is in consequence of a deep yellow tint

expressed on the Lovibond tintometer scale by 0.25 yellow -|- 0.17 orange.

*This colouring matter is soluble in alcohol and ether, but is insoluble in

distilled water. It is somewhat readily soluble in dilute alkalies, and is

discharged from solution by acids. (It is probably as a result of a similar

reaction that flour is stained yellow by the addition of sodium carbonate.)

Protein. — The following are the means of a number of determinations

made on durum flours : —

Crude Protein . . . . . . 15.00 per cent.

Wet Gluten 53.77

Dry „ 17.68

Gliadin . . . . 7.87

of total Protein 47.17 „

The gliadin determinations are calculated on a water-free basis.

The durum flours have a large gluten content, but the quality is not
good, usually showing very poor adhesive qualities, and but little elas-
ticity. These are properties commonly ascribed to lack of gliadin. Though
all the durum flours have high gluten and sugar contents, yet the bread
from many of the poorer durum wheat flours neither rises during the
fermentation nor in the oven.

258 THE TECHNOLOGY OF BREAD-MAKING.

Bakers' Tests. On being subjected to a baker's sponging test in which
the flour is made into a sponge, allowed to ferment, and the volume read
off, the volume of the best durum flours was as high as that of the bread
wheat flours. In baking tests, durum flour becomes more sticky than
bread wheat flours ; also if the doughs are a little too stiff they do not rise
properly, and the bread is heavy and of poor texture. With a sufficiency
of water, the volume, weight, and texture of the best durum wheat breads
compare favourably with those from the best bread wheats, arid the
flavour is decidedly pleasing (Jour. Amer. Chem. Soc., 1905, 922).

416. Voller on Wheats.— The tables on pages 260-5, headed "Dic-
tionary of Wheat, ' ' are taken from Voller 's excellent work on ' ' Modern
Flour Milling." They are particularly valuable as a succinct record of
the milling and baking characteristics of the most important wheats and
their flours of the world 's supply. Mr. Voller has very kindly made spe-
cially for this work a number of corrections and additions to these
tables.

Voller also gives some useful rules as to selection of wheats for differ-
ent characters, and also a table of mixtures equivalent to certain single
wheats, which may be used to replace the latter on their becoming ex-
hausted. Thus —
For largest loaf, use good Minnesota or Manitoba, run very close by fine

Saxonska, Azima or Ghirka.
For whitest flour, use good White English, Oregon, Australian, or Ros Fe

Plate, with choice for the latter.
For sweetest bread, use good English and Manitoban in about equal parts.

The following are examples of replacing mixtures, but are not in-
tended as exact equivalents in any sense : — *

Single Wheats. May be replaced by

1 Manitoban.

2 American Spring

0 ^ , ^T. 1 Bahia Plate.

2 Red Winter American. . . l Ros Fe plate

2 Saxonska.

3 Manitoban

1 Red Winter Kansas.

1 Manitoban ............. 1 Ghirka, Azima, or Ulka.

,. 1 Calif ornian or Walla.

2 Australian ............. _ a w_ Kurrachee.

2 California (or Walla) . . .

1 Australian.
1 Chilian.

1 Plate

2 Red Winter American .... Canaaian (Soft) .

,. White Bombay.

2 Cahfornian or Australian ^ Walla

o TVT- j T j- \ 1 Australian.

2 Mixed Indian j l Bahia

\ 1 Manitoban.

2 Bar-Russo Plate | l Calcutta? Na 2? or Ked Kurrachee.

417. Chemical Changes during the Formation and Ripening of the
Wheat Grain, Teller. — The following experiments were made in Ar-
kansas, U. S. A., 1897. Half an acre of growing grain was purchased

*The best substitutes for English sorts are the following: — Soft Canadians,
and Winter Americans, Dantzic, German, French and Mild Plates.

CHEMICAL COMPOSITION OF WHEAT. 259

early in May, and on the 22nd instant, when the wheat was past blossom-
ing, and the grain was set, a portion was cut. A further portion was cut
on each successive day, till forty-two portions in all were obtained. The
portions ranged in weight from 80-90 pounds at the commencement to
about 50 pounds at the close of the series. Immediately on cutting they
were carefully air-dried, and then stored in bundles till threshing time.
The summer was unusually dry. The wheat was threshed and cleaned at
the end of September. Analyses were then made on samples which were
hand-picked to free them from all foreign matter.

For various reasons the forty-two samples were arranged in fourteen
groups of three each. The following table shows the —

STAGE OF DEVELOPMENT OF WHEAT WHEN CUT.

Roman numerals indicate number of the group of three cuttings each.
Figures in parenthesis indicate numbers of the cuttings.

I. (1, 2. 3) A little past blossom. Grain set.
II. (4, 5, 6) Berries one-half to full length of ripe grain.

III. (7, 8, 9) Crushed berries exude a thin milky liquid. Lower
leaves beginning to die.

IV. ( 10, 11, 12 ) Grain well in milk.

V. (13, 14, 15) Heads and kernels well developed. Interior of

the grain a thin dough.
VI. (16,17,18) Grain in dough.
VII. (19, 20, 21) Grain in stiff dough. Straw becoming yellow at

butt. Grain shells a little with rough handling.
VIII. (22, 23, 24) Straw in field much yellowed but still decidedly

green.

IX. (25, 26, 27) Grain oozes a thin liquid when crushed between
the thumb nails. Contents still slightly viscid. Straw still a
little green.

X. (28,29,30) Wheat fit to cut at beginning of this period.
Straw has lost all its green colour and is dark purple immedi-
ately below the heads. Berry nearly dry. May be crushed
between the thumb nails but without contents adhering to
them.

XI. (31,32,33) More than ripe. Straw bright and stands up well.
XII. (34,35,36)

XIII. (37,38,39)

XIV. (40,41,42)

The wheat was of the variety known as the Fulcaster. It is a red,
bearded, wheat which is extensively grown in Arkansas.

260 THE TECHNOLOGY OF BREAD-MAKING.

DICTIONARY OF WHEAT (FOREIGN

WHEAT.

QUALITY OF BREAD.

Yield
of
Flour.

Weight
of
Wheat
per
Bushel.

Sort.

Colour

Structure

Taste.

Strength.

Colour.

AMERICA

(UNITED

STATES).

Michigan

White

Soft or mild

Sweet

Moderate

Good

68-72

60-63

Oregon

White

Mild

Dry insipid

Low

Fine

70-74

61-63

Blue Stem

White

Mild, dry

70-74

61-63

Walla Walla

White

Dry to brittle

3oor, insipid

Fair to

68-71

60-62

good

Calif ornian

White

Good to

68-72

60-63

fine

Goose or Durum

Yellow

Very hard

Dry, coarse

Low to fair

62-66

60-62

Wheat

CANADIAN

White

Mild, soft

Sweet

Fair

Good to

68-72

60-63

(Soft)

fine

CHILIAN

WorM

Dry to hard

Insipid

Low

68-73

60-64

ARGENTINE.

Plate— Candeal. .

Yellow

Hard, flinty

Coarse

Fair to

Poor to

62-66

60-64

good

fair

" Saldome...

Yellow

62-66

60-64

OCEANIA.

Australian — Vic-

White

Soft to dry

Sweet

Fair

Good to

70-74

61-64

torian &N.S.W.

fine

South and West

White

70-74

61-64

Australian

New Zealand. . . .

White

Soft, mild

Low to fair

Fine

70-73

61-64

INDIA.

Bombay (Soft) . .

White

Mild, dry, or

Strong

Fair to

Good to

70-73

62-64

brittle

good

fine

Delhi

White

« «

70-73

62-64

Kurrachee

WorM

« «

Fair to

66-70

60-64

good

Calcutta

WorM

« a

66-70

60-64

GERMANY.

Dantzic

White

Soft, mild

Sweet

Fair

Good to

68-71

60-63

fine

Konigsberg

White

68-71

60-63

Rostock

White

68-71

60-63

RUSSIA.

Taganrog Cones. .

Yellow

Hard, flinty

Dry, coarse

Low

Low to fair

62-66

60-63

Kubanka Cones. .

Yellow

Good or

Good

Fair to

64-70

60-63

sweet

good

EGYPTIAN

White

Mild to hard

Dry, coarse

Low

Low to fail

64-72

58-62

mixed

ENGLAND.

Talavera

White

Mild, soft

Sweet

Low to fair

Good to

68-72

60-64

fine

Chidham

White

68-72

60-64

Rough Chaff

White

68-71

60-64

Webb's Challenge
Hallett's Victoria

White
White

u
u

68-71
68-71

60-64
60-64

Salvator

White

67-70

60-63

Essex White

White

68-71

60-64

CHEMICAL COMPOSITION OF WHEAT.
WHITES AND ENGLISH).

261

IMPURITIES PRESENT.

GENERAL REMARKS.

Regular.

Occasional.

Pro-
bable

Chaff, screening,
seeds, maize
Chaff, oats, barley,
seeds

« « u

Chaff, smut, oats,
barley, seeds
Short straws, smut,
seeds,screen'gs
Maize, chaff,
screenings

a « «

Dirt, oats, barley
Smut, stone

Smut, dirt, stone
Dirt, stone

Oats,barley, stone,
scented seeds
Peas, oats, barley,
dirt

« it u

1-3
1-3

1-3
1-4

1-5
1-4
1-5

Clean, good wheat. Satisfactory substitute for
English.
Fine handsome grain. Low cleaning loss. High
flour yield.

u u u u u

Yellow tint to flour. Fair quality as 2nd class
white wheat.
Invaluable mixing sort. Useful all-round white.

Low flour yield. Washing alone can tone its
hardness. Difficult to finish.
A good coloury wheat of mild character.

Stone, dirt, seeds,
chaff

Oats and barley

2-6

Variable quality. Well worked mills a dead
white flour. Very fine in grain.

Oats, barley, seeds

u u u

Dirt, smut

u u

2-6
2-6

Needs careful washing and milling. Not good
flouring wheat.

It U U U U

Chaff, screenings

u u

Oats, barley, seeds

U U It

1-3
1-3

Choice colour wheat. Valuable with reds as
mixing.

« u u u u

u «

u u tt

1-3

u u u u u

Stopes, dirt, gram,
seeds

u u u
u u u

u u u

Oats, barley

u u
u u

3-6

3-6
3-6

3-6

Variable. Often fine quality, but purchases
need close watching. Indians all need wash'g.

It U U it U

Useful blending sorts. Absorb water freely.
Fair colour.

tt It U tl U

Chaff, screenings,
dirt

« tt u
u u u

Oats, barley, smut

« It U

u u u

2-5

2-5
2-5

Excellent mild working colour wheat.

u u u u

tt tt u u

Oats,barley,seeds,
rye

« u u

Smut, dirt, stone

« « «

2-6
1-5

Very hard to mill. Low in flour yield.
Strong hard grain. Washes to advantage.

Dirt, stone, seeds,
barley

Peas, beans

3-8

Washing absolutely needed. Colour of flour
dead white.

Chaff, screenings

u u
u u
u u
u u

It U

u u

Seeds,garlic,smut,
dirt, vetches

u u
u

u
u u

1-2

1-2
1-2
1-2
1-2
1-2
1-2

Large good wheat of top quality.

Brilliant handsome qual. Highest colour form.
Very reliable and a general favourite.

tt U U tt U

Unexcelled for colour when well grown.
Large, but hardly fine quality. Too coarse.
Fine medium grain, clear skinned and white.

262 THE TECHNOLOGY OF BREAD-MAKING.

DICTIONARY OF WHEAT (FOREIGN

WHEAT.

QUALITY OF BREAD.

Weight

Yield

Wheat

Flour.

per

Sort.

Colour.

Structure.

Taste.

Strength.

Colour.

Bushel.

ENGLAND-cont.

Red Lammas. . . .

Red

Mild, soft

Sweet

Low to fair

Good to

67-70

60-64

fine

Nursery

Red

67-70

60-64

Biddle's Imperial

Red

67-70

60-64

Browick

Red

Good

67-70

60-63

Square Head

Red

67-70

60-63

Square Head's

Red

67-70

60-63

Master

April

Red

Fair to g'd

65-68

60-62

Blue Cones

Red

Dry to hard

66-69

60-63

Rivetts Cones —

Red

66-70

60-63

Golden Drop

Red

Mild, soft

66-68

60-63

Prolific

Red

Good

67-70

60-64

Windsor Forest. .

Red

67-70

60-64

FIFE (new type).

Red

Firm to Hard

Good

68-72

60-66

SCOTCH

Ror W

Low

67-70

60-63

IRISH

RorW

67-70

60-63

DICTIONARY OF WHEAT

WHEAT.

QUALITY OF BREAD.

Weight

Yield

\\J U «

of
Flour.

W neat
per

Sort.

Colour.

Structure.

Taste.

Strength.

Colour.

Bushel.

AMERICA

(U. S.)

No. 1 Hard Spring

Red

Hard

Sweet

Full

Good

70-72

60-65

No. 1 Northern "

Red

68-71

58-64

No. 2

Red

Good to

67-70

57-63

full

No. 2 Chicago "

Red

Good

67-70

57-62

No. 3 Spring "

Red

Fair to

Fair

62-66

56-60

good

No. 1 Red Winter

Red

Mild, dry

Fair

Good to

70-73

60-64

(Choice)

choice

No. 2 Red Winter

Red

Good

68-72

58-62

Kansas Winter

Red

Hard

Fair to

67-71

58-62

(Hard)

good

Western Winter. .

Red

Mild or hard

u .

66-70

57-61

CANADIAN.

No. 1 MANITO-

Red

Hard

Good to

Good

70-73

60-65

BAN

full

No. 2

Red

Good

68-71

58-64

No. 3

68-70

58-62

CHEMICAL COMPOSITION OF WHEAT.
WHITES AND ENGLISH)— continued.

263

IMPURITIES PRESENT.

Pro-
bable

GENERAL REMARKS.

Regular.

Occasional.

Chaff, Screenings,
vetches

it u «

11 11 U

Smut, garlic, seeds,

dirt

tt tt tt

u it n

1-3

Safe old-fashioned sort. Works very white.
Small regular grain. Excellent quality.

tt tt it
ti u «

u u tt

1-3
1-3
1-3

Large bright red wheat. Average working sort.

tl tl It It U
tt (I ti tt U

u a «

a a a

« « U

tt n u
tt tt tt

tt tt tt
tt tt tt

U tl U

1-3
1-3
1-3

Thin grain. Not of highest milling quality.
In good repute for fine taste and colour.
Makes weak, coarse grained flour of dead
white colour.
Rather a low class among the native reds.
Good standard quality. Liked by millers.

u u ti u

u tt tt

Seeds and dirt

1-2

Valuable type grown from Manitoban seed.

tt tt tt
tt it it

tt u tt

1-3
1-3

Like much of the English, rather too soft and
weak.

11 U It It tt

(FOREIGN REDS).

IMPURITIES PRESENT.

GENERAL REMARKS.

Regular.

Occasional.

Pro-
bable

Cockle, seeds, spelt,

Peas, barley smut,

1-3

The premier strong wheat. Reliable for grade

white oats, chaff,

stone

and working quality.

maize

a u u

U tl 11

1-3

Nearly equal to No. I. Hard for strength. In

good repute amongst millers.

11 11 11

U 11 U

2-5

Less reliable than No. I of same class. Thinner,

with more waste.

u it it

U U tl

2-5

A safe grade of moderate strength. Small

bright wheat.

11 It It

tl U 11

3-8

Must be handled with caution as being dis-

tinctly a risky grade.

Cockle, grass seeds,

Peas, seeds, garlic,

1-3

Should be long "berried of brilliant quality.

oats, maize

stone, barley

Works mild and white.

U It tl

Stone, garlic, peas,

2-4

A safe and favourite grade. Dry and mild,

barley

without great strength.

a u n

Stone, peas, barley

2-4

Usually clean and regular. Of hard ricey

structure. Moderate strength.

U U 11

Smut, peas, barley

2-5

An off grade — not invariably regular in quality

Cockle&seeds,spelt,

Peas, dirt, stone,

1-3

Fine handsome as grain. Larger, but hardly

white oats,maize

barley

as strong as Duluth I.

U tl U

it u u

2-4

Good as a substitute for I. Northern Spring,

though a trifle weaker.

u it u

u u u

2-4

Useful as a cheaper substitute for No.2 grade.

264 THE TECHNOLOGY OF BREAD-MAKING.

DICTIONARY OF WHEAT

WHEAT.

QUALITY OF BREAD.

Yield
of
Flour.

V eight
of
Wheat
per
iushel.

Sort.

Colour.

Structure.

Taste.

Strength.

Colour.

CANADIAN-cont.
No.4MANITOB.

Red

Hard

Variable

Low to fair

Fair

62-65

56-60

(Sometimes Frosted)

Canadian (Soft)..

Red

Soft or mild,

Sweet

Fair

Good

70-72

60-62

dry

RUSSIAN.

Choice Azima. . . .

Red

Hard or med.

Dry, strong

Good to

Good

68-72

60-65

hard

full

" Ghirka.....

Red

« «

Good

68-72

60-65

Azima, 2nd qual..

Red

« u

Fair to

64-68

58-62

good

Ghirka "

Red

u u

& «

64-68

58-62

Azima or Ghirka,

Red

Soft or med.

Fair

Low, un-

60-65

55-60

third quality

hard

certain

Saxonska

Red

Dry, hard

Good

Good to

Good

68-72

60-65

full

North Russian . . .

Red

68-72

60-65

Polish

Red

Med., hard, or

Sweet

Fair to

66-71

60-62

mild

good

Siberian . . .

Red

Medium

Dry, strong

Fair

65-70

56-60

Ulka

Red

Mild to Hard

Good

66-72

60-64

TURKEY.

Danubian, first

Red

Hard or flint}

Dry

Low, fair

Fair to

68-72

60-64

quality

to good

good

Danubian, second

Red

Med. hard to

Low to fair

66-70

59-63

quality

flinty

Salonica

Red

Dry to hard

Fair to

66-70

60-63

good

Dede Agatch

Red

66-70

60-63

HUNGARIAN

Red

Dry hard to

Dry, sweet

Good to

Good

68-72

60-64

(Hard)

flinty

full

ARGENTINE.

ChoicePlate,No.l

Red

Mild to dry

Sweet

Fair to

Choice

67-70

62-64

Barletta(RosFe)

hard

good

F.A.Q.Plate,No.2

Red

Mild to med.

Good to

65-68

59-63

Barletta

hard

choice

Bar-Russo

Red

Hard

Sweet

Fair to

Bright

66-72

60-65

(Barisco)

good

Bahia

Red

Mild to dry

Sweet

Fair to

Good to

67-70

60-64

hard

good

choice

CALIFORNIAN

Red

Brittle to dry

Dry, rough

Low

Fair to

68-72

60-63

hard

good

DANTZIC

Red

Soft, mild, to

Sweet

Fair

Good

68-71

60-63

dry

KONIGSBERG.

Red

« «

68-71

60-63

INDIAN, No. 1

Red

Hard to flinty

Dry, ricey

Fair to

68-72

62-65

(Hard Delhi

good

" No. 1 (Soft)

Red

Mild-drv hard

Dry

66-70

61-64

« No. 2(Mxd.

Red

U it

66-70

60-63

SAMSOON (Asia

Red

Dry to brittle

Low to f ai

Low to fai

66-70

60-63

Minor)

PERSIAN

Red

Brittle to hard

65-70

60-63

MANCHURIAN

Red

Medium, hare

Fair

65-70

56-62

MOLDAVIAN..

Red

Dry to hard

Dry or swee

Fair to

68-72

60-64

good

Weight per bushel is for Imperial measure, and wheat supposed uncleaned as imported unless grossl
mixed with coarse light refuse — then after a light screening only. The weights, flour yields, and losses in-j
cleaning, as also the ordinary refuse contained in the different sorts, are all to be taken as the fair averagd

CHEMICAL COMPOSITION OF WHEAT.
(FOREIGN REDS)— continued.

265

IMPURITIES PRESENT.

GENERAL REMARKS.

Regular^

< Occasional.

Pro-
bable

Smut, seeds, oats,

Peas, dirt, stone

3-6

The presence of frosted grain should induce

barley

caution. Low yields.

White rnaize, oats,

Dirt, stone, smut

2-4

Excellent substitute for English. Decidedly

seeds, peas

weak in baking.

Rye, seeds, dirt,

Smut, barley, oats

2-3

The best all the year round wheats to fill place

screenings

of American Springs.

u « a

u u u

2-3

u u u u u

u « u

u u u

3-8

More waste than in No. 1 grades, and a lower

flour yield to be expected always.

« « u

u u u

3-8

u u u « tt

Rye, smut, dirt,

Barley, oats, stone

5-12

Excess of rye, smut, and seeds demands great

seeds

care in working.

Cockle, screenings,

Smut, rye, oats,

2-6

When available a useful change for best

dirt

barley

Ghirkas.

u u. u

u u u

2-6

u u u u u

Cockle, rye; dirt,

Smut, oats, barley

3-8

Somewhat softer than Azimas and Ghirkas.

seeds

Often a better colour.

Rye, seeds, dirt

u u u

3-8

Inferior to standard grades of Russian.

U U U

u u u

3-8

Now largely used to replace Azima and

Ghirka.

Tares, seeds,

Smut, oats, barley

2-4

Clean bright grain. Hard usually, and re-

screenings

quires plenty of water.

Tares, rye, smut,

Dirt, oats, barley

3-8

Often difficult to clean satisfactorily owing to

seeds

large tares and other seeds.

Screenings,barley,

Stones, rye

3-8

Not a high grade, though useful cheap mixing

smut, dirt

sort.

u 'u u

a u

3-8

u u u u u

Seeds and screen-

Rye, oats, barley

1-4

Bright regular grain. Should be of maximum

ings, dirt

strength.

Black oats, barley,

Smut, dirt

2-4

Long berried and fairly clean. Will produce

seeds

very white flour.

Black oats, barley,

Dirt, stone

3-6

Variable as to waste and grown grain. Well1

smut, seeds

cleaned will work white.

Oats, barley

Smut, seeds

2-6

Dry brittle variety very useful for replacing

American Winters or Ros Fe Plates.

Black oats, barley,

Smut, maize, dirt

2-5

Nearly as good quality as good Plate Barlettas

seeds

Short straws, oats,

Dirt,stone,scented

2-5

Yields a characteristic yellow flour. As a

barley, seeds

seeds

rule very weak.

Seeds, barley, oats

Dirt, smut, rye

2-5

More akin to English in work than any other.

White flour.

u u u

2-5

Generally as the Dantzic grades. Mild coL-

oury wheat.

Dirt, stone, seeds,

Gram, oats, spice

3-6

Often large and good grain. Requires great

barley, peas

u u u

3-6

care in cleaning and milling.

u u u u u

u u u

5-12

Being under top grade, will call for greater

care in working.

Dirt, stone, barley,

Oats, peas, beans

4-12

Variable as a rule; needs extreme care in clean-

seeds

ing.

u u u

4-10

Must be washed well to get full value from

these hard. wheats.

Rye, seeds

Barley, oats

3-8

Useful to replace any secondary reds of fair

strength.

Tares, seeds, rye,

Barley, oats, dirt

2-6

At times will mill and bake very well. Heavy

smut

sound wheats.

range. Russian samples admit of almost endless classification under names of ports — Berdianski, Novorros-
sisk, Ghenighesk, Marianople, Nicolaieff, Odessa, and many others. The general types are in all these
instances Azimas and Ghirkas, and the above analysis will therefore apply unless a new grade is specified.

266

THE TECHNOLOGY OF BREAD-MAKING.

The composition of the wheat at each stage is given in the following
table : — •

TABLE SHOWING THE PROXIMATE COMPOSITION OF WHEAT, IN PER CENT.
OF THE TOTAL DRY MATTER, AT FOURTEEN DIFFERENT PERIODS OF
THREE DAYS EACH FROM THE SETTING OF THE GRAIN TO PAST RIPE-
NESS, THE WHEAT BEING GATHERED AND DRIED ON THE STRAW.

Groups.

Ash

4.81

n.
4.16

in.
3.24

IV.

2.52

v.
2.16

VI.

2.07

VII.

1.82

Proteins

17.80

17.30

15.36

14.30

13.75

13.15

13.64

Amides

2.83

1.40

1.01

0.91

0.78

0.56

0.51

Fats ..

4.32

3.09

2.64

2.51

2.31

2.38

2.45

Crude Fibre . .

8.69

6.96

5.50

4.56

3.72

3.30

3.10

Pentosans

13.54

12.84

12.28

11.10

9.73

9.66

9.32

Dextrins

2.00

3.07

2.86

2.66

2.26

211

1.94

Sucrose

2.95

2.80

2.26

1.94

1.42

1.45

Glucose

1.55

0.64

0.17

0.08

0.07

0.05

Starch and Un-

determined

41.51

47.74

54.68

59.42

63.80

65.27

65.72

Groups.

VIII.

XI.

XII.

XIII.

XIV.

Ash ..

1.80

1.68

1.79

1.77

1.59

1.87

1.67

Proteins

14.55

15.40

16.24

14.96

16.59

16.56

17.26

Amides

0.50

0.44

0.50

0.44

0.61

0.62

0.56

Fats

2.59

2.60

2.44

2.50

2.37

2.46

2.52

Crude Fibre . .

3.11

3.01

3.03

3.04

2.98

3.00

2.96

Pentosans

8.82

8.50

8.41

8.08

8.16

8.33

8.63

Dextrins

1.75

1.72

1.83

2.46

1.77

1.79

1.75

Sucrose

1.43

1.28

1.44

1.52

1.51

1.53

1.50

Glucose

Trace

0.01

Trace

Starch and Un-

determined

65.45

65.36

64.32

65.23

64.42

63.84

63.15

(Bull. 53, 1898,

Arkansas

Agric.

Expt. Stn

418. Effect of Shade on Wheat Composition, Thatcher and Watkins.

— As a result of comparative experiments made on the same wheat
grown and ripened in sunshine and in shade respectively, Thatcher and
Watkins find that the shaded wheat gives grains which are darker in
colour. The protein is slightly higher and the starch lower than in the
unshaded samples (Jour. Amer. Chem. Soc., 1907, 764).

419. Frosted Wheat, Shutt.— Shutt finds on analysis that the protein
content of frosted wheat is considerably higher than that in the unfrosted
mature grain. The effect of frost is a premature ripening, or rather
dryirig-out of the grain, with as a consequence, a kernel high in protein,
but low in starch (Jour. Amer. Chem. Soc., 1905, 368).

CHAPTER XV.
THE STRENGTH OF FLOUR.

420. Physical Properties of Flour. — In addition to its purely chemi-
cal composition, flour possesses certain physical properties which are of
the highest importance to the baker, and consequently to the miller.
These are "Strength" and "Colour." Flavour may also be mentioned,
but this is essentially rather a matter of the palate than of chemical
analysis, hence a judgment of the flavour of flour is best made by the
actual consumer. These three properties of Strength, Colour, and Fla-
vour, together with certain side issues connected with them, largely, if not
entirely, determine the commercial value of a sample of flour.

421. Nature of Strength. — There are certain desirable qualities in a
bread-making flour which commonly go together. Among these are a
large relative yield of bread due to a high water-absorbing capacity, the
power of producing a large loaf, that of producing a bold loaf, and a well-
piled loaf. In consequence of these usually, but not invariably, accom-
panying each other, strength has been variously described as the property
of causing one or other of these effects. In the 1895 edition of this work
the following definition is given: — Strength, then, is defined as the
measure of the capacity of the flour for producing a bold, large-vol-
umed, well-risen, loaf, It is in this sense that the word is throughout
used in the present work.

422. Home-grown Wheat Committee's Definition. — Humphries and
Biffen, in a paper on * ' The Improvement of English Wheat, ' ' define their
view of "strength." They dismiss those estimates which are based on
measurements of water-absorbing power to produce a dough of standard
consistency, remarking that bakers do not make the various kinds of flour
up to one and the same consistency in the doughs. To give the best pos-
sible loaves, some require to be made into "tight," others into slack
doughs, and the baker simply learns by experience what particular degree
of consistency is the most suitable for the flour in hand. Number of
loaves per sack is another common method (being a variant of water-
absorbing power). But some Russian and most Indian wheats give a
large number of loaves but small and close of texture. This also is re-
garded as unsatisfactory. "A third view, apparently largely adopted by
the bakers, is to judge strength by the way a flour behaves in the doughs,
by its toughness, elasticity, freedom from stickiness, etc. ; in other words,
by the facility with which large masses of dough can be handled in the
bakehouse. It seems more satisfactory to regard them as separate charac-
teristics, for though of undoubted importance to the baker, they are not
necessarily associated with the production of satisfactory loaves. The
fact that some of the Russian wheats from St. Petersburg or Reval are
esteemed strong, but work very badly in the doughs, will show the neces-
sity for this distinction. ' '

"The definition finally adopted by the Committee [Home-grown
Wheat Committee of the National Association of British and Irish
Millers] is, that a strong wheat is one which yields flour capable of
making large well-piled loaves, the latter qualification thus excludes

268 THE TECHNOLOGY OF BREAD-MAKING.

those wheats producing large loaves which do not rise satisfactorily. To
estimate the strength of any particular sample of wheat then it is neces-
sary to grind it and make the final tests in the bakehouse. ' '

The baking tests were carried out in the following manner : — * ' In the
first place the baking trials are made with sufficient flour to yield a batch
of about half-a-dozen loaves — the 'cottage' shape being considered the
most satisfactory. With each set to be tried, loaves are baked from flour
whose quality has been accurately ascertained. To these standard loaves
a certain number of marks are assigned, and by comparison the baker
records in marks his opinion of the strength of the flour under test. On
this arbitrary scale the strongest wheats in commerce mark about 100,
'London Households' 80 to 85, and average English 60 to 65. The tests
are always carried out by a man who devotes the whole of his time to this
kind of work, and repeated trials have shown that they may be relied
upon to express the strength with substantial accuracy" (Jour. Agric.
Science ,1907, II., 1).

This definition of strength is practically a paraphrase of that of one
of the authors, previously quoted. In the one there is the expression
"well-risen," and in the other "well-piled"; the latter term being em-
ployed to exclude large loaves which do not rise satisfactorily. A large
loaf of coarse and ragged texture, and full of big holes, would not be re-
garded as either well-risen or well-piled.

423. Definition of Pile. — An explanation of the meaning attached to
the word ' ' pile ' ' may here be of service. It is stated on the authority of
a well-known Scottish baker, that the baker's use of the word originated
in Scotland. Their very high close-packed loaves are smeared on the
sides with melted lard before being placed in the oven. They are then
easily pulled asunder, and the surface of the separated sides should have
a smooth silky texture, a texture in fact recalling the "pile" of velvet.
Such loaves are said to have a good pile, or to be well-piled. A good pile
is associated with the same fine evenness of texture throughout the in-
terior of the loaf, and hence the term has acquired the secondary mean-
ing of an even, finely vesiculated, and silky texture of the substance of
the loaf.

424. Value of Baking Tests. — Any carefully devised method of mak-
ing baking tests can scarcely fail to differentiate strong from weak flours.
The difficulty is with those of intermediate and approximating character
and quality, and here much must depend on the suitability of the method
of working to the particular flour. To give an example of what is meant,
suppose a baker of one district adopts a four hours' system of fermenta-
tion, and another a six hours' system. A flour which is just exactly ripe
at the end of four hours would appear much stronger to the four hours'
baker than to the latter. Conversely a six hours' flour would be rela-
tively strong to the six hours ' baker and weaker to the four hours ' work-
man. An alternative method would be to allow the fermentation to pro-
ceed to the best possible point for each particular flour and then bake it.
This, however, introduces another element, in which there would almost
certainly be considerable variations in judgment. As a result of varia-
tions such as these, it is probable that out of six baking experts no two
would arrange a series of flours in quite the same order. Therefore,
though Humphries' and Biffens' baking tests may be regarded as com-
parative among themselves, the reservation must always be borne in mind
that there is no absolute and unvarying standard of strength. That flour
is strongest which under the particular conditions of fermentation em-
ployed or required by any particular baker or district best conforms to
the definition previously given of strength.

THE STRENGTH OF FLOUR. 269

425. Conditions requisite for Strength. — A loaf of bread consists of
a baked aerated mass of elastic dough. The first requisite of a strong
flour is that there must be a sufficiency of sugar or other material avail-
able for fermentation and consequent production of gas in the dough.
As dough fermentation involves a series of changes in which the disten-
tion by gas is but one, the source of gas must be sufficient for its con-
tinuous production, not only at the earlier stages, but throughout the
whole process, and essentially during that period in which the loaf is
acquiring its final shape and volume ; that is to say, some little time be-
fore and after it is placed in the oven.

The next there must be some substance present in the flour which
shall be capable of retaining a sufficiency of the gas generated in the
dough, and elastic enough to be evenly distended by such gas. Accord-
ing to the kind of loaves to be made, the requirements for strength some-
what vary. If the bread is to be baked in a tin, it is supported on all its
four sides, the top only being open; the same holds good, though to a
slightly lesser degree, in close-packed oven-bottom bread, where the loaves
support each other. For bread of this kind, the dough may be very soft
and even ''runny," provided it is elastic and of good gas-retaining capac-
ity. But when the bread is baked into crusty loaves, whether of the cot-
tage or Coburg type, the dough must not only be elastic and gas-retain-
ing, but it must also possess sufficient rigidity to maintain its shape when
standing alone and independently. Otherwise it may make a large but
flat loaf, and not a bold well-risen one. The requisites necessary for
strength under one of these sets of conditions are not precisely the same
"as in the other.

It is generally recognized that the constituent of wheaten flour in
virtue of which its dough possesses these qualities of gas-retaining power
and elasticity, is that known as gluten, that curious body largely com-
posed of gliadin and glutenin. There must be sufficient gluten present to
adequately retain gas and confer elasticity. Too much may be injurious,
inasmuch as it may offer too great a resistance to the action of the dis-
tending gas ; the consequence of this is the production of small and what
are sometimes called ' ' gluten-bound ' ' loaves. Further the gluten must be
of the right quality, it must be sufficiently impermeable to gas ; it must be
highly elastic, yielding readily to distention without breaking, and yet
it must be sufficiently rigid, particularly in the case of crusty loaves, to
maintain a well-upstanding bold shape. Quantity and character of
gluten may to a certain extent compensate each other. If the gluten is
exceptionally good, a little less of it may suffice, while slight deficiency
in quality may be made up by a little extra in amount. Added to air tins,
important changes are going on in the gluten during the whole of the
time of its fermentation. Normally, it is softening as fermentation pro-
ceeds, and becomes more yielding and gas-retaining during that opera-
tion. There comes a time, however, when the gas-retaining power is at its
best, and further change simply injures and diminishes its tenacity. The
art of the baker in part consists in so balancing all these various factors
as to get the best possible result out of the flour with which he is working.

426. Commercial Wheat Testing, Snyder. — In 1905, Snyder commu-
nicated a paper on this subject to the American Chemical Society in
which he first points out that the percentage of proteins in a flour is not
necessarily a measure of its value for bread-making purposes. The

270 THE TECHNOLOGY OF BREAD-MAKING.

following are some examples taken from the work of the Minnesota
Agricultural Experiment Station: —

Grade of Flour. Protein Commercial Rank

l>er cent. of Loaf.

First Patent 13.19 1

14.47 2

Second " 14.15 5

15.32 . 9

The following determinations are recommended as having given the
best satisfaction in flour-testing: Moisture, ash, total nitrogen, gliadin
nitrogen, granulation, absorptive capacity, and colour.

Moisture. — Especially helpful, as an excessive moisture content, above
13, has a tendency to induce fermentative changes.

^5/j,, — The determination is exceedingly useful in establishing the
commercial grade of flour. First and second grades of patent flour in-
variably contain less than 0.48 per cent, of ash; in case a flour contains
0.5 per cent, of ash it would not be entitled to rank with the patent
grades. Straight grade flour rarely contains more than 0.55 per cent, of
ash, while the first and second clear grades contain higher amounts, 0.8
and 1.75 per cent, respectively.

Nitrogen content. — The best bread-making flours have a total nitrogen
content of from 1.8 to 2.1 per cent. A lower figure than 1.5 per cent,
indicates deficiency in gluten, and poorer bread. Flours containing an
excess over 2.1 do not as a rule have improved bread-making values, as a
very high gluten is not beneficial for bread-making purposes.

Gliadin Nitrogen. — The principal proteins of flour being gliadin and
glutenin, it has been believed that their ratio determines largely the value
of the glutinous material for bread-making purposes. Snyder finds, how-
ever, that "during some years as high as 70 per cent, of the total nitro-
genous material of wheat is soluble in 70 per cent, alcohol, while in other
years flour from wheat grown under similar conditions contains as low as
45 per cent, of its proteins soluble in 70 per cent, alcohol, and that these
differences have been associated with only minor variations in the size of
the loaf or general bread-making value of the flour. ' '

Snyder believes that the percentage of gliadin in a flour is of more
importance than the gliadin-glutenin ratio. In flours from the same
wheat, the lower grades contain more total protein, but proportionately
less gliadin than the higher ones. He also finds that any slight increase
of acidity of the grain materially influences the gliadin percentage, which
fact is shown in the following table : —

FLOUR.

Constituents, etc. First Second Clear

Patent. Patent. Grade.

Ash . . per cent. 0.39 0.47 0.84

Protein 13.56 14.70 7.27

Gliadin, of total Protein . . . . „ 59.07 56.25 54.21

Acidity 0.07 0.08 0.12

Commercial rank of loaf .... I II III

Snyder does not find gliadin to be of uniform composition, there being
as great a difference as one or more per cent, in the nitrogen content of
gliadin from different wheats milled under similar conditions. This sug-
gests that gliadin is lacking in definite chemical composition, possibly as a
result of wheat containing more than one protein soluble in 70 per cent,
alcohol. He concludes that wheat gliadin is not as constant in chemical
composition or physical properties as would be expected of a definite
chemical compound.

THE STRENGTH OF FLOUK. . 271

Granulation. — This should be of medium fineness as such insures more
complete digestion and absorption of the nutrients of flour by the body.
Colour. — This' is one of the main factors in determining flour value,
as each type of wheat has a tendency to produce flour of a distinct shade.
Bread-making Tests. — As yet chemical tests are not capable of ac-
curately determining the bread-making value of a flour. They often in-
dicate, however, why a flour is deficient in desirable bread-making char-
acteristics, and from the chemical tests ways are suggested for improving
the flour, but the actual bread-making value can be determined only by
comparative bread-making tests. These give accurate data, including ab-
sorptive capacity and consequent yield. (Jour. Amer. Chem. Soc., 1905,
1068).

With an excess of nitrogen the "gluten-bound" condition before re-
ferred to comes into operation. The abstract of this paper is purposely
introduced here because of the strong expression of opinion as to effect
of the ratio of gliadin to glutenin on the quality of a flour. Snyder's
authoritative statement as to variations in the composition of gliadin also
deserves careful attention. It should be compared with that following
of Wood, paragraph 428. Snyder ultimately falls back on the baking
test as most accurately determining the bread-making value of a flour.

427. Crude Gluten, Norton, — Norton has made a very full analysis
of crude gluten as obtained from durum flour. The gluten was washed
out, partly dried, finely ground and again dried until it ceased to lose
weight at 100° C. On analysis it then gave the following results : —
Fats or ether extract . . . . . . . . 4.20 per cent.

Carbohydrates other than fibre . . . . . . 9.44

Fibre . . . . 2.02

Mineral Matter 2.48

Gliadin 39.09

Glutenin .. 35.07

Globulin, 10 per cent. NaCl extract . . . . . . 6.75

99.05

The gliadin was first removed from the gluten by alcohol, the residue
was then extracted with 10 per cent, sodium chloride solution for globu-
lin, and the residue finally extracted with 0.2 per cent, potassium hy-
droxide. Nitrogen was determined in each extract and multiplied by 5.7
for protein. From the above analysis, crude gluten may be regarded as
consisting of about 75 per cent, of true gluten (gliadin and glutenin)
together with other matters as indicated, and which include approxi-
mately 7 per cent, of non-gluten protein matter.

In summarising his results, Norton points out that the crude gluten of
flours is very close in amount to that of total protein (N X 5.7), the
variation being in a number of samples from an excess of crude gluten of
2.31, to a deficit of 1.30. As a rule the crude gluten is the higher for
straight and low grade flours, nearly the same for patents, and less for
whole wheat meal. It follows that crude gluten is- a body in which there
has been a loss of non-gluten proteins, more or less balanced by the re-
tention of non-protein matters. Crude gluten is a very rough expression
of the gluten content of a flour or wheat, and the determination has but
little worth in the valuation of flours. The determination of total nitro-
gen and gliadin-nitrogen with expression of the ratio of gliadin to total
protein (N X 5.7) seems to be the best simple method at hand for esti-
mating the gluten content and ascertaining the character of the gluten in
the valuation of wheats or flours (Jour. Amer. Chem. Soc., 1906, 8).

272 THE TECHNOLOGY OF BREAD-MAKING.

Any review of opinions as to the value of gluten determinations is
best postponed until a later stage. Meantime, the results of a very com-
plete analysis of crude gluten is here placed on record. The most notice-
able feature is the retention of 6.75 per cent, of globulin, a non-gluten
protein. The comparative purity of crude gluten must depend somewhat
on the thoroughness of the washing treatment ; it will be observed that in
the 1895 edition of this work about 80 per cent, of crude gluten is as-
sumed to be true gluten. This was determined by a direct nitrogen
estimation and substantially agrees with the sum of gliadin, glutenin, and
globulin found by Norton.

Chamberlain, another American chemist, practically agrees with Nor-
ton and affirms that the determination of gluten is not able to yield any
information that cannot be gained either from the determination of total
proteins or that of the alcohol-soluble and insoluble proteins (Jour. Amer.
Chem. 8oc., 1906, 1657).

428. The Chemistry of Strength of Wheat Flour, Wood.— This sub-
ject has been dealt with in papers published by Wood in the Journal of
Agricultural Science, of which the following is a statement of his chief
conclusions : — It may be regarded as proven that neither the absolute
percentage of gliadin in the flour, nor the ratio of gliadin to total pro-
tein gives satisfactory indications of strength. Strength may be sepa-
rated into at least two independent factors, those of volume and shape.
In investigating the volume factor, Wood attaches great importance to
the presence of sugar or sugar-producing substances in the dough. Sum-
marising a number of experiments he states that they "seem to justify
the conclusion that the capacity of a flour for giving off gas when in-
cubated with yeast and water is the factor which in the first instance
determines the size of the loaf. ' ' Particular attention should however be
paid to the rate of gas evolution in the later stages of fermentation, as
this is shown to be more directly connected with the size of the loaf.
(Wood, Journ. Agric. Science, 1907, 2, 139).

The suggestion in this paper that strength runs parallel with percent-
age of sugar is somewhat contrary to the hitherto generally accepted
views. Thus the descriptions "a weak sweet flour," and "a strong,
harsh, dry flour" are very familiar. A reference to the 1895 edition of
the present work shows (page 291) that No. 2 Calcutta yields 8.34 per
cent, of soluble extract, and (page 339) that the loaf is small and runny,
devoid of texture, and foxy. On the other hand reference (page 292)
shows that a sample of No. 1 American Hard Fyfe Wheat, yielded 4.35
per cent, of soluble extract, while the corresponding Spring American
patent flour (page 338) yielded a loaf which was very bold and of good
texture, but with a tendency to become somewhat rapidly harsh and dry,
and comparatively flavourless. No determinations were made of sugars,
but it is practically certain that they rise and fall with the total soluble
extract. In paragraph 427 an account is given of some investigations of
durum wheat by Norton. He there remarks that though all the durum
flours have high gluten and sugar contents, yet the bread from many of
the poorer durum wheat flours neither rises during the fermentation nor
m the oven.

429. Effect of Sugar on Flour. — An interesting side-light is thrown
on the effect of the presence of sugar in flour by the following experi-
ments. In sweet biscuit doughs it is well-known that the physical condi-
tion of the dough is materially affected by the presence of the sugar.
Thus a dough made from 100 grams of flour and 50 grams of water is
much stiffer than one made from 100 grams of flour, 20 grams of sugar,

THE STRENGTH OF FLOUR. 273

and 50 grams of water, the latter being soft and sticky. For example,
with such doughs, when tested with the viscometer, the following results
were obtained. In order that the sugar dough should register equally the
water had to be reduced to slightly less than 40 grams thus : —

Viscometer Time.

I. Flour 100, water 50 106 seconds.

II. Flour 100, sugar 20, water 50 .. . . 9

III. Flour 100, sugar 20, water 48 . . . . 16

IV. Flour 100, sugar 20, water 46 . . . . 28
V. Flour 100, sugar 20, water 44 . . . . 50

VI. Flour 100, sugar 20, water 42 . . . . 64

VII. Flour 100, sugar 20, water 40 . . . . 86

VIII. Flour 100, sugar 20, water 38 .. ..364

for the half descent of the viscometer piston.

In view of these facts, tests were made on behalf of a firm of biscuit

manufacturers, and communicated to them by one of the authors in 1902.

Particulars of the flours are given. The sugar was supplied by the firm

in question and gave the following results on analysis : —

Cane Sugar from opticity . . . . . . 98.45 per cent.

Reducing Sugar as Glucose . . . . . . 0.80 „

Water 0.10

Mineral matter . . . . . . . . 0.04

I. Doughs were made with flour A and B. The wet and dry g 'ten
were determined by washing and drying ; the true gluten by a KjelJahl
estimation on dry gluten ; gliadin by dissolving the wet gluten with 70
per cent, alcohol, filtering and Kjeldahl estimation on the filtrate;
glutenin by subtracting gliadin from the true gluten.

II. Doughs were made from 100 parts of flour and 20 parts of sugar
(sugar-dough). The gluten was washed out with water, and weighed
wet and dry. True gluten was determined as before. Gliadin was deter-
mined by dissolving wet gluten with. 70 per cent, alcohol, containing to
100 parts of alcohol, 20 parts of sugar (sugar-spirit), filtering, and a
Kjeldahl estimation on the filtrate ; glutenin, by subtracting gliadin from

true gluten.

A B.

Constituents. Ordinary. Sugar-dough. Ordinary. Sugar-dough.

Gluten, wet . . . . 37.2 35.9 26.7 23.9

" dry .. .. 11.3 11.7 8.2 7.7

" true .. '.. 10.4 10.0 7.5 7.2

Gliadin ex Gluten . . 3.6 7.2 3.0 5.6

Glutenin . . . . 6.8 2.8 4.5 1.6

In all cases the sugar caused a diminution of the quantity of gluten
recovered, except in the case of the dry gluten of flour A. When ex-
tracted with alcohol, much more of the gluten was dissolved by the sugar-
spirit, than the ordinary alcohol, showing that sugar has a marked sol-
vent action on wet gluten. (As all these gliadin determinations were
made in the presence of excess of carefully washed precipitated chalk,
CaC03, there could have been no free acid present.)

In the next place, the total protein of the flours was directly estimated
by Kjeldahl's method. The proteins soluble in water were determined
by directly treating the flour, filtering and Kjeldahl's process on the
filtrate. The proteins extracted by a 20 per cent, aqueous sugar solution
were similarly determined. The proteins soluble in 70 per cent, alcohol
were estimated by direct treatment of the flours, and a Kjeldahl estima-
tion on the filtrate. The proteins similarly dissolved by 20 per cent, of

274 THE TECHNOLOGY OF BREAD-MAKING.

sugar in 70 per cent, alcohol (sugar-spirit) were also determined. The
following are the results in percentages obtained on the same two flours :

Constituents. A. B.

Total Proteins . . . . 11.6 11.6 9.9 9.9

Proteins soluble in Water . . 1.0 0.5

11 " Sugar-water 1.5 2.5

Gliadin and Glutenin . . 10.6 10.1 9.4 7.4

Soluble in Alcohol, Gliadin

" Sugar-spirit" .. 6.4 7.5 4.6 5.7

a tt

Insoluble, Glutenin . . . . 4.2 2.6 4.8 1.7

It is assumed here that water and sugar-water respectively do not
dissolve the same proteins as are dissolved by alcohol and sugar-spirit ;
probably however there is some overlapping. As the experiments are
comparative this does not affect the point under consideration. It will be
noticed that in every case there is an increased solvent power exerted
when sugar is present. These tests were confirmed by others on four
other samples of flour. In all cases, sugar-spirit dissolved considerably
more protein than did plain alcohol. Sugar diminishes rather than in-
creases the water absorptive power of the flour. In small quantities it is
very possible that its solvent action on the gluten may effect sufficient
softening to increase the gas-retaining power of the dough and thus in-
directly increase the strength of the flour.

430. The Shape of the Loaf, Wood. — Following up his previous
paper, Wood made a subsequent communication on what he regards as
the second factor of strength, viz. that which decides the shape of the
loaf, and this was tentatively ascribed to the soluble salts present in the
flour. A further investigation was made of this hypothesis, with the re-
sult that Wood concluded that the variations in coherence, elasticity, and
water content, observed in gluten extracted from different flours, are due
rather to varying concentrations of acid and soluble salts in the natural
surroundings of the gluten than to any intrinsic difference in the compo-
sition of the glutens themselves. These properties must undoubtedly
have a direct bearing on the power which some flours possess of making
shapely loaves. I suggest therefore that the factor of strength on which
the shape of the loaf depends is the relation between the concentrations
of acid and soluble salts in the flour." The author of the paper realises
that his ' ' results are at present only in what may be called a suggestive
state." (Wood, Jour. Agric. Science, 1907, 2, 267.)

431. An Analysis of the Factors contributing to Strength in
Wheaten Flour, Hardy. — Hardy elaborated and explained his views
on the relation of strength to electric potential in a paper read by
him at the meeting of the British Association for the Advancement of
Science, 1909. He compares dough to rubber loaded with solid particles,
the gluten being the analogue of the rubber, and the starch contributing
the solid particles. He goes on to say : — There has, so far as I know, been
no exact work upon the influence of the size and number of the starch
grains upon the mechanical properties of dough ; in the absence of such
information it is idle to pursue the point further. This may, however,
be said: judging by what is known of the influence of embedded small
particles in other cases, the power of the dough to retain its shape may
be due in some cases primarily to the nature and number of the starch
grains. But the essential active agent is the protein-complex gluten.

THE STRENGTH OF FLOUR. 275

Now gluten, even though it be prepared from the best Fife flour, has
of itself neither ductility nor tenacity. In presence of ordinary distilled
water it partly dissolves, the residue — the larger portion — forming a
semi- fluid sediment destitute of tenacity. Why ? Because tenacity and
ductility are properties impressed on gluten by something else — namely,
by salts, by electrolytes, that is, which may be organic and may therefore
be unrepresented in an ash analysis.

This being the case, it is obvious that any attempt to correlate
strength with the physical properties of gluten washed out in the ordi-
nary way must end in failure, since the properties of washed gluten de-
pend upon the electrolytes which happen to be left in after the washing
is concluded. *

Electrolytes — that is to say salts, acids and alkalies — intervene in two
absolutely distinct ways. They control the physical properties of the
gluten in the dough, and they must also profoundly modify the tempera-
ture relations and the rapidity of the change undergone by the gluten
and other constituents of the dough in the process of baking — a change
which, so far as the proteins are concerned is, broadly speaking, a lower-
ing of solubility. We know something of the way in which they act on
gluten in the dough, but of the more complicated action during tempera-
ture changes we know nothing; it is possible that the same electrolyte
may increase the mechanical stability of the loaf in the dough and yet
diminish it in the oven.

The writer next summarises the results of Wood 's experiments before
described, in which it is shown that certain very dilute acids disperse
gluten in fine particles, which are so changed that they actually repel
one another, such repulsion being overcome and cohesion restored by the
neutralisation of the acid or the addition of any salt such as common
table salt. The cohesion of gluten is due to the salts naturally present ;
and their removal, as by washing with distilled water, causes the break-
ing down of the gluten. When gluten is thoroughly extracted with dis-
tilled water it loses cohesion and disperses as a cloud, not owing to the
action of the water, but because of the faint acidity due to the carbonic
acid dissolved from the air. In the absence of salts, this is sufficiently
strong to destroy cohesion. In cases where the quantity of salt is insuffi-
cient to counteract that of the acid, the gluten is in a state of colloidal
solution, containing exceedingly fine particles of gluten. With an in-
crease of salt the particles become continually coarser, until finally they
run together into a coherent mass of gluten. As the salts present still
further increase, there is still further separation of water, and as the
water-holding power of the protein diminishes, so also does its ductility,
while at the same time there is an increase in the tenacity.

Electrolytes, therefore, do more than confer on gluten its mechanical
properties; they determine also its power of holding water. They also
determine the water-holding power of any other colloid matter present in
the dough.

Acids and alkalies destroy cohesion and disperse the particles of gluten
just as they produce and stabilise non-settling suspensions in many types
of colloidal solution— namely, by the development of a difference of
electric potential between the particles and the water. The curve which
connects the potential difference with the concentration of acid has the
same form as that which represents the region of gluten non-cohesion.

The foregoing analysis of the factors which control the physical pro-
perties of gluten in moist dough lead us to a brief analysis of the source
of "strength" in flour. It must be borne in rnind that loaf -making

276 THE TECHNOLOGY OF BREAD-MAKING.

includes two distinct operations, the making and incubation of the dough
and the fixation of the incubated dough by heat. Every factor which
contributes to the rising of the dough — that is, to the size of the loaf—
and to the power of the dough to preserve its shape (saving only the vital
activities of the yeast plants) intervenes also in the fixation of the dough,
where it may undo what it has already done. Successful incubation de-
pends upon : ( 1 ) The suitability of the dough for the active growth and
production of carbonic acid by the yeast plant, which again depends upon
the concentration of sugar, the intrinsic diastatic power of the dough
and the concentration and nature of the electrolytes. (2) The physical
character of the dough, which depends upon the size, shape, and number
of starch grains, the nature and concentration of the electrolytes, since
these determine the physical properties of colloids present, notably the
gluten. The electrolytes will also direct those molecular rearrangements
which occur during the baking process and which give fixity and stability
to the entire structure. (Supplement, June 4 ,1910, p. 52, Jour. Board of
Agric.)

Snyder had previously dealt with the effect of variations in the quan-
tity of starch on the character of dough, and concluded that they were
without any marked effect. One of the authors had previously shown
that with flours having different quality glutens, such glutens main-
tained their individual character through a long range of variations
produced by the addition of starch. Hardy advances the paradox that
gluten, even of the strongest flour, "has of itself neither ductility nor
tenacity." The correctness of this dictum depends on the definition of
the word "gluten." In the primary sense in which that word is
almost universally employed, gluten is the name of that elastic, ductile,
and tenacious mass, whatever may be its composition, which is obtained
by washing dough in the recognised manner. Gluten has hitherto
been supposed to consist essentially of protein matter, but Wood's
researches go to show that certain salts exercise a profound influence
on its character. The presence of these may in fact be regarded as
a necessity, and if they be removed the remaining body or bodies is
no longer gluten in the generally accepted sense of the word. Putting
it another way, the proteins of gluten, in the absence of electrolytes,
are collectively neither ductile nor tenacious. But from this it does
not follow that no relation exists between the strength of a flour and
the physical properties of its washed-out gluten. It is generally agreed
that the physical strength of dough, i. e.f its ductility and tenacity, de-
pends on the quantity and quality of the gluten it contains, using that
word in its evident sense as including proteins, electrolytes, and all that
jroes to give that body its essential characters. As a matter of fact, the
general rule is that a properly washed-out gluten correctly reflects by its
quantity or quality, or both, the strength of the flour from which it was
obtained. To this the exceptions are remarkably few, and interesting
evidence of the value of this test was given by Saunders in the course of
a paper read by him at the same meeting, and quoted at the close of this
chapter. When gluten washing is done with suitable water, sufficient
electrolytes remain in the gluten to conserve its characteristic properties,
and enable a judgment to be based thereon.

The writer's speculations as to the effect of electrolytes through the
whole process of baking, as well as of fermentation, are of interest, and
may very probably indicate the direction in which the future solution of
many problems may be found. The relationship of cohesion of gluten to
electric potential is clearly indicated, but the question remains whether

THE STRENGTH OF FLOUR. 277

any part of the operations of baking falls within, or even approaches, the
region of non-cohesion of gluten. Taking the figures given in the writer's
paper, about 22 grains cf common salt per 1,000 litres is sufficient to
neutralise the maximum disintegrating effect of sulphuric acid. The
word grain may possibly be a misprint for gram, and if so the figure is
22 grams per "1,000 litres. Assuming this latter to be correct, then the
degree of concentration is 22 grams per 1,000 litres = = 22 grams per
1,000,000 grams of water. In bread-making salt is always used, and to
an extent of about 3 Ibs. to the sack of 280 Ibs. of flour. To the water,
salt is taken in the approximate proportion of 2 Ibs. of salt per 100 Ibs.
of water, which equals 2,000 grams of salt to 1,000,000 grams of water, or
about ninety times the concentration for the critical point in Hardy's
curve. The question of the influence of sugar upon strength has been
already discussed, and with it much of the importance or otherwise of the
diastase of dough is closely connected. Snyder's work already referred
to goes to minimise the efiect of starch grains.

432. Size of Starch Grains, Armstrong. — The size of wheat starch
grains was also referred to by Armstrong in a paper read at the same
meeting. He states that microscopic examination shows flour to consist
of starch granules of three different sizes. The smallest granules which
preponderate in amount are from 3 to 5 ^ in diameter, the largest gran-
nies are about 30 to 35 u. and there are also granules of intermediate size.
The microscopic examination of a large number of flours of different
origin has shown that the large granules very in number from 6 to \l/2
per cent, of the total number of granules. In other words, in one flour as
much as 30 to 40 per cent, of the total weight of starch is in the form of
large grains, whilst in another only 7 to 10 per cent, is in this condition.

Before a starch grain can be converted into sugar the cellular en-
velope has first to be destroyed. Obviously, when the envelope of the
large granule is destroyed a much larger proportion of starch is rendered
available than when the contents of a small granule are liberated.

Whymper has made a microscopic study of the changes occurring
during the germination of wheat. He finds that the larger and more
mature granules are the most readily attacked by the enzymes of the
plantalet. Though there is no general relation between the size of
starch granules of different origin and the ease with which they are at-
tacked by diastase and other agents, it appears that the larger granules
of any particular starch are affected sooner than the smaller granules.
(Supplement, June 4, 1910, p. 49, Jour. Board of Agric.)

Armstrong's examination of starch is evidently the result of his con-
clusions that flour does not contain sufficient sugar for bread-fermenta-
tion, and that the requisite sugar is always provided by the hydrolysis of
starch.

With the object of further investigating the effect of different sizes of
starch granules, the authors made the following experiments. A strong
American flour was taken, being No. 6 in the Table of Flours and
Wheats, described in Chapter XXIII. To 80 parts of this flour there
were added and thoroughly mixed 20 parts of potato, wheat, and maize
starches respectively. The potato starch granules are considerably larger
than those of wheat, while those of maize starch are very much smaller.
[Compare with dimensions given in Plate I and accompanying descrip-
tion in letterpress. 1 In these three mixed flours the average size of the
starch granules was therefore increased in the first, unaltered in the
second, and diminished in the third. The original flour yielded 15.02
per cent, of dry gluten, which gives the mixed flours an amount of 12.01

278 THE TECHNOLOGY OF BREAD-MAKING.

per cent, in each case. Viscometer determinations of water absorption
gave the following results in quarts per sack : —

Flour only. Flour & Potato Starch. Flour & Wheat Starch. Flour & Maize Starch.

Quarts. Seconds. Quarts. Seconds. Quarts. Seconds. Quarts. Seconds.

G5 315 65 90

66 81 66 102

66.5 60

67.0 60

68 227 68 42 68 48 68 54

70 52 70 27 70 28 70 37

72 43

The figures in heavier type are those which practically agree with the
sixty seconds standard. The whole of the starched flours have fallen off
in water-absorbing power. Throughout the series of tests, this falling off
has been greatest with the potato starch and least with that of maize. The
difference may probably be accounted for by the greater surface offered
by the smaller starches in proportion to their weight.

Baking tests were next made with the flours with the special object of
observing their strength behaviour both in the dough and the loaf. A
stiff dough was made from each for crusty Coburg loaves. The water
taken was in the same proportions as in the viscometer tests. Those from
the three mixed flours fermented much more rapidly than did the un-
mixed flour, which latter made a bold sweet loaf, while the former on
falling in the dough was unable to rise again .either during fermentation
or in the oven. The starch-mixed loaves were all distinctly over-worked
and sour to the nose. A second test was made in which the three mixed
flours were fermented for a shorter time, as nearly as possible three-
quarters of that required by the unmixed flour only. In this case much
better results were obtained, but all the doughs fell off in the latter stages
of fermentation, and had comparatively little * ' spring ' ' in the oven. The
differences in behaviour were very slight; but if anything the potato
starch loaf was least tough and ''springy7' (elastic) in the dough, and
rose least in the oven. The wheat starch loaf came next, and the maize
starch gave the best results of the three.

433. Water-soluble Phosphates in Wheat, Wood.— Professor Wood
kindly forwarded to the authors in 1910 an advance note of experi-
ments recently performed by him, of which the following is a summary :
—Wood made a number of analyses of the water extract of different
flours. The method used was to shake up 200 grams of flour witli 2,000
c.c. of water containing a few drops of toluene to delay fermentation. The
shaking was continued for one hour, and the mixture then filtered. Ali-
quot portions of the clear solution were then evaporated to dryness, and
their content of phosphoric acid, lime, magnesia, chloride, and sulphate
determined. He finds that in all the flours made from Fife wheat, the
water soluble phosphate is high — over 0.1 per cent, of the flour, and the
chlorides and sulphates very low. They also contain more magnesia than
lime. Wood has examined about half a dozen samples of Fife, some
grown in Canada and some grown in various parts of England, and they
all agree in these respects. Weak wheats of the Square Head's Master
type, and in fact all the wheats he has examined, except the Fifes, and
one which came from Japan, contain from 0.8 per cent, to as low as 0.04
per cent, of water-soluble phosphoric acid, and correspondingly higher
amounts of sulphate and chloride, and as a general rule more lime than
magnesia. Wood has little doubt that the peculiar properties of the
gluten of the Fife wheats is due to their high content of water-soluble

THE STRENGTH OF FLOUR. 279

phosphate, and believes that the determination of the water-soluble phos-
phate gives a great deal of information as to the character of the gluten
content in a flour. (Personal Communication, May, 1910.)

434. Strength of Wheat Flours, Baker and Hulton. — This paper is
marked by the writers' recognition of the fact that the strength of flour
depends on more than one factor. In connexion with the enzymic ac-
tivities of flour, they examined the effect of the proteolytic enzymes both
of the flour itself and of yeast on gluten. It is of special interest to note
the recognition they give to the possibilities of "profound change" in
physical character of substances such as gluten without any corresponding
chemical changes in the ordinary use of that term. They also consider
that the gas concerned in the rise of bread, especially in the latter stages
of doughing and the early part of baking, is derived from the starch of
the flour. Gas retention is recognised by the writers as more important
than gas production. Careful attention was given to the amylolytic en-
zymes of flour, and especially to the presence or absence of a liquefying
enzyme. This they regard as having an important bearing on strength,
and produce results in support of their conclusion. The difference in
activity of flour diastase to soluble starch and starch paste respectively
was made the subject of experiments by one of the authors, and recorded
in the 1895 edition of this work. In summarising their conclusions, the
writers emphasize the fact of its close connexion with gluten.

435. Present-day Conclusions. — In paragraph 425, in the early part
of this chapter, it is laid down that there must be a sufficiency of sugar or
other material available for fermentation in the dough. It has also been
suggested that the presence of much maltose is evidence of unsoundness.
and reference has already been made to the fact that certain very strong
flours contain comparatively little sugar, while in others which are weak
sugar is present in comparatively large quantity. Flours from sprouted
wheats are comparatively weak and with high maltose contents; in such
cases there is probably practical agreement with the view that the high
sugar is associated with low strength. If wheat is gathered and milled
in an unripe condition, there is again a lack of strength, and yet there is
a relatively high percentage of sugar. Thus in the account given in
paragraph 417 of Teller's researches on the composition of wheat at dif-
ferent stages of ripeness, it is shown unripe wheat contains more sucrose,
2.95 to 1.43 per cent., than ripe wheat at 1.44 per cent. (There is one
rather anomalous figure, viz. 1.28 per cent, for the third day immedi-
ately preceding ripeness.)

Parenti states that the reducing sugar of flours is reduced during
fermentation from 2.31 to 0.13 per cent. ; that is a consumption of 2.18 per
cent. In Wood 's paper he lays great stress on the importance of sugar as
a factor of strength, and remarks of one flour, that it cannot make large
loaves because of the low percentage of sugar present. He accordingly
tested the flours by a fermentation test, and 20 grams of flour and 20
grams of water (112 quarts to the sack) and 0.5 gram of yeast (7 Ibs.
to the sack) were taken and fermented at 35° C. (95° F.) for twenty-four
hours, at the end of which time the volume of gas was observed. In the
case of the lowest flours there was a gas equivalent of 1.6 per cent, of
sugar, while the highest amounted to 2.6 per cent, of sugar. The flour
iwith 1.6 is that before referred to as being deficient in sugar. Arm-
strong states yet more definitely that the amount of sugar actually pres-
ent in flour is not sufficient to give the necessary volume of gas required
in bread-making. Again, Ford and Guthrie, in Jour. Soc. Chem. Ind.,
1908. 389, state that they are of opinion that the greater part of the

280 THE TECHNOLOGY OF BREAD-MAKING.

carbon dioxide liberated in panary fermentation must be derived from the
starch of the flour. They quote an experiment in which on fermenting a
flour in the usual way with yeast they obtained 350 c.c. of gas from 20
grams of flour, which corresponds roughly with the fermentation of 1.3
grams of sugar or 6.5 per cent, of the flour. Direct estimations gave
respectively 0.82 per cent, of sucrose and 0.1 per cent, of reducing sugar
in the flour, special precautions being taken to eliminate all diastase from
the flour before the determination. Baker and Hulton also express the
opinion that the carbon dioxide concerned in the rise of bread during the
later doughing and the early period of baking has as its source the starch
of the flour.

436. Fermentation Experiments by Authors. — In view of these opin-
ions it was thought advisable by the authors to make some fermentation
experiments which should be as nearly as possible conducted under pre-
cisely the same conditions as occur in actual practice. A baker was asked
for samples of respectively the strongest and weakest flours he then had
in stock, and supplied the following: —

A. A strong Spring American Patent Flour.

B. A very weak French Flour.

Doughs were made from each of these in the following manner : —

A B

Flour, 200 grams at 17° C. 200 grams at 17.5° C.

Salt, 2 grams. 2 grains.

Yeast, 1 gram. 1 gram.

Water, 100 grams at 31° C. 100 grams at 31° C.

Dough, 303 grams at 26° C. 303 grams at 26.5° C.

The following are the proportions of each ingredient per sack — salt
2 Ibs. 13 oz. ; yeast, 1 Ib. 6 2/5 oz. ; and water, 56 quarts.

After being made, the doughs were transferred to enamelled steel
beakers and weighed; after fermentation they were again weighed with
the following results : —

A B

Weight of unfermented dough . . . . 301.6 298.7

„ fermented dough 299.8 296.6

Loss in weight during fermentation . . . . 1.8 2.1

Immediately after being weighed, each beaker was placed in a con-
taining vessel of convenient size, and the lid fastened down so as to make
an air-tight joint. This vessel was in turn submerged in a water-bath
maintained at a constant temperature of 25° C. (77° F.) and fermenta-
tion was allowed to proceed for six hours. To the containing vessel was
attached a leading tube through which the generated gas was passed, and
was collected over brine and measured in the usual way. (The whole
apparatus is described in paragraph 522, Figure 33.) The times and
temperatures were practically copied from those in actual use, and cov-
ered the whole period to the arrestment of fermentation in the oven, they
were in fact the same as those which the baker employed when working
with flours of this stronger type. The volume of gas was read at the
expiration of one and a half hours and every half hour until the six
hours had elapsed. The results are recorded in the following table. The
gas was collected at a temperature of 18.0° C. and 760 m.m. of pressure.

THE STRENGTH OP FLOUR.

281

A. Strong Flour.

3as Evolved.

B. Weak Flour. C

Jas Evolved.

Time.

Total.

Per Half-hour.

Total.

Per Half-hour.

Start

0.0

I'l hours

40. ON

35.0^

2 "

63.0J

71.o(

I
(

2J "

110.0

125.0

}

3 "

157.0J

195.0

31 "

216.0

277.0

100

4 "

296.0

377.0

105

41 «

383.0

482.0

117

125

5 "

500.0

607. o(

140

51 "

6 "

592.0
705.0^

113

747.0J
883.0^

136

From the volume of gas evolved, its weight, and that of the sugar re
quired for its production, are easily calculated. The results of such cal-
culations are given in the upper table on the following page. In each
pair of columns the first contains the various data as calculated on the
dough as used ; in the second column they are reckoned as percentages of
the dried or water-free solids of the dough. In view of the very small
loss of weight by the dough during fermentation, it must be assumed that
very nearly all the alcohol remains in the dough and is weighed therewith.

A number of analytical determinations were also made on the flours
and doughs at the close of fermentation respectively, the results of which
appear in the lower table on page 282. For soluble matters 10 per cent,
solutions of the flours were prepared, allowed to stand for half-an-hour in
the cold, and filtered bright. No attempt was made to discriminate be-
tween previously existing sugars and those produced from the starch dur-
ing this period of standing, as sugars from the both sources are in prac-
tice equally available for gas production from the start of the fermenta-
tion. With the fermented doughs, these were kneaded until as much as
possible of the gas had been forced out ; 50 grams were then taken, and
washed for gluten in successive small quantities of tap water (from deep
wells in the chalk). The washings were added together and made up to
500 c.c., including the starch, for the presence of which no correction was
made. This solution was filtered bright and soluble matters estimated in
the filtrate. It is interesting to place on record that on washing the
dough with distilled water, at the end of the second washing the gluten,
which at first separated out very well, became completely disintegrated.
There was no tendency in this direction when tap water was employed.

282

THE TECHNOLOGY OF BREAD-MAKING.

Particulars.

IV' al volume of gas evolved in c.c.
Weight of gas evolved (C02), in grams . .
Approximate weight of sugar required for

the production of the gas, in grams
Approximate weight of alcohol produced

in grams
Weight of sugar required per 100 grams of

dough, i.e. per cent.
Weight of alcohol produced per 100 grams

of dough, i.e. per cent
Loss of weight during fermentation, per

cent.
Sum of the two preceding quantities, which

practically agrees with sugar required . .

A. STRONG FLOUR.

Constituents.

Moisture . . . . ...

Total Solids ......

Gluten, Wet ......

„ Dry ......

Ratio of Wet to Dry

„ True

„ „ Percentage of Dry
Soluble extract
Reducing Sugars as Maltose
Non-reducing Sugars as Sucrose
Added Salt . .

DOUGHS.

A. Strong Flour. B. Weak Flour.

As Dried As Dried

Used. Solids. Used. Solids.

705
1.30

2.82
1.41

883
1.63

3.53
1.76

0.93 1.58 1.18 2.05

0.46 0.79 0.59 1.02

0.59 1.00 0.70 1.22

1.05 1.79 1.29 2.24

Flour.
As Used. Dried Solids.

11.29

Fermented Dough.
As Used. Dried Solid

41.11

88.71

100.00

58.89

100.00

40.5

45.64

29.90

50.77

13.5

15.21

9.54

16.20

3.0

3.1

10.23

11.53

7.32

12.43

75.57

76.67

6.12

6.90

4.12

6.99

1.48

1.67

1.00

1.70

0.93

1.05

Nil

—

0.66

1.12

B. WEAK FLOUR.

Moisture
Total Solids
Gluten, Wet

13.50

42.58

—

86.50

100.00

57.42

100.00

30.5

35.26

22.22

38.68

11.1

12.83

7.10

12.36

2.7

3.1

8.74

10.10

5.89

10.25

78.74

83.04

5.76

6.66

5.44

9.47

1.17

1.35

1.30

2.26

0.21

0.24

0.10

0.17

—

0.66

1.15

„ Ratio of Wet to Dry

„ True

„ „ Percentage of Dry
Soluble Extract
Reducing Sugars as Maltose
Non-reducing Sugars as Sucrose
Added Salt . .

Baking tests were also made on the flours with the following results : —
In each case 24 oz. of flour were taken. With A, 13^ oz. of water were
required to make the dough, and with B, 12 oz. of water. With these
quantities the consistency of the two doughs was the same. They were
worked with the same quantities of yeast and salt, and at the same tem-
perature. The dough from A was springy, tough, and wiry ; that from B
was dead and putty-like. The A dough was ready for the oven in five
hours, and B in four hours. They were baked into crusty loaves, and
awarded bakers' marks for strength, on the scale of maximum 100, mini-
mum 50. The awards were A, 95, B, <60 marks. If there was any error

THE STRENGTH OF FLOUR. 283

it was in the direction of undue generosity to B. The difference in water-
absorbing capacity is equivalent to 17.5 Ibs. or 7 quarts to the sack of 280
Ibs., and this figure agrees with the vendor baker 's estimate of the water-
absorbing power of the two flours in practice.

437. Consideration of Results. — In examining the results, the first
subject is naturally that of the gas evolved. The quantity obtained from
the strong flour must be regarded as amply sufficient to ensure the pro-
duction of a bold well-risen loaf. The evolution increased until the end
of the fifth hour, when for one reading there was a diminution. The
slight irregularities were apparently due to the sudden liberation of gas
by the ' ' dropping ' ' of the dough. The sugars obtained by direct extrac-
tion of the flour by cold water, 2.72 per cent, were considerably in excess
of the amount required in order to produce the evolved gas, viz. 1.58 per
cent. In each case, and throughout these comparisons, the percentages on
the dried solids are taken. Turning next to the weak flour, there is con-
siderably more gas evolved over the whole process of fermentation, and
even to the end the evolution is more rapid than with the strong flour.
The gas was evolved much more regularly, because, no doubt, of the less
retaining power (greater porosity) of the weak dough. The total sugars
of this flour amounted to 1.59 per cent, and are less than those required
for the fermentation, viz. 2.05 per cent., by 0.46 per cent. Against this
it must be remembered that with such a very weak flour a much shorter
period of fermentation would be essential to the production of a moder-
ately passable loaf, than would be employed with the stronger flour. A
baker would probably give it no more than from two-thirds to four-fifths
of the amount of fermentation that would be employed for the strong
flour. If the dough were got into the oven at the end of the fifth hour,
607 c.c. of gas would have been evolved, as against 588 c.c., which amount
is two-thirds of the 883 c.c. produced in six hours. This latter amount of
gas requires for its production 1.37 per cent, of sugar as expressed in
the dried solids of the dough, leaving a margin of 0.22 per cent, surplus
of sugars in the flour. Taking these -as extreme types of strong and weak
flours, the pre-existent sugars of flour, together with those readily-
formed in the cold on the addition of water, are in themselves sufficient
for the production of all gases necessary in the normal fermentation of
dough.

Comparing the above conclusion with those previously cited, Parenti
notes a consumption of 2.18 per cent, of the flour, amounting to about
2.45 per cent, of the dried solids, while in the case of the authors' very
strong flour, 1.58 per cent, only of sugars were required. Judging by
recognised English methods, Parenti 's doughs were considerably over-fer-
mented. In Wood's fermentation tests, volumes of gas ranging from 131
to 345 c.c. were obtained from 20 grams of flour. Multiplying these num-
bers by 10 in order to compare the results with those obtained by the
authors from 200 grams of flour, there is a minimum of 1,310 c.c. as
against a working requirement of 705 c.c. with a strong and about 600 c.c.
with a weak flour. Similarly, when Ford and Guthrie produced 350 c.c.
from 20 grams of flour (or 3,500 c.c. from 200 grams), they obtained
about five times as much gas as is evolved in the normal fermentation of
dough.

If in flours of ordinary type, whether weak or strong, there are always
sufficient pre-existent and readily-formed sugars for the usual require-
ments of fermentation, it is not very apparent that any excess of
amylolytic enzymes over those necessary for the production of such read-
ily formed sugars, has any direct bearing on the strength of the flour.

284 THE TECHNOLOGY OF BREAD-MAKING.

(And the enzymic activity of all flours seems sufficient for this particular
purpose.) But so far as these recent experiments go, the following cal-
culations are of interest : —

A. Strong Flour. B. Weak Flour.

Soluble Extract in Fermented Dough . . . . 6.99 . . 9.47
Subtract added Salt 0.66 . . 0.66

6.33 . . 8.81
Add Sugar consumed in Fermentation . . . . 1.58 . . 2.05

7.91 . . 10.86
Subtract Soluble Extract of the Flour 6.90 . . 6.66

Soluble Matters produced during Fermentation . . 1.01 . . 4.20

In these particular instances there is, during ordinary fermentation,
over four times as much diastatic action with the weak than there is with
the strong flour. This result seems to be borne out by general experience,
for strong flours are liable to produce dry flavourless bread, while that
from the weaker varieties is more usually moist and sweet.

Humphries informs the authors that with the flours of some very
hard, ricy wheats, there are insufficient pre-existent and readily-formed
sugars to yield the quantity of gas produced in even the limited fermen-
tation here described. It is 'suggested that such flours are, however,
scarcely commercial varieties in their separate state.

438. Gas-retaining Power. — Comparatively recently the opinion has
been expressed that the strength of flour depends not upon its gas-pro-
ducing but on its gas-retaining power. This is only another way of
formulating the old view that strength depends on the gluten of the flour.

439. Relation between Gluten and Proteins of Flour. — The fore-
going researches serve to throw considerable light on the actual composi-
tion of gluten and its relation to the total proteins of the flour. Norton
made a very complete analysis of crude gluten, which he found to contain
a.bout 74 per cent, of gliadin and glutenin, and about 7 per cent, of a non-
gluten protein. The remaining 19 per cent, was made up of fat, carbo-
hydrates, fibre, and mineral matter. These figures confirm the opinion
in the 1895 edition that crude gluten contains about 80 per cent, of pro-
teins as determined by nitrogen estimation. Norton points out that the
percentage of crude gluten from flour roughly approximates to that of
total protein present, there being a loss of non-gluten proteins, more or
less balanced by the retention of non-protein matters; in his view evi-
dently the proportions of the two are regarded as being fairly constant.
Tn consequence he regards crude gluten as but a very rough expression of
the protein content, and the determination as of but little worth in the
valuation of flours. Chamberlain goes over much the same ground, and
substantially agrees with Norton. He finds about 75 per cent, of pro-
teins, and 25 per cent, of non-proteins in crude gluten. Of all the pro-
teins present in wheat 60 to 65 per cent, are found in the gluten, and 35
to 40 per cent, are lost in the washings. Evidently all the bran proteins
must of necessity be thus lost. He agrees that the balance of losses of
proteins and retention of non-proteins make the gluten estimations agree
roughly with the total proteins calculated from total nitrogen. A further
and more important conclusion is that gluten contains less total protein
than the sum of the gliadin and glutenin present in the wheat by about-
15 per cent. ; and consequently that the loss of proteins in the determina-
tion of gluten is at the expense of gliadin or glutenin, the true gluten

THE STRENGTH OF FLOUR. 285

proteins of wheat. He therefore regards gluten determinations as not being
able to yield any information that cannot be obtained from determina-
tions of total proteins and alcohol-soluble and insoluble proteins. If Nor-
ton's and Chamberlain's results both be regarded as accurate, Chamber-
lain's 15 per cent, loss would have to be increased by the 7 per cent, of
globulin contained in the gluten, which is included in the total proteins,
but is neither gliadin nor glutenin. Dealing, however, with the 15 p^r
cent, loss only, in the case of a flour yielding 39 per cent, of wet gluten,
and 13 per cent, of crude dry gluten, such weights ought to have been,
had there been no loss, 44.85 per cent, of wet, and 14.95 per cent, of dry
gluten. The question suggests itself, to what is such loss due? Is it
caused by an actual failure to recover some 6 per cent, of wet gluten that
was present in the dough and necessarily lost in the washing ; or at the
time of washing was this gluten, or its components gliadin and glutenin,
in a non-elastic and non-adhesive condition, and therefore not gluten at
all in the sense of possessing the physical properties of wet gluten ? To
the authors, the latter alternative seems the more probable, and conse-
quently there may be present in dough, gliadin and glutenin constituents
which at the time of making the estimation are not fulfilling the physical
functions of gluten proper in the usually accepted sense of the term.
Some light is thrown on this point by the gluten determinations made on
the flours used for the fermentation experiments just described. That of
the strong flour, A, was when washed at the end of an hour's standing,
and dried, 15.21 per cent, of the dried solids. The corresponding fer-
mented dough yielded 16.20 per cent. In the case of the weak flour, how-
ever, there was a slight diminution in the dry gluten of the fermented
dough. Nitrogen determinations were accordingly made on the whole
four dry glutens, and the results calculated into "true gluten." These
figures are included in the foregoing table on page 282. The true gluten
obtained from the fermented dough of the strong flour is 12.43 as against
1.1.53 per cent, on the flour. There is also an increase with the weak flour,
the figures being 10.25 on the dough as against 10.10 per cent, on the
flour. During fermentation therefore the quantity of proteins which pos-
sess the physical character of gluten show an increase. Recent research
must therefore be regarded as confirming the view that crude gluten con-
tains from 20 to 25 per cent, of non-proteins. Further, it goes to show
that about 7 per cent, of the proteins present may be non-gluten protein,
and that of the gluten proteins (gliadin and glutenin) some 15 per cent,
of the total in the wheat or flour are not obtained in the gluten. Obvi-
ously, a dry gluten determination must not be regarded as an estima-
tion of the proteins of the wheat or flour.

The above limitation being accepted, the question naturally arises as
to what a gluten determination really is. The best answer seems to be
that a gluten determination is an estimation of the amount of those
bodies which are in such a physical condition as to impart elasticity
and gas -retaining power to the dough at the time when the determina-
tion is made. The exact nature of its constituents is of secondary
importance, and whether gluten consists of protein matter only, or of
75 to 80 per cent, of proteins together with a complement of non-proteins,
does not affect the value for the purposes of comparison of the results
'obtained. A point worthy of consideration about gluten estimations is
whether they might not be advantageously made on the dough at a stage
ef its fermentation when its strength is of the greatest importance. That
stage by general consent would be when the dough is ready to go into the
oven. This end might be attained by making the flour to be used for this

286 THE TECHNOLOGY OF BREAD-MAKING.

estimation into a dough with yeast, salt, and water, in the proportions
and at the temperatures employed in actual bread-making. The doughs
would then be kept in a fermenting vessel at a constant temperature, such
as that employed in the recently described experiments, for a time similar
to that taken in the bakehouse for the completion of the fermentation of
the dough. In order to prevent drying, the atmosphere of such a vessel
should be kept saturated with moisture. If the gas evolution were simul-
taneously observed a still more complete record of the behaviour and
properties of the flour would be obtained.

440. Mechanical Disintegration of Gluten. — It is a fact well-known
in the experience of bakers that mechanical over-kneading kills, or
''fells," a dough. The consequence is that a dough, which would ordi-
narily produce a bold well-risen loaf, becomes soft and putty-like, and
yields small sodden bread, just as though a very weak flour had been
used in its preparation. In practice, any serious injury from this
cause is avoided by careful watching ; further, the dough has while stand-
ing the power of recovery in some degree of its strength. It is not so
well-known that such over-kneading materially alters the physical char-
acter of the gluten. In order to investigate the point, the following
experiments were made with a very strong American wheat flour.

No. 1. The flour was made into a dough by hand-kneading, and the
various determinations carried out on the gluten from this dough.

The total soluble matter and proteins soluble in water were deter-
mined direct on the flour.

The water absorption by viscometer was determined on hand-made
doughs, and amounted to 70 quarts per sack.

Nos. 2 and 3 were machine-made in the manner described.

No. 2. Water was taken in the proportion of 66 quarts to the sack,
The machine was turned until the flour and water were incorporated : 30
additional revolutions were then given. The dough stood an hour, and
was then passed through the viscometer. The time is given below. For
gluten and other determinations 31.8 grams of dough were taken at the
close of the hour, being equivalent to 20 grams of flour. The water used
for washing gluten was reserved and made up to 1,000 c.c. On this solu-
tion, the soluble proteins and other soluble matter were determined.

No. 3. Water was again taken in the proportion of 66 quarts to the
sack. After incorporation, 250 revolutions were given to the machine.
The dough stood one hour, and was then passed through the viscometer.
It was then returned to the machine, and received another 250 revolu-
tions. The dough was now very sticky to handle, and was once more
tested by the viscometer. It was again returned to the machine and sub-
jected to another 250 revolutions. By this time it was much more sticky,
presenting in fact the appearance of bird-lime. The dough could be
drawn out into long threads, was very moist, and in fact appeared as
though it contained much more water.

The following are the viscometer results : —

No. 2. No. 3.

After one hour . . . . . . 873 seconds. 520 seconds.

After another 250 revolutions . . 16 ,,

After a further 250 revolutions . . 7 „

In No. 3, compared with No. 2, there is a marked diminution in water
absorbing power. But with the further kneading, No. 3 dough became
altogether altered in properties, and had in fact entirely lost the charac-
teristics of a bread-making dough.

THE STRENGTH OF FLOUR. 287

EFFECT OF MECHANICAL TREATMENT ON DOUGHS.

No. 1. No. 2. No. 8.

Wet Gluten 42.30 37.10 35.45

Ratio of Wet to Dry Gluten 2.8 2.9 3.1

Dry Gluten 15.02 12.70 11.44

Non-protein Matter in Dry Gluten . . . . 4.25 1.40 0.92

True Gluten 10.77 11.30 10.52

Gliadin ex Gluten '. . . 7.36 7.19 6.24

Glutenin ex Gluten,, by difference . . . . 3.41 4.11 4.28

Percentages on Dry Gluten.

Non-protein Matter in Dry Gluten 28.29 11.02 8.04

Gliadin 49.00 56.61 54.54

Glutenin 22.71 32.37 37.42

Total Proteins 12.95 12.95 12.95

Proteins soluble in Water 1.49 1.26 1.56

recovered as True Gluten . . . . 10.77 11.30 10.52
lost in washing Gluten . . . . 0.69 0.39 0.87

Gliadin ex Flour 6.43 6.43 6.43

Glutenin ex Flour, by difference . . . . 5.03

Percentages on Total Proteins.

Proteins soluble in Water 11.50 9.73 12.04

recovered as True Gluten . . . . 83.16 87.26 81.23
lost in washing Gluten . . . . 5.34 3.01 6.73

Gliadin ex Flour 49.65 49.65 49.65

Glutenin ex Flour, by difference . . . . 38.85

Non-protein Matter soluble in Water . . . . 3.35 5.82 6.00

On making gluten tests, No. 2 yielded less wet and dry gluten than
No. 1, but washed quite normally. The true gluten was slightly the
higher, showing that the loss in washing was almost entirely non-protein
matter. On proceeding to wash gluten from No. 3, the whole dough broke
down into a flocculent and non-coherent mass. It was only by pouring
this on to a sieve, and collecting by pressing the particles together, that
any gluten was recovered. When thus obtained the gluten was soft and
flabby and possessed scarcely any coherence or elasticity, whereas those
of Nos. 1 and 2 were tough and resilient. Although so profoundly
altered in physical character, the chemical composition of the gluten does
not show correspondingly great changes, the principal being a diminution
in the gliadin, which was estimated by the ''starch method." (See Chap-
ter XXIII.) Determinations were made on the collected washing
water, but these cannot be regarded 'as perfectly accurate, since some loss
is inevitable. They may, however, be taken as comparative between Nos.
2 and 3. A decidedly greater amount of protein was soluble in water in
No. 3 than No. 2. The total loss of protein in washing was also higher,
though in none of the experiments was the loss very great. The whole of
the results are set out in detail in the preceding table. They go to show
that not only is the gluten physically altered, but there is some change also
in solubility in various media. In addition to the alteration in the gluten,
there is a considerable increase in the amount of soluble non-protein
matter.

The interesting point of these experiments is that by simply mechan-
"ical attrition of the dough, profound changes are made in the character
of the gluten and apparently in the same direction as those which result
from treatment with dilute acids as carried out by Wood.

441. Relation of Gliadin Ratio to Strength of Flour. — With Osborne
and Voorhees' demonstrations of the insoluble proteins of flour consisting

288 THE TECHNOLOGY OF BREAD-MAKING.

of gliadin and glutenin, a very natural development of inquiry was along
the lines foreshadowed in the 1895 edition of this work, and consisting oi
determinations of the total amount of each of these present in a flour,
and the ratio such amounts bore to each other. Guthrie, Fleurent,
Snyder, and others have contributed to this research, and each has em-
ployed methods of determination more or less original. A consequence is
that different proportions of the total protein is returned as gliadin or
glutenin according to the process adopted, and as a result differing con-
clusions have been formed as to the most desirable ratio between these
bodies. Guthrie obtained from about 59 to 78 per cent, of gluten as
glutenin (which figure also includes the non-proteins.) He concludes that
a preponderance of glutenin is preferable, and that increased gliadin pro-
duces a weak, sticky, and inelastic gluten. With a totally different
method of extraction, Fleurent found his best results with 25 per cent.
of glutenin to 75 per cent, of gliadin, and a deterioration with a de-
parture in either direction. Guess extracted his gliadin direct from the
flour, and without any limitation found that the more gliadin present, the
more elastic and better was the gluten. Snyder places on record that the
alcohol-soluble portion of flour protein (gliadin) may vary from as high
as 70 to as low as 45 per cent, with only minor, variations in the size of
the loaf or the bread-making value of the flour. Further he regards
gliadin as not being of uniform composition. In Chamberlain's opinion,
so-called gliadin contains also albumin and globulin. Wood finds that
flours which are at the extreme ends of the scale of strength may have
substantially the same proportions of gliadin to total nitrogen. Snyder
in fact shows that widely different gliadin contents may occur in prac-
tically identical flours: Wood supplements this by showing that widely
different flours may be practically identical in their gliadin contents. In
other words, glutens containing the same proportions of gliadin and
glutenin may be either weak or strong. The natural conclusion is that
strength or weakness is independent of the ratio of gliadin to glutenin
in the gluten. As gluten is not subjected to the solvent action of 70 per
cent, alcohol in the process of bread-making, it does not seem that it
would necessai ily follow that a connexion must as of course exist between
the degree of solubility in that reagent and the strength of the flour.

Gluten is probably a loose compound of gliadin and glutenin in vary-
ing proportions, and its qualities as a whole, from the bread-making
standpoint, are apparently not closely related to its protein composition.
For its marked differences in properties, the most likely explanation is
that they are based on variations in physical rather than chemical char-
acter. This fact has been recognised by Baker and Hulton, who in dis-
cussing enzyme action on gluten remark that "the physical character of
the gluten may be much modified during the early stages of enzyme
action without the production in large quantity of soluble decomposition
products. In this connection may be noted the profound change in the
viscosity of a starch paste under the influence of a trace of liquefying
diastase before any maltose is produced." Strength, then, must be
regarded as depending on the quantity and physical character of the
gluten of the flour.

442. Conditions affecting the Quantity and Physical Character of
Gluten. — These naturally constitute the subject of the next line of in-
quiry. As to quantity, that is largely a question of selection of seed and
circumstances of cultivation, and therefore mostly lies outside the scope
of the present work. Much careful and successful research has, however,
been devoted to such questions as the choice of seed, and effect of soil,
climate, and manuring on the development of the gluten content of

THE STBENGTII OF FLOUR. 289

wheat. But the miller and baker (in those capacities) have only to
manipulate and do their best with wheats and flour as they find them.
Turning next to the question of physical character and how it may be
modified, that also is a problem which largely lies within the domain of
the agriculturalist and his advisers rather than the miller and baker.
Again, the choice of seed and other factors previously mentioned have a
most important bearing on the subject. In particular, the researches of
Wood have evidently been conducted with the object of assisting the
farmer in growing strong wheats and with a full realisation of limits and
possibilities which do not so much concern the subsequent handlers of
wheat and flour. Among the factors which have been suggested as modi-
fying agents on gluten are sugar, proteolytic enzymes, acidity, and cer-
tain mineral salts of the wheat or flour. Sugar has already been dis-
cussed, and reference has been made to its power of increasing the pro-
portion of gluten which is soluble in 70 per cent, alcohol. Ford and
Guthrie point out that certain flours contain a proteolytic enzyme which
has an extremely detrimental effect on the tenacity of the gluten, and
described methods by which this body can be detected. Baker and
Hulton have also investigated the matter of the presence of proteolysts in
flour. They, however, came to the conclusion as far as concerned the
flours examined by them, that there was no soluble proteolytic enzyme in
flour capable of degrading albumin or gluten with the production of
soluble nitrogenous bodies. They find, on the other hand, that the gluten
in dough is attacked by yeast enzymes, with an increase in the amoiint
of soluble proteins. It is in this connection that they make the remark
before quoted as to the possibility of profound physical changes in gluten,
with no (or but little) chemical change. Fermentation, as already shown,
may increase the quantity of protein recoverable as gluten; it also pos-
sesses the property of materially softening that body, and at the same
time increasing the amount of protein which while insoluble in water is
soluble in 70 per cent, alcohol. The following results were obtained on a
flour by the authors. The percentage of constituents is calculated on the
dried solids of the flour, and the fermented dough respectively : —

Flour. Fermented Dough.

Dry Gluten 12.14 . . 11.08

True „ (Proteins) . . . . 10.33 . . 10.14

Gliadin ex Gluten 2.80 . . 3.20

Glutenin 7.53 . . 6.94

Ratio of Gluten to Gliadin . . 2.7 . . 2.2

Any reagent or action by which this change is assisted is therefore
aiding in the development of the strength of the dough, provided such
changes are not thereby carried too far, since the weakness of an over-
worked dough is probably due to the same causes as those which are bene-
ficial in a lesser degree. Although strength seems independent of the
original proportions in which gliadin and glutenin exist in a flour, yet
those changes during fermentation which result in increased elasticity of
the dough are usually accompanied by an increase in the alcohol-soluble
content of the gluten. Both sugar and proteolysts may therefore in this
manner exert a beneficial influence on the dough.

Snyder finds that any slight increase of acidity in the grnin dimin-
ishes the percentage of gliadin (paragraph 426). On the other hand,
Wood (paragraph 430), finds acidity to have no relation to strength.
Wood states that certain acids in small quantity have a marked disinte-
grating action, on gluten, which effect increases with the degree of acidity,
until with further concentration a reverse action occurs, and at a certain
point the effect of the acid is to harden the gluten and render it more

290 THE TECHNOLOGY OF BREAD-MAKING.

elastic and coherent than was its original condition. Other acids show
no such reverse action, but up to any limit of concentration effect a dis-
integration which becomes more rapid as the acidity increases. It is dif-
ficult to say whether in actual dough fermentation the effect of acid on
gluten is in its earlier stages capable of inducing beneficial changes there-
on. At the later and overworked stages, the acid developed is probably
one of the factors in carrying the changes in gluten to a condition of less
gas-retaining power.

443. Effect of Mineral Salts on Gluten. — Wood has made a series of
most important investigations as to the effect of certain mineral salts on
gluten. His most recent conclusions are embodied in a personal com-
munication from Professor Wood, kindly made for the purposes of this
book, and contained in paragraph 433. In determining whether a wheat
shall be weak or strong, Wood is of the opinion that the effective action
of beneficial salts occurs during the growth of the grain, while the endo-
sperm is being formed and is in a comparatively milky stage. In order
to improve wheat at this stage, the salts must evidently be obtained from
the soil. Experiments made by Chitty and one of the authors go to show
that wheats may be improved in this direction, when in the hands of the
miller, by treatment of the grain itself (paragraph 541). Additions to
the flour as flour, or at the time of doughing, are also capable of effecting
material improvements. Interesting examples of this are the at one time
prevalent addition of alum when flours were exceedingly weak, and the
bakers 's well-known expedient of using an extra quantity of salt with a
very weak flour. Though the former addition is condemned on other
grounds, it undoubtedly considerably improved the strength of the flour.
So, too, salt has a decided "binding" effect on a weak and runny dough.
The problem cannot at present be regarded as completely worked out, but
the results already obtained, confirmed as they are by practical experi-
ence, go to show that the presence or absence of certain mineral salts is
a most important factor in determining the strength or weakness of
gluten and consequently of flour. Bearing in mind that flour of itself is
toxic to some varieties of yeast, and that certain mineral salts act as
an antidote to the poisonous action, it is of interest to note that some
mineral salts increase the strength of gluten. Indirectly they may
further benefit the working properties of a flour by nullifying its toxic
action to yeast.

444, Gluten Determinations, — From the foregoing expressions of
opinion, it will be gathered that the authors continue to attach importance
to properly conducted gluten determinations. The estimation of wet
gluten is a measure of the amount of that constituent of flour, which by
its physical character determines the quality and nature of the resultant
dough and bread. It further determines this in a way which is compara-
tively easy of performance and affords results which are readily under-
stood by all concerned. In the hands of an expert flour valuer, not only
the quantity of gluten, but its appearance and general characters give
most valuable indications as to the type and quality of a flour, even
though they cannot be expressed in percentages' or other forms of figures.
The following remark of Saunders is an interesting confirmation of the
practical value of the gluten test : — ' * In addition to the final baking tests
1 have used for several years a simple chewing test (taking only a few
kernels of wheat) as a valuable guide to gluten strength and probable
baking strength in the earlier stages of selection. This test was advocated
as an essential aid in the selection of crossbred varieties of wheat in the
Bulletin on Quality in Wheat, published at Ottawa, October, 1907."
(Supplement 4, June, 1910, p. 29, Jour. Board of Agriculture.)

CHAPTER XVI.

COMPOSITION AND PROPERTIES OF FLOUR AND OTHER
MILLING PRODUCTS.

445. Flour Properties. — Among the general properties of flour, that
of Strength has been deemed of sufficient importance to warrant its treat-
ment in a separate chapter. Flour also possesses certain other physical
characters of which some explanation must be given. These include
Colour and Water-absorbing power. For scientific purposes it is neces-
sary to have not only means of judging and comparing these, but also
some method of registering for future reference, and for the institution
of comparisons between the results obtained by one observer and those of
another. In order to do this, these properties must in some way be
expressed numerically.

The whole subject of these various measurements is exhaustively dis-
cussed in a subsequent chapter on Flour-Testing, but as in this section
a number of analyses are quoted, in which estimations of colour, etc., are
inserted, a brief mention is here made of the principle of the method by
which these have been judged.

446. Colour. — Every miller and baker will be acquainted with the
ordinary method, devised by Pekar, of determining the colour of a sample
of flour by compressing a small quantity into a thin cake or slab, which
is wetted and allowed to dry. The depth and character of the colour are
then observed. This test has been in use for some time, and answers
admirably the purpose of comparing the relative colour of two or more
samples.

447. Water-Absorbing Power. — The water-absorbing power of a
sample of flour is one of the most important properties it possesses, and
its determination is of great value to both miller and baker. It not only
governs the yield in bread of the sample, but also affords evidence of its
other qualities. Hence, water-absorbing determinations are valuable in
several respects. Although not always applied in precisely the same
sense, for our present purpose, Water-absorbing power may be defined
as the measure of the water -absorbing and retaining power of the flour,
or of the water absorbed by the flour in order to produce a dough of
definite consistency: it always being understood that the dough shall be
capable of yielding a well-risen and properly cooked loaf without clammi-
ness. The water-absorbing power of the flour from any particular wheat
is in practice governed by the way in which it has been treated during
milling. Thus an excess of water used in the conditioning process will
reveal itself in a deficiency in the water-absorbing capacity of the flour.

448. Composition of Roller Milling Products. — As milling is an art
in which the wheat is changed into flour and offal, it is a matter, not only
of interest, but of importance, that it should be known what is the consti-
tution of the flour and various other products of milling. The following
table is given on the authority of Richardson, Chemist to the Department
of Agriculture of the United States Government, who made a most im-
portant and exhaustive series of analyses of products of roller milling.

292

THE TECHNOLOGY OF BREAD-MAKING.

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COMPOSITION OF FLOUR AND MILLING PRODUCTS. 293

Richardson selected samples from three mills ; the first being from Messrs.
Pillsbury's mill at Minneapolis, where a straight run of spring American
wheat was used; the second, Messrs. Herr and Cissel's mill, employing
soft winter wheat; and the third from the mill of Messrc< W? •
Barnett, of Ohio, using all red winter wheat.

449. Damping Wheats. — It is the custom of millers to add to some
of the harder and more flinty wheats, particularly those of India, more
or less water as a preliminary to milling. The addition of such water is
generally supposed to have two effects, the first being a softening of the
bran, and the second an increased yield of flour. The softening of the
bran renders it less brittle, and so less gets broken up, and thus into the
flour.

It is essentially a question for the miller, rather than the chemist, to
decide whether the damping of Indian wheats renders them more work-
able and amenable to milling processes generally. It is quite conceivable
that a "mellow" wheat is more easily converted into flour than one which
is hard and brittle ; but, against any consideration of ease in milling must
be set the effect, if any, of damping on the after quality of the flour
produced.

In connection with this subject the authors have analysed a number
of samples of Indian and other hard wheats, dry and damped, and also
the flours produced therefrom. The following are the general conclusions
derived from an extended and exhaustive series of experiments : —

In artificially damping wheats, but a small proportion of the water
finds its way into the flour. The actual amount varied from 3.8 to 17.1
per cent, of the total quantity added. This depends on the length of
time allowed to elapse before grinding. The water penetrates evenly
through hard Indian wheats in about forty-eight hours.

The addition of water to wheats already containing an average
quantity of water (in experiment cited, 13.2 per cent.) is decidedly
deleterious; strength and colour are both injuriously affected. But
this will depend somewhat on the nature of the wheats. Thus some
Indians may be damped to contain 15 per cent, of moisture, while Rus-
sian wheats should be restricted to a limit of 13 per cent.

With wheats in a dry state (11.0 to 11.5 per cent, of water) damp-
ing in a slight degree does not seriously affect the colour or strength of
the flour.

On making baking tests with the flours from such slightly damped
wheats compared with those of the wheats milled dry, the damped
wheat flours fall off less during fermentation, yield bread of better
colour and flavour, and in practically the same quantity.

The slight damping of the very dry wheats enables the miller to
produce a better quality of flour.

450. Washing Wheats. — In view of the growing importance at-
tached by millers to rigidly clean flours, and the consequent necessity for
the removal of the dirt and other impurities often associated with wheat ;
the grain, and especially the more dirty varieties, is now thoroughly
washed before being milled. Although Indian and the more flinty types
of wheat bear a prolonged submergence in water, the softer kinds of grain
are injured by any but the shortest washing process. The modern wash-
ing machines are therefore not intended to soak wheat, but to wash it
clean from extraneous dirt as rapidly as possible. The grain is then dried
by treatment in a centrifugal machine, or "whizzer." This operation not
only frees the wheat from ordinary dirt, but also largely removes bac-
teriological impurities which may be of an objectionable nature.

294 THE TECHNOLOGY OF BREAD-MAKING.

The question frequently arises, what kind of water is fit for wheat
washing purposes? The quantity used is large, amounting sometimes to
as much as 20 gallons per bushel of grain washed per hour. Thus to wash
100 bushels of wheat hourly, in extreme cases, 2,000 gallons of water per
hour may be required. The purchase of water of drinking quality for
this purpose is very expensive, and may even in some places be prohibi-
tive. Millers are consequently compelled to seek some other source of
washing water if possible. Among these, sea-water, if free from contami-
nation, is employed, or river water is frequently used. The latter may
of course be of almost any degree of purity. There is little doubt that
the standard of purity for this purpose need not necessarily be so high as
that required in water for drinking purposes. But taking a filtered river
water which yields on analysis —

Nitrogen as Free Ammonia . . 14 parts per 100,000

Nitrogen as Albuminoid Ammonia 5 „ „ „

may it be used or not for wheat washing ?

It need scarcely be pointed out that these data entirely condemn the
water for drinking purposes. But in rapid washing as distinct from soak-
ing, the exposure to the water is only for a very short period of time.
In some experiments made, in which wheat was subjected to more pro-
longed treatment with water than occurs in the mill, it was found that the
resultant flour had its moisture raised from 13.2 to 13.7 per cent., being
an absorption of 0.5 per cent, of the weight of the flour. In washing,
therefore, but very little water is absorbed by the grain, and of that little
by far the greater part does not penetrate beyond the bran and into the
flour. Corroboration of this is afforded by washing with sea-water; the
flour is not perceptibly rendered salt, and the bran is eaten and keenly
relished by animals. In event of the washing water containing bacteria,,
there may be some apprehension of these finding their way into the flour.
But although they may possibly find a lodgment on the outer skin of the
bran, in practice there is no contamination of any of the flour, except
possibly the very last reductions from the bran. Unwashed wheats will
usually contain more bacteria than any water used for washing, and con-
sequently are rendered bacteriologically cleaner by washing with any
ordinary water. Further, washing with an abundance of a slightly im-
pure water will produce a cleaner wheat than is obtained by the use of a
purer water in stinted quantity. Naturally the washing water should be
as clean as practicable, and of a good quality ; but it is not necessary that
it be judged by the same standard of purity as is required of a drinking
water. Where the washing water is of the ordinary river type, a good
plan is to use an abundance of this to remove the bulk of the dirt and
then to give a final rinsing with a small quantity of clean water.

451. The Germ. — This most interesting body differs remarkably in
composition from the other parts of the grain. The percentage of con-
tained water is somewhat low, but the soluble extract is remarkably high,
amounting to just one third of the whole of the body as removed in the
modern processes of roller milling. Of the soluble extract, 15.51 per cent,
consists of proteins. There is no gluten recoverable. The ash and phos-
phoric acid are high ; the fat also is much higher than in any other part
of the grain, amounting to from 12 to 15.6 per cent. The cellulose is
moderately high.

Detailed analyses of germ have been made from time to time; there
follow results of such analyses made respectively by Richardson, Teller,
and one of the authors.

COMPOSITION OF FLOUR AND MILLING PRODUCTS. 295

ANALYSES OF GERM.

/ — Richardson. — >
Per ct. Per ct.

Water — 8.75

Ash 5.45

Oil 15.51

Soluble in 80 per cent, alcohol .... 26.45

Insoluble in water .... .... 1.98

Soluble in water 25.47

Sugar or Dextrin .... 18.86

Non-reducing substance .... 2.94

Proteins 3.35

Soluble in water .... .... .... 4.44

Dextrin — 1.14

Proteins 3.00

Starch, etc, undetermined 9.95

Cellulose 1.75

Insoluble Proteins 26.60

100.00

Teller.
Per ct.
6.80
4.65
. 14.38

Jago.
Per ct.
.... 13.23
.... 4.94
.... 12.03

'. —

.... Dextrin 1.24
Maltose 5.54

.... Prote
Carbo-hydra

! 1.60
ns 39.62
*s 32.95

".". 33.78
Sol. proteins 15.51
Insol. proteins 13.73

100.00

Osborne and Campbell find that germ contains a nucleic acid in con-
siderable quantity, and having the following composition : —

Carbon 36.48

Hydrogen . . » . . . . . . . . 4.48

Nitrogen . . . . . . . . . . . . 16.17

Phosphorus . . . . . . . . . . . . 8.96

Oxygen 33.91

100.00

There are also present the following proteins — leucosin, a globulin,
(contains only two kinds of the sulphur of edestin) and a proteose.
(Jour. Amer. Chem. Soc., 1900, 379.)

As one of the objects of modern milling is to thoroughly remove the
germ from flour, the actual effiect produced by germ, when present, is a
subject of great importance. An account of some experiments on mix-
tures of germ and flour is given later in this chapter.

452. Effect of the Germ on Flour. — One of the questions which for a
considerable time has occupied the attention of the milling world, is
whether or not the removal of the germ affects the flour injuriously or
otherwise. Among the various authorities on this point, Graham, Rich-
ardson, and others, are unanimous in expressing a strong opinion in
favour of its removal. Briefly stated, the reasons that render this course
advisable are that the presence of the germ discolours the flour, and also,
as a result of its high percentage of fat, gives it a decided tendency to be-
come rancid. In addition, the germ exerts a marked diastatic action on
the imperfectly matured starch of slightly unsound flours. On the other
hand, the advocates for the retention of the germ assert that it renders
the flour sweeter, and also causes the bread to have a pleasant moistness
on the palate. Under any circumstances these results are not likely to be
attained except by using the flour immediately it is milled; this is fre-
quently impossible, and even then the baker must be prepared to face all
those difficulties caused by the presence of an undue quantity of active
diastatic agents in the sponge and dough. Milling experiments on a large
scale have been made on the germy semolina produced during gradual
reduction. Such semolina, on being reduced on stones, yields a dark col-
oured unsatisfactory flour, which produces a low quality bread. On
rolling and repurifying these semolinas, the resulting flour is of good
colour, and yields bread of high quality. So far, these experiments afford
evidence directly in favour of the removal of the germ. An extensive
series of experiments made by one of the authors, and previously pub-
lished, prove most conclusively the ill effects resulting from the admixture
of germ with flour.

296

THE TECHNOLOGY OF BREAD-MAKING.

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GENERAL CHARACTERISTICS.

ard, dry flour, with unusually high percentage of gluten;
very yellow, almost pea shade; bakes very foxy. Bread
flavour. Sponging — long sponges — not good doughing floui
ard flours, with good percentage of gluten, but soften more ]
than spring American grades, for which these flours make
of patents good; rather more tendency to foxiness than
but if the dough is permitted to lie, frequently shows tern
paratively flavourless; in lower grades coarse in flavour. .'
grade may be used, one-third in sponge and one-third in d
ry and comparatively soft flours; only medium percentag
soft but elastic. Water-absorbing power remarkably hi
most delicate shade of bloomy yellow. Loaf riot very larg
ture; crust yellow without foxiness. Bread moist and of (
Doughing flours, but may be used in rapid sponges taken c
ours with less gluten and lower water-absorbing power the
Colour very good, but usually full yellow. Bread moist,

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dian flours generally are hard flours of a ricy character. Th
and usually very deficient in elasticity. The quality of wate
is low, except with very great milling precautions. Loaf i
of texture, and foxy. Bread is harsh and beany in flavour,
ours from English wheats are usually soft and damp. Ver
of climate and locality. Proportion of gluten low and <
Water-absorbing power low. Patent flours are of very
bakers' grades dark and grey. Loaf small and compact; ci
free from foxiness. Bread is moist, and has a very sweet,
flours of all grades; may be used alone, doughing direct,
otch flours are even moister and softer than those from E]
they are low in gluten and water-absorbing capacity. Loaj
flavour pleasant. Doughing flours all grades; may be used
•ench flours have been- again placed on the English markets,
of English milled flours, of the same price, in strength a
but in most cases possess good colour and flavour.

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298 THE TECHNOLOGY OF BREAD-MAKING.

453. Fatty Matters and Acidity of Flours. — Balland has made a
series of determinations of these with the following results : —

Wheat germs mixed with bran from a recent milling. — The fatty mat-
ter extracted by ether contained about 83.34 per cent, of a fluid oil, and
16.66 per cent, of solid fatty acids. The original substance also contained
other acids insoluble in ether.

Flour from soft wheat, for army rations, from an old milling. — The
fatty matters contained about 18 per cent, of a very fluid oil, and 82 per
cent, of mixed fatty acids. The acidity of the flour was due to several
acids, some soluble in water, alcohol, and ether, and others insoluble in
water and in ether.

Flour from hard wheat, for army rations, from an old milling. — The
fatty matters were composed entirely of free fatty acids, which hindered
the hydration and extraction of the gluten. Balland deduces the follow-
ing general conclusions: — The fatty matters of freshly milled flour con-
sist of a very fluid oil and solid fatty acids of different melting Doints. In
course of time the oil, which is very abundant at first, gradually dimin-
ishes and disappears, with a corresponding increase of the fatty acids, so
that the ratio of oil to fatty acids is a measure of the age of the flour.
The fatty acids themselves disappear in time and are not found in very
old flours. The conversion of the oil into fatty acids is not limited to the
flour only, it takes place also in the products isolated by ether. The
acidity, which is the first indication of alteration of the flour, is not con-
nected with the bacterial decomposition of the gluten, but is derived
directly from the fat. The gluten is not attacked until the fatty acids
produced from the oil begin to disappear. The richer the flour is in oil,
the more liable it is to alteration — as, for instance, flour from hard wheat.
In order to have a flour which will keep well, it is advisable to select a
soft wheat with a low percentage of fat. (Comptes rend., 1903, 137, 724.)

454. Distribution of Gluten in Wheat. — Considerable interest at-
taches to the relative proportions of gluten in the flours produced during
the different operations of gradual reduction. Closely connected with
this question is that of the distribution of gluten in the wheat grain. A
number of writers on wheat make the statement that gluten is found
almost, if not quite, exclusively in the inner layer of the bran ; and that
it constitutes the contents of those cuboidal cells seen so prominently in
the inner layer of bran when microscopically examined. These cells are
even now frequently termed ' * gluten cells ' ' from this supposed property.
The bran of wheat contains, however, no gluten whatever, the whole of
that body being derived from the contents of the endosperm. Hence it
follows that flour contains more gluten than does whole wheat meal.

455. Baking Characteristics of Typical Flours. — The tables on pages
296 and 297 record not only the gluten and other determinations in
certain typical flours, but also contain a statement of their general baking
characteristics.

456. Seasonal Variations in Flours. — Balland arrived at the follow-
ing conclusions from the analysis of 2,500 samples of flour analysed in the
Laboratory of the French War Department between September, 1891,
and June, 1894. He finds the water to vary from 9.40 to 16.20, being at
a maximum in February and a minimum in August. The lowest per-
centage of acid found by him was 0.013 per cent, in January, while sam-
ples examined in August contained as much as 0.037. From this he draws
the conclusion that flours for long storage should be made and packed in
dry cold weather. The moisture present in wet glutens is found to vary
from 52 to 71.3 per cent. ; that in the best flours for bread-making being

COMPOSITION OF FLOUR AND MILLING PRODUCTS. 299

about 70 as against 62 to 65 in those of medium quality. As the acidity
of the flour increases the percentage of water in the wet gluten dimin-
ishes. None of these flours contained either foreign mineral matter or
farinaceous substances as adulterants. (Comptes Rend., 119, 565.)

457. Preservation of Flour by Cold. — Balland finds that flour stored
for three years in a vessel maintained at a temperature ranging between

— 2 and -f- 2° C. underwent very little change. The sample was some-
what tasteless, a result probably of moisture in the apparatus. The
amount of gluten had slightly increased, as compared with a test on the
new flour; it was homogeneous, sweet, and contained 71 per cent, of
water. The fatty matters and acids were present in the same quantities
as in the original flour. (Comptes Rend., 1904, 139, 473.)

The Bleaching of Flour. — Attention has recently been directed to
the possibility of removing more or less of its natural colour from flour,
and this problem has been made the subject of much investigation.

458. Sources of Colour in Flour. — The following may be taken as a
classification of the nature and sources of the colouring matter present in
flour.

1. Bran. — The outer envelope of the wheat grain is from a pale yellow
to a reddish-brown tint, and contains large quantities of colouring matter.
If finely ground bran finds its way into flour, the particles impart their
own tint to the flour, and when made into bread this colour is intensified
by being dissolved and permeating the whole of the substance of the
bread.

2. Crease and other Dirt. — Outside dirt, especially that of the crease
of the grain, may be ground up into the flour, and will thus give it a sad,
bluish-grey tint.

3. Colouring Matter of Endosperm. — In some wheats the whole endo-
sperm is more or less coloured yellow. A notable instance of these is
Walla Walla wheat of Oregon (before referred to), which yields a flour
sometimes as yellow as a primrose.

REMOVAL OF COLOUR.

1. Bran. — This is now removed by careful milling and purification
from all small bran particles.

2. Crease Dirt. — To get rid of this and other outside dirt, the grain is
thoroughly scoured and polished in the dry state, or washed and dried.
Further, the grains are in the first operations of milling carefully split
longitudinally along the crease, and the dust lodged therein got rid of
before any further reduction of the broken grain into flour.

Note. — Regarding the flour as consisting only , of the endosperm of the
grain (or, as it is sometimes called, the kernel or the berry), ground into
a fine powder, the removal of bran and crease dirt is only a removal of
foreign substances, and a consequent purification of the flour.

3. Colouring Matter of Endosperm. — This evidently stands in a dif-
ferent category, because it is the colour of the flour itself, and not that
of any foreign matter, even from other parts of the grain.

This colouring matter is somewhat unstable in character, as it dimin-
ishes very noticeably on keeping flour some two or three months, and
also varies considerably in different flours.

459. Flour Bleaching, Snyder. — A very systematic exposition of the
whole subject of flour bleaching is contained in a bulletin issued by the
University of Minnesota in 1908. The writer, Snyder, regards the bleach-
ing of flour as a natural process, and introduces his subject by a refer-
ence to —

300 THE TECHNOLOGY OF BREAD-MAKING.

The Colouring Material of Flour. — The composition of the colouring
matter of wheat has never been determined, because it cannot be sepa-
rated in a pure state from the fat and gluten with which it is mechan-
ically associated. It is soluble in ether, and in flour analyses it forms one
of the well known impurities of the "ether extract" or "crude fat."
When the gluten is obtained mechanically, by washing the dough, it is
tinged yellow with the natural colouring matter of the flour.

Avery has suggested that the colouring matter of flour is a nitrogen-
ous compound containing an ammo radical. In Bulletin No. 85 of this
fetation it was suggested that the colouring matter was a nitrogenous
compound. Other investigators believe it is a non-nitrogenous body akin
to xanthophyll and carotin, the natural yellow pigments of plants. It
has certain characteristics of carotin as capability of being decolourised
by heat, light and chemical reagents. Whatever the composition of the
colouring matter of wheat may prove to be it is not a stable compound.
After flour has undergone natural bleaching various tints and shades of
colour are developed, particularly of grey and light yellow. These vari-
ous shades and tints may serve as an index of bread-making value, but
it is not possible from the colour alone of either freshly milled or cured
flour to determine bread-making value. Flours that are pure white, or
tinged slightly yellow, have the highest bread-making value. A dark
grey or slaty colour is usually an index of poor bread-making qualities.
Flours of poor colour when milled, often develop even more undesirable
tints by storage. If the flours are not well milled the branny particles
become discoloured through oxidation of the cellulose and the flours then
show black specks. Hence it is that only well-milled flours from sound
wheat are capable of being improved by storage.

Bleaching Agents. — Of the various methods proposed for the bleach-
ing of flour practically the only one that has survived the experimental
stage is the nitrogen peroxide process, in which the bleaching reagent is
produced directly from the union of the nitrogen and oxygen of the air
by electrical action.

In the bleaching of flour the unstable yellow colouring matter is acted
upon by the nitrogen peroxide, and from a study of the properties of
nitrogen peroxide it would appear to be an oxidation change. As will be
shown later, this change, if it be oxidation, does not extend to the other
constituents of the flour as fat and gluten, inasmuch as flour bleaching
as now practised leaves these and other constituents unaltered as far as
chemical tests are capable of determining. As a result of the nitrogen
peroxide treatment, some nitrogen trioxide reacting material is left in the
flour. For convenience it is assumed to be a nitrite, but cannot be a
mineral nitrite like that of potassium or sodium, as it has entirely differ-
ent properties. That the material is present largely in physical form
can be shown by heating bleached flour to a temperature of 95° C. The
flour will then be found free from nitrite reacting material provided it
has been heated out of contact with a gas flame or combustion products
that yield nitrites, or the flour was made from wheat free from mineral
nitrates or nitrites.

Fat of Bleached and Unbleached Flour. — When the fat of flour is ob-
tained by the official method of analysis, the colouring matter, lecithin,
chlorophyll residue products and other substances are recovered as me-
chanical impurities mixed with the fat. The chemist uses the term ' ' crude
f at " or " ether extract ' ' because of these known impurities. Somt- of the
impurities are nitrogenous and some are non-nitrogenous compounds.
Hence any change produced by bleaching in the colour of the fat cannot

COMPOSITION OF FLOUR AND MILLING PRODUCTS. 301

be said to denote change in the composition, when it is known that the
colour is one of the impurities of the fat.

In the bleaching of flour it has been suggested that a slight oxidation
of the fat is one of the possible chemical changes which may occur, since
nitrogen peroxide, a carrier of atmospheric oxygen, is employed. Should
any appreciable oxidation of the fat take place during bleaching, the fat
of the bleached flour would have different properties from that of the un-
bleached flour. Any such change in the fat would necessarily affect such
determinations as those of the iodine absorption number and the heat of
combustion. Four typical samples of flour (two bleached and two un-
bleached) were selected for the purpose of extracting the fat in quantity.
The flours were dried in such a way as to prevent oxidation, and the
iodine number was determined. The following results were obtained I—-
iodine

Absorption
Number

Patent flour, unbleached, No. 1 102.9

Same flour, bleached, No. 2 103.7

Patent flour, unbleached . . . . . . . . . . . . 101.1

Same flour, bleached 102.6

Practically no greater differences were observed between the fat of the
bleached and unbleached flours than between duplicate analyses of the
'same sample. As far as the iodine number of the fat is concerned no
appreciable difference was observed between those of the bleached and
unbleached flours.

It has been suggested that the nitrogen peroxide chemically unites
with the fat, resulting in the production of nitrogenous compounds.
Should any such change occur it would affect the nitrogen content of the
product, and the fat from the bleached flour should show a higher nitro-
gen content. A number of investigators have shown that lecithin, a
nitrogenous compound soluble in ether, is present as an impurity in the
ether extract or crude fat obtained in the analysis of flour. Hence it is,
wheat fat as ordinarily obtained contains nitrogenous compounds, render-
ing it exceedingly difficult if not impossible to separate from that nat-
urally present any new nitrogenous compound that may possibly be
formed during the process of bleaching. The ether extract or crude fat
of three samples of unbleached flour was obtained in quantity by extrac-
tion with one of the best grades of commercial ether. Also the ether was
purified as directed in the official method of analysis and the nitrogen
content of the crude fat extracted with the purified ether by the official
method was determined.

NITROGEN CONTENT OF FAT OF UNBLEACHED FLOURS.

Commercial Purified
Sample. Ether. Ether.

1 0.887 0.873

2 0.919 0.901

3 .. .. 0.931 0.942

It is to be noted that approximately 0.9 per cent, of nitrogen was
found present as a natural constituent of wheat fat. There was no dif-
ierence in the results whether the ordinary or the modified Kjeldahl
method was used for determining the nitrogen content of the fat. In
determinations (qualitative or quantitative) of the nitrogen content of
the fat of bleached flour, the nitrogen that is naturally present must be
recognised, and the presence of nitrogenous compounds in the fat cannot

302 THE TECHNOLOGY OF BREAD-MAKING.

be ascribed to bleaching. The nitrogen content of the fat of three samples
of flour before and after bleaching was determined with the following
results : —

Nitrogen of Fat.
Bleached. Unbleached.

Flour A 0.866 0.887

Flour B . . ' . . . . 0.930 0.919

Flour C 0.927 0.931

Duplicate determinations were made and no greater differences in the
nitrogen content of the fats from bleached and unbleached flours were
found than between duplicate analyses of the same sample. The quan-
titative determinations of nitrogen showed the bleaching of the flour did
not increase the nitrogen content of the fat.

The heat of combustion of the fats was also determined in a Berthelot
calorimeter and practically the same caloric value was obtained for the
fat from the bleached as from the unbleached flour. The differences in
the heats of combustion were no greater than in the case of duplicate
determinations on the same sample. If any oxidation or nitration had
taken place during the process of electrical bleaching, it would have
manifested itself in lowering the heat of combustion. Neither the iodine
number, nitrogen content, nor heat of combustion shows any change to
have occurred, or that the fats from bleached and unbleached flours
differ.

The Glutens of Bleached and Unbleached Flours. — Snyder finds the
gluten of flour to be unchanged by the act of bleaching, except in the
direction of colour. He further finds that the quantity and composition
of the gliadin is unaffected by the bleaching process.

It would not be possible for nitro- or nitrosyl-compounds to be formed
during bleaching, because not enough nitrite or nitrate reacting materials
are present to permit such reactions taking place. Furthermore nitrous
and nitric acids, if present in sufficient amounts to cause a reaction,
would produce yellow coloured products in accord with the well known
xantho-protein reaction of Fourcroy and Vanquelin, and consequently
the flour would have a yellow tint. Such a procedure would be directly
opposite to bleaching, and in that event the nitrogen peroxide would act
as a stain and not as a decolourising reagent. The trace of nitrogen
peroxide employed in the bleaching of flour cannot be regarded in any
way as a dye or stain, as it does not unite chemically with either the fat
or the gluten, or form a coating over the surface of the flour particles.
Its action upon the colouring matter of flour is similar to the change that
takes place naturally when flour is cured and bleached by storage.

Physical Absorption of Gas by Flour. — Since analyses of the fat and
gluten of bleached flour indicated that no chemical combination had
taken place with the trace of nitrogen peroxide used in the bleaching
mixture, experiments were undertaken to determine whether the nitrite
reacting material in the bleaching gas could all be accounted for as ab-
sorbed in the flour. From these experiments Snyder arrived at the fol-
lowing conclusion. The nitrite reacting material in flour appears to be
in physical rather than chemical combination. When the flour is heated,
the nitrite reacting material imparted by bleaching is expelled. All of
the nitrite reacting material in the gas employed for bleaching can be
accounted for as soluble and volatile nitrites in the flour and in the air
turrounding the flour, leaving no nitrite reacting material to chemically
combine with the fat or gluten. When the bleaching gas was brought in
contact with pure sand, with which it cannot unite chemically, the same
amounts of nitrites were absorbed as in the case of flour.

COMPOSITION OF FLOUR AND MILLING PRODUCTS. 303

Loss of Nitrites in Bread-Making. — Bread made from bleached flours
containing 0.00004 per cent, nitrogen as nitrites and baked out of con-
tact with combustion of gases gives no reaction for nitrites. Bread made
irom unbleached flour and baked in a gas oven in which there is direct
connection between the combustion chamber and the oven shows appre-
ciable amounts of nitrites formed from combustion of the gas. When
the bread was properly made and baked in an electric oven there was no
reaction for nitrites from either the bleached or unbleached flours, that
is provided the flour itself was free from nitrite and nitrate reacting
material except that imparted by the bleaching gas. Snyder regards the
nitrite of bleached flour as being more probably ammonium nitrite than
that of either sodium or potassium.

Influence of Bleaching of Flour upon the Digestibility of Bread. — In
order to determine the influence which commercially bleached flour may
exert upon the digestibility of bread a series of digestion experiments
was undertaken to determine the digestibility of bread made from
bleached and unbleached flour milled from the same wheat. In all, fifteen
digestion experiments with men were made. The ration consisted of
bread and milk and the general plan of the experiments was as follows.
Samples of bleached and unbleached flours and of the wheat from which
the flours were made were drawn from a large commercial mill. Diges-
tion experiments were made with bread baked from the bleached and the
unbleached flours. Some of the wheat was then milled in the experi-
mental mill of the Minnesota Experiment Station. One-half of the flour
was bleached, and digestion experiments were made with bread from this
bleached and unbleached flour prepared under chemical control. The
results of these five series of digestion experiments f re given in the table
011 page 304.

In one of the trials or series, the nutrients of the bread made from the
unbleached flour were found to have a slightly higher digestibility than
the bread made from the same flour that had been bleached, while in an-
other series the bread from the bleached flour was somewhat more com-
pletely digested. The difference in digestibility of the nutrients of the
bread made from the bleached and unbleached flours was too small to be
attributed to the treatment the flour had received, The average of the
two series shows the bread made from both the bleached and the un-
bleached flours to have the same degree of digestibility, and that the
process of bleaching had no influence upon the digestibility or nutritive
quality of the flour. The bread for these experiments was baked in an
ordinary cook stove heated by coal, and all the products of combustion
of the fuel were excluded from the baking chamber. The bread both
from the bleached and unbleached flour gave no reaction for nitrites, the
nitrous acid products formed during the bleaching of the flour , and pres-
ent to the extent of 0.00004 gram of nitrogen determined as nitrites per
100 grams of flour, being entirely dispelled during the process of baking.

Digestion Experiments ivith Pepsin Solution. — Digestion trials were
made with bleached and unbleached flours in acid pepsin solution. The
flours used contained 2.04 per cent, nitrogen. The insoluble nitrogen
obtained after digestion with pepsin was found to be as follows : —

Bleached Flour. Unbleached Flour.
Trial No. Per cent. Per cent.

1 0.392 0.378

2 0.343 0.356

Average . . 0.367 0.367

304 THE TECHNOLOGY OF BREAD-MAKING.

It is to be noted that the differences between the duplicate trials of the
same sample are as great as between the two samples of flour tested.

DIGESTIBILITY OF NUTRIENTS.

Car bo-

Trial 1. Bread from Bleached Flour. ~. ~s Iffi

Man 1 . . 85.74 96.96 91.67

Man 2 84.53 97.52 90.62

Man 3 84.96 97.28 90.35

Average- 85.08 97.25 90.88

Trial II. Bread from Unbleached Flour.

Man 1 86.97 98.47 91.46

Man 2 ..-:••• 87.93 98.14 90.89

Man 3 87.63 98.28 91.35

Average .. .. 87.51 98.29 91.23

Trial III. Bread from Unbleached Flour.

Man 1 " -.. .. 91.76 99.02 93.87

Man 2 92.14 98.08 94.97

Man 3 91.67 99.08 95.09

Average 91.86 98.73 94.64

Trial IV. Bread made from Bleached
Flour.

Man 1 92.04 99.07 94.41

Man 2 . . . . 93.24 98.89 95.49

Man 3 93.00 98.88 95.66

Average 92.76 98.95 95.19

Trial V. Bread from Unbleached Flour
with Nitrites.

Man 1 93.56 99.14 95.21

Man 2 : 93.98 99.19 95.76

Man 3 95.96 99.18 —

Average 94.50 99.17 95.43

As far as digestibility in the acid pepsin solution was concerned no
difference whatever was found in the digestibility of the bleached and
the unbleached flours.

Are Flours Bleached with Minute Amounts of Nitrogen Peroxide In-
jurious to Health f — This is a question that can well be raised, because if
the bleaching leaves any material in the bread chat is injurious to health
the practice should be discontinued and condemned. The form in which
the flour is consumed as food, or the finished food product, is what should
be considered in answering this question. Flour is never eaten in the
raw state, but in the process of bread-making, cake-making, and indeed
in all the various ways it is prepared for food it is always subjected to
the action of heat. As previously stated, when flour is warmed out of
contact with combustion gases the nitrite reacting material imparted dur-
ing bleaching is removed, and the bread and other articles made from the
Hour give no reaction for nitrites imparted by the bleaching gas. Since
the material used in the bleaching of flour is expelled in the preparation

COMPOSITION OF FLOUR AND MILLING PRODUCTS. 305

of the food, there remains no question for physiological consideration.
But since breads made from bleached and unbleached flour give prac-
tically like amounts of nitrite reacting material when baked in gas, gaso-
line or kerosene ovens, it would seem that the broader question could well
be raised : is the use of gas and liquid fuels for the preparation of foods,
where the food comes in direct contact with the products of combustion,
injurious to health? This broader question lies outside the province of
Ihe chemist, and also the scope of the present work. Snyder, however,
points out that when breathing the air of a room it not infreque|jUly
happens that a person inhales during a day more nitrogen trioxide
is present in a pound of bleached flour in the raw-^ate. He furt
points out that various other articles of food contain*mtrites in cons
erably greater quantity than does bleached flour, ififche pragence
nitrites generally in these minute traces is to be regardejLas injSious to
health, then the national food menu must be materially ^&tailec£^

Use of Chemicals in Preparation of Foods. — The prinprple of^e use
of chemical reagents in the manufacture and refining of3foods is^cog-
nised in the rules and regulations for the enforcement oithe Na4&mal
Pood and Drugs Act. Circular No. 21, U. S. Department o©^gricu*£ire,
Office of the Secretary, Regulation No. 11, states: "Substan^ps properly
used in the preparation of food products for clarifying or ^fining and
eliminated in further process of manufacture" are exempt. f^bere is no
substance or material used in the manufacture of food product^fthat is as
completely eliminated from the finished product (bread) as is the nitro-
gen peroxide and its products, used in the bleaching or refining of flour.
Jn the manufacture of sugar, sulphur in the form of sulphur dioxide gas
is used for bleaching purposes. Lime is employed later in the process
for neutralising the sulphurous and sulphuric acids formed and for pro-
ducing insoluble products which are later removed by filtration. The
last traces of the sulphur, however, are not entirely removed, and careful
analysis of commercial samples of granulated sugar after combustion in
a calorimeter have shown .0098 per cent, of total sulphur. On a percent-
age basis this is nearly fifty times more than the total nitrate and nitrite
products retained in flour, bleached by the use of nitrogen peroxide. Fur-
thermore sugar is used directly as food without any of the sulphur being
volatilised. Notwithstanding the presence of this trace of sulphur, gran-
ulated sugar is practically pure, as it is unacted upon by the sulphur.
The sulphur acts only upon the colouring matter and not upon the sugar.
However, a much larger amount of it is used than of nitrogen peroxide
in the bleaching of flour. With large amounts of sulphurous and sul-
phuric acid, chemical reaction takes place with sugar, but the little used
as a bleaching reagent fails to produce such a change. In the same way
the small amount of nitrogen peroxide used in flour bleaching acts upon
the colouring matter of the flour without uniting with any of its consti-
tuents. A large amount of gas, however, would produce chemical changes,
as would a large amount of sulphur dioxide acting upon granulated
sugar. Sugar is a food consisting of only one nutrient. In order to refine
and improve it the colouring matter is removed by bleaching. This
bleaching is done without affecting the composition. Flour is a food con-
sisting of several nutrients, and the colouring material is bleached by a
trace of nitrogen peroxide, without otherwise affecting the composition.
Snyder concludes his paper by the statement that in bread-making tests
of commercially bleached flours no difference whatever was observed be-
tween the breads produced from the bleached and the unbleached flours
milled from the same wheats, except that the bleached flours produced-

306 THE TECHNOLOGY OP BREAD-MAKING.

a whiter bread and also showed a tendency to produce larger sized loaves.
Bleaching of the flour did not impart any odour or taste to the bread or
leave in it any residue.

The bleaching of flour enables the miller to manufacture a more uni-
form product and to place his flour directly on the market without neces-
sitating its undergoing bleaching and curing in storage. No difference
whatever was observed between the naturally bleached flours and those
bleached by the electrical process except that the latter contained traces
of nitrite reacting materials which were expelled during bread-making.
(University of Minnesota Agric. Expt. Station. Bull., No. 111).

460. Bleached Flour, U.S. Board of Food Inspection Decision. — By
their decision, No. 100, the United States Board of Food Inspection have
given it as their unanimous opinion that flour bleached with nitrogen
peroxide is an adulterated product under the Food and Drugs Act, 1906 ;
and also that no statement on the label can bring such bleached flour
within the law, and that such flour cannot legally be made or sold in the
District of Columbia or in the Territories, or be transported or sold in
interstate commerce. (Jour. Soc. Chem. Ind., 1909, 157).

461. Decision of English Law Courts. — An action was brought in
March, 1909, in the Chancery Division of the High Court of Justice,
England, before Mr. Justice Warrington, in which it was alleged by the
defendants that the baking qualities of bread made from bleached flour
were not improved, that such bread was less digestible, and that the
treated flour was deteriorated by the introduction or formation therein
of a toxic poisonous substance. , In giving judgment, Mr. Justice War-
rington concluded by saying : "It seems to me, therefore, that, whether
you regard it from the point of view of digestion, whether you regard it
from the point of view of nutrition, or whether you regard it from the
point of view of positive harm, I must come to the conclusion that the
Plaintiffs have established the truth of the statement that no deleterious
action on the flour is caused by the above-mentioned treatment." (Re-
ports of Patent Cases, XXVI, 1909, 597.)

Bleaching is permitted in England.

462. Bleaching and Flavour and Texture. — Although bleaching may
materially improve the colour of a flour, it does not thereby change a
lower grade flour into a higher grade one. There may be some condition-
ing, but the essentials of the lower grade flour still remain unchanged.
Flour of the highest grade possesses a delicacy of flavour, and in the
resultant bread or biscuits, a silkiness of texture, which are not present
in inferior grades. Even if bleaching causes the lower grade to simulate
the highest in colour, it is not simultaneously converted into flour of the
flavour and texture of the highest grade.

This line of argument must not, however, be pushed too far. During
the whole development of milling processes, there has been a steady in-
crease in the amount of patent flour obtainable from the wheat. At first,
only a very small quantity of patent flour of the very best colour was
produced. The remainder contained the rest of the flour, darkened by
the presence of milling impurities. The patent flour was not only of
good colour, but it was also distinguished from the residual flour by the
greater delicacy of flavour and fine texture before referred to. With im-
provements in milling more of this residual flour was freed from its im-
purities, and obtained of equal colour to the so-called patent flour. The
yield of patent flour of the standard colour was thereby increased; but
save in colour, the better purification of the former residual flour did not
alter the inherent qualities of the flour itself. Yet no one has regarded

COMPOSITION OF FLOUR AND MILLING PRODUCTS. 307

this transference of such flour to the patent portion as being in any way
illegitimate. By parity of reasoning, an increase of the amount of flour
of patent colour standard, by harmless bleaching processes, cannot be
regarded as an adulteration, nor is such flour misbranded when called
"patent flour."

463, Detection of Bleached Flour, Griess-Ilosvay Test. — This was a
test for nitrites, devised originally by Griess, and improved by Ilosvay.
The test is so delicate that one part of nitrous anhydride, N203, in a
thousand millions parts of water may be detected by its means.

The Griess-Ilosvay Reagent is prepared in the following manner : For
solution No. I., 0.5 gram, of sulphanilic acid is dissolved by heat in 150
c,c. of dilute (20 per cent.) acetic acid. Solution No. II., 0.1 gram of
a-naphthylamine is heated with 20 c.c. of strong acetic acid, the colourless
solution is poured off and mixed with 130 c.c. of dilute acetic acid. The
two solutions are kept separate, and when required for use are mixed in
equal proportions. The mixture is not affected by light, but should be
protected from the air. This reagent produces a more or less intense pink
colouration in the presence of nitrous acid and nitrites.

Mode of Testing. — The writers found no unbleached flour to respond
to this test when made with the necessary safeguards; but they regard
the precautions necessary as being extraordinary. The nitrous acid
present in the air of laboratories is sufficient to give a pink colouration
with unbleached flours. The following method of working is therefore
recommended. A laboratory table should be fitted up in the open air.
The water to be used must be tested by the Griess-Ilosvay reagent in
order to ensure the absence of nitrites. All apparatus, and especially the
filter papers placed in funnels, are to be washed with nitrite-free water,
and in the case of the latter until the washings give no reaction when
tested for nitrites. Twenty grams of the flour to be tested, and 200 c.c.
of water, are to be placed in a stoppered bottle and shaken at intervals
for half-an-hour. The mixture is allowed to settle, and a portion of the
supernatant liquid filtered through a washed filter. Ten c.c. of this
filtrate are diluted with 50 c.c. of water, 2 c.c. of the Griess-Ilosvay
reagent added, and heated in a water -bath to 80° C. for 15 minutes. In
the absence of a pink colouration, there are no nitrites in the flour. In
the presence of a pink colour, a comparison is made in Nessler glasses
with a solution of a known quantity of nitrite tested in the same way.
Tested in this manner, twenty-one samples of flour from mills without
bleaching plant gave no reaction for nitrites. Of samples sent as bleached
flours fifty-six reacted, while two gave no reaction. These two were prob-
ably sent by mistake, as their colour gave no signs of bleaching.

From experiments made the writers satisfied themselves that bleached
samples of flour lying side by side with unbleached ones do not impart
any nitrous fumes or nitrites to the latter.

The average amount of nitrite, expressed as sodium nitrite, in all the
bleached samples was 6.3 parts per million.

In a graduated series of tests, nitric oxide with excess of air was
added to flour in measured quantity. There was a gradual increase in
whiteness up to the addition of 125 c.c. of gas to a kilogram of flour
(37.5 of nitrites per million) after which larger quantities of gas pro-
duced a less white flour. With even the maximum bleaching effect, the
odour of the flour remained perfectly agreeable.

CHAPTER XVII.
BREAD-MAKING.

464. Salt, Sodium Chloride, NaCL— Having fully dealt with flour
and yeast, there now remain only salt and water as essential constituents
of bread ; some brief reference must be made to these compounds. Salt
is a white crystalline body, about equally soluble in either hot or cold
water, and having a characteristic saline taste. Salt is used in the mak-
ing of bread for two reasons — first, to give the necessary flavour, without
which bread would be tasteless and insipid. In addition to its own saline
flavour, experiments have shown that the presence of salt stimulates the
capacity of the palate for recognising flavours of other substances. Thus,
minute quantities of sugar are recognised in the presence of salt which
in its absence would be unnoticed. This doubtless is one of the reasons
for the importance of salt as a flavouring agent.

In the second place, salt actively controls some of the chemical
changes which proceed during fermentation ; thus, salt, in the quantities
employed in bread-making, produces a decidedly binding effect on the
gluten of the dough. It further checks diastasis, and so retards the con-
version of the starch of the flour into dextrin and maltose. Salt also
checks alcoholic fermentation ; the results of careful measurement of this
action are given in Chapter XI., paragraph 371. The retarding influence
of salt also extends to the other ferments, as lactic, viscous or ropy fer-
ffients, and so tends to prevent injurious fermentation going on in the
dough.

465. Water. — In considering the quality of water for dietetic pur-
poses, the chemist, first and foremost, addresses himself to the task of
determining whether or not the water shows evidences of previous sewage
contamination. He next ascertains the hardness and also the amount of
saline matters present. The methods he adopts for this purpose vary,
but the conclusion at which he seeks to arrive is practically the same. It
may be safely laid down as a rule for the baker that a water which would
be rejected, on analysis, as unfit for drinking purposes, should also with-
out hesitation be rejected by him. Water containing living organisms
should in particular be carefully avoided, as these might very possibly
set up putrefactive fermentation during panification.

Among the waters which would be passed by the chemist for drinking
purposes, there exist, however, considerable differences. Thus, some are
hard, others are extremely soft; salt may be present in certain waters,
while in others it may be almost absent. The difference between hard and
soft waters is that the former contain carbonates ind sulphates of lime
or magnesia in solution ; the act of boiling precipitates the carbonates as
a fur on the vessel used, and so hardness due to the carbonates is termed
temporary hardness, in distinction from that of the sulphates which, not
being removed by boiling, constitutes permanent hardness.

Much speculation exists as to whether or not the hardness or other-
wise of a water exerts any practical influence on bread-making. In brew-
ing it is recognised that a soft water obtains more extract from the malt
than a hard one, but the comparison with the case of bread is scarcely fair,

BREAD-MAKING. 309

because in the wort the liquid is filtered off from the "grains," while in
bread the whole mass, whether soluble or insoluble, goes into the oven
together. The general tendencies of hard water would be to dissolve less
of the proteins than would a soft water, and consequently the dough in
the former case would be, to the extent of the action of the hard water,
tighter and tougher than that produced when the water is soft. (It will
be remembered that gliadin is soluble in distilled water, but that the salts
of the flour itself are sufficient to prevent its going into solution.) The
use of very soft water is very nearly equivalent to the result produced by
using softer flours. Thus, hard water will tend to make whiter bread,
because, not only is the quantity of proteins dissolved smaller, but with
the same quantity in solution their action would be checked by the pres-
ence of the soluble lime salts. At the same time the bread would eat
somewhat harsher and drier than that made with soft water. Speaking
generally the changes which go 011 during panification proceed more rap-
idly with soft than with hard water. Working in a similar manner, i. e.,
with the same times and temperatures, hard water is not likely to produce
as good results as soft water at its best. In order to obtain the same
results, the various steps in the process of fermentation should be some-
what modified; thus, the bread would probably require to lie somewhat
longer in the sponge and dough stages, or the temperature employed
might be somewhat higher. Both colour and flavour of bread depend on
fermentation being allowed to proceed to exactly the right point and no
further — hence hard water, by altering the length of the fermenting
process, will affect both these when fermentation is carried out under
precisely the same conditions with hard water as with soft. Further,
as the keeping moist of bread depends largely on the degree of change
produced in the gluten and other constituents, it is quite possible that the
rate of drying may be affected by the use of hard water. Some years
ago one of the authors made a series of experiments on the manufactur-
ing scale on the comparative advantages of hard and soft water for
bread-making purposes. The use of a water-softening plant was af-
forded him by the inventors, and over some weeks the character of bread
made with the very hard water of the district compared with that made
from the softened water. The general conclusion was that no very great
difference was caused, or at least no difference that could not be produced
by other modifications under the control of the baker, such as slight alter-
ations of the blend of the flour, or mode of fermentation. So far as it
went the action of soft water was considered, everything else being equal,
an improvement on the hard.

466. Objects of Bread-Making. — The miller's art is directed to the
task of separating that part of wheat most suitable for human food from
the bran and other substances whose presence is deemed undesirable. The
flour thus produced requires to be submitted to some cooking operation
before it is fitted for ordinary consumption. Given the flour, it is the
baker's object to cook it so that the result may be an article pleasing to
the sight, agreeable to the taste, nutritious, and easy of digestion. It is
universally admitted that these ends are best accomplished by mixing the
flour with water, so as to form a dough ; which dough is charged, in some
way, with gas, so as to distend it, and then baked. The result is a loaf
'whose interior has a delicate, spongy structure, which causes good bread
to be, of all wheat foods, the one most readily and easily digested when
eaten. This charging with gas is most commonly effected by fermenta-
tion, but other methods are also to a limited extent adopted : these will be
described in turn. Fermentation has one great advantage over other

310 THE TECHNOLOGY OP BREAD-MAKING.

bread-making processes, in that it not only produces gas, but effects other
important changes in certain of the constituents of flour.

467. Definitions of various Stages of Bread-making. — The methods
employed in the manufacture of bread differ in various parts of the
country : it will be well to first give a few definitions, and then proceed
to describe and discuss the principal methods and their underlying
principles.

468. The Ferment. — Among the older bakers the first step in bread-
making was the preparation of a "ferment." This most commonly con-
sisted of potatoes, boiled and mashed with water into a moderately thin
liquor, to which a little raw flour was generally added. The yeast was
next introduced, and fermentation allowed to proceed until the whole of
the fermentable matter was exhausted, and a quiescent stage reached.
The essential point about a ferment is that it shall contain saccharine
matters and yeast stimulants in such a form as to favour growth and
reproduction of yeast, and growth and reproduction in a particularly
vigorous condition. For this purpose it is necessary that the ferment be
not too concentrated, because no yeast reproduction occurs with too great
a degree of concentration. On Briant's authority the following table is
given in the Quarterly Trade Review (Bakers' Q.T.R.) : —

Concentration of the Medium Extent of Yeast

in which Yeast was grown. Reproduction.

6 per cent, of solid matter . . . . 6.60 times.
10 .... 7.37 "

14 " " .... 14.20 "

19 .... 10.10 "

25 " .... 12.50 "

36 .... No reproduction.

A medium containing about 14 per cent, of solid matter is here in-
dicated as being most favourable for reproduction. Independently of
this, too, the actual quantity of ferment, as compared with quantity of
yeast, is of importance ; for on referring to Adrian Brown on fermenta-
tion (Chapter IX.), it is seen that too great a crowding of yeast cells, in-
dependently of the composition of the liquid, may permit fermentation,
while absolutely inhibiting reproduction.

The introduction of raw flour possesses some interest in view of the
light thrown on the toxic nature of flour toward yeast in paragraph 377.
Such raw flour cannot act as a stimulant to the yeast in the ferment, but
may possibly serve to inure the yeast to the effects produced thereon by
flour.

Various substitutes for potatoes may be used in the ferment ; among
these are raw and scalded flour, malt, malt extracts, and other prepara-
tions.

469. The Sponge. — This consists of a portion only of the flour that it
is intended to convert into bread, taken and made into a comparatively
slack dough, with a portion or the whole of the water to be used in mak-
ing all the flour into bread. The yeast or the "ferment" (together with
usually a small proportion of salt) is incorporated into the sponge.
•Sponges containing the whole of the water are termed "batter" or "fly-
ing" sponges. Because of its greater slackness, compared with dough,
fermentative changes proceed more rapidly in the sponge. One of the
authors made a series of observations on small fermenting sponges made
in the laboratory with distillers ' yeast ; these were very slack, and the
number of yeast cells was counted by means of the hasmatimeter imme-
diately on mixing, and again subsequently at intervals of about two

BREAD-MAKING. 311

hours. Not only was there no reproduction, but the cells present grad-
ually lessened in number, doubtless as a result of disintegration of those
deficient in life and vigour. From this, and the reproduction table given
under the heading of Ferment, the conclusion is drawn that no repro-
duction whatever of yeast (Saccharomyces cerevisice) occurs in the
sponge.

470. The Dough. — This consists of the whole of the flour to be used,
together with the whole of the water and other constituents of the bread,
whether mixed straight off or with intermediate stages of ferment and
sponge.

471. Various Methods of Bread-Making. — Among these may be in-
cluded the following : —

Dough made right off — Off-hand or Straight Doughs.

Ferment and Dough.

Sponge and Dough.

Ferment, Sponge and Dough.

Flour Barm, Sponge, and Dough — Scotch System.
A useful classification of bread-making processes on this principle is
given in an article on ''The Best System of Bread-Making," contributed
to the National Association Review (late Q.T.R.), by W. T. Callard. The
following arrangement has been suggested by Callard 's paper: —

472. Off-hand Doughs. — In this system the dough is made direct,
without any preceding stages of ferment or sponge.

Types of Bread made by Method. — Sometimes employed in making tin
bread (i. e., bread baked in tins) but also at times for making crusty
bread.

Flours Used. — Strong patent flours, mixed very slack for tin bread.
Strong London households for crusty cottage bread.

Dough-Making. — Generally from \y\ Ibs. to 2 Ibs. of distillers' yeast
taken to the sack (280 Ibs.), with sometimes a little brewers' yeast in ad-
dition. Formerly from 10 to 14 Ibs. of boiled potatoes were also added,
but this appears to be no longer the rule. Salt from 3 to 3^ Ibs. per
sack. The slack tin-bread doughs, containing 70 quarts water per sack,
are frequently made by hand, and fermented at a temperature of about
76-80° F. when mixed : they lie for about ten hours, and yield about 104
loaves per sack.

For cottage bread the dough is made much stiffer, about 60 quarts of
water per. sack, and usually allowed to ferment at a higher temperature,
so as to be ready in about six hours. These tight doughs are generally
made by machinery, or else the dough is made at first somewhat slack,
and then "cut back" and dusted up at intervals.

Economic Advantages and Disadvantages. — All labour of sponging
and extra manipulation saved, bread produced in less time, only one
blend of flour and one doughing operation. An increased cost results
from the large quantity of yeast required; also number of troughs and
consequent space necessary is considerable.

Character of Bread — Appearance. — Very red and fiery in crust, not
clear in the partings of the crust, volume fair. When used for cottage
bread, a small and rough-looking loaf is the result.

Yield. — Large, the high proportion of yeast enabling the flour to carry
considerable quantities of water.

Flavour. — Sweet, but somewhat neutral at times, and even harsh,
when fermentation has been pressed to the utmost extent. In cottage
bread, when forced, to get a big loaf, there is often a tendency to
sourness.

312 THE TECHNOLOGY OF BREAD-MAKING.

Texture. — Poor, loaf devoid of silkiness or pile, holes of aeration un-
equal, and cottages small and close.

Colour. — Dull, and devoid of sheen.

Moisture. — High, even to clamminess in some loaves.

Summary. — A system in which colour and appearance are sacrificed
to moisture and convenience of working.

473. Ferment and Dough. — As the term implies, this bread-making
system is one in which a ferment and dough are employed.

Types of Bread made by Method. — Used very largely in London and
the South of England in the manufacture of crusty bread, and also well
adapted for tin bread.

Flours Used. — These should be fairly soft, and spring Americans
should not exceed 40 per cent, of the whole mixture. Of hard wheat
flours, Russians seem to suit this method of bread-making better than the
spring American, owing to their glutens mellowing down more rapidly.
Some bakers who work by this method claim to use English wheat flours
to the exclusion of all other varieties. Winter American patents and
also Hungarian flours answer well in this type of bread.

The Ferment. — This most frequently consists of from 10 to 14 Ibs. of
potatoes to the sack, boiled or steamed, and then mashed with water so as
to yield about 3 gallons of liquor. Brewers' yeast is frequently used in
ferments, although recently distillers' yeasts have been similarly worked.
The ferment is "ready'7 in about six hours. Various substances are em-
ployed as substitutes for potatoes in ferments.

Dough-Making. — The ferment is taken, together with about 2*/£ to 3
Ibs. salt to the sack, water over all to the extent of about 56 quarts to
the sack, and allowed to work fairly warm, say 80-84° F. The dough is
allowed to lie for various times, from two to about five hours. This will
depend on the working temperature, character of flour, and strength or
quantity of ferment used.

Economic Advantages and Disadvantages. — After the labour of pre-
paring the ferment, all that of making and breaking down the sponge is
avoided ; there is but one blend of flour required ; and altogether the cost
of manipulation is very little more than that of off-hand doughs subse-
quent to the ferment. It has the advantage that comparatively few
troughs are necessary, because in most cases each can be used several
times over during the day's work. The yeast required is not high in
amount, but the potatoes used sensibly increase the cost of production,
and from their dirty character are a nuisance in the bakery.

Character of Bread — Appearance. — Loaf is usually well risen, bearing
in mind the class of flours employed. The crust is rough, inclined to
break, and usually "short" and crisp in texture. Is bright and clear,
except when too strong dark flours are used.

Yield. — Small, because soft flours are generally employed, say about
90 loaves to the sack.

Flavour. — Good, and particularly suited to the London palate, there
being considerable sweetness. As in all cases where ferments are used,
there is danger of "yeastiness," unless care is taken that the ferment is
not allowed to stand sufficiently long for lactic or other foreign fermenta-
tion to proceed unduly at the close of the alcoholic fermentation.

Texture. — Close and even (i.e., holes of aeration regular), but not
silky.

Colour. — Good, with nice bloom ; crust tendency to brownness, but
should be free from any foxy tint, the result of absence of very hard
flours. Crumbs clear and bright, but comparatively devoid of sheen.

BREAD-MAKING. 313

Moisture. — Fair, when bread is first made ; but all bread of this kind
has seen its best twelve hours after leaving the oven.

Summary. — A very useful system of bread-making, well adapted to
districts where bread is eaten very fresh.

474. Sponge and Dough. — This is probably the most widely used of
all bread-making methods, and evidently therefore adapts itself well to
diversified requirements.

Types of Bread made by Method. — Almost every kind of bread, from
the tightest crusty bread dough to that for the slackest tin bread, may be
made in this manner.

Flours Used. — Practically every variety of bread-flour offered to the
baker can be utilised in this method; the great advantage is that hard
flours can be used in the sponge, thus giving them the advantage of long
fermentation, while softer flours are appropriately worked in at the
dough stage.

Sponge-Making or "Setting." — A blend of hard flour is used for this
purpose, and a quantity taken equal to from a quarter to a half the whole
of the flour to be used. A frequent plan is to take a bag (140 Ibs.) of
spring American patents for the sponge, and a sack of home-milled softer
flour for the dough. Sufficient water must be taken to make the sponge-
dough very slack, say from 6^ to 8 gallons of water to the 100 Ibs. of
flour. Distillers' yeast is now most frequently employed, and a quantity
may be taken of from 6 to 10 ounces to the sack of flour (over sponge and
dough) ; if wished brewers' yeast may be employed instead, but the
quantity must considerably vary according to the strength of the yeast.
A little salt is usually added to the sponge, say about ^ Ib. to the sack.
Formerly potatoes were occasionally added direct to the sponge : this cus-
tom seems now, however, almost obsolete. On being set, the sponge is
allowed to ferment for from six to ten hours, according to the tempera-
ture, quantity of yeast, character of flour, and other considerations. In
machine-bakeries sponges are usually set somewhat stiffer than where
sponges and doughs are made by hand.

The Dough. — The sponge, when ready, is taken, mixed with the
remainder of the flour, the water, and the salt. Soft, flavoury flours are
introduced at -this stage, and the dough allowed to lie about two hours.
The temperature both of sponges and doughs is governed by how soon
either may be wanted, the atmospheric temperature, and other considera-
tions.

Economic Advantages and Disadvantages. — The adaptability of this
method is one of its great advantages, and also the readiness with which
it lends itself to the selection and use of any variety of flour. There is
somewhat greater expense in working, because of the double handling
involved in working the sponge as well as the dough. It is doubtful, how-
ever, whether this is appreciable in the hand-made bread bakery, as it
amounts simply to making the dough in two instalments in the same
trough — there is, in fact, an advantage, as the sponge flour will have had
time to soften, and get to work more kindly before the full quantity is
worked in in the dough.

Character of Bread — Appearance. — Almost any shape of loaf is well
. made in this manner, the bread is bold, and, generally speaking, of good
ttppearance.

Yield. — With the great elasticity of the system, as a whole, the yield
varies considerably according to the character of flours used. Taking a
general average, 93 to 96 loaves per sack is a good proportion. If an
excess of hard, strong flour is used in order to get more bread than this,
the flavour is likely to suffer.

314 THE TECHNOLOGY OP BREAD-MAKING.

Flavour. — One of the essential characters of this type of bread is that,
if well made, it embodies to perfection the natural flavour of the flours,
without any adventitious characters introduced with foreign flavouring-
ingredients. If the flours are well selected, both for sponge and dough,
there should be, on the one hand, an absence of that "rawness" charac-
teristic of under fermentation, and of any harshness resulting from
destruction of all moisture and sweetness-conferring constituents by over
fermentation.

Texture. — The bread should have a good pile, crumb even, white and
silky, with full sheen on the fibre of the bread.

Colour. — The crust should be golden brown, without foxiness or
abnormal paleness. In the crumb the colour advantage of the class of
flour used should be fully developed.

Moisture. — Bread made in this manner is free from any clamminess,
and may easily pass over the line into harsh dryness — this, however, is a
fault that should not occur, rather than a necessity of the method. From
the very even sponginess of the bread, although when fresh cut it may be
very moist, yet it tends to rapidly dry out when cut slices are allowed to
lie about. But when properly made, this bread retains its moisture in the
uncut loaf remarkably well.

Summary. — An interesting point about the sponge and dough method
is its comparison with that of ferment and dough ; both have their advan-
tages, but that just described for most purposes has the preference. Com-
paring breads made by the two methods, ferment and dough made bread
is at its best when quite fresh; while suitably made sponge and dough
bread retains its eating properties considerably longer.

475. Ferment, Sponge, and Dough. — This is essentially a combina-
tion of the two immediately preceding methods, and is frequently chosen
where brewers' yeast is used, as the ferment exerts a specific and valuable
action on yeast of that description. A ferment being employed, instead
of adding yeast to the sponge direct, a description of the sponge and
dough method applies also to this process. One of its advantages is that
it permits more individuality in character of the bread than where a
compressed yeast is used, which can be freely purchased by any baker.
When by means of a "ferment" the baker practically makes his own
yeast, he becomes liable to the risks as well as the advantages accruing
from being his own yeast manufacturer. This method is frequently asso-
ciated with the manufacture of patent yeast by the baker himself. The
whole of the various methods previously described are susceptible of the
same modifications, except perhaps tight, off-hand, crusty bread doughs
which would rise with difficulty under the action of this usually com-
paratively weak yeast.

476. Present Review of Bread-making Methods, Callard. — Mr. Cal-
lard has kindly furnished the authors with the following note on his
paper herein quoted : —

' * Since writing the paper referred to, considerable changes have taken
place in the general practice of bread-making. In the main these changes
are due to two causes: (1) the great improvement in the preparation of
compressed yeasts, and (2) the advance of English milling.

(1) Compressed yeasts today are of a much higher quality and lower
price than when that paper was written. They are much less susceptible
to atmospheric changes, and consequently are less damaged in transit.
They are stronger, or, to be more correct, they mature quicker in the
dough than did yeasts of years ago. This has enabled bakers to dispense
with ferments or sponges, and the system of straight doughs has become

BREAD-MAKING. 315

almost universal. Where the sponge and dough system survives today, it
is on account of attachment to old methods and not because of the neces-
sity of so treating the yeast.

(2) The English miller has for many years aimed at producing a
flour of an all-round quality, avoiding harshness on the one extreme and
softness on the other. He has tried to produce a flour capable of being
used alone. In this he has succeeded, with the result that the flours of
today are more mellow than in the past and require less softening during
the process of fermentation.

The straight dough system (off-hand) with 1% Ibs. to 1J4 Ibs. of
yeast, taking about 5 hours to the oven, is general. This occupies the
same relative place at present as the sponge and dough did when the
paper was published. Here and there a modified ferment is used in con-
junction with it to give the yeast a start. When the desire is To shorten
the time the yeast is increased, in fact with automatic plants 6 Ibs. of
yeast is used to the sack, and the dough passes from the mixer to the
divider without delay." (Personal Communication, October, 1910.)

477. Flour Barm, Sponge, and Dough — Scotch System. — The flour
barm is practically a combination of the making a baker's malt and hop
yeast with a slow, scalded flour ferment. The preparation of the flour
barm has been fully described in the earlier part of this work, page 236.

Type of Bread made ~by Method. — This is the well-known close-packed
" Scotch brick," being a high and comparatively narrow loaf, prepared
from tough, hard flour of the highest class.

Flours Used. — In sponges, strong patents or straight grades from
Duluth or Russian wheats. In doughs, winter Americans and softer, but
still tough, home-milled flours.

Sponges. — These are known as "half" or "quarter" sponges, and
consist of either the half or quarter of the whole liquor employed to the
sack of flour. The requisite quantity of flour barm is taken, for which,
however, distillers' yeast may be substituted without materially altering
the character of the bread. About 6 Ibs. of salt are used to the sack, one-
sixth of which goes into the sponge.

Doughs. — These are made in the usual way, but it is customary to give
the dough a very thorough working after it has laid some time. One of
the most suitable ways of doing this is by passing the dough repeatedly
through a dough-brake.

Economic Advantages and Disadvantages. — The cost of production is,
according to the views of the Scotch baker, very low, as he views the
yeast as costing him very little, the flour used coming back into the bread.
This is not quite correct, because a certain portion must have been
changed into alcohol and carbon dioxide during fermentation ; and, again,
the labour of preparation must cost something.

Character of Bread — Appearance. — The appearance is attractive, the
loaves are high, and the sides, where they have been separated from each
other, have a very smooth, silky appearance.

Yield. — Large, the character of the flours used permitting this, and
also the fact of most of the bread being close packed. An average yield
in a large factory has for some months been as much as 101 quarterns per
sack.

Flavour. — Characteristic, and marked by the presence of a decided
acidity of pure and pleasant taste, due largely, if not entirely, to the
presence of lactic acid. The large quantity of salt used gives a saline
character to the taste, immediately recognised by the English palate,
which also usually misses the sweetness generally found in the best qual
ities of bread made in the south.

316 THE TECHNOLOGY OF BREAD-MAKING.

Texture. — Scotch bread has the perfection of texture, being silky with
large bulk and pile, and small regular holes of aeration.

Colour. — The long system of baking employed gives the crust a dark
brown colour, and hence the bloom of crust is not such an important char-
acteristic as in south country crusty bread. The crumb is exceedingly
white, but has comparatively rarely the creamy, yellow bloom seen in
some of the bread made in other localities. The sheen of the bread is
remarkably distinct, the holes having a rich, full glaze.

Moisture. — Good, and the bread keeps remarkably well.

478. Scotch Bread-making Processes, Meikle, — Mr. J. Meikle, of
Glasgow, has favoured the authors with the following specially obtained
information. The various data have been submitted to several experi-
enced Scottish bakers, and therefore may be regarded as perfectly trust-
worthy.

Scottish systems of breadmaking differ a good deal from the processes
that obtain in England. Sponging is almost as popular today as it was
two decades ago; all serious operations indeed being carried through
under some kind of sponging system. The two leading processes, how-
ever, are the " quarter" and the "half" sponge.

QUARTER SPONGE, FOR \y2 SACKS OF BREAD.

28 Ibs. Water. 10 Ibs. Barm.

70 Ibs. Flour. 10 oz. Salt.

80° F. Temperature. Time — 13 hours.

Sponge.

160 Ibs. Water. 2>^ Ibs. Salt.

126 Ibs. Flour.

78° F. Temperature. Time — 1% hours.

Dough.

20 Ibs. Water. 5^ Ibs. Salt.

224 Ibs. Flour. 78° F. Temperature.

Scale in \l/2 hours: the temperatures given are those of sponge, etc.,
when made.

The quarter system is a three process system. The quarter is made up
at night generally and lies about 13 hours; it should then be up and
dropped an inch, and is turned into a "sponge" tub — a tub of a capacity
of 48 gallons — then water is added, the quarter is well broken, then salt
and flour are put in to make a thin sponge. The sponge lies about 75
minutes and is doughed as soon as it shows signs of settling down : this
is of course for square batched bread, and nothing can touch this system
for appearance : nearly all the bread of Glasgow and the West is made in
this way.

HALF SPONGE, \y2 SACKS.

100 Ibs. Water. 20 Ibs. Barm.

185 Ibs. Flour. \y2 Ibs. Salt.

80° Temperature. Ready 13 hours time.

Dough.

105 Ibs. Water. 6y2 Ibs. Salt.

235 Ibs. Flour. 78° F. Temperature.

Scale in 1^4 hours. Both this and the previous system dough want at
least one turn or cut back while lying in dough. This system does not
make such picture bread as the quarter, but it eats better, particularly so

BREAD-MAKING. 317

when distiller's yeast is used. This is the kind of system worked in the
North of Ireland; but the length of time the sponge lies is being consid-
erably curtailed in these days.

SHORT SYSTEM.

Short systems of fermentation are making some little headway in
Scotland, but probably as a novelty; the following turns out a passable
loaf when suitable flours are used.

Short Process Sponge.

70 Ibs Water. */2 lb. Salt.

74 Ibs. Flour. 3 Ibs. Yeast.

86° F. Temperature. Time— 1 hour.

Dough.

145 Ibs. Water. 7 Ibs. Salt.

346 Ibs. Flour. 82° F. Temperature.

Lie 3 hours before scaling. This process does not give the "pile" of
sponge bread, but it makes a much better square loaf than a short
straight dough system does.

FLOUR USED IN SCOTLAND.

The flour trade in Scotland has undergone great changes during the
iast fifteen years, for whereas at that time American flour was the only
flour that mattered, the imports from the United States are now almost a
negligible quantity. But Scotch bakers need strong flours, or what is the
same thing practically, they think they need them, and the home millers
supply them. Minnesota spring wheat of good quality is of course as
scarce as Minnesota flour, and millers use strong Russians and Manitoban
wheats instead. Flours from those wheats are used for sponging. For
doughing a proportion of American Winters was at one time a favourite,
and even now American Winters, or home-milled flours from Australian
and Argentine wheats, blended to work like Winters, are much used, with
say a proportion of Kansas flour, and some flours of the "Millennium"
and "As You Like It" type of English milled flours. There is a wider
range of doughing flours, for the kind of flour wanted for this purpose
depends upon what has been used in the sponge. The wheats of Mani-
toba, Kansas, Australia, Argentina, and so on, all come in useful.

For barm flour fine Russian and Manitoban wheats are favourites.
This flour is very often a straight run flour ; straights suit barm-making
best. By the way, about the best virgin barm the writer ever saw made
for a length of time was made from Scotch kiln-dried wheat milled on
stones. Hungarian flour, once a prime favourite for good class bread, is
now almost unknown in Scotland. (Personal Communication, October,
1910.)

479. American and Canadian Me/hods. — The following are repre-
sentative processes, but the authors had hoped to have opportunities of
more closely studying these on the spot.

No. I :—

Flours Used. — Hard flours from Northwest wheats; soft flours from
winter wheats. Used in proportions of from two to four parts hard to
one of soft.

Yeast. — Almost entirely distillers' compressed yeasts, though baker's
malt and hop yeasts are used also.

Improvers. — Malt extract, sugars, fat and milk are used, and to a
much greater extent than in British methods.

318 THE TECHNOLOGY OF BREAD-MAKING.

Modes and Time of Fermentation. — Straight doughs taking from 6 to
8 hours to the table ; 12 to 14 hour sponges are also used. The following
are quantities for two types of bread—

Real Home Made. — Flour, 784 Ibs. ; water, 420 Ibs. ; salt, 14 Ibs. ;
cottolene, Yll/2 Ibs.; yeast, 6 Ibs.; malt extract, 5^ Ibs. Temperatures:
Flour, 70° ; bakehouse, 80° ; water, 84° ; dough, 82° F.

G. Crust.— Flour, 972 Ibs.; water, 520 Ibs.; salt, 18 Ibs.; cottolene,
13^2 Ibs.; yeast, iy\ Ibs.; condensed milk, 13 Ibs.; malt extract, 5 Ibs.
Temperatures : Flour, 70° ; bakehouse, 80° ; water, 86° ; dough, 83° F.

Machinery is extensively used. Mixers, dividers, moulding machines
and rounding-up machines are used in the larger shops, and automatic
provers are being introduced. The quantity of hand-made bread is small
and decreasing.

Kind of Loaf. — Tin bread almost entirely. Output of hearth baked
bread is less than three per cent, of the total, and would probably repre-
sent the average.

No. II :—

Flour. — Three parts Minnesota patent to one part Kansas hard wheat.

Yeast. — Compressed yeast.

Improvers. — Malt extract, sugar, lard, milk, cornflour.

Quantities.— 350 Ibs. flour, 525 Ibs. water, 6y2 Ibs. yeast, 12^ Ibs. salt,
20 Ibs. sugar, 17 Ibs. lard, 5 Ibs. milk powder, 5 Ibs. malt extract and 25
Ibs. cornflour.

A short time ferment is made with the yeast, malt extract, part of the
water, and the cornflour. This is added to the dough after the flour is in.
The temperature of the dough is 84° F., and the time from mixer to
bench is 5^2 hours.

REVIEW OF PANARY FERMENTATION.

480. It is proposed in the succeeding paragraphs to consider the
nature of the chemical changes which occur during bread or panary
(from panis, bread) fermentation. Suggestions will also be made as to
possible improvements in methods of carrying out the various processes,
with the hope that they may lead to the avoidance of those causes which
result in the production of bad or inferior bread.

481. The Ferment. — Potatoes, termed by the baker "fruit," consti-
tute the principal ingredient of the ferment ; their composition is indi-
cated in the following analyses. No. 1 was grown with mineral manure,
No. 2 with a rich nitrogenous manure : —

No. 1. No. 2.

Water 76.40 75.20

Starch .. .. 14.91 1558

Proteins 2.17 3.60

Dextrin , . 2.34 1.29

Sugar 0.15 1.11

Fat 0.29 0.31

Extractive Matter 1.70 1.99

Cellulose 0.99 1.03

Ash 1.00 0.90

Roughly speaking, a potato contains three-quarters of its weight of
water and about 15 per cent, of starch ; the remainder being made up of
nmall percentages of proteins, dextrin, sugar, and other substances. On
being boiled, the starch is gelatinised, and on mashing the potatoes,
together with the liquor in which they have been boiled, a stareh paste is
formed, containing also considerable quantities of dextrin and sugar, and
what is of great importance, soluble nitrogenous compounds. Yeast on
being sown in this medium sets up an active fermentation, largely due to

BREAD-MAKING. 319

the sugar already present, together with the strong nitrogenous stimulant.
In Chapter XI. it has been demonstrated that the fermentation is almost
as active in the filtered potato water as in the mash. It must also not be
forgotten that yeast alone is incapable of inducing diastasis in starch
paste. Consequently any unaltered starch suffers little change in a fer-
ment containing only boiled potatoes and yeast. But raw flour being also
commonly added, the yeast induces a change in the flour proteins, in vir-
tue of which they become somewhat active hydrol}rsing agents, and so
the potato starch is indirectly converted in part into sugar. The yeast,
when sown in a ferment, multiplies by growth, and thus a relatively
smaller quantity of yeast is enabled to do the after work. A large pro-
portion of the starch of the potato still remains unchanged at the close
of the fermentation of the ferment ; so also, the nitrogenous matter of the
potato in great part remains. When the ferment is added to the sponge,
the smaller quantity of yeast not only does more work because of its
having had the opportunity of growth and reproduction in the ferment,
but also because the nitrogenous matter of the potato still acts as a yeast
stimulant in the sponge. The active effect of potato water alone shows
that this stimulating action of the ferment on yeast must not be entirely
ascribed to the starch present. From the active stimulating nature of the
nitrogenous matter of potatoes on yeast, it seems probable that that mat-
ter consists of nitrogen in some other form than albuminous compounds.
Summing up these changes into one sentence, in the ferment the yeast
acts on the soluble proteins of the flour and enables them to effect, to
a limited extent, diastasis of the starch ; this results in the production
of a saccharine medium in which the yeast grows and reproduces;
further, the soluble nitrogenous matter of the potato acts as an ener-
getic yeast stimulant.

It is essential that the. potatoes used in the ferment be sound : they
should first of all be washed absolutely clean. A common practice is to
place them in a pail or tub, with water, and scrub them with an ordinary
bass broom ; this treatment is inefficient, as potatoes served in this way
still retain a considerable amount of dirt. The potatoes are then boiled
in their jackets, and afterwards rubbed through a sieve in order to sep-
arate the skins. By far the best plan to clean potatoes is by means of a
machine, of which the following type answers well for all practical pur-
poses. The machine consists essentially of an outer tub, in which is fixed
a vertical revolving brush : the potatoes are put in, and about two minutes
turning the brush cleans them most effectually. The dirt is removed and
also a good deal of the outer skin, while the interior of the potato remains
intact. Treated in this manner the potatoes have only just the slightest
film of skin to be removed, after boiling, by means of the sieve. In the
next place, the pan, or other vessel used for boiling the potatoes, should
be kept clean ; this is only done by its being washed, drained, and wiped
dry every day. Not only the potatoes, but the water in which they are
boiled, should be quite clean enough, if need be, to go into the bread. At
present, many bakers steam their potatoes in preference to boiling: this
modification is cleanly and convenient. The potatoes are placed in a
metal work cage, which in its turn is placed in a box arrangement,
through which steam is conducted from a boiler : when sufficiently cooked,
4he cage, together with the potatoes, is lifted out. and its contents poured
on to a sieve. The ferment should be rapidly cooled to the pitching tem-
perature of about 80° F. in summer, and 85° in winter : in summer it is
very important that the baker should throughout conduct his fermenta-
tion at as low a temperature as possible. During the time that a ferment

320 THE TECHNOLOGY OF BREAD-MAKING.

is working the temperature should be kept even : for this purpose select
a place in the bake-house free from draughts or excessive heats.

At present, flour, together with malt extract and a number of other
materials, are being used as substitutes for potatoes in ferments, the use
of which is now the exception rather than the rule.

482. Panary Fermentation. — The consideration of the division of
this process into sponging and doughing may be postponed until after a
study of the nature of the changes occurring during panification as a
whole. Yeast, flour, and water, at a suitable temperature, on being mixed
so as to form a dough, immediately begin to react on each other. The
flour, it must be remembered, contains sugar, starch, and both soluble and
insoluble proteins. The yeast consists essentially of saccharomyces ; but
bacterial life is also present in greater or less quantity, not only in the
yeast but also in the flour. The yeast rapidly sets up alcoholic fermenta-
tion, thus causing the decomposition of the sugar into alcohol and carbon
dioxide gas; the latter is retained within the dough and causes its dis-
tension. Functioning in dough, no reproduction of the yeast occurs;
after a time the yeast cells disappear through the degradation and rup-
ture of their walls. In addition, the yeast attacks the proteins present,
effecting changes in them which are similar to, if not identical with, the
earlier processes of digestion. Albumin and its congeners are, in fact,
more or less peptonised. The gluten, from being hard and india-rubber
like, become softer, and within certain limits more elastic; but if fer-
mentation be allowed to proceed too far, the gluten softens still further,
and its peculiar elasticity in great part disappears. It is uncertain to
what extent these changes in the gluten are due to the specific action of
yeast, as they also occur, although more slowly, in flour which has simply
been mixed with water. It has been already explained that under the
action of yeast the albuminous bodies of flour acquire the power of effect-
ing the diastasis of starch ; this compound is consequently to some extent
converted into dextrin and maltose during panification. The amount of
starch so hydrolysed depends largely on the soundness of the flour. In
addition, the diastase of the flour itself will probably have some action in
inducing starch conversion. The lower the grade of the flour, the more
raw grain diastase it usually contains. When potatoes are used, whether as
a ferment or as a direct addition to the flour, they furnish soluble starch,
and also act as a nitrogenous yeast stimulant. While the yeast effects
important changes in the albuminous compounds of flour, experiments
made and described in Chapter XI. show that little or no gas is evolved
as a consequence of such changes. The gas produced in dough during
bread-making is the result of normal alcoholic fermentation of sugar by
the yeast. Summing up the changes produced in panification — they are
alcoholic fermentation of the sugar, softening and proteolytic action on
the proteins, and a limited diastasis of the starch by the proteins so
changed.

So much for the action of yeast on dough. The next point of import-
ance is the effect produced by such other organisms as may be present.
The principal one of these is the lactic bacillus; under its influence the
sugar of the dough is converted into lactic acid. Either the organism
itself, or the acid produced by its action on sugar, has a softening and
dissolving effect upon gluten. Opinions differ as to the desirability, or
otherwise, of the presence of lactic ferments in yeast used for bread-
making. It has already been explained that their being found in any but
the smallest quantity in brewers ? or compressed yeasts is an unfavourable
sign, as they show that due care has not been taken in the manufacture of

BREAD-MAKING. 321

the yeast; for that reason their presence is deemed unfavourable. In
Scotch flour barms the presence of lactic ferments in not too great
amount is deliberately encouraged ; experience having shown that if the
barms be brewed so as to exclude these organisms such good bread is not
produced. In Scotch bread-making very hard and stable flours are used ;
the lactic ferment does good service in softening the gluten. It is possible
also that during .the long period of sponging and doughing, the changes
induced by the lactic ferment may cause slight evolution of gas; but so
far as actual aeration of the dough is concerned this may be viewed as a
negligible quantity. It must be remembered that the soupgon of slight
buttermilk flavour is a valued characteristic of Scotch bread. In bread-
making, as conducted by most English processes, particularly with soft
flours having but little stability, there seems no useful function which the
lactic ferment can perform; its absence is therefore rather to be desired
than its presence. A yeast may contain other organisms in addition to
those just mentioned ; these are capable of inducing changes of a far more
serious nature than does the lactic ferment. Among these there are the
organisms which cause butyric and putrefactive fermentation. That bane
of the baker, sour bread, is commonly ascribed to the action of either
lactic or acetic fermentation ; it is, however, far more probable that this
unwelcome change is due to incipient putrefactive and butyric fermenta-
tion ; since the odour of a sour loaf is very different from that of either
the vinegar-like smell of acetic acid or the buttermilk odour accompany-
ing lactic acid in altered milk. The souring takes place more usually in
the bread rather than in the dough.

In order to produce a healthy fermentation in dough, healthy yeast is
of vital importance : purity from foreign organisms is desirable (saving,
perhaps, a small proportion of lactic ferment in flour barms), but above
all the yeast itself must be active and in good condition. Given a yeast,
which contains a certain percentage of foreign ferments, those ferments
will be held in abeyance while the yeast itself is energetic and healthy.
Bakers are often puzzled by microscopic observations of yeast ; they find
that, of two yeasts, one produces sour and the other a good bread, and
yet that the two contain about the same quantities of disease ferments.
They are consequently very apt to despise any conclusions they may have
drawn from microscopic observations; but the difference in such cases
lies in the yeast itself : the one will be healthy, the other weak and languid.
Quoting again from previously described experiments, in the same sample
of wort, divided into two portions, the one only of which was sown with
yeast, and both equally exposed to the air, it was found that in the pres-
ence of yeast life, bacteria refused to develop, while in its absence they
reproduced with enormous rapidity. In the same way the healthy yeast
suspends the developments of bacteria in dough, while the yeast being
weak and almost inactive, bacterial life flourishes apace. Examination
would reveal that in most cases of unhealthy panary fermentation the
fault is as much due to the yeast itself as to the abnormal presence of for
eign ferments.

483. Sponging and Doughing, — This division of the process of
panary fermentation into two distinct steps is of extreme interest. The
•origin, and reasons which led to the adoption, of this mode of procedure
are probably due to the exigencies of dough-kneading by hand. For even
when using flour from the lot which has been placed in his trough, the
baker usually elects to work a part of it into a sponge first. The rea-
son, or at least one reason, is that the dough softens on standing, and

322 THE TECHNOLOGY OF BREAD-MAKING.

therefore there is less work involved in mixing in the flour in two instal-
ments than in one, as the ~first lot will have got considerably softer.
Further, very little experimental work in this direction will have shown
the baker that he required to use less yeast, and got better results when
working in this way. Hence, doubtless, for original reasons such as these,
the division of bread-making into sponge and dough. Independently of
this, they have for other reasons a most important scientific justification.
The reader will by this time be familiar with the division of flours into
strong and weak varieties. The various tests given in a preceding chapter
show not merely that one flour absorbs more water than another to form
a dough of standard stiffness, but also that some flours fall off far more
rapidly in stiffness than do others when kept in the condition of dough.
There are therefore two distinct properties here to be considered in rela-
tion to flour, the absolute quantity of water it absorbs, and also the rate
at which slackening goes on during panification. Remembering the previ-
ous definition of water-absorbing power, the relative capacity of
resistance of flours, to a falling off in water -retaining power during
fermentation, may appropriately be termed their "Stability." As a
rule, the strong flours are also the more stable, but this does not neces-
sarily hold good in all cases. It has been already explained that, for the
production of the best bread, fermentation should be allowed to proceed
sufficiently far to soften and mellow the gluten, but no further. At
stages either earlier or later than this, the bread will lack both in appear-
ance and flavour. It is therefore necessary to so regulate fermentation as
to stop at precisely this point ; unfortunately no exact means are at pres-
ent known whereby it can be determined with precision. The more stable
a flour is, the longer it requires to be fermented before this point is
reached, hence where flours of different qualities are being used, the more
stable should be set fermenting earlier than the others. In this lies the
reason for using some flours at the sponge and others at the dough stage.
Flours from hard wheats, such as Spring American or Russian, should be
used in the sponge; and American Winter or English wheaten flours in
the dough. Working with stable flours in the sponge, experience has
shown according at least to the London practice, that the best results are
obtained by allowing the sponge to rise and fall once, and then to rise
again. The time taken for this rising and falling is found to agree with
that necessary for the sufficient mellowing of the gluten. This empirical
test, which is the result of careful watching and experience, is at present
the baker's principal guide in determining the progress of fermentation.
It affords evidence of the degree of rapidity with which gas is being
evolved, and indirectly of the extent to which the other chemical changes
have proceeded.

Reference has already been made to the great change which has dur-
ing the past few years eome on baker's practice. For various reasons,
among which those cited by Callard are some of the leading ones, the
sponge and dough methods have largely given place to straight or off-
hand doughs. Possibly the exigencies of hand kneading, referred to at
the commencement of this paragraph, have so completely disappeared,
with the greater adoption of machinery, by which a stiff straight dough
is readily made, that any division of the dough-making process is 110
longer found or deemed necessary.

484. Variety and Quantity of Yeast Used.— The variety of yeast em-
ployed produces a marked effect on the character of the resultant
bread. Good brewers' yeast is almost universally admitted to induce a
characteristic sweet or * ' nutty ' ' flavour, hence it has been largely used in

BREAD-MAKING. 323

the manufacture of so-called farmhouse bread. Colour in this variety of
bread is secondary to sweetness of flavour. While brewers' yeast has a
somewhat energetic diastatic action on the proteins and starch of dough,
its fermentative power is comparatively low in that medium. Undoubt-
edly, one of the reasons which has led to the comparatively extensive use
of potatoes in bread-making is their stimulant action on the gas-pro-
ducing power of brewers' yeast in dough.

Compressed distillers ' yeasts, on the other hand, are marked by their
rapid power of inducing alcoholic fermentation in dough : experience
indicates that neither potato nor flour ferments are necessary, at least as
stimulants, when working with these yeasts.

Motives of economy on the part of the bakers, and competition on the
side of the yeast merchants, both lead to a certain rivalry among the lat-
ter as to whose yeast is able, weight for weight, to adequately ferment the
greatest quantity of flour. Now, while it is important that the baker
should know with accuracy the relative strengths of different brands of
yeast, it is nevertheless not wise to be too sparing in the quantity em-
ployed to a sack of flour. First, select the strongest and purest yeast you
can get for the money, and then don't be afraid to use sufficient of it.
This advice should have especial weight where soft, weak flours, having
comparatively little stability, are so largely employed. Flours of this
kind will not bear being kept so long in the sponge and dough stage as is
necessary to ferment them with a very small quantity of yeast ; they, if so
treated, produce sodden, heavy, and sometimes sour loaves; when any
saving in yeast is more than compensated by a less yield of bread.

485. Management of Sponging and Doughing. — In order to insure
success in the manufacture of bread, sound materials are the first
requisite ; after that the most important in this, like all other operations
in which fermentation employs an important part, is the proper regula-
tion of temperature. The yeast should always be stored where it will get
neither too hot nor too cold ; for extremes of temperature in either direc-
tion weaken the action of yeast. Brewers' yeast in particular suffers
from this in summer weather ; and so, many bakers who use it in the win-
ter change over to compressed yeast in the summer. In summer time
the compressed yeasts, are when fresh more active than in winter : in the
latter season, the strength of the yeast may be increased by allowing it to
stand for a time in water at 85° F. before being used. A still better plan
is to stir a small quantity of sugar or malt extract into a bowl of water
and then add the yeast ; let this stand for about an hour, gently stirring
now and then in order to aerate the liquor. Such treatment refreshes and
invigorates the yeast, and so enables it to afterwards work more actively.
Both sponge and dough, or straight dough, should be so managed as to
keep the temperature as nearly constant as possible during the whole of
the fermentation. Good yeast works well at from 80° to 85° F., and at
that temperature lactic and butyric fermentation proceed but slowly, even
in the presence of the special organisms which induce these types of fer-
mentation. Sudden cold should also be avoided, as a chill to working
yeast is most detrimental, causing fermentation to entirely cease, or at
the best to proceed most sluggishly. Such a sudden lowering of tempera-
ture may indirectly be the means of producing a sour loaf.

486. Use of Salt. — A great deal has been written as to the use of salt
as a guiding agent in fermentation ; so far as the yeast is concerned, salt
is generally viewed as having a retarding influence ; although the opinion
has been expressed that quantities of salt under 3 per cent, of the water
used stimulate the action of yeast. This opinion is based 01? certain

324 THE TECHNOLOGY OP BREAD-MAKING.

observations of Liebig. The authors' own experiments (vide Chapter
XL, paragraph 371) lead them to conclude that salt, in all proportions
from 1.4 per cent, upwards, retards alcoholic fermentation, and dimin-
ishes the speed of gas evolution. Salt acts still more powerfully as a
retarding agent 011 lactic and other foreign ferments, and so aids in the
prevention of unhealthy fermentation. In addition, salt also checks
diastasis, and thereby prevents undue hydrolysis of the starch of the
flour. In summer time, or when any suspicion of instability attaches to
the flour, it is well to add some portion of the salt to the sponge ; but
when the flour is good, and the yeast pure and healthy, the whole of the
salt may be deferred to the dough stage.

In the Scotch methods of bread-making, flours of a very strong and
stable character are used in the sponge, which altogether is allowed to
stand about 12 hours. A slight amount of lactic acidity is developed in
this, and is viewed as normal ; it has an important function in softening
and mellowing the gluten. It will be noticed that a small proportion of
salt is, in the Scotch process, added to the sponge.

487. Loss during Fermentation. — This has been variously estimated,
among the highest figures being that of Dauglish, who introduced the
aeration process, and expressed the opinion that this loss amounted to
from 3 to 6 per cent. In order to determine the maximum amount of loss
possible, the authors made a direct experiment — 100 parts by weight of
soft flour from English wheats were made into a dough with distilled
water, two parts of pressed yeast being added ; no salt being used. This
dough was allowed to stand for from 8 to 9 hours at a temperature of
about 85° to 90° F. ; fermentation proceeded violently, but towards the
end of the time had apparently ceased. The dough was then placed in a
hot-water oven, and maintained at a constant temperature of 212° F. for
10 days ; the same weight of flour and yeast, but no water, was also placed
in the oven. At the end of that time the fermented dough was found to
have lost 2.5 per cent, compared with the flour. Now in this extreme case
a soft flour was used with distilled water and no salt, and about six times
the normal amount of yeast; the temperature was purposely maintained
at a high point, and the fermentation carried on so long as any decided
evolution of gas occurred. Yet, under these conditions, which far and
away exceed in severity any such as are met with in practice, the loss was
less than Dauglish 's minimum estimate. In the fermentation experi-
ments described in Chapter XV., paragraph 436, the total loss in weight
of the dough during fermentation was only 0.59 per cent, with a strong
flour, and 0.70 per cent, with a weak flour. In both cases the extent of
fermentation was as nearly as possible that normally employed in modern
bread-making processes.

488. Baking. — For baking, the oven should be at a temperature of
450-500° F. Most modern ovens are now fitted with a pyrometer, by
means of which the temperature may be read off. If depending on this
instrument, care must be taken that it is in efficient working order. In
the oven the dough rapidly swells from the expansion of the gases within
the loaf by the heat. Its outside is converted into a crust; th^ starch
being changed into gum and sugar : these are at the high temperature
slightly caramelised, and so give the crust its characteristic colour. The
effect 'of the heat on the interior of each loaf is to evaporate a Dortion of
the water present in the dough : the carbon dioxide, and a portion of the
alcohol produced by fermentation, escape with the steam, and may be
recovered from the gases within the oven. While any water is present
in the bread, the temperature of its interior can never rise above the

BREAD-MAKING. 325

boiling point of that liquid. Owing to the pressure caused by the con-
fining action of the crust, that boiling point may, however, be somewhat
higher than under normal atmospheric pressure. The increase due from
this cause is probably not more than some two or three degrees. As
baked bread still contains some 35 to 40 per cent, of moisture, it may be
safely stated that the inside of the loaf never rises to a higher tempera-
ture than 215° F. It is commonly stated that, in the act of baking, the
starch of flour is gelatinised. This, however, is only partly the case. The
temperature of a baked loaf rises considerably above that requisite for
gelatinisation, but there is also another condition necessary. Gelatinisa-
tion is essentially an act of union with water, and a loaf does not contain
sufficient moisture to anything like gelatinise the whole of the starch. At
the moment of writing, a fragment of bread has just been examined
microscopically, and field after field is seen of unbroken and apparently
unaltered starch corpuscles. One of the largest present was measured
and found to be 0.057 m.m. in diameter, showing that the starch had not
even materially swollen. Doubtless under the influence of heat the starch
has become softened, but the larger proportion of the granules still remain
intact. (Compare paragraph 172, page 80.) At the temperature of the
interior of the loaf, the coagulable proteins will have been coagulated, and
their diastatic power entirely destroyed. The composition of bread, com-
pared with that of flour, is dealt with subsequently.

489. Time Necessary for Baking. — The time during which bread is
kept in the oven varies considerably in different parts of the country:
much must depend on the temperature — whether the oven be quick or
slack. For 4 lb. crusty loaves an hour to an hour and a quarter seems to
be an average time. The half -quartern or 2 lb. loaf is a much commoner
size in England, and loaves of this description can readily be baked in
from 40 to 50 minutes in any well constructed oven.

490. Glazing. — The admission of steam to an oven, when properly
managed, has the effect cf producing a glazed surface on the outside of
the crust : this operation is familiar to bakers as that by which Vienna
rolls are glazed. In order that the operation shall be effective, the Drear-
er rolls should be as cool as possible. The steam should be simply at
atmospheric pressure, and saturated with moisture. At the instant of the
cool loaf entering the steam atmosphere of the oven, a momentary con-
densation of steam occurs over the whole surface, which is thus covered
with a film of water at the boiling point. This renders the starch of the
outside surface soluble, and as the water dries off leaves a glaze of soluble
starch, part of which possibly has been converted into dextrin. The in-
jection of steam into the oven not only helps to dextrinise and glaze the
crust, but also serves the purpose of keeping the interior of the loaf
moist by preventing too rapid evaporation.

491. " Solid" and "Flash" Heats. — These terms are frequently used
by the baker in speaking of the character of the heat of different ovens.
The former is applied to heat which is continuous, the latter to heat which
is very temporary, but frequently for the moment intense. It will be
found that the so-called ' ' solid ' ' heat is usually evolved from the walls of
a well heated oven. A good oven should have plenty of material about
it; this gets hot through, and afterwards radiates heat slowly but con-
tinuously. If the oven walls be too thin they cool too quickly ; in conse-
quence they have to be heated very intensely at the start; the result is
that the oven at first burns the bread, and towards the end has not heat
enough to complete the baking of the batch. With thicker walls the
initial temperature of the oven need not be so high ; the fall in temperature

326 THE TECHNOLOGY OF BREAD-MAKING.

taking place more slowly, the oven still retains a good heat at the
close of the baking. The heat which reaches the bread from the walls of
the oven is largely in the form known as "radiant" heat ; it is continuous,
and need not be of abnormally high temperature in order to thoroughly
and efficiently bake bread. The consequence is that the interior of the
bread is well baked, while the crust is not burned.

A "flash" heat, on the other hand, is produced by the contact of
highly heated gases with the bread. Certain varieties of ovens are fired
by the introduction of flame into the oven itself. Such introduction of
flame should be employed to previously raise the temperature of the oven,
not, if used at all, to bake the bread itself. The reason is obvious; it is
exceedingly difficult to regulate the temperature of a current of hot air
from a flame with great exactitude. The temperature is sufficiently high
at one time to burn the crust ; at another so low as to prevent, during the
time the bread is in the oven, its inside being sufficiently cooked. Fur-
ther, if the bread is to be heated by the hot air resulting from the direct
admission of flame into the oven, there must necessarily be also some
means of exit for the gases from the flame. The hot air from a furnace
cannot, in fact, be drawn into the oven without some means for their after
escape. The result is that these gases carry with them the steam evolved
from the baking loaves, and so subject the bread to a dry, instead of a
steam saturated, atmosphere.

492. Cooling of Bread. — The loaves on being taken from the oven
should be cooled as rapidly as possible in a pure atmosphere j for this pur-
pose, where practicable, open-air cooling sheds should be provided. Fail-
ing these, the cooling-room must be well ventilated. It goes without
saying that the cooling loaves must be adequately protected from rain.

493. Summary of Conditions Affecting Speed of Fermentation.—
Where fermentation starts with the first addition of yeast to the other
materials, it does not conclude till the bread has been for some time in the
oven, and possibly not even then. At this stage of work, with both prin-
ciples and details of methods of working explained, a bird's-eye view of
the whole course of fermentation should be of service.

A ferment, when used, is a means of making yeast by a process of
reproduction from that originally added. Steps are taken at the same
time to ensure vigour in the new yeast formed. The speed of fermenta-
tion of the ferment is hastened by increase of temperature, but beyond a
certain point that of acid-producing organisms is also more than propor-
tionately stimulated. Aeration during fermentation tends to increase the
vigour of the produced yeast. (Compare Adrian Brown on the action of
oxygen on fermentation, paragraph 310).

Assuming a start has been made with either sponge or off-hand dough,
the same laws govern fermentation.

First, let us see what conditions accelerate fermentation.

With regard to yeast, the greater the quantity, the more quickly it
proceeds : with sound yeast there is no fear of imparting a yeasty taste to
bread with many times more than necessary for ordinary bread-making.
The strength of the yeast will also directly tend to increase the rate at
which fermentation proceeds.

Flour. — Soft flours tend to hasten fermentation; they contain more
sugar and more starch in a condition susceptible to diastasis. Their pro-
tein matter is more likely to act as a yeast stimulant, while the softness
of the gluten lessens a physical obstacle to rapid action of yeast.

Potatoes, Saccharine Extracts. — These act as stimulants, and tend to
increase the speed of fermentation.

BREAD-MAKING. 327

Water. — The principal way in which this acts is in virtue of the pro-
portionate quantity used. When doughs are slack, fermentation proceeds
much more rapidly.

Aeration. — Flour well aerated is likely to work more rapidly, espe-
cially in slack sponges. Notice how in Vienna bread the batter sponge is
beaten and worked, and how much more vigorous and " lively" it is in
consequence.

Temperature. — This governs all ; with low temperatures yeast works
very slowly, if at all, and with higher temperatures fermentation is
accelerated.

Next, as to conditions retarding fermentation: these may be
summed up as the opposite of the accelerating agents — yeast, weak or in
small quantities ; hard, dry flours ; stiff, unaerated doughs ; low tempera-
ture ; and finally, the addition of salt, which has a very marked retarding
effect.

By modifying one or more of these conditions, the baker is able to
regulate the speed of his fermentation ; and, where certain of them are
altered by causes beyond his control, is able to more or less compensate
the disturbance by introducing changes in one or more of the others.
Suppose, for example, the working of a sponge is unduly hastened by
having to use a softer flour than usual, this may be modified by making it
tighter, or working with less yeast, or at a lower temperature. A good
deal of the art of the baker consists in properly adjusting these variable
factors so that they shall properly balance each other, and all conduce to
the production of a good loaf of bread.

494. Quick versus Slow Fermentation. — This is probably a conven-
ient place to make some reference to the relative merits of quick as
against slow fermentation processes. One fact revealed by the record of
modern methods given in paragraph 477 is that as a whole the various
operations of baking have been materially shortened during the past few
years. Reference is made in a subsequent paragraph, No. 497, to some
experiments on the comparative effect on acidity production of working
at comparatively high and low temperatures. The lesson taught by these
experiments is that for the same amount of alcoholic fermentation a com-
paratively high temperature is at least not more productive of acidity
than a much lower one. These tests were taken as the starting point of
an investigation by one of the authors into the broader question of the
effect of speed on bread-making processes generally. The results, of which
the following is a resume, were published in 1897. The various baking
tests were made by Mr. Ellis, an experienced baker, who was then a stu-
dent in the authors' laboratory.

A London "whites" flour was taken and worked throughout by means
of ferment and dough method. All the water and sufficient of the flour
were taken to form a batter ferment, the remainder of the flour being
used in the dough.

-Quantities in Grams.-

Flour .. 560 560 560 560

Water ...... 320 320 320 320

Yeast ...... 5 5 5 15

Salt ...... 6 6 6 6

Temperature of water 70° F. 80° F. 85° F. 115° F.

Time taken to oven . . 13 hrs. 10^ hrs. 10 hrs. 3 hrs.

(Note, 560 grams are about equal to 20 ounces. If these quantities
throughout be halved they give in every case Ibs. to the sack of 280 Ibs.)

328

THE TECHNOLOGY OF BREAD-MAKING.

REMARKS ON WORKING.

No. 1. Ferment started at 8.0 a.m., well risen by 12.35, dropped 4.20
p.m., dough made 4.35, ripest at 7.10, handed up 8.5, least spring. When
baked was closer in pile, good colour crumb, few small holes, not quite
equal in sheen to No. 4; crust thin, rather dull in colour.

No. 2. Ferment started at 10.20 a.m., dropped 5.0 p.m., doughed 5.5,
handed up 8.20, fairly springy. When baked, was best loaf of those slow
worked. Good pile and colour, crumb better texture than others. Nice
coloured crust, good appearance, and best shaped.

No. 3. Ferment started 10.35, dropped 4.15, doughed 4.30, handed up
8.10, moulded well, fairly springy, good colour crumb, fair sheen, very
sweet to smell and taste, not quite so good a texture or appearance in
crust as others.

No. 4. Ferment started at 10.0 a.m., dropped at 11.30, made up 11.37,
skin just cracking 12.32 when handed up, moulded 12.50. Much the
boldest and best when baked, good pile, good crumb, few small holes,
rather best sheen, not quite so sweet to smell, but nicer flavour to palate
than No. 1. Crust thin and good colour, although well baked.

In the following table the working character and keeping qualities
are summarised. Percentages are also given of acid reckoned as lactic
acid, sugar reckoned as maltose, and soluble matter in the breads.

No.

Character in
Working.

Keeping Quality and Flavour.

Sweetness.

Acid-
ity.

Malt-
ose.

Soluble
Matter

Very little spring,

1st. day — Slightly drier

Smells

0.18

0.32

6.04

dead to handle

than No. 4. Not so

sweet.

all the way
through.

good flavour.
4th. day — Considerably
the driest when cut.

6th. day — Much the

driest.

Fairly springy,
moulded well.

1st, day — Rather moister
than 1 or 4, and better

Sweetest
to smell

0.20

0.35

4.28

flavour.

and taste.

4th. day — Keeps its

moistness.

6th. day — Has not kept

its moistness as well as

No. 4 for the longer

time.

Rather more

1st. day — The moistest.

Very

0.18

0.28

5.68

springy than
No. 2, but not

4th. day — Kept much
moister.

sweet.

so good as No.

6th. day — About as moist

4, handled well.

as No. 4. Sweeter in

flavour.

Handled well;

1st. day — Rather moister

Does not

0.19

0.10

5.28

full of spring.

than No. 1.

smell so

4th. day— Much the

sweet.

moistest.

6th. day — Moistest and

good flavour. The

pleasantest flavour of

all.

The general conclusions to be drawn from this series of experiments is
in favour of the quick fermentation method. It is somewhat curious to
find that the long fermentation loaf dried off the quicker, especially as
there is a somewhat widespread opinion that short fermentation bread
loses its moisture the more rapidly.

BREAD-MAKING. 329

In the next place experiments were made with larger quantities;
straight doughs being employed, in order to determine the minimum of
time in which they could be satisfactorily fermented. The following are
particulars of quantities and temperatures : —

280 Ibs. of flour at 72°' F. 70°' F. 68°' F. 70°' F.

Water at . . . . 85° F. 95° F. 112° F. 105° F.

Yeast . . . . 20 oz. 19 oz. 18 oz. 22 oz.

Salt . . . . 3 Ibs. 3 Ibs. 3 Ibs. 3 Ibs.

Temperature of dough when made, 91° F.

REMARKS ON WORKING.

No. 1 was taken 5 hours after being made, and set in oven in another
50 minutes. Loaf of good appearance and very sweet. Dough might
have been taken half-an-hour sooner without injury.

No. 2. Taken 3^4 hours after making, and set in oven in another 50
minutes. Good bold loaf, no foxiness, very sweet.

No. 3. Made 2 quarts of water slacker than No. 2. Fifteen pounds
of flour were reserved and dusted in when the dough was cut back at the
end of 2 hours. Taken 3 hours after making. Loaf small and runny,
probably rather more time required.

No. 4. Taken at end of 3 hours, in oven in 3^ hours. Bread small
and rather flat.

A repeat was next made of No. 2, with the result that the loaf was in
every way satisfactory and compared favourably with bread made from
the same flour by a long system of fermentation.

The whole of these were fairly stiff doughs for crusty cottage bread,
probably the same degree of stiffness as is employed in London for bread
of this kind. It was found that a working time of 3*/2 to 3^4 hours was
the best to employ, as when an effort was made to get down to 3 hours
the bread fell off in quality. Endeavours were made to shorten the time,
both by raising the temperature and increasing the yeast, but the results
in neither case could be considered encouraging. No doubt with slacker
doughs such as are made for tinned bread, the time might still further be
shortened. The flour used was a hard mixture and required to be fer-
mented sufficiently to be free working, and not yield a pinched loaf.
Softer flour again would work through in less time. The conclusions
drawn were that in appearance and general character at least as good
a loaf can be obtained by quick as by slow fermentation processes. The
subsequent adoption of quick processes by so large a proportion of bak-
ers is an ample justification of the forecast of 1887.

495. Summary of Course of Fermentation. — A very useful lesson
may be learned by making a batch, say of 20 Ibs. of flour, into a slack
dough, with a full allowance of distillers' yeast, say 3 ounces; salt and
water in proportion, and working the batch fairly warm. Let a piece be
cut off and moulded into a loaf immediately the dough is made and at
once baked — the result will be a close, small, very moist loaf, not much
bigger than the piece of dough cut off. Next bake a similar loaf from
the same piece of dough at the end of every hour from the time of start-
ing, keeping the main mass covered, and in a warm place.' An instructive
series of changes will be observed in the successive loaves. In boldness the
bread improves for some hours, then remains stationary, and finally be-
comes ' ' runny ' ' and flat. The colour of the crust is at first ' ' foxy, ' ' then
of a golden yellow or brown tint, and finally abnormally pale. The

330 THE TECHNOLOGY OF BREAD-MAKING.

crumb during the first three or four loaves of the series gradually im-
proves, and becomes more bloomy, then changes to a greyish white, losing
the bloom, and then ''saddens" and darkens, becoming a dull, cold grey,
merging ultimately into a brown. At the same time it becomes ragged on
the outside edges, and dark where a soft crust has been produced by two
loaves being in contact with each other in the oven. In flavour, the first
loaf will be sweet, but "raw" and "wheaty," characters which will be
lost as fermentation proceeds; at its best the raw taste will have gone,
leaving only a sweet clean-palate flavour. This will be succeeded by a
gradual disappearance of the sweetness, the bread being neutral and
tasteless : at the same time the loaf will have lost its moisture, and will
be harsh and crumbly. As fermentation is pushed still further, the
bread commences to be "yeasty" (to taste of the yeast) ; but this de-
pends somewhat on the original soundness or otherwise of the yeast. This
condition merges into one of slight sourness, first of pure lactic acid
flavour, accompanied by buttermilk odour ; but gradually becoming
worse, until, finally, not only is the taste offensive, but so also is the
smell, partaking not only of sourness in character, but also of incipient
putrefaction and decomposition. During these latter stages the bread
again becomes soft and clammy. The first drying off, until the bread
reaches the harsh stage, is due to the disappearance of soluble starch and
dextrin by diastasis into sugar, and then fermentation : the subsequent
clamminess is the result of degradation, not only of a portion of the
starch, but also the insoluble proteins of the dough.

Such are, in brief, the changes observable in dough under ordinary
conditions of working, from the first start of fermentation to the com-
mencement actually of putrefaction. These may be slightly modified by
character of the flour and other constituents of the dough; but if the
conditions of fermentation be healthy and normal, the whole series of
changes substantially follows the order given here. Changes in tempera-
ture, degree of stiffness of doughs, etc., within recognised and approved
limits, may accelerate or retard fermentation as a whole, but they do
not alter its character and general course.

SOUR BREAD.

496. Souring of Bread. — When dough has been allowed to overwork
a frequent consequence is that the resultant bread is sour. Among the
earlier views of the causes of such sourness was that which regarded it as
being due to the oxidation of alcohol. A fully worked sponge or dough
contains considerable quantities of that substance, and it was argued that
the well-known change of alcohol into acetic acid by oxidation,

C2H5HO + 02 HC2H302 + H,0,

Alcohol. Oxygen. Acetic Acid. Water.

was the cause of the acidity of sour bread, especially from overwrought
sponges or doughs.

It will be convenient at this early stage to differentiate between
f< acidity" and "sour bread," using each of these terms in their gener-
ally accepted sense. "Acidity" is a chemists' term and is caused by the
presence of free acid; the measure of acidity is the amount of alkali of
definite strength required to produce neutrality. "Sour bread" is a
baker's term, and is applied to bread which has a sour odour and flavour
to the organs of smell and taste respectively. Experiments show that
acidity, as measured by chemical means, and sourness, as judged in bread
by the nose and palate, are not necessarily alike in intensity or entirely
dependent on each other: for this reason the limitation of the sense in
which the authors personally use each term is here indicated.

BREAD-MAKING. 331

An explanatory remark may be appropriately introduced here as to
the acidity of flour. In dealing with the composition of malt, paragraph
280, it is stated that although its acidity is usually returned as lactic
acid, yet a considerable amount is due to the presence of acid phosphates.
Now the mineral content of flour contains about 50 per cent, of P205, and
corresponds very closely with the acid phosphate of potassium, KH2P04,
so that the acidity of flour is also partly due to the presence of acid
phosphates. Balland, again, paragraph 453, points out that acidity de-
velops in flours as a result of age in consequence of the increase of the
fatty acids. Notwithstanding this, as with malt, the acidity is commonly
returned as lactic acid. It is the developed acidity, and not the normal,
which points to unsoundness in both malt and flour, as well as bread ; and
hence the custom of reckoning such acidity in terms of one of its causes,
viz., lactic acid. The normal acidity of flour is largely of mineral origin,
its sourness and that of bread are the result of the production of organic
acids.

As opposed to what may be called the acetic acid hypothesis, it must
be remembered that yeast has a great avidity for oxygen, and according
to Pasteur's view alcoholic fermentation was a starvation phenomenon
in the absence of oxygen. This theory is no longer tenable, but in any
case the fact remains that yeast readily absorbs oxygen from any fluid
in which it is actively at work. As the acidity of a sponge or dough is
the effect of acid fermentation following the normal alcoholic, there can-
not be within the mass of dough any oxygen by which the alcohol dis-
seminated through it can be oxidised to acetic acid. For this reason,
therefore, it is only on the surface of the dough exposed to air that such
action is possible. And even here it must be exceedingly superficial, for
in the presence of the possibly slow, but continuous, exhalation of gas
from the sponge, it is very improbable that any perceptible absorption
of oxygen is occurring. Even when quiescent, it must be remembered
that a sponge contains an abundance of yeast ready to start again in
active fermentation as soon as supplied with food. There will therefore
be on the surface of such a sponge yeast in far greater plenty than acetic
acid germs, and with the greater vigour of the former organism, it is a
fair assumption that of the very limited amount of surface assimilation
of oxygen, the lion's share will be taken by the yeast and converted into
carbon dioxide. As both lactic and butyric acids are products of anae-
robic ferments, and are the result of chemical changes which are ab-
solutely independent of external free oxygen, the same objections do not
apply to these as sources of acidity. For these very cogent a priori rea-
sons, the authors have viewed the presence of acetic acid as being (under
any normal conditions such as are commonly found in a bakery) an ex-
ceedingly limited and practically negligible cause of acidity.

497. Personal Researches. — The authors have devoted much atten-
tion, both in the bakery and also the laboratory, to this problem of sour
bread, and have made a number of experiments of which an account of
some of the more important follows.

As a preliminary to the analyses, various tests were made on the meth-
ods themselves. It is obvious that the separation of lactic from acetic and
butyric acids by the process of distillation is only trustworthy on the
assumption that under the conditions of the estimation, lactic acid is non-
volatile. But in Miller's Elements of Chemistry (Armstrong & Groves),
it is stated that * ' on distilling an aqueous solution of lactic acid, a certain
amount of acid volatilises with the steam." In order to investigate this
point, the following experiments were made: — A sample of lactic acid

332 THE TECHNOLOGY OF BREAD-MAKING.

was taken, which had been sold as chemically pure; this was tested for
acetic and butyric acids, but gave no indication whatever of a trace of
them being present. This was diluted with pure distilled water, free
i'rom carbon dioxide, and absolutely neutral to phenolphthalein, until of
a strength equivalent to 7/10 of that of centinormal acid. In a distilling
apparatus, consisting of a Wurtz flask and glass (Liebig's) condenser,
110 c.c. of this dilute acid was subjected to distillation until 100 e<c. had
come over : the distillate on titration possessed an acidity equal to 2.1 c.c.
of centinormal acid. The residuum in the flask when titrated was found
to require 63.3 c.c. of centinormal soda. In another experiment the
original acidity was equivalent to 45 c.c., that of the 100 c.c. of distillate
to 3.7, and that of the residual 10 c.c. to 35.1 c.c. of centinormal acid.
In the one case about a thirty-seventh, and in the other a twelfth, of the
total lactic acid had come over with the distillate. It may be taken as a
general result that, working with very dilute acids, the quantity of lactic
acid found in the distillate is not very large, but it is to be feared that it
is liable to obscure conclusions based on Duclaux's system of fractiona-
tion. It will be noticed that in these experiments there is a considerable
loss of acid, as the sum of the acidity of the distillate and the residuum
does not agree with that of the quantity of acid originally taken. In
order to determine whether there was any loss by a portion of the acid
escaping condensation, the apparatus was fitted with nitrogen bulbs con-
taining centinormal soda. In a number of experiments higher and more
regular results were thus obtained, showing that some of the acid escaped
as steam. This was particularly noticeable when the distillation was
accompanied by l i bumping. ' ' Still the amount of loss thus accounted for
was nothing like sufficient to cover the whole of the deficiency.

A further investigation was made as to the reaction to acids of the
flasks themselves, and it was found that the alkalinity of a number of
flasks was more than sufficient to entirely vitiate the result of experiments
made with them. Thus, for the purpose of testing, 110 c.c. of distilled
water, free from carbon dioxide and neutral to phenolphthalein, were
distilled in a Wurtz flask until reduced to 10 c.c. This residuum was
titrated, and required 13.6 c.c. of centinormal acid. Another 110 c.c. of
the same water was boiled down in a platinum basin, and the remaining
10 c.c. titrated: 0.1 c.c. of JV/100 acid produced distinct acid reaction.
New flasks are found to yield a much larger quantity of alkali to water
than old, and no doubt the glass of some flasks is far more soluble than
that of others Thus a new 400 c.c. Wurtz flask was washed thoroughly,
rinsed in dilute sulphuric acid, then washed with distilled water, and
attached to a "return condenser" (see fat determination, Fig. 83,
Chapter XXII). In the flask were placed 250 c.c. of distilled water, 3
drops phenolphthalein, and 1 c.c. of decinormal acid. The leading tube
of the flask was closed, and the water caused to boil until a pink coloura-
tion appeared. Another c.c. of decinormal acid was then added and the
boiling continued, this operation being several times repeated. The fol-
lowing are the results : —

1st. c.c. of acid was neutralised by alkali dissolved

from flask in . . . . . . . . . . 35 minutes

2nd c.c. of acid " " 28 "

3rd. c.c. of acid 37 "

4th. c.c. of acid 45 "

5th. c.c. of acid 40

In the next place a flask of "Jena Utensil Glass" was similarly
tested. One c.c. of decinormal acid was added to water, as before, and

BREAD-MAKING. 333

the boiling continued for 2l/2 hours ; at the end of which the contents of
the flask were titrated, and found to possess an acidity of 0.5 c,c., show-
ing that only 0.5 c.c. of decinormal acid had been neutralised in that
time.

The following experiment may now be described : — A mixture of one
part * * Red Dog ' ' flour with four of baker 's grade spring American flour
was made. There were taken 3 Ibs. of this mixture, Y^ oz. distillers'
yeast, l/2 oz. salt, and very warm water. A sponge was first made, which
had a temperature of 109° F., afterwards a dough which stood at 84° F.
The sponge and dough stood altogether 24 hours in a warm place, and
then smelt sour and incipiently putrescent. During the time of standing
it was freely exposed to the air, and several times was "handed up" so
as to work the outer skin into the mass of the dough.

At the end of this time a portion of the dough was reserved for direct
tests, and the remainder baked slowly in a slack oven. (The object of the
whole of the treatment was, of course, to get as sour a sample as was well
possible.)

Dough. — To determine total acidity 10 grams of the dough were taken,
broken down with neutral distilled water and titrated with JV/10 soda
and phenolphthalein (this indicator was used throughout) : — required,
10.9 c.c. = 0.981 per cent, of total acidity, reckoned as lactic acid.

For the subsequent tests 50 grams of dough were taken and made up
to 400 c.c. with distilled water, 1 c.c. of chloroform having been added.
This was thoroughly mixed by repeated shakings, and allowed to stand
over night : of the clear supernatant liquid, 230 c.c. were pipetted off the
next morning. In 10 c.c. of this the acidity was determined, being equiv-
alent to 11.8 c.c. of centinormal acid. Of this liquid, 110 c.c. were taken
and subjected to distillation by Duclaux's method in a "Jena" flask:
the liquid frothed so that distillation could only be conducted with ex-
treme slowness, occupying altogether about 2 hours. The following are
the results : —

1st. 10 c.c. distillate, 0.35 c.c. N/lOO acid = 3.6% of total distillate,

2nd. " 0.45 " = 4.7

3rd. 0.55 " =5.7

4th. 0.55 =5.7

5th. " 0.60 " =6.2

6th. " 0.60 " =6.2

7th. " 1.05 " =10.9

8th. 1.70 =17.7

9th. " 1.75 " =18.2

10th. " 2.00 " =20.8

llth. in flask 115.4

Total acidity of 110 c.c. = 129.8 ; total acidity of distillate = 9.6 ;
acidity of residuum = 115.4; loss, 129.8 — 125.0 = 4.8 c.c. (The same
flask evolved, in the blank experiment, alkali equivalent to 5.0 c.c. of
N/1QQ acid in 2^ hours.)

These results not only afford no evidence of the presence of butyric
acid, but are even lower in the early stages than those of pure acetic acid.
It seems probable that with the very slow rate of distillation absolutely
necessary, the acid in the earlier stages recondenses in the upper Darts of
the flask, and so the proportion distilled over does not conform to Du-
claux's table. Another 110 c.c. of the same 230 c.c. of liquid was evapo-
rated to dryness in a platinum basin over a water bath, re-diluted with
50 c.c. of water, and again evaporated to dryness: the residual acidity
was equivalent to 113.5 Af/lOO acid. The division of acid in this liquid

334 THE TECHNOLOGY OP BREAD-MAKING.

into fixed and volatile agrees closely in both tests. Taking that in the
platinum basin as being the more correct, we have out of 129.8 of total
acidity, 113.5 of fixed, arid 16.3 c.c. of volatile acidity. Reckoning these
as percentages on the whole dough, we have in solution 0.74 of fixed acid
(lactic) and 0.07 per cent, of volatile (acetic) acid. In strictness, it must
also be remembered that cny carbon dioxide present in the dough is also
estimated as acetic acid, making this result too high rather than too low.
Bearing in mind Balland's investigations, Chapter XXIII., in which he
shows that a considerable quantity of the acid of flour is retained by the
solid matter, and not given up to a filtered solution, the acidity of the
remaining 170 c.c. of mixed liquid and residual flour solids wos also de-
termined. This was found to contain acid equivalent to 275 c.c. N/100
acid. As dough contains approximately 42 to 45 per cent, of water, the
50 grams taken will contain about 50 — 22 = 28 grams of solid matter.
Therefore the residual 170 c.c. will consist of about

170 — 28 = 142 c.c. of liquid and 28 grams of solid residue : and the
total 400 c.c., of 372 c.c. of liquid and 28 grams of solid. But as the
residual 170 c.c. contains 142 c.c. of liquid, the acidity of which is 1.18
per c.c. (by direct determination), then

142 X 1-18 == 167.5 c.c. acidity due to the liquid portions.

Its total acidity, 275 -- 167.5 == 107.5 acidity remaining in the solid
matter. Calculating this as lactic acid,

107.5 X 0.0009 X 2 = 0.193 per cent, of acid remaining in solid mat-
ter.

The 372 c.c. of solution must contain, as by estimations on 110 c.c., the
following quantities of fixed and volatile acid : —

113.5X372X0.0009X2

— ~~ — = 0. /9Z per cent, nxed acid reckoned as lactic.

16.3X372X0.0006X2

— -~^ — = 0.066 per cent, volatile acid reckoned as acetic.

Summing up these results we have —

Dissolved fixed acid (lactic) . . . . . . 0.792 per cent.

Dissolved volatile (acetic) 0.066

Undissolved acid, remaining in solids . . . . 0.193

1.051
Total acidity by direct determination . . 0.981

Difference 0.070

Bread. — In common with the dough, the bread smelt not only sour,
but of putrefactive products. The first estimation made was of moisture,
of which there was 40.4 per cent., leaving 59.6 per cent, of dry bread
solids. The percentages of acid are given on both the moist and dry
bread. The total acidity was determined on 10 grams, and amounted to
10.1 c.c. of JV/10 acid = 0.912 per cent, of acid reckoned as lac-:ic acid on
the moist bread. It may be of interest here to point out that 10 grams of
dough = 10.9 c.c. of JV/10 acid, and that approximately 10.6 grams of
dough are required to make 10 grams of bread.

10.6 grams of dousrh have an acidity = 11.55 c.c. N/W acid.
10.0 ll bread " =10.10

Acidity lost during baking = 1.45

1.45 X 0.006 = 0.0087 grams acetic acid.

BREAD-MAKING. 335

By this estimation, therefore, the bread has lost of acidity, reckoned
as acetic, 0.08 per cent. As the bread still contains volatile acidity, and
this amount is slightly less than the volatile acidity of the dough, the as-
sumption is that a slight amount of lactic acid has been volatilised in the
oven.

An aqueous extract of the bread was made in precisely the same
manner as with the dough, 50 grams being taken and made up to 400 c.c.
with the addition of 1 c.c. of chloroform. The following data were
obtained on the clear supernatant liquid, of which 220 c.c. were removed :

Total acidity of 10 c.e. = 9.3 TV/100 acid.

110 c.c. were subjected to distillation by Duclaux's method, and boiled
regularly and speedily. The following are the results : —

1st. 10 c.c. distillate, 0.80 c.c. TV/100 acid = 6.5% of total distillate.

2nd. „ 0.85 „ = 6.9

3rd. „ 0.85 „ = 6.9

4th. „ 0.95 „ = 7.7

5th. „ 1.10 „ = 9.0

6th. „ 1.10 „ = 9.0

7th. „ 1.25 „ =10.2

8th. „ 1,.4f> „ =11.7

9th. „ 165 „ =13.5

10th. „ 2.20 „ =17.2

llth. in flask 90.7

Total acidity of 110 c.c. = 102.3 ; total acidity of distillate = 12.2;
acidity of residuum = 9G.7 ; gain, 102.9 — 102.3 = 0.6 c.c. of TV/100 acid.

These results are not very far apart from acetic acid, but are slightly
on the formic rather than the butyric acid side.

100 c.c. were evaporated in a platinum basin, and gave 79.0 c.c. TV/100
acidity, equal to 86.9 on 110 c.c. 102.3 -- 86.9 = = 15.4 c.c. of volatile
acid. Working these out as percentages of lactic and acetic acids, we
have 0.626 of lactic and 0.075 of acetic acid on the whole bread.

The residual liquid together with bread solids was next examined:
the total volume was 400 — 220 == 180 c.c. As 50 grams of bread were
taken, the bread solids were 30 grams. Therefore the residual 180 c.c.
consisted of

180 — 30 == 150 c.c. of liquid and 30 grams of solids, and the total
400 consisted of 370 c.c. of liquid and 30 grams of solid.

The total acidity of the residual liquid and solids together is 306.0 c.c.
TV/100 acid. But as this contained 150 c.c. of liquid, the acidity of which
is 0.93 per c.c., then

150 X 0.93 = 139.5 c.c. acidity due to the liquid portion.

The total acidity, 306.0 - - 139.5 = = 166.5 acidity remaining in the
solid matter. Calculating this as lactic acid,

166.5 X 0.0009 X 2 = 0.299 per cent, of acid remaining in solid mat-
ter.

The 370 c.c. of solution must contain, as by estimation on 110 c.c., the
following quantities of fixed and volatile acid : —

86.9X370X0.0009X2

= U.ozb per cent, fixed acid reckoned as lactic.

15 4V370VO 0006V2

= 0.062 per cent, volatile acid reckoned as acetic.

336 THE TECHNOLOGY OF BREAD-MAKING.

Summing up these results, we have —

Dissolved fixed acid (lactic) . . . . 0.526 per cent.

„ volatile acid (acetic) . . . . 0.062 „
Undissolved acid remaining in solids . . 0.299 „

0.887
Total acidity by direct determination . . 0.912

Difference . . 0.025

Distillation in Vacuo. — In the next place, 500 grams of the bread were
taken and distilled in vacuo, the bread being raised to a temperature of
120-125° C. The amount of distillate was 220 c.c., of which 10 c.c. were
taken for determination of total acidity, and were found to possess acid-
ity equal to 11.4 c.c. N/1QQ acid. Ten grams of the residual dry bread
had an acidity equal to 16.0 N/W acid. Calculated as percentages on the
whole bread, these are equivalent to 0.30 per cent, of volatile (acetic)
acid, and 0.864 per cent, of fixed (lactic) acid.

Of the distillate, 100 c.c. were evaporated to dryness in a platinum
basin and taken up with distilled water; the addition of one drop of
JV/100 soda gave an alkaline reaction with phenolphthalein, showing that
the distillate was to this extent free from fixed acid The remaining 110
c.c. were distilled by Duclaux's method in a "Jena" flask, with the fol-
lowing results :

A. B.

N/100 acid — Per cent, of — Per cent, of
total distillate, total acid
in 110 c.c.

1st 10 c.c. distillate .. .. 5.80 c.c. 6.4 4.6

2nd. " " .. .. 6.60 " 7.3 5.3

3rd. " .. .. 7.70 " 8.5 6.2

4th. " " .. .. 8.30 " 9.2 6.6

5th. " " .. .. 8.40 " 9.3 6.7

6th. " " .. .. 8.80 " 9.8 7.1

7th. " " .. .. 9.65 " 10.7 7.7

8th. " " .. .. 9.80 " 10.9 7.9

9th. " .. .. 11.35 " 12.6 9.1

10th. " " .. .. 13.50 " 15.0 11.0

llth. in flask .. .. 34.35 " 27.9

Total acidity of 110 c.c. = 125.4; total acidity of distillate == 89.9;
acidity of residual 10 c.c. = 34.35 ; loss, 125.4 - - 124.25 = 1.15 c.c. of
AyiOO acid.

A reference to tables of distillation of mixtures of acetic and butyric
acids by Duclaux's method shows that the figures in column A agree
closely with those for a mixture of 20 parts acetic to 1 part butyric
acid, being distinctly on the butyric acid side of pure acetic acid. It
may be considered proved that a trace of butyric acid is present equal
to approximately 1/20 of the amount of acetic acid.1

1 Duclaux points out that with the use of a larger distilling flask a higher
proportion of acid remains in the residual 10 c.c., that is, that with a greater
proportion of return condensation, more acid escapes distillation. As slow dis-
tillation also means more return condensation, the same result follows. The use
of charged trap-bulbs with the distilling apparatus, necessitated slow working;
hence the general error of experiment is in the direction of lessening the
apparent quantity of butyric acid.

BREAD-MAKING. 337

Calculating into percentages, we have of the total acidity,

125 4 'V' 20

- ' - = 119.4 c.c. JV/100 acid due to acetic acid ;

' = 6.0 c.c. „ butyric acid.

Then as 110 c.c. of distillate were obtained from 250 grams of bread,

119.4 X 0.0006 X 2 nnOQ „ , , ,

— £— - = 0.028 per cent, of acetic acid in whole bread,

6 0 'V 0 00088 \? 2

and — — '-=— — — — = 0.002 per cent, of butyric acid in whole bread.

Summing up, we have the following as the general results of the dif-
ferent analyses, expressed in percentages, those on bread being calculated
on both the whole bread and dry residue : —

Bread.
Dough. Whole. Dried.

Total acidity by direct determination 0.981 0.912 1.521

Dissolved fixed acid (lactic) . . 0.792 0.526 0.876

Dissolved volatile acid (acetic) . . 0.066 0.068 0.103
Undissolved acid, remaining in solids 0.193 0.299 0.498

Distillation in Vacuo —

Fixed acid (lactic) 0.864 1.440

Volatile acid (acetic) , 0.030 0.050

Fractional Redistillation of Vacuum Distillate —

Acetic acid 0.028 0.047

Butyric acid 0.002 0.003

Comparing the results of the two different methods of analysis em-
ployed, we find that with aqueous distillation about 1/15 of the total acid
in both dough and bread was found to be volatile. Employing the dry
distillation method on bread, 1/30 of the total acid was volatile at 120° C.
in vacuo. As to the relative accuracy of the two processes, the former
presents the initial difficulty that the whole of the acid is not obtained in
the aqueous extract ; and, further, that a portion at least of the lactic acid
distils over with the steam. It may, on the other hand, be objected that
the whole of the acetic acid is not volatilised by the treatment in vacuo.
Weigert, however, has shown that by distilling wines in a vacuum, the
whole of the acetic acid can be obtained (Zeitsch, filr Analyt Chemie.,
1879, 207). A number of other comparative determinations were made,
but in all cases the aqueous extract method gave considerably higher vola-
tile acids than distillation in vacuo.

The following experiments were conducted with the view of studying
the progress of sourness with the prolongation of fermentation : —

A. Series. — Quantities taken — 15 Ibs. spring American 1st patent
flour, 9 Ibs. water at 40° C. (104° F.), 4 oz. compressed distillers' yeast,
and 2 oz. salt.

A ferment was first set with all the water and a portion of the flour :
in 40 minutes the dough was made, and had a temperature of 27° C. (80°
F.). It was maintained at this temperature for 20 hours, and then
allowed to stand at the temperature of the room for another 24 hours. At
intervals, as given in the following table, the dough was "knocked
down," re-kneaded, and a portion of 2 Ibs. 3 oz. taken and baked into a
loaf.

338 THE TECHNOLOGY OF BREAD-MAKING.

B. Series. — Quantities taken — 12 Ibs. spring American bakers' grade
and 3 Ibs. low grade (red dog) flour, other ingredients as in A. Treat-
ment precisely as in A.

The following are the times at which loaves from both series were
baked : —

No. 1. Put in oven 31/, hours after setting ferment.

11 "• 11 " 11 11
^ Q

11 °- 11 11 11

11 4. ,, 12 ,, ,,
11 "• 11 1" 11 11
11 6. „ 20

7 44.

11 ' • 11 11 11

The following were the characteristics of the respective loaves : —

A. SERIES.

No. 1. Sweet in smell and taste.
„ 2. If anything, slightly darker in colour; slightly mawkish smell

and taste, not sour or yeasty, crust paler.
„ 3. Colour darker, mawkish flavour disappeared, incipient sour smell,

but no sour taste.
,, 4. Colour darker, loaf heavy and close, somewhat yeasty smell, but

no decided sour flavour.
„ 5. Small and close, colour about same as 4, sour smell ; taste, acid and

disagreeable,
fi i

" H • Sour and putrescent.
11 '• )

B. SERIES.

No. 1. Characteristic odour of bread from low grade flours, but perfectly

sweet in taste and smell.

,, 2. Colour very dark, sour smell, taste slightly sour.
„ 3. Colour changed from yellowish to dark reddish brown. Less sour

smell than 2. Unpleasant taste, rather of decomposition than

acidity.
„ 4. Reddish brown colour much intensified. Slightly sour smell.

Taste similar to 3, but more marked.
,, 5. Colour as 4. Smell and taste intensified.
„ 6. Sour and putrescent.
„ 7. Sour and putrid.

None of these had the characteristic sour smell of bakers' sour bread.

The following are the results of determinations of acidity, the total
being determined on the whole bread : the volatile by distillation in
vacuo; and the fixed or non-volatile, in the dried residue from this dis-
tillation.1 As the moisture in the different samples varied, the results are
throughout calculated on the dry solids. These can be approximately
converted into those on the whole bread by multiplying by 0.6.

1 The whole of these distillates were subjected to fractional distillation by
Duclaux's method. Owing, however, to subsequently finding that the flasks used
gave a strong alkaline reaction, the authors do not feel justified in quoting the
results as trustworthy, and therefore have not inserted them. The same remark
applies to a large number of other Duclaux estimations.

BREAD-MAKING. 339

PERCENTAGES OF ACIDITY IN SOUR BREAD.

A. Series. B. Series.

No.

Ratio of

Total.

Volatile.

Fixed.

Volatile to

Total.

Volatile.

Fixed.

Volatile to

Total.

0.477

0.003

1/160

1.140

1.125

0.407

0.015

0.405

1/27

1.041

0.042

0.972

1/25

0.491

0.030

0.441

1/16

1.300

0.102

1.143

1/12

0.671

0.090

0.549

1/7

1.647

0.252

1.269

1/7

1.108

0.120

0.720

1/9

2.289

0.128

1.314

1/17

1.110

0.087

0.747

1/12

2.600

0.113

1.746

1/23

1.457

0.059

0.900

1/24

2.828

0.131

1.980

1/21

Curiously in both series the total acidity is less in the second than in
the first loaf : with this exception the total acidity steadily rises through-
out the two series. The volatile acidity (reckoned as acetic) attains its
maximum in Series A. in 12 hours, and in series B. in 15 hours, after
which it diminishes. The ratio of volatile to total acidity is in both cases
highest with the No. 4 loaf. Apparently after that time the production
of volatile acid does not keep pace with its evaporation from the dough.
(It should also be mentioned that, as the loaves were analysed in the
order made, the latter ones had become somewhat drier when subjected to
analysis.) In consequence of the dark colour of the dried bread, the deter-
mination of fixed acid was difficult owing to uncertainty as to the exact
point of neutrality as shown by the indicator. In these breads No. 2 's are
worked more than the baker would work them in actual practice ; while
No. 3 of each series is far sourer than even a baker's very sour loaf. The
others, of course, represent extreme results altogether outside those of
actual practice. Note that in No. 3 A. the volatile acidity is only 1/16 of
the total, and in No. 3 B. 1/12 of the total acidity.

In the next place are given the results of an experiment with a potato
ferment, purposely allowed to proceed to extreme sourness. A potato fer-
ment was made from 30 grams of potato, 100 grams of water in which the
potato was boiled, 5 grams raw flour, and 10 grams of yeast. This was
fermented at 95° F., and maintained at that temperature over night in
an uncovered shallow basin. The next morning the ferment was made up
to 300 c.c., with water at 120° F., and sufficient flour added to make a
slack sponge, which had a temperature of 95° F. The total acid reckoned
as lactic was determined in 10 grams of the whole sponge, and the volatile
and fixed acids in the filtered chloroformed aqueous extract in the man-
ner previously described. The following were the results : —

Total acidity as lactic acid . . . . 1.197 per cent.

Dissolved fixed acid (lactic) . . . . 0.248

„ volatile acid (acetic) . . . . 0.053 „

Ratio of volatile to total acid . . . . 1/22

The sponge was allowed to work for 6 hours and then doughed up
with more flour, allowed to work \l/2 hours and baked. The following are
the results of determinations on the bread. The total acidity was deter-
mined on the whole bread, and volatile and fixed acids by distillation in
vacua.

Whole Bread. Dried.

Total acidity as lactic acid . . 1.158 1 935

Fixed acid by distillation in vacuo (lactic) 1.015 1692
Volatile (acetic) 0.038 0.064

Ratio of volatile to total acid . . . . 1/30 1/30
The principal feature is that again neither in sponge nor in dough is
there more than a very small proportion of volatile acid.

340

THE TECHNOLOGY OF BREAD-MAKING.

Following on these were some experiments made on bakers' breads.
One firm in the south of England, and another in Glasgow, were kind
enough to reserve a loaf of one batch baked in the usual manner (No. 1),
and also to set aside dough for two other loaves, one of which (No. 2)
was baked in each case when at the utmost limit of sourness ever found
in practice, and the other (No. 3) several hours after. The following are
the results of analysis made as before by vacuum distillations, and in fil-
tered, chloroformed, aqueous extract: —

English.

Scotch.

No. 1. Total acidity as lactic acid . .
Fixed acid by distillation in

vacua (lactic)
Volatile acid by distillation

in vacuo (acetic) . .
Ratio of volatile to total acid
Dissolved fixed acid (lactic)

by aqueous distillation
Dissolved volatile acid (acetic)
Ratio of volatile to total acid
No. 2. Total acidity as lactic acid ..
Fixed acid by distillation in

vacuo (lactic)
Volatile acid by distillation

in vacuo (acetic)
Ratio of volatile to total acid
No. 3. Total acidity as lactic acid. .
Fixed acid by distillation in

vacuo (lactic)
Volatile acid by distillation

in vacuo (acetic)
Ratio of volatile to total acid

Whole
Bread.

0.362

Dried.
0.604

0.351

0.585

0.0006

0.001

— .

1/604

0.184

0.307

0.009

0.016

1/19
0.535

1/19
0.891

Whole
Bread.

0.258

0.243
0.005

0.491 0.819

0.025
1/21
0.759

0.696

0.036
1/21

0.042

1/21

1.265

1.161

0.060
1/21

0.342
0.324

0.008
1/44
0.342

Dried.
0.431

0.406

0.008
1/50

0.570
0.540

0.013
1/44
0.570

0.318 0.531

0.017
1/20

0.028
1/20

Throughout this series also the proportion of volatile acid is very low.

Excluding those examples in which acidity was pushed far beyond
any instance ever occurring in practice, the volatile acids found by dis-
tillation amounted to from 1/20 to 1/30 the total acid of the dough. In
the instance quoted of a loaf in the last stage of sourness, an amount of
butyric acid was found approximately equal to about 1/20 the total vola-
tile acid. The acidity of bread may be divided among the following acids
in approximately the following proportions : —

Lactic acid . . . . . . . . about 95 per cent.

Acetic „ „ 5

Butyric „ . . . . from 0.0 to about 0.5 „

The question has been already raised as to how far the bakers' sour-
ness is dependent on the chemists' acidity of bread: this problem merits
further examination. The particulars of the progressive series of tests
given on page 338 should be studied in this connection. Taking first the
A. series on patent flour, No. 4 loaf had no decided sour flavour, while
No. 5 tasted acid. No. 4 had a total acidity of 0.671, while that of No. 5
was 1.108 per cent., so that a marked increase had occurred. Comparing
the B. series, No. 2 was slightly sour with an acidity of 1.041, although
No. 1 with a slightly higher acidity was sweet to the taste. It must be
remembered that in the B. series the naturally strong coarse flavour of

BREAD-MAKING. 341

the flour used made it difficult to detect shades of acidity with the palate.
Dealing with the smell, No. 3A. was found to have incipient sour smell,
with a volatile acidity of 0.030 : turning to the B. series, No. 2 has a sour
smell with a volatile acidity of 0.042. On studying the higher number of
each series there is a steady increase of total acid, but in both A. and B.
the volatile acid is lower in these higher numbers. So that 7 A., with an
exceedingly sour smell, has less volatile acid than No. 4, which it far
transcends in odour. The same applies to the B. series where No. 6 con-
tains practically the same amount of volatile acid as does No. 3, although
No. 3 smells less sour than 2, while No. 6 smelt sour and putrescent.
Speaking in a general way, sourness and acidity go together, and bread
with a total acidity of about 0.5 per cent, and a volatile acidity of about
0.025 begins, especially in the highest class breads, to both taste and smell
sour. But lower grade breads can carry a much higher proportion of
total acidity, and have its taste masked with the natural strong flavour of
the flour. But although sourness and acidity are closely associated, yet
the bakers' sourness comprehends more than is expressed by acidity, as is
shown by the increasing "sourness" to the nose of Nos. 5, 6, and 7 of"
both series, and the simultaneously decreasing volatile acidity. As indi-
cated in the description of the various breads, bakers' sourness also
includes and takes cognisance of incipient putrefactive changes. If this
be the case, "sourness" should be accompanied by evidence of other
chemical changes : as proteins break down in putrefaction into compound
and simple ammonias, the following determinations were made on bread.
Five grams of the bread were taken, broken down in water, and large
excess of caustic soda added: the mixture was then distilled in a cur-
rent of steam and the distillate collected in 50 c.c. of N/1Q acid. Deter-
minations were made on the three samples of English bread, particulars
of which are given on page 340. The following are the percentages of
ammonia (reckoned as NH3), calculated on the whole bread: —

English Bread, No. 1 0.39 per cent.

„ No. 2 0.40

„ No. 3 0.42

The amount of increase is not very great, but as a similar increase of
ammonia has been noted in other breads tested, evidence is afforded that
bakers ' sourness is accompanied by other changes in the constituents of
the bread in addition to the development of acidity.

This question of sourness is of vast importance to the baker, and is also
the baking problem on which chemistry has the most direct bearing; it
therefore merits most careful attention in all its details. Because lactic
and acetic ferments flourish best at a high temperature, it has been
assumed that therefore ' ' high temperatures for panary fermentation are
in all cases undesirable." The assumption that high temperatures are
more usually accompanied by the production of sour bread than lower
ones is so directly the opposite of many bakers' practical experience that
it requires most careful examination. Among breads which are normally
worked at a high temperature, the following are well-known examples : —
Nevill's bread, made in London from straight grades of comparatively
weak flour ; and Hovis bread, made from a meal containing 25 per cent,
of germ. The temperature of the dough for the latter is about 90°-95°
F., and yet these two varieties of bread are remarkably free from sour-
ness. In preceding paragraphs a summary of the course of fermentation
has been given, while high temperatures have been mentioned as acceler-
ating the whole of that course; consequently, at a high temperature,
everything else being equal, the sour stage is reached in less time from

342 THE TECHNOLOGY OF BREAD-MAKING.

the commencement of setting a ferment, sponge, or dough, than if a lower
temperature be adopted. But if fermentation be arrested at the same
stage of its progress, there is no more danger of bread worked warm be-
coming sour than that which is worked cold. The crucial point as to
temperature is whether, for the same amount of carbon dioxide gas
evolved during alcoholic fermentation, more acid is produced at a high
temperature than a low one. In order to elucidate this point the follow-
ing experiments were made : — Mixtures were prepared of 50 grams flour,
200 c.c. water, and 2.5 grams distillers' yeast, and 10 grams brewers'
yeast respectively. These were placed in the yeast-testing apparatus, Fig.
21, and fermented at the respective temperatures of 75° and 95° F., which
in each case were maintained constant until 350 c.c. of gas had been
evolved. The original acidity of the mixtures was determined in dupli-
cates made up for the purpose. As soon as the 350 c.c. of gas had been
obtained, 2 c.c. of chloroform were added to the contents of the bottle,
which was shaken up and allowed to stand until all were ready for titra-
tion, when the acidity was once more determined. Two complete series
of estimations were made on successive days. In another similar experi-
ment with distillers ' yeast the fermenting mixture was first maintained at
95° F. until 175 c.c. of gas had been evolved : it was then cooled to 75° F.,
and kept at that temperature until 90 c.c. more had come over. The tem-
perature was then again raised, and maintained at 95° until the whole
350 c.c. of gas had been evolved. The following table gives the time re-
quired for the evolution of 350 c.c. of gas, the original acidity, the final
acidity, and the amount produced during fermentation, reckoned in each
case as lactic acid : —

Produced

Time taken. Original Final during

Hours. Acidity. ' Acidity. Fermentation.

Distillers 'yeast at 75° F. .. 10^ 0.175 0.394 0.219

„ 95° F. .. 3y2 0.175 0.290 0.115

Brewers' 75° F. . . 11 0.228 0.424 0.196

„ 95° F. .. 6 0.228 0.442 0.214

Repeats —

Distillers 'yeast at 75° F. .. Iiy2 0.315 0.540 0.225

„ 95° F. .. 4y4 0.315 0.495 0.180

Brewers' „ 75° F. .. 11 0.157 0.679 0.522

„ 95° F. .. 5^ 0.157 0.670 0.513

Distillers ' yeast, partly at

75° F. and partly at 95° F. 7*/4 0.315 0.495 0.180
With the distillers' yeast, in both instances there is for the same
amount of alcoholic fermentation a greater development of acidity at the
lower temperature ; while with the brewers ' yeast there is in the one case
slightly more acid at 75° F., and in the other a slightly greater quantity at
the higher temperature. In passing, attention is directed to the much
higher acid-producing power of the brewers' yeast on the second day
(with a different sample) than the first. Both the practical experience of
the bakery and these tests go to show that for the same amount of
alcoholic fermentation a comparatively high temperature is at least not
more productive of acidity than a much lower one. Further confirma-
tion of this is afforded by the advent of short systems of fermentation in
which the dough is worked at high temperatures, and with great freedom
from sourness. The last experiment was made with the object of deter-
mining whether a sudden lowering of temperature during fermentation
had a tendency to increase acidity. The results show that no such in-
crease was caused in this instance.

BREAD-MAKING. • 343

Slackness of dough is only a cause of acidity in the same sense as high
temperature, in that it accelerates the whole course of fermentation.
Among breads made from very slack doughs are Manchester tin bread
and Vienna bread, but neither of these are specially liable to sourness.

Holding the view that much of the acidity of bread is due to acetic
acid, and that the production of this acid is stimulated by the presence of
oxygen, Briant advises that "therefore fermenting dough should be kept
as much out of contact with air as is possible. ' ' If the quantity of acetic
acid present in doughs which are most intensely sour in character is but
trifling, then this reason for exclusion of air no longer exists. To refer
again to Vienna bread, the ferments and dough for this are beaten and
exposed to air almost as much as an egg in the act of whisking, and these
are rarely, if ever, sour. If a baker finds a sponge working too rapidly,
and in such a condition as his experience tells him means that fermenta-
tion is likely to have overshot the mark by the time he wishes to take it,
then, in order to lessen risk of sourness, he very commonly throws off the
trough lid and freely exposes it to air. He finds practically that this
treatment, instead of causing sourness by oxidation of alcohol, obviates
it by lowering the temperature, and so retarding the whole course of
fermentation.

The following may be taken as a summary of the authors' views on
sour bread.

1. "Sour bread," as understood by the baker, is the result of a com-
bination of bacterial fermentations. Principal among these is that pro-
ducing lactic acid, which constitutes about 95 per cent, of the total
acidity. The remainder is due to acetic acid, with, in very bad cases,
traces of butyric acid. In addition to the development of acidity, sour,
as distinct from acid bread, shows signs of putrefactive decomposition.

2. The acid and putrefactive fermentations are produced by bac-
teria to be found in the dough.

3. These bacteria may be introduced by the yeast, by the use of
dirty vessels, and by the flour; but their presence in the flour is the
most general cause of ' ' sourness, ' ' and the lower the grade of the flour,
the greater is the risk of sour bread.

4. The activity of these bacteria is dependent on that of the yeast :
while the latter is active, the bacteria are comparativly quiescent. With
the exhaustion of the yeast, or cessation of active fermentation through
the assimilation of all fermentable material, a stage is attained in bread
fermentation when bacteria are excessively active, and sourness rapidly
develops.

5. Temperature and slackness of dough have but little effect on
sourness, except in that indirectly they affect the speed of the whole
course of fermentation, and so hasten or retard the arrival of the bac-
terial fermentation stage. This stage being reached, the production
of sourness is accelerated both by high temperature and slackness of
dough.

6. Exposure to air has no appreciable effect on sourness, and may
even through its cooling action be beneficial.

7. The two principal causes of sourness are — Allowing the fermenta-
tion to proceed beyond the normal into the souring stage ; and the use
of materials or vessels containing abnormally high proportions of bac-
teria, especially when employed with weak and inactive yeasts.

498, Effect of Baking on Bacterial Life. — Differences of opinion
exist as to whether the act of baking destroys the life of all organisms
that may be present in the dough. Unless the baking is most inefficiently

344 THE TECHNOLOGY OF BREAD-MAKING.

conducted the temperature within the loaf should be sufficiently high to
kill the yeast. The doubt is whether or not the germs or spores of other
organisms are also destroyed — thus, the spores of some of the 'bacilli can
withstand a quarter of an hour's boiling, while a sensible proportion out-
live an hour's subjection to a boiling heat. These experiments afford
grounds for supposing that such germs might continue to exist even dur-
ing an hour's baking. The observed facts of the souring of bread also
point in the same direction. Two loaves may be taken, each of which is
sweet when removed from the oven, and kept under precisely the same
conditions ; the one after a few hours becomes sour, the other retains its
sweetness. Here there is a difference in behaviour which is not due to ex-
ternal conditions, but to some inherent quality of the two loaves. The
undestroyed germs of acid fermentation have, in the bread in which they
are present, induced sourness. The only other explanation of souring is
that the germs of the specific 'bacilli have found their way from the atmos-
phere into the baked loaf.

Walsh and "Waldo subjected this matter to exhaustive investigation.
Using the accustomed precautions in bacteriological work, they procured
a number of loaves of bread, and sowed portions of the interior crumb in
sterilised gelatin and glucose mixture, and made plate cultivations. A
few of the loaves were found to be practically sterile, while others con-
tained a large number of organisms, including bacillus siibtilis and other
'bacilli, also sarcina and micrococcus. Many of these organisms were
unidentified by Walsh and Waldo, but it may fairly be assumed that,
with lactic and butyric ferments present in the dough, they may be
among those organisms which have lived through the baking. Hence
they may set up their characteristic fermentations in the baked bread.

It should be mentioned in passing that Walsh and Waldo base a very
powerful argument for sanitation in bakehouses on this fact, that baking
does not necessarily sterilise bread. Their view is that if non-pathogenic
organisms may thus survive, so may also the pathogenic forms ; and so
bread, if contaminated during manufacture, may afterwards become a
source of infection. Goodfellow finds that, provided the bread be allowed
to stand for three hours in a germ-free atmosphere after being baked, the
loaf is absolutely sterile. That is, the act of baking, coupled with the con-
tinuance of the baking heat on the loaf, for the period of time mentioned,
is sufficient to destroy the life of all micro-organisms. If Goodfellow 's
view be correct, then the position assumed by Walsh and Waldo is no
longer tenable.

The conditions of keeping make a considerable difference in the after-
sweetness of baked bread. Where bread is kept in a close, warm, moist
atmosphere, from the time of baking or when new, it is far more likely to
develop sourness and mould than if stored where it may rapidly cool and
lose any excess of moisture.

499. Remedies for Sour Bread. — These are to a large extent indi-
cated in the preceding paragraphs, but as one possible cause of sour bread
is a want of absolute cleanliness, it should be seen that all the precautions
to insure the same are rigidly adopted. Supposing, as is sometimes the
case, that batch after batch of bread is sour, or rapidly becomes so ; then
see that the flour is sound and discard any very low grades ; next examine
the yeast ; see more especially whether disease ferments are plentiful, and
whether the yeast-cells themselves look healthy and vigorous. The baker
who is not able to do this for himself should place himself in the hands of
an analyst to do it for him. If any suspicion whatever attaches to the
yeast or the flour, change to some other variety which is known to be

BREAD-MAKING. 345

doing good work. In the next place, thoroughly clean the bakehouse from
floor to ceiling. Procure some solution of bisulphite of lime, and with a
brush wash floor, walls, and ceiling with it. Clean out all troughs and
boards, and also wash them with the bisulphite, letting it remain in the
troughs for some time. Then either scald or steam them out, and dry as
rapidly as possible. These steps should succeed in freeing the bakehouse
from any disease ferments which may be present.

In conducting fermentation, use a sufficient quantity of good yeast,
and work at such a temperature as to get sponging and doughing over
quickly.

As souring is largely produced by some cause unduly accelerating fer-
mentation, investigate the whole of these, and modify one or more, accord-
ing to which seems faulty, so as to retard to the normal rate. Or, if
deemed preferable, set later or take sooner so as to use sponges or doughs
at the right stage of fermentation. Use regular brands of yeast and
flour, watching and adjusting these as may be necessary. Souring, if due
to sudden atmospheric changes, is to a certain extent beyond control ; but
it may be checked somewhat by cooling, if the too quickly working mate-
rial can be caught in time. The addition of salt to a too rapidly working
sponge retards the whole rate of fermentation, and particularly that of
bacteria. In exceptional cases, through the presence in undue quantities
of bacteria, and the use of weak yeasts, the fermentation may become ab-
normal, and "sour" fermentation accompany, or even precede, the full
development of normal alcoholic fermentation. Give the bread a good
baking, as bread which leaves the oven in a damp, sodden condition is spe-
cially liable to become sour. When baked, cool rapidly in a pure at-
mosphere. Weak, unstable flours used with excess of water very fre-
quently turn sour ; the reason is that the gluten breaks down, and much
of the starchy interior of the loaf is dextrinised : the damp, clammy mass
resulting constitutes a favourable nidus, or home, for after-fermentation.

500. Ropiness, Watkins. — One of the most valuable contributions to
the bibliography of this subject is a paper on "Ropiness in Flour and
Bread, and its Detection and Prevention," read by E. J. Watkins before
the Society of Chemical Industry, on April 2, 1906, and published in the
Journal of the Society for 1906, p. 350. The following is an abstract of
this important paper : —

Occurrence. — During hot weather bread is liable to an outbreak of the
disease called "rope." Its first manifestations usually occur in from 12
to 48 hours after the bread leaves the oven.

Nature and Symptoms. — The bread acquires a faint sickly odour, and
the crumb is infected with brownish spots, which are larger the nearer
the centre of the loaf. With the progress of the disease, the spots spread
and the interior of the loaf becomes moist and sticky. The infected por-
tions may be drawn out into long threads, and hence the name of rope.
With the continuation of the disease, the crumb of the bread breaks down
into a molasses-like mass, and emits an exceedingly disagreeable valerian-
like odour.

Susceptibility. — Breads containing bran and germ, such as whole-
meal, certain patent breads, and rye bread, are all particularly suscepti-
ble. Of those made from white flour, the grades composed of the heart of
the endosperm, i. e., the best patent flours, are less likely to produce rope
than the lower grade flours, which are more or less contaminated with
dust and bran fragments.

Origin. — All modern writers agree in ascribing rope to bacterial
activity. In the case of liquors, such as beer, the condition of ropiness

346 THE TECHNOLOGY OP BREAD-MAKING.

has been exhaustively examined, and various organisms identified as the
active agents. Morris and Moritz have traced ropiness in beer to
Pediococcus Cerevisiae, while Pasteur has associated it with a small glob-
ular organisin 0.0012 to 0.0014 mm. in size. Ropy bread has been com-
prehensively investigated in Germany by Vogel, who isolated two species
of bacteria which he identified as belonging to the potato bacilli group,
and which he named B. Panis Viscosus I. and B. Panis Viscosus II. re-
spectively. Other workers also agree in finding potato bacilli in bread.

WATKINS' PERSONAL RESEARCHES.

Cultivation of Organism. — The sticky material from the centre of a
ropy brown loaf was removed with a sterile platinum needle and mixed
with sterilised water. Nutrient gelatin, agar-agar, sterilised bread, and
peptonised wort respectively were inoculated with this solution, and cul-
tivated at 26° C. in the incubator. Growth occurred in all cases, and
microscopic examination showed the organism to be a short motile bacil-
lus. This was regrown several times in peptone wort, until a practically
pure culture was obtained.

Experiments on Sound Bread. — Sound loaves, two days old, were
taken and cut in two with a sterilised knife. On one half three loopsful of
the wort culture of the organism were sown, and tjie bread placed in a
moist incubator at a temperature of 28° C. The companion was as a
check placed by its side. In four such tests at various temperatures
ropiness was found to have developed in the inoculated bread within 12
hours. The temperatures ranged from 28° to 35° C. and the growth of
rope was much accelerated by the higher temperatures. In no case did
the uninfected portion develop ropiness, though the test was continued
until moulds had made their appearance.

Baking Tests. — These were made with a sound patent flour, the ma-
terials being mixed in a porcelain trough, and the proportions similar to
those in daily use for "straight doughs," viz., 280 grams of flour, 150
grams of distilled water, 5 grams of yeast, 1 gram of sugar, 3.5 grams of
salt, thus making a miniature sack batch with a yield of one loaf of about
400 grams. [In passing, it may be pointed out that the yeast is in higher
proportion than is used in a sack batch, but no higher than is customary
and advisable in making small trial loaves.] The temperature of the
dough was about 31° C. ; fermentation was allowed to proceed for 2
hours; the dough was then moulded, proved, and baked for 40 minutes
at an oven temperature of 204° C. (400° F.). A series of seven such
tests was made. In five tests a quantity of water, increasing from 1 to 5
c.c., was taken from the 150 c.c. of doughing water, and replaced by a
corresponding quantity of the peptone wort culture of the organism. The
fermentation and baking of these loaves proceeded normally, and the re-
sultant bread was light, with a sweet normal odour, flavour and appear-
ance on leaving the oven. The loaves were cut in two with a sterilised
knife, and one half of each was placed in the incubator at a constant
temperature and in moist air. The check halves were kept at room tem-
perature (14°-18° C.) in a dry atmosphere for seven days, and then for
another four days at the same temperature in a damp atmosphere. In
every case where the temperature of the loaf was kept below 18° C., and
whether in the presence or absence of excessive moisture, there was no
development of ropiness. On the other hand, every portion to which any
quantity of the culture had been added, became ropy at temperatures
between 25° and 30° C. in a moist atmosphere. The presence of the dis-
ease could be detected by the characteristic smell long before any other
obvious changes in the bread had made their appearance.

BREAD-MAKING. 347

Further Temperature Test. — A sound loaf was cut in two and each
portion inoculated with 1 c.c. of a wort culture. One portion was placed
in the moist chamber at 28° C. and the other in a dry cupboard at 16° C.,
the crumb being kept moist by the addition of sterilised water. The por-
tion at the higher temperature became ropy in 24 hours, while that at
16° C. showed no signs of the disease at the end of 28 days though still
quite moist.

Conclusions.— Elevated temperature appears to be absolutely neces-
sary to the development of ropiness in bread. Even when the bacillus is
present in large numbers, moisture alone, when the temperature is low,
is incapable of causing its appearance.

Effects of Acidity. — In making wort cultures, it was found that the
presence of 0.1 per cent, of acetic acid prevented the growth of the or-
ganism. Lactic acid has a similar effect. The author of the paper was
therefore led to try the effect of the presence of small quantities of acid
in the dough. A number of tests were made and the results recorded in
which acetic acid in quantities varying from 0.3 to 1.06 Ibs. to the sack
were used, and large amounts of wort culture added. The general result
was that acetic acid in quantities of from 0.3 to 0.7 Ib. to the sack in-
hibited the development of rope. The minimum quantity would appear
to be 0.3 Ib., while any excess over 0.7 Ib. injuriously affected the
gluten. The smaller quantity of acetic acid is not prejudicial to the gen-
eral qualities of the bread. Lactic acid may be employed instead of acetic
acid, but the action is somewhat uncertain with quantities below 0.6 Ib.
per sack.

Resistance of Organism to Heat. — The bacillus of rope or its spores is
exceedingly resistant to heat. Thus an active wort culture was immersed
in a boiling water bath for 30 minutes on three successive days. Cultures
were made from the wort after each boiling, and yielded vigorous
growths. The repeatedly boiled culture was then used in the dough of a
trial loaf, and baked for 40 minutes. Notwithstanding the severity of
this treatment, the organism was still extremely active and rapidly de-
veloped ropiness in the bread. The author of the paper draws the con-
clusion that it is hopeless to recommend the baker to give bread liable to
rope an extra long baking in order to prevent the appearance of the dis-
ease.

Morphology and Identity of Organism. — The following are the char-
acteristic details of this organism : A short rod with rounded ends, fre-
quently united in pairs, seldom in chains of more than three. It readily
forms ovoid spores which almost entirely fill the cell. In length, it is
from 1-1.25 /* ; in breadth, 0.75/x.

When cultivated in hanging drop, the organism is sluggishly motile,
and is surrounded by a translucent capsule.

It stains well by Gram, f uchsin and methylene blue. Spore staining
very difficult, usually only successful by Miiller's method.

The growth is best at temperatures between 25-40° C., stagnates at
15° C.

On agar-agar, smeary white growth, brownish on looking through the
medium, edges of growth irregular.

On gelatin, shining, barely visible, filmy growth, very slowly liquefy-
ing the medium.

On wort gelatin, white crinkled growth, slowly liquefying medium.

On peptonised wort, rapid growth, rendering liquid turbid, and form-
ing a slimy gelatinous film on the sides of flask and surface of liquid. The
wort acquires a faintly urinous odour.

348 THE TECHNOLOGY OF BREAD-MAKING.

On sterilised bread the bread becomes brownish as if saturated with
syrup, and is gradually converted into a moist viscous mass, emitting a
strong valerian-like odour.

Jn milk, causes coagulation, and subsequent partial re-solution of clot.

On potato, rapid white crinkling growth ensues, which turns brown
with age. A peculiar burnt musty odour is observed.

The foregoing characteristics point to the organism as being identical
with Bacillus mesentericus fuscus (Fliigge, Lehmann and Neumann's
Atlas of Bacteriology, p. 326, Plate 43).

Habitat. — The bacillus is a frequent inhabitant of soils, vegetables,
including potato, and doubtless also the cereals.

Infection of Doughs. — The most important question to the practical
baker is how his doughs become infected. Methods generally advocated
for prevention and cure of rope hold bakers almost entirely to blame for
its appearance in the bakery. For example, it has been ascribed to damp-
ness, accumulation of dirt in false bottoms and crevices of troughs, etc.
The suggested remedies have consisted of directions for purification and
sterilisation of the bakehouse and all its appliances. These have fre-
quently proved totally inadequate.

Flour. — A complete change of flour has in more than one case resulted
in the complete disappearance of the disease. The experience was cited
of one large firm of bakers who found that this discarding of their old
flours and their replacement by flours from another source resulted in an
immediate disappearance of the trouble. Baking tests were then made on
each brand of flour in the old stock, taken separately, and all but one
were found to be perfectly sound. Every blend used into which this flour
had entered was found to yield ropy bread. The evidence was conclusive
that this flour had been the means of introducing rope into the bakery.

The author of the paper made a series of bacteriological tests with this
flour. One gram of the flour was mixed with 100 c.c. of sterile distilled
water, and 1 loopful of the mixture added to various culture media. The
growths obtained were identical with those previously isolated from ropy
bread. Sterilised bread was successfully inoculated by the addition of 1
loopful of the flour mixture, blank check tests remaining unchanged. Re-
peat cultures of the organism were made in peptone wort, and these in
turn, when added to the dough, induced rope in loaves made from sound
flour. On making loaves from the suspected flour alone, portions main-
tained at 26°-30° C. in a moist atmosphere developed rope, while the
check portions, preserved at a temperature of 14°-16° C., remained sound
for as long as 14 days. These tests show that the bacillus was undoubt-
edly present in this sample of flour.

Effect of Yeast. — In order to determine whether the yeast played any
active part in the development of rope, some loaves were made with this
flour and a commercial baking powder. On being tested, rope developed
in the same way and at the same rate as in the yeast-made bread, show-
ing that ropiness is independent of the presence of yeast.

Modern Practice. — In modern practice, the author of the paper re-
gards the flour as the only material responsible for the appearance of this
disease. Occasionally in the past, the bacillus may have been introduced
by the use of potato ferments ; but the employment of potatoes is now al-
most obsolete, and the fact that the rope bacillus is known to commonly
exist in potatoes should furnish a strong additional reason for their aban-
donment in bread-making.

Practical Test for Rope in Flour. — The following test is intended for
the use of practical bakers and millers. It is so delicate that a positive

BREAD-MAKING. 349

result is obtained from 0.02 gram of a ropy flour, while there is no fear
that a genuinely sound flour will be condemned by its employment. Ten
test tubes (6 in. by 1 in.) are washed, thoroughly boiled in water for 1
hour, rinsed and drained. When drained, they are baked at 232° C.
(450° F.) for 3 hours in order to completely sterilise them. [A baker's
oven at full bread-making heat sufficiently answers the purpose.] When
cool, place in each tube a finger of bread 3 inches by ^ inch by y?. inch,
cut from the centre of the same 2-day old loaf. (The average weight of
each piece is 5 grams.) Moisten each piece with 5 c.c. of recently boiled
distilled water, then plug all tubes with cotton-wool [previously sterilised
by baking to a very light brown tint]. Sterilise the tubes and their con-
tents by immersion in boiling water for 1 hour on three successive days.
These tubes are conveniently prepared in batches a few days previous to
being required.

In order to test a flour, 2 grams are taken from the sample and well
mixed with 100 c.c. of distilled water. The beaker containing the mixture
is placed in a boiling water bath for 30 minutes, in order to destroy all
organisms except spore formers like the rope bacillus, etc.

To seven of the series of ten prepared tubes add successively 1 to 7
c.c. of the boiled flour mixture, leaving the three remaining tubes to serve
as checks. Immediately the tubes have been inoculated, the wool plugs are
replaced and the whole ten tubes put into an incubator of 28° C. In the
bakery, they may be put- in a prover, or in a. position near the oven where
that temperature is attained and where they will be free from dust. The
tubes must be examined at the end of 24 hours, both for the appearance
of the bread, and for the smell of ropiness. If the rope bacillus is pres-
ent, the whole of the inoculated tubes will usually show signs of it.
Should only a portion of them, it is well before condemning the flour to
repeat the test. In any case the check tubes must remain perfectly
sound, or the experiment must be rejected. The experiment should be
continued for another 24 hours, and the tubes again examined at in-
tervals. If there is no indication of ropiness in 48 hours, the flour may
be passed as sound. Beyond that time the development of moulds and
other organisms interferes with the success of the test.

Summary. — Ropiness in bread is produced by varieties of B. Mesen-
tericus (Fliigge), introduced into the dough through the flour, in which it
sometimes occurs in large numbers, possibly coining from the bran coat-
ings. Breads containing bran and low grade white flours are most prone
to develop ropiness.

The bacillus, is a prolific spore former, the spores being capable of
resisting high temperatures for prolonged periods.

Once present in the dough, development of the bacillus, after bread
has been made, depends partly upon the reaction of the bread and partly
upon atmospheric conditions.

Bread is only faintly acid in reaction and always insufficiently so to
naturally prevent the development and spread of ropiness, but if the
acidity be increased by addition of small quantities of acetic acid to the
dough, development can be prevented.

Low temperature arid dryness of the bread store tend to suppress de-
velopment, but the maximum temperature of 18° C. (65° F.) cannot be
exceeded without great risk.

When a batch of bread is found to be ropy, all flour in stock should be
at once tested, so as to locate the infected stock, and in the meantime
fresh supplies of flour from a different source should be laid in.

350 THE TECHNOLOGY OF BREAD-MAKING.

When the infected batch of flour has been discovered, it should be
isolated, so that it can be worked up under those conditions which are
most unfavourable to the development of the bacillus, i.e., the doughs be-
ing made slightly acid and the bread being quickly cooled and kept at
low temperature during storage. Such flour might advantageously be
kept until the colder months, when the prospects of development are at a
minimum.

During the summer months, the danger of purchasing ropy flour may
be entirely obviated by the application of the bread tube test before buy-
ing. (Jour. Soc. Chem. Ind., 1906, 350.)

Watkins' experiments would have been more complete had they in-
cluded investigations as to how far the development of ropiness was
affected by the comparative moisture of bread at temperatures slightly
higher than the lower limit of activity of the rope bacillus. He has made
it perfectly clear that with a temperature below 18° C. the presence of
moisture does not cause the development of ropiness. At 20° C., there
would probably be a much more rapid development in a moist loaf than
in a very dry one. Some measurements of this stimulating effect of mois-
ture would have added to the value of a very valuable paper. Previously
published recommendations to the baker to give his bread an extra long
baking, in case of his being troubled with rope, were not probably based
on any hope thus to kill the rope organism, but rather to make the bread
drier, and thus a less favourable medium for the spread of this disease.

There can be little doubt that Watkins has traced the source of many
if not most of the cases of ropiness which trouble the baker. But granted
that the flour is the channel of introduction ; when once the rope bacillus
has permeated the troughs and other utensils, the whole of the advocated
precautions for cleaning and sterilising these have all the force and neces-
sity which has been attributed to them.

The rope bacillus is a very ready spore-forming bacillus, and a bakery
is from its nature and character a place where spores are readily liber-
ated and disseminated through the atmosphere. There are frequently
cases of rope which it is almost impossible to explain otherwise than by
aerial infection. Such cases are those in which a complete change of flour
has not cured the disease, and where one miller's flour is producing ropy
bread in one bakery, while the same flour is yielding perfectly sound
bread in another. The cleansing and sterilising of a whole bakery is not
necessarily therefore a useless proceeding, but may be an absolute neces-
sity, should the entire building become infected with the rope bacillus.
These references are made not with the view of discounting the conclu-
sions arrived at by Watkins, but rather with the object of indicating some
possible additional sources of infection and the precautions to be in those
cases taken.

The reading of the paper was followed by an interesting discussion,
the more important points of which are here given. The chairman, Sala-
mon, drew attention to the strong smell of acetic acid exhibited by a
specimen loaf, and inquired as to what would be the effect of traces of
nitrogen peroxide on this bacillus in flour, in the manner used for bleach-
ing purposes. Jago asked whether the author had tried using the odour-
less mineral acids as sulphuric or phosphoric acid, and expressed a doubt
as to whether the baker would regard the substitution of sourness for
ropiness as an advantage. He pointed out that the presence of dextrinous
or gummy bodies in bread, caused it to become ropy much more readily
than did the drier types of bread. Hooper insisted on the necessity of
flour being kept dry and no tallowed to get damp, remarking that many

BREAD-MAKING. 351

possibly mischievous organisms were more widely spread than was com-
monly supposed, and were held in check by avoiding the conditions neces-
sary for their development. Humphries found that the addition of 0.25
per cent, of lactic acid was quite sufficient absolutely to spoil bread for
commercial purposes. Briant found ropiness to be generally associated
with excessive moisture in bread, and also regarded the addition of acid
as causing bread to become chaffy in character. Rideal recommended the
use of bisulphite of soda in the place of free acids for the inhibition of
ropiness. Several other speakers dealt with the question of the identity
of the organism. Watkins briefly replied on the whole discussion. He
did not regard bleaching as having a sterilising effect on flour, since one
of the flours which yielded ropy bread had as a matter of fact been
bleached. Mineral acids should not, he thought, be used in an article of
diet. Calculation showed that 0.3 Ib. of acetic acid to the sack only in-
creased the percentage of acid by 0.0708 per cent., and that quantity did
not interfere with the production of a good sweet loaf. ( Jour. Soc. Chem.
Ind., 1906, 350).

FAULTS IN BREAD.

501. Holes in Bread. — Instead of the even sponginess which should
characterise the crumb of good bread, one is occasionally confronted with
loaves in which large holes occupy considerable spaces in the interior of
the loaf. For their occurrence various explanations have been offered,
many of which are ingenious, while others are impossible. An interesting
object lesson in their production may be gained by taking a basin of
strong solution of soap in water, and blowing into it through a glass tube.
A mass of bubbles is formed on the surface of the solution, which fills the
whole vessel. Let it rest, and watch the gradual disappearance of the
bubbles — careful inspection will show in the interior of the mass some of
the bubble walls getting thinner and thinner, until at last they collapse,
and several small bubbles coalesce to form one of large size. Practically
the same thing occurs in dough ; if allowed to get over-proved, it will be
seen, on being cut, to contain a number of large holes. Good firm mould-
ing will remove the gas from these, and make a piece of homogeneous
dough for the loaf, thus remedying one cause of holeyness ; for if a loaf
containing these large holes be placed in the oven, they will expand there,
and thus give still more irregular aeration. The same process of a num-
ber of small holes breaking down into one big one may occur during bak-
ing in a piece of dough, which, if cut prior to its going into the oven,
would show no signs of large holes. Here the cause must be lack of
tenacity in the dough which forms the hole-walls, and the cause of such
holes must be found in the constituents of the dough. The elasticity of
dough at this stage is principally due to the gluten present, and when
fermentation has been carried sufficiently far to destroy the tenacity of
the gluten, breaking down into holes is a normal result : holeyness, there-
fore, for this reason may be an accompaniment of over-worked dough. If
. a series of loaves be made as suggested in paragraph 495, it is very rarely
that holes are found in the earlier and under-fermented loaves. Another
cause of this irregularity is the insufficient breaking down and mixing of
the sponge with the water and flour of the dough. The latter is frequently
made from a comparatively soft, weak flour, and if not thoroughly in-
corporated with the sponge, leaves portions of inferior tenacity which
may readily break into holes. The production of holes by dusting flour
being folded up in the interior of the loaf during moulding, and then

352 THE TECHNOLOGY OF BREAD-MAKING.

not thoroughly worked in, thns leaving blebs, which expand into holes on
baking, is so absolutely a result of carelessness as to need no further ref-
erence.

A curious problem about holes is the liability of cottage loaves to this
fault. If some of the same dough be made into " cakes" or "Coburg"
loaves, while the remainder is made into cottages, the latter are far more
likely to contain holes than the former. One cause of this is possibly the
inefficient "bashing" down of the tops of the cottages. A more likely
reason is, however, the actual shape of the loaf itself. The top, being
smaller, acquires a rigid crust before the lower part of the loaf, and
therefore forms a sort of protecting cap over the centre. As expansion
goes on in the interior during baking, there is a line of comparatively
little resistance immediately underneath the top, and greater expansion
takes place in this direction. Evidence of this is afforded by the species
of risen waist one sometimes sees in a cottage loaf, consisting of what
looks like a third or middle piece in the loaf. This development occurs
after the rest of the loaf has set ; and, as probably the interior dough has
also lost much of its elasticity, there is the formation of a large hole
rather than even expansion. Of course the occurrence of such holes
means a predisposition of the dough to breaking down into irregular
aeration.

The causes of holes in bread may be summed up as being — careless
moulding, especially of over-proved dough ; lack of tenacity and elasticity
of the dough itself, due to soft and irregular flours ; insufficient mixing of
sponge and dough. Cottage loaves are prone to holes because of the phys-
ical effect of their shape on expansion during baking.

502. Protruding Crusts. — On crusty bread being packed a little too
close in the oven, the loaves, on expanding, touch their neighbors, and a
soft crust is formed when they are in contact. Occasionally, when the
dough is weak and inclined to "run," it may be observed that the loaves
definitely grow toward one another, forming a distinct protuberance on
the side of each, as though an endeavour was being made on the part of
the loaves to effect actual contact. This apparent attraction is due to the
mutual cooling effect of the loaves retarding the formation of a rierid
crust on the contiguous parts : expansion continues there after the other
parts of the loaves are set, and hence the "kissing" growth toward each
other.

503. Crumbliness. — The crumbling away, instead of cutting cleanly,
exhibited by some bread may be due to the use of harsh, dry flours, not
sufficiently fermented ; or may also be caused by over-working and proof,
making the loaf bigger than the gluten of the dough, at the stage of fer-
mentation when baked, is able to stand and still hold the bread well to-
gether. A deficiency of dextrin and soluble starch in the bread also con-
tributes to crumbliness.

504. Dark Line in Cottages. — At times, on cutting a cottage loaf, a
dark line is seen across the contact surface between the top and bottom of
the loaf. Generally when this is the case, if the loaf has any soft crust,
that too is seen to be discoloured. The bread is under these circumstances
frequently either sour, or approaching it. The primary cause of this
dark line is the darkening by oxidation of some of the constituents of the
flour; this darkening goes on more rapidly in doughs made from low
grade flour or which have been overworked. Proof of this darkening of
dough is afforded by pressing a piece of dough down into contact with
colourless glass, and letting it stand a time. The air-exposed surface
rapidly becomes the darker of the two. This darkening has been found

BREAD-MAKING. 353

to be the result of the action of an enzyme to which the name of oxydase
has been given. In making sample loaves, especially from dark flours, a
streakiness is often observed. The proportionately large external surface
darkens, and each time the dough is moulded, the dark portion is worked
into the interior, and hence the streaky-baked bread. In any loaf which
has been allowed to stand there is more or less darkening of the exterior
by oxidation — on baking, this colouration is altogether masked by the
caramelisation of the crust. But where the two exteriors have been
placed together, as in the surface of contact of the two parts of a cottage,
the darkening effect of oxidation is preserved, and may be noticed in the
baked loaf.

505. Working with Unsound or Very Low Grade Flours. — In the
older literature of bread-making it is interesting to read the directions
given under this head ; when, through a bad harvest, wheat has either not
ripened properly, or has after the reaping been badly wetted, 'great care
is necessary in order to make a passable loaf of bread from the flour
produced.

In composition the unsound flours have a low percentage of gluten,
and that badly matured; while the soluble proteins are high, and in a
comparatively active diastatic condition. The starch granules have their
walls softened down and often fissured. The moisture is high, so also,
owing to the degradation of starch and proteins, is the soluble extract.
These flours are found on testing to be weak and unstable. So far as
their treatment is concerned, that commences with the wheats rather than
with the flours. A wheat harvested damp is not necessarily unsound;
these chemical changes are to a great extent an after-consequence of the
dampness. Such wheats should immediately on being harvested be kiln
dried at a gentle heat of about 38° C. (100° F.), until the moisture pres-
ent is reduced to 10 per cent, of the whole grain. While the flour pro-
duced from the wheat thus treated may be weak, it will be fairly stable
and not unsound. The gluten will be higher, and the soluble extract and
proteins comparatively low.

Having by preliminary treatment made the best of an unsound flour,
it should be used in the dough, which should be got into the oven as
speedily as possible. Or, the whole of the flour may be worked with a
straight dough on a very short system, using yeast in good quantity.
A little compressed yeast added at the dough stage will often be found
of service by hastening the fermentation. As unsound flours are particu-
larly liable to produce sour bread, special attention should be paid to the
suggestions made in paragraph 497 on Sour Bread. Further reference to
unsound flours will be found in the paragraphs describing other methods
of aerating bread.

The low grade flours of gradual reduction processes are, if from a
sound wheat, perfectly sound in themselves; yet they require some care
in manipulation, because they contain the active diastatic constituent of
the bran, cerealin, in considerable quantity. Where these flours are em-
ployed, a sponge should be prepared from a strong flour and the low
grade used in the dough, or the low grade flour worked by a short
straight dough system.

506. Use of Alum, Copper Sulphate, and Lime. — Alum, the double
sulphate of aluminium and potassium, A12K2(S04)424H20, was formerly
largely used as an adulterant of bread. This, and the other substances
mentioned, behave as retarding agents to diastasis ; with unsound flours
they prevent or lessen the degradation of the gluten and starch during
fermentation, and so cause a loaf made from a bad flour to be larger, less

354 THE TECHNOLOGY OF BREAD-MAKING.

sodden, and whiter, giving it the appearance of bread made from far bet-
ter flour. So far, and considered from this aspect alone, the action of
alum is remedial ; it prevents undesirable changes occurring in the flour
during fermentation. There is no doubt that by the use of alum, flour, so
bad as to render bread-making in the ordinary manner impossible with
it, can be converted into eatable loaves; but if necessity arises for re-
course to such flours for bread-making, other processes are now known
which achieve the same object by methods that are absolutely unobjec-
tionable. The continued use of alum, even in small quantity, is, accord-
ing to medical evidence, injurious to health: in particular, the alum re-
maining, as it does, unchanged in the bread, retards the digestive action
of the secretions of the mouth and stomach. As alum is injurious, and
as it is used with the object of enabling inferior flour to be substituted
for that of good quality, to the prejudice of the consumer, it is rightly
considered as an adulterant, and its use made penal.

Minute quantities of copper sulphate, CuS04, have also been em-
ployed : its action is very similar to that of alum ; but as all copper salts
are very poisonous, its use is even more reprehensible than that of the
former adulterant.

Liebig suggested the employment of lime in solution, lime-water,
CaH202, as a means of preventing excessive diastasis during panary fer-
mentation. This substance is quite as effective as alum so far as the effect
on diastasis is concerned, but unlike alum it exerts very little retardation
on the alcoholic fermentation caused by the yeast. Lime-water is used
by some of the Glasgow bakers, who advertise bread containing it as a
specialty. The bread made with lime-water is more spongy in texture,
pleasant to taste, and quite free from sourness. In the finished bread the
lime no longer exists as free alkali, because the carbon dioxide gas gen-
erated during fermentation will have completely changed it into calcium
carbonate —

CaH202 + C02 CaCO3 + H20.

Lime. Carbon Dioxide. Calcium Water.

Carbonate.

Calcium carbonate, which is identical in composition with chalk, has in
small quantities no deleterious action when taken into the system, and
may very possibly add to the nutritive value by remedying the natural
deficiency of wheat in lime salts. See paragraphs, 536-539.

507. Special Methods of Bread-making, — There are certain special
processes employed for bread-making which must next be described.

508. "Vienna Bread." — This is the name applied to rolls and other
light fancy bread. Vienna bread is made with patent flour and com-
pressed yeast. No potatoes or ferment is used. Instead of water, the
bread is sometimes made with milk or a mixture of milk and water. The
following recipe is quoted from The Miller: —

Proportions. — 8 Ibs. of flour, 3 quarts of milk and water in equal
proportions, 3^ ounces of compressed yeast, and 1 ounce of salt. The
warm water is first mixed with the milk, so as to give a temperature of
from 80° to 85° F. Sufficient flour is then added to make a weak sponge,
not much thicker than a batter. The yeast is crumbled, mixed well in,
and the sponge allowed to stand for about 45 minutes. The rest of the
flour is next added slowly, together with the salt ; the dough is then thor-
oughly kneaded and set to ferment for 2y2 hours. All Hungarian flour
may be used throughout, or the finest English milled flour may be sub-
stituted therefor. The bread is glazed during baking by the introduction
of a jet of steam into the oven.

BREAD-MAKING. 355

509. Leavened Bread. — In France and other parts of the continent
bread is made from leaven, which consists of a portion of dough held over
from the previous baking. The following description is given on the au-
thority of Watt's Dictionary of Chemistry. A lump of dough from the
preceding batch of bread is preserved; this weighs about 12 Ibs., made up
of 8 Ibs. of flour to 4 Ibs. of water, and is the fresh leaven (levain de
chef). This fresh leaven, after remaining for about 10 hours, is kneaded
in with an equal quantity of fresh flour and water, and thus produces the
levain de premiere- again, this is allowed to stand for some hours (about
eight), and is kneaded in with more flour and water. After another in-
terval of 3 hours, 100 Ibs. of flour, 52 of water, and about 1/3 Ib. of beer
yeast are added; this produces the finished leaven (levain de tout point).
The finished leaven weighs about 200 Ibs., and is mixed, after standing
2 hours, with 132 Ibs. of flour, 68 Ibs. of water, J^ Ib. of yeast, and 2 Ibs.
of salt. The dough thus formed is divided into two moieties ; the one is
cut into loaves which are kept for a time at a moderate temperature (77°
F.) and then baked. The bread thus produced is sour in taste and dark
in colour. The remaining half of the dough is kneaded with more flour,
water, y^ast, and salt and divided into halves ; the one quantity is made
into loaves, which are allowed to ferment and then baked; the other is
subjected again to operation of mixing with more flour, etc., and working
as before. The subdivision is repeated three times ; the bread improving
at each stage, and the finest and whitest loaves being produced in the last
batch. In the more important towns this mode of bread-making-is now
largely supplanted by the use of distillers' yeast, and seems now to have
largely given place to methods more nearly allied to Viennese and Eng-
lish processes.

Leaven fermentation is due to the presence in the leaven of certain
species of yeast, which grow and multiply in that medium. These induce
alcoholic fermentation of the sugar of the flour.

510. Alcohol in Bread, Proof of Presence of. — Pohl determined the
quantity of alcohol in bread in the following manner: — A Papin's
digester of about 8 litres capacity was fitted to a Liebig condenser. Into
this was placed a charge of 2 litres of water and 990 grams of bread cut
up into small cubes. On distillation there was obtained about 500 c.c. of
distillate, having a strong odour of new bread. The liquid had an acid
reaction and required 1.15 c.c. of normal potassium hydroxide solution
for neutralisation. The united distillates from four charges of the ap-
paratus amounted to about 2 litres, and represented 4,419 grams of brea^l.
The distillate was saturated with sodium chloride and re-distilled in a
flask fitted with a fractionating (Hempel) still-head, until half the vol-
ume had come over. The re-distillate was again saturated with sodium
chloride and re-distilled until again half its volume had come over. This
operation was repeated until a distillate having a volume of 120 c.c. was
obtained. This was then saturated with calcium chloride and distilled
until 50 c.c. had come over. The specific gravity of this final distillate
was 0.9885, and corresponded to 6.66 grams of alcohol in 100 c.c., so that
100 grams of bread contained 0.0753 gram of alcohol. (Z. angew. Chem.,
1906, 19, 668.)

511. Methods of Aerating Bread Other Than by Yeast.— Carbon
dioxide is not only produced by alcoholic fermentation, but may also be
generated within dough by purely chemical means, or may be mechanic-

IP ally introduced by first effecting its solution in water. The following de-
scription applies to aerating agents used for confectionery as well as
bread-making purposes.

356 THE TECHNOLOGY OF BREAD-MAKING.

512. Aerating Agents. — These essentially consist of (1) substances
containing carbon dioxide in a loosely combined condition, as in certain
carbonates, and (2) of acids or acid-containing bodies which liberate the
carbon dioxide from the members of the first group. The following is a
description of the more important of these bodies.

Sodium bicarbonate, NaHC03. — This body evolves carbon dioxide gas
on the application of heat alone, thus : —

2NalIC03 COg + Na2C03 + H20.

Sodium Bicarbonate. Carbon Dioxide. Sodium Carbonate. Water.

The reaction leaves a residue of normal sodium carbonate, which has
a very marked and disagreeable alkaline taste. A very slight excess
causes a yellowness in flour and an objectionable smell. These qualities
are emphasised where there are lumps of the bicarbonate not properly
broken down, or when there is imperfect mixing.

On treatment with acids, the bicarbonate evolves double the quantity
of carbon dioxide gas : —

NaIIC03 + HC1 CO2 NaCl + H20.

Sodium. Hydrochloric Carbon Sodium Water.

Bicarbonate. Acid. Dioxide. Chloride.

With the use of hydrochloric acid as in this case the residual body is
sodium chloride or common salt. These bodies are at times used in the
aeration of whole-meal bread. The salt produced takes the place in whole
or in part of that always added for flavouring purposes.

Ammonium carbonate ("Volatile"}. — Under the name of "Volatile,"
the commercial ammonium carbonate is also sometimes used as a source of
carbon dioxide gas. This body is really a mixture of ammonium carbon-
ate and carbamate, and may be represented by the formula 2(NH4)2C03.-
C02, and contains in 100 parts, NH3, 28.81 ; CO,, 55.93 ; and H20, 15.26.
On being dissolved in water and heated, the normal carbonate is first
formed with the liberation of carbon dioxide, after which the whole of the
carbonate completely volatilises, being converted into gaseous ammonia
and carbon dioxide : —

2(NII4)2C03.C02 2(NH4)2C03 + C02.

Commercial Ammonium Normal Ammonium. Carbon Dioxide.

Carbonate. Carbonate.

2(NH4)2C03 4NH3 + 2H20 + 2C02.

Ammonium Carbonate. Ammonia. Water. Carbon Dioxide.

On being heated, therefore, the whole of the carbonate is converted
into gaseous products.

This residue is therefore entirely gaseous, and consists of carbon
dioxide and ammonia. Until the latter gas leaves the goods in which
"volatile" has been used, they have the disagreeable odour and flavour
of ammonia. This substance is mostly used for aerating small porous
articles which readily permit its escape. It is obviously not suited for
the aeration of bread.

Tartaric Acid, H2C4H406. — This acid, of which a description has al
ready been given, is very soluble in water, hot or cold, and acts imme-
diately on sodium bicarbonate in the cold, liberating carbon dioxide : —
H2C4H406 + 2NaHC03 == 2C02 + Na2C4H406 + 2H20.

Tartaric Sodium Carbon Sodium Water.

Acid. Bicarbonate. Dioxide. Tartrate.

The residual body is sodium tartrate ; it is soluble and has a bland and
faintly saline taste, which ic, practically imperceptible in the baked goods.
Commercial tartaric acid may now be obtained almost chemically pure.
Cream of Tartar, KHC4H406. — This body, known also as hydrogen
potassium tartrate, is tartaric acid with half its acid properties neutral-
ised by combination with potassium. Consequently it has only half the

BKEAD-MAKING. 357

strength of tartaric acid. Cream of tartar differs remarkably from tar-
taric acid in that it is only very slightly soluble in cold water, whereas it
is readily soluble in hot water. The result of this is that when cream of
tartar is used with sodium bicarbonate very little action goes on in the
cold. But when the goods get hot in the oven a very rapid and energetic
evolution of gas occurs just at the time when it is wanted. For this rea-
son cream of tartar is an exceedingly useful body to the baker and con-
lectioner. Its chemical action is shown by the following equation : —

KHC4H4O6 + NaHC03 C02 + KNaC4H406 + H20.

Cream of Sodium Carbon Potassium Wetter.

Tartar. Bicarbonate. Dioxide. Sodium Tartrate.

The residual body is potassium sodium tartrate, known commercially
as "Rochelle Salts," which like sodium tartrate is possessed of very little
taste. Both sodium tartrate and Rochelle salts are aperient bodies, the
latter being the active ingredient in the well-known Seidlitz powders.
For the same amount of gas evolved, cream of tartar leaves double the
residue in the goods that is left with tartaric acid. Commercial cream of
tartar differs very much in its degree of purity. It can, however, be
bought with a guarantee of containing 98 per cent, of the pure substance ;
and this no doubt is the best form in which to buy the salt for aerating
purposes.

Acid Calcium Phosphate, CaH4(P04)2. — This salt is used to a consid-
erable extent for aerating purposes. It is soluble in cold water, and there-
fore behaves somewhat similarly to tartaric acid. In view of the fact that
there is a number of possible phosphates, several reactions may occur be-
tween this body and sodium bicarbonate. The following are among the
most important : —
CaII4(P04)2 + NaHC03 CO2 + CaNaH3(P04)2 + H20.

Acid Calcium Sodium Carbon Calcium Sodium *" Water.

Phosphate. Bicarbonate. Dioxide. Trihydrosen Phosphate.

CaH4(POJ2 + 2NaHC03 = = 2C02 + CaNa2H2(P04)2 + 2H20.

Acid Calcium Sodium Carbon Calcium Di-sodium Water.

Phosphate. Bicarbonate. Dioxide. Di-hydrogen Phosphate.

In the former of the above equations, one molecule of acid calcium
phosphate has reacted with one molecule of bicarbonate, and has liberated
one molecule of carbon dioxide. Mixed in these proportions the resultant
phosphate is acid to litmus and to the taste. In the case of the second
equation, one molecule of the acid phosphate has reacted with two mole-
cules of bicarbonate, and has liberated two molecules of carbon dioxide.
The resultant body still contains acid hydrogen, but is neutral to litmus
and also phenolphthalein : also it is neither acid nor alkaline to the taste
but only just saline in flavour. These are the correct proportions for use
as an aerating mixture, and correspond to 13.9 parts of the pure acid
salt to 10 parts of bicarbonate. As to how much of the commercial salt
must be used will depend on its degree of purity, which varies greatly,
as will be seen from the following table of analyses of samples which
have recently passed through the hands of the author : —

I. II. III. IV.

True acid phosphate . . . . 11.23 34.39 69.50 74.18
Neutral phosphate, etc. . . 31.18 19.80 28.73 23.64
Matter insoluble in hydro-
chloric acid . . ' . . Trace 0.90 0.26 0.84
Calcium sulphate .. .. 57.59 44.91 1.51 1.34

Totals 100.00 100.00 100.00 100.00

358 THE TECHNOLOGY OF BREAD-MAKING.

Numbers I. and II. are practically valueless, besides which their use
would render the person so doing liable to a prosecution for adultera-
tion with calcium sulphate. Numbers III. and IV. are very good samples,
and taking their mean as 71.84 it is easy to calculate how much of the
commercial salt must be taken to equal 13.9 parts of the pure body.

As 71.84 : 13.9 : : 100 : 19.3 parts of the commercial phosphate re-
quired.

The rule of double quantity of phosphate to bicarbonate is therefore a
safe one for good samples but would have to be exceeded for those of low
quality.

A higher degree of purity than that of No. IV. is scarcely desirable,
since the pure salt is somewhat deliquescent.

Much of the acid calcium phosphate on the market is exceedingly im-
pure, some samples containing as much as 50 per cent, of calcium sul-
phate. It can, however, be bought from the best makers with a guarantee
of 98 per cent, pure phosphate salts. Numbers III. and IV. in the pre-
ceding table are in practical conformity with this standard.

Acid Potassium Phosphate, KH2P04.— The potassium salt has been,
and still is at times, employed instead of that of calcium. The reaction
between it and sodium bicarbonate is as follows: —

KH2P04 + NaHC03 = C02 + KNaHP04 + H20.

Acid Potassium Sodium Carbon Potassium Sodium Water.

Phosphate. Bicarbonate. Dioxide. Hydrogen Phosphate.

There seems to be no advantage in having a residue of potassium
phosphate rather than calcium phosphate in the goods, provided that the
calcium phosphate used is commercially pure. Further, potassium salts
are now exceedingly expensive.

Acid Potassium Sulphate, KHS04. — This salt is soluble in cold water
and acts similarly to tartaric acid when used as an aerating agent. It is
much the cheaper of the two and produces the following changes with
sodium bicarbonate : —

KHS04 + NaHCO3 = C02 + KNaS04 + H20.

Acid Potassium Sodium Carbon Potassium Sodium Water.

Sulphate. Bicarbonate. Dioxide. Sulphate.

The residual potassium sodium sulphate is a comparatively tasteless
body with aperient properties.

"Cream Substitutes."- — These substances are lower in price than
cream of tartar, and mostly consist of acid phosphates or sulphates, or
mixtures of the two. The acid strength is let down to that of cream of
tartar by the addition of starch, usually in the form of rice or cornflour.
Strictly, these bodies are not substitutes for cream of tartar as they do
not possess the same property of insolubility in cold water, and ready
solubility in hot water. By careful selection and admixture, their rate of
cold water solubility is considerably slowed down, and within limits they
can be used instead of cream of tartar. Their true analogue is not, how-
ever, cream of tartar, but rather tartaric acid.

Alum, A12K2(S04)4, 24H20. — The alums liberate carbon dioxide from
sodium bicarbonate according to the following equation : —
A12K2 (S04)4,24H02 + 6NaHC03 = 6C02 + A12(HO)6 4-

Potash Alum. Sodium Bicarbonate. Carbon Dioxide. Aluminium Hydroxide.

K2S04 + 3Na2S04 + 24H20.

Potassium Sodium Water.

Sulphate. Sulphate.

The employment of alum in the preparation of food is regarded as an
adulteration.

BREAD-MAKING. 359

Equivalent Weights. — The following table gives the weight of each
substance required by 10 parts by weight of sodium bicarbonate : —

Name. Weight.

Tartaric Acid 8.93

Cream of Tartar 22.38

Acid Calcium Phosphate, pure, . . . . . . 13.90

Acid Calcium Phosphate, commercial, about 20.00 to 22.50
Acid Potassium Sulphate . . . . . . . . . . 16.19

Comparative Evolution of Gas. — The comparative volume of gas,
measured at 100° C., evolved by one part by weight (1 gram) of various
aerating mixtures, is given in cubic centimetres in the following table : —

NAME OF AERATING AGENT.

Ammonium carbonate (volatile), on being heated yields — ammonia

gas, 516 ; carbon dioxide gas, 387 . . . . . . . . . . 903

Sodium bicarbonate by action of heat alone . . . . . . . . 181

Mixture in proportion of 10 parts sodium bicarbonate to 8.93 parts

tartaric acid . . . . . . . . . . . . . . . . 191

Mixture in proportion of 10 parts sodium bicarbonate to 22.38 parts

cream of tartar . . . . . . . . . . . . . . 112

Mixture in proportion of 10 parts sodium bicarbonate to 22.5 parts

acid calcium phosphate . . . . . . . . . . . . 112

In summing up the general behaviour of these, and deciding as to
their suitability for aerating purposes, the first consideration is whether
rapidity of action is objectionable or otherwise. If the goods can be
baked at once before the action of the acid and soda on each other is
over, then tartaric acid and soda answer well. But it must be remem-
bered that this action commences immediately the ingredients are wetted.
On the other hand, if it be desired that no action shall occur before the
goods are heated in the oven, then cream of tartar and soda are prefer-
able, as this mixture remains quiescent until the temperature is raised.
Where immediate action is no detriment, acid and soda are indicated, and
this mixture possesses the advantage of leaving only about half the
residue left by cream of tartar and soda. Ammonium carbonate has also
a deferred action, but there is the unpleasant ammoniacal odour left in
the hot baked goods. Provided this is allowed to escape, and the goods
are odourless, then no residue whatever remains in them.

513. Baking Powders. — These consist of bicarbonate of soda put up
with one or more of the acid bodies previously described. Baking pow-
ders are used more extensively in America than in England for bread-
making purposes, and their composition has been made the subject of
investigation by one of the State departments. They are classified accord-
ing to the nature of the acid constituent they contain into three groups,
Tartrate, Phosphate, and Alum powders.

In the manufacture of baking powders, the acid ingredient, together
with the proportionate quantity of bicarbonate of soda, is mixed with air-
dried starch. This latter component increases the weight of the baking
powder ; it also, owing to the hygroscopic nature of starch, helps to keep
the active ingredients free from moisture.

514. Self -Raising Flour. — The articles sold under this name consist
of flour, mixed with acid tartrates or phosphates, and the bicarbonate of
soda : as with baking powder, the addition of water causes the evolution
of gas. Self-raising flours may be viewed as being flours sold with baking
powder already mixed with them. It is claimed for the use of phosphates
in this manner that it replaces these important salts which are removed
from the wheat in the bran.

360 THE TECHNOLOGY OF BREAD-MAKING.

515. Use of Hydrochloric Acid. — In the manufacture of wholemeal
bread the method is sometimes adopted of employing hydrochloric acid
and sodium carbonate in the exact proportions in which they neutralise
each other : they then not only evolve carbon dioxide gas, but also yield
sodium chloride, or common salt, thus : —

NaHC03 + HC1 = NaCl + H20 + C02.

Sodium Hydrochloric Sodium \Yater. Carbon

Bicarbonate. Acid. Chloride. Dioxide.

The salt thus formed lessens the quantity which otherwise would have
to be added to the bread. Great care is requisite in the proper mixing
of the acid and the carbonate with the meal: it is also important that
exactly the right proportions should be taken. A rough measurement of
the strength of the acid may be made by taking a weighed quantity, say
an ounce, of the bicarbonate of soda, dissolving it in boiling water in a
beaker, and then adding a few drops of methyl orange solution. The
hydrochloric acid should be measured, or else a quantity placed in a
beaker, and weighed in it ; then add the acid little by little until one drop
changes the colour of the bicarbonate of soda solution from yellow to red.
Then again weigh the acid containing beaker ; the loss in weight gives the
quantity of the hydrochloric acid, equivalent to an ounce of the bicar-
bonate. Commercial hydrochloric acid is usually sold with a guaranteed
density of 1.15 ; this is equivalent to about 30 per cent, of the anhydrous
acid. As 84 parts of sodium bicarbonate are exactly neutralised by 36.5
of anhydrous hydrochloric acid, and as this amount is contained in 122
parts of the commercial acid, the bicarbonate of soda and hydrochloric
acid of this density should be used in the proportions of 84 of the bicar-
bonate to 122 of the acid, or practically in the proportions of 2 to 3 by
weight. It has been recommended that 3 Ibs. each of the acid and bicar-
bonate be used to the sack of flour: these proportions leave, however, a
considerable excess of the carbonate in the bread. The great objection to
the hydrochloric acid method is that the commercial acid frequently con-
tains traces of arsenic, and thus a minute quantity finds its way into the
loaf.

516. Whole-Meal Bread. — It is principally in making whole-meal
bread that the hydrochloric acid and bicarbonate method is employed.
The reason is that, with the presence of the bran, cerealin is introduced
into the dough in such quantity that, if ordinary fermentation processes
be employed, diastasis proceeds to a very serious extent. The excess of
dextrin thus produced causes the dough to become soft and clammy, and
so to offer a matrix in which sour and other unhealthy fermentations are
apt to proceed rapidly. The brown colour is due to the excess of dex-
trinous matter contained in the bread. The rapidity of the acid treat-
ment enables the bread to be got into the oven before diastatic action can
have proceeded to any extent. When the fermentation method is em-
ployed for making whole-meal bread, it is customary to make a sponge
with a small quantity of very strong flour, and only add the whole meal
at the dough stage. However made, whole-meal bread has a great
tendency to become sodden : in order to drive off excess of moisture it has
to be baked for a considerable time, consequently the loaf has often a very
thick crust, while the interior is still unduly moist. In summer time par-
ticularly the making of whole-meal bread is an unsatisfactory operation,
as great difficulty is often experienced in producing a sound and well-
risen loaf.

In all the operations just described, carbon dioxide is formed in
dough, and thus raises it. The chemical action which under these cir-
cumstances takes place is not, however, a complete representative of that

BREAD-MAKING. 361

which occurs with yeast. One of the functions of this body during the
fermentation of bread is to act on the protein, and also to a certain extent
on the starch ; the result of such action, when normal, is to impart to the
bread a characteristic flavour that can be obtained by no other means at
present known.

517. The Aeration Process. — One other method of aerating bread re-
mains for consideration, and that is the system associated with the name
of Dr. Dauglish. The carbon dioxide is in this method prepared apart
from the bread and forced into water under pressure ; this water, which
is akin to the aerated water sold as a beverage, is then used for converting
the flour into dough, the whole operation of kneading being performed in
a specially prepared vessel in which the pressure is maintained. The
kneading being completed, the dough is allowed to emerge from the
kneading vessel, and immediately rises, from the expansion within it of
the dissolved carbon dioxide. Such was the nature of the method orig-
inally employed by Dauglish ; but now the following modification is.
used : — A weak wort is made by mashing malt and flour ; this is allowed
to ferment until through the agency of bacteria it has become sour, in all
likelihood through the presence of lactic acid. The water to be aerated is
first mixed with a portion of this weak acid liquid : it is then found to
absorb the carbon dioxide gas much more readily. The acid also softens
the gluten. So far as the actual aeration process is concerned, this
method is mechanical rather than chemical. The great objection is that
those more subtle changes by which flavour is produced do not occur here
more than in the other purely chemical methods of bread-making before
described. A common experience in eating aerated bread for some time
is that it after a while gives the impression of rawness. This is doubtless
due to there being no such enzymic action on the proteins as results from
fermentation. It is partly to meet this want that the fermented wort is
now added as a part of the process. On the other hand, as a compensa-
tion for this lack of flavour-producing changes, the operation is one in
which there is no danger of those injurious actions occurring of which
much has already been said. Working with flours that are weak and
damp, or even bordering on the verge of unsoundness, it is still possible
to produce a loaf that should be wholesome and palatable, certainly
superior to many sodden and sour loaves made from low quality flours
fermented in the ordinary manner. In thus stating that it is possible to
treat flours of inferior quality by this aerating method, the authors wish
specially to carefully avoid giving the impression that it is the habit of
those companies which work Dauglish 's method to make use of only the
lower qualities of flour; they have never had any reason whatever for
supposing such to be the case. Their object in the present remarks is sim-
ply to point out the advantages possessed by this method, should circum-
stances unfortunately arise rendering it necessary to have recourse to
inferior flours for bread-making purposes.

Richardson claims for the aeration process that it is eminently suited
for the manufacture of whole-meal bread. Of this there is not the slight-
est doubt : whole-meal is not well fitted for fermentation methods, and the
aeration process distends the dough with gas, without the addition of any
foreign substance whatever.

It is also claimed for the aeration process that it enables the cerealin
to be retained within the bread ; and that this is "a most powerful agent
in promoting the easy and healthy digestion of food." It is stated that
this agent is retained uninjured by the aerated bread process. The
author of this statement apparently overlooks the fact that diastatic

362 THE TECHNOLOGY OF BREAD-MAKING.

action is destroyed by the subjection of proteins to a temperature
approaching 212°F. However active, therefore, cerealin may be in effect-
ing diastasis of starch during panary fermentation, its power is destroyed
by efficient baking, and the bread contains no active diastatic principle.
This remark applies with equal force to bread containing malt; it is so
well known that malt infusion converts starch into dextrin and maltose,
that from time to time it has been introduced into bread. It must here,
too, be remembered that the baking entirely destroys its diastatic action,
and so causes the malt to be inert as a digestive substance.

518. Gluten Bread. — It is important that the diet of diabetic
patients should contain no sugar, starch, or other compounds capable of
being converted into sugar. For their use bread is prepared containing
the gluten only of the flour. A strong flour should be selected and made
into a stiff dough with water only ; this is allowed to stand for almost an
hour, and then carefully kneaded in small pieces at a time in a vessel of
water ; the starch escapes and the gluten remains behind. Care is neces-
sary in prforming this operation, as otherwise the lump of dough does not
hold together. Should there be any difficulty, the dough may be enclosed
in muslin prior to being kneaded. The gluten must be washed in suc-
cessive waters until it no longer contains starch ; at this point the gluten
ceases to render the washing water milky. When properly washed the
gluten is ready for the oven, and is usually baked in small rolls or buns.
As it swells enormously during baking, a very small piece is sufficient for
each roll.

519. Rye Bread. — On the European Continent, bread is made to a
considerable extent from rye. The following are the results of analyses
of samples of two such breads: —

Pumpernickel. Vienna

Black Bread. Rye Bread.

Proteins 8.90 . . 8.30

Starch, etc 39.74 . . 55.14

Sugar 3.28 .. 1.46

Fat 2.09 .. 0.33

Cellulose 1.79 .. 0.97

Mineral matters 1.29 . . 1.90

Water 42.90 .. 31.91

Pumpernickel is the well-known black bread of Northern Germany.

The Vienna sample is of a whiter type, containing considerably less of the

bran.

520. Unsuitability of Barley Meal, etc., for Bread-making.— Ques-
tions often arise as to why barley and other cereals do not make such
good bread as does wheaten flour. One reason has already been given:
wheat is distinguished from the other somewhat similar foodstuffs by its
containing gluten; it is the presence of this peculiar albuminous body
that confers on wheat flour its characteristic bread-making qualities.
The proteins of the other cereals, and also of peas and the other legumin-
ous seeds, possess more active diastatic properties — consequently during
fermentation they yield much dextrin, and produce dark coloured, sod-
den, and often sour breads. The diastase of rye is particularly active.
In addition to the colour produced by diastasis, peas have naturally a
dark colour of their own, so that their introduction into bread would very
materially affect the colour. In comparing barley and rye flours against
that of wheat, the differences in the respective milling processes must not
be ignored. The bran and germ of wheat are separated. from the flour by
most refined methods, while barley and rye are ground, and the meal
purified, by the crudest appliances. This must of necessity make a differ-
ence in the character of the flour.

BREAD-MAKING. 363

521. Wheat and Flour Blending. — The consideration of the whole
problem of blending flours and wheats has been purposely postponed
until this stage, in order that the reader may have before him an account
of the various changes which flour undergoes during the operations of
panary fermentation. These changes, in short, consist in more or less
conversion of starch into dextrin and maltose, and in the gradual soften-
ing and otherwise altering the gluten of the flour. As has been previ-
ously insisted on, the gluten must have had during fermentation sufficient
opportunity to hydrate and soften sufficiently; but must not have been
allowed to further change, as if so it will have lost its tenacity, and will
produce an inferior loaf. A great deal of the success of a skilled baker
depends on his having acquired the experience which enables him to take
his dough and place it in the oven just at this right point when fermen-
tation has proceeded sufficiently far to get the gluten of the flour in its
best possible condition.

The problem is further complicated by the fact that different flours
require, in order to arrive at this stage of maturity, different lengths of
time in fermentation; hence, as already explained, flours from hard
wheats are commonly used in the sponge, while those from soft wheats
are employed in the dough. There can be no doubt whatever that by this
arrangement far better bread is produced than if the flours be used in
the reverse order. It is, then, perfectly safe to state that the length, of
time flours require to stand in fermentation is in proportion to their
hardness or stability. This being the case, the question arises as to how
this end may best be secured.

Probably the most keenly contested question on this whole problem of
blending is whether it shall be done by the miller or the baker. Of prior
importance, however, to this matter of by whom the blending shall be per-
formed is that of the baker 's actual requirements in flour. Evidently the
baker who works either with a ferment and dough, or an off-hand dough,
needs but one flour for each quality of bread, and may therefore either
buy a flour which suits his requirements, ready mixed by the miller, or
may purchase individual flours and mix them together. With the
increased adoption of straight dough systems, there is naturally a larger
demand for ready blended flours. But even those who employ this
method may often find a blend of their own more suited to their par-
ticular requirements than a single miller's flour. On the other hand, the
baker who employs the sponge and dough system will, in the great
majority of cases, find it advantageous to use flours of a different class
for his sponges and doughs respectively. As already explained, for the
former he almost invariably selects a hard, strong flour, which is best
made from either Spring American or the harder Russian wheats. For
some methods of working, an admixture of a small proportion of softer
flour is an improvement, as the proteins of the latter exercise a distinct
mellowing and ripening effect on the glutens of the hard flours.

For doughing purposes the wheat or flour mixture is more varied;
thus the soft, sweet, "coloury" flours are used at this stage; so also is
usually a certain proportion of hard flour, which, if not too much, is
sufficiently softened by the diastatic action of the softer flours by which
it is accompanied.

There is always a demand by the more advanced bakers for flours
milled from single wheats, a demand evidently based on the greater in-
dividuality which such flours naturally possess. Among these are hard
Spring Americans, which can be differentiated into Manitoban wheat
flours, Northern Minnesota flours, and Southern Minnesota flours, all of

364 THE TECHNOLOGY OF BREAD-MAKING.

which have their special characteristics. Prime hard Russian wheat
flours would also find a market were they obtainable. Winter American
flours, both from soft wheats and also the hard Kansas wheats, may also
be included in this group. So, too, may best English wheat flours, and
also those from Hungarian wheats.

The following are among the advantages which accrue to the baker by
working on the principle of blending flours : —

(1) There are frequently offering parcels of flour which possess in a
marked degree some one quality, but are deficient in others. Because
they cannot well be used alone, they may be purchased at a lower figure,
and the blender, by mixing, can utilise such flour to advantage. In other
words, given the requisite knowledge, it is often cheaper to prepare the
quality and character of flour required for use from a mixture of differ-
ent qualities obtainable on the market, than to buy the actually wanted
quality mixed ready for use.

(2) The baker who blends flours has a greater control over the quality
and character of the flour he uses in his work. Thus, he can readily
either improve or diminish the value of his sponging flours by the addi-
tion of a bag or a sack of a better or worse flour : so, too, colour, flavour,
and other characteristics of his flours can be readily modified at will, and
much more effectively than if he simply obtains one ready-made flour
from the miller. He can similarly modify a flour used for straight
doughs.

(3) The baker can introduce each particular variety of flour at that
stage of fermentation which best suits its particular characteristics.

Blending affords greater chances of successful work with flour, but at
the same time entails greater risks, because accurate knowledge of the
properties and the characters of the various flours blended is requisite,
and also of their effect on each other when blended.

The baker who blends should lay himself out to select flours for their
predominant quality; for example, one brand for strength, another for
colour, another for flavour, and so on. By appropriate means he will
judge the exact character of each of these flours in the separate state, and
then can readily,, with a little care, prepare whatever blends best suit his
work. The modern baker will have no difficulty in finding his require-
ments in this direction met by the modern miller.

Millers, in blending, usually first mix their wheats, and let them lie a
time before sending to the rolls — if hard and soft wheats are thus
blended, each exerts a favourable influence on the other in the way of
rendering it more amenable to milling. Thus, a very hard wheat, and
also a very soft one, are each more difficult to mill successfully than a
mixture of intermediate character ; and consequently a miller 's argument
is this — if the two flours are to be mixed after being milled, why not have
the wheats first mixed, as the resultant flour is of better quality, every-
thing else being equal, than if the two separate flours are mixed after
milling? On the other hand, certain millers have distinct and separate
plants, the one for hard wheats and the other for soft, and mill and treat
each separately, afterwards mixing the flours. The evidence, therefore,
of even millers themselves is undecided on this point of blending before
or after milling.

Whether blending be done by the miller or the baker, an undoubted
advantage arises from the latter having a clear idea of his exact require-
mnts in flour, and how they may best be met. With clear and full knowl-
edge on these points, whether the baker blends himself or gets that serv-
ice performed for him by the miller, the result is the more economic pro-
duction of a better and higher class loaf.

BREAD-MAKING.

365

522. Changes in Flour Resulting from Fermentation. — A series of
experiments has been made by the authors with the following objects : —

I. Determination of the amount of gas evolved during fermentation
under the described conditions.

II. Investigation of the changes produced by fermentation in the com-
position of the flour.

III. Effect produced by the addition of various substances to the
flour on the quantity of gas evolved, and on the changes therein resulting
from fermentation.

Outline of Experimental Method. — In each test, 200 grams of flour
were taken, and 100 grams of water at 30° C. ; these with 2 grams of salt,
and 4 grams of fresh distillers' compressed yeast formed the basis of the
dough. Various additions were made as subsequently described. The
doughs were carefully mixed with a spatula in a basin, and finally made
by hand, but with as little handling as possible. They were then trans-
ferred to a weighed enamelled steel beaker and the weight ascertained.
Waste and loss in making were thus determined. A small portion of the
dough was then taken for estimation of water and solids. The remainder
was carefully weighed, and the beaker, a, at once inserted in the ferment-
ing apparatus. This consisted of a gun-metal vessel, &, Fig. 33, fitted
with a glass lid, c, and an outlet tubulure, d. The vessel, ft, was fixed in
a water bath, e, maintained at a constant temperature by means of an
automatic gas regulator, /. The tubulure, d, was connected with a gas
measuring apparatus, g, similar to that described in par. 364. The joint
between b and c was made with rubber solution, and the two fastened
together by means of four screw clamps, In, applied round the edges. The
doughs when made had a temperature of 26° C., and the water bath was
kept at that temperature throughout the whole series of experiments.
The volume of gas evolved was read off at intervals, usually of one hour,
and the readings continued for 6 hours, with the exception of No. IV., in

FIG. 33. — Fermenting Apparatus.

366

THE TECHNOLOGY OF BREAD-MAKING.

which they were taken for 20 hours. The beaker of fermented dough was
then removed from the apparatus and weighed. An analysis was subse-
quently made on the fermented dough.

The following table gives the numbers of the experiments, arid the
substances used in each. As already mentioned, the four principal ingre-
dients were always taken in the same proportions, viz., flour, 200 grams ;
water, 100 grams ; salt, 2 grams ; and yeast, 4 grams. The yeast through-
out was the same brand, and that employed was selected each day from
the centre of a fresh and previously unopened bag.
No. I. Flour, water, salt, no yeast.

„ II. Flour, water, salt, malt flour 1 gram, no yeast.

„ III. Flour, water, salt, yeast.

„ IV. Flour, water, salt, yeast (2nd experiment).

„ V. Flour, water, salt, yeast, sugar 2 grams.

„ VI. Flour, water, salt, yeast, starch 2 grams, gelatinised in portion
of the water.

„ VII. Flour, water, salt, yeast, malt flour 1 gram.

„ VIII. Flour, water, salt, yeast, starch 2 grams, gelatinised in por-
tion of the water, malt flour 1 gram.

GAS EVOLVED.
No evolution of gas occurred in Nos. I. and II.

Time.

No. III.

No. IV.

No. V.

No. VI.

No. VII.

No. VIII.

°1

245

350

170

256

343

•187

1 hour

245

350 <

170

256

343

187

>365

384

240

316

440

- 293

2 hours

610

734

410

572

783

480

440

416

360

490

536

342

3 "

l,050l

1,150

770

1,062

1,319

822-

330

•209

380

400

475

360

4 "

1,380

1,359

1,150

1,462

1,794

1,182<

165

198

340

185

258

344

5 "

1,545

1,557

1,490

1,647

2,052

1,526'

125

104

•330

180

^268

310

6 "

l,670j

1,661 <

1,820

1,827'

2,320'

1,836

7 "

1,757

8 "

1,849

176

10 "'

2,025

156

12 "

2,181

109

14 "

2,290

109

16 "

2,399

106

18 "

2,505

104

20 "

2,609

BREAD-MAKING. 367

Numbers I. and II. were made up in order to make subsequent tests
on the doughs after standing. As would be expected, there was no evolu-
tion of gas in either case. No. III. may be compared with a somewhat
similar experiment described in paragraph 436. There the conditions
were as nearly as possible those of actual practice : it may be taken there-
fore that the fermentation in this latter case was more than double that
which occurs in normal bread-making/ being represented by 1,670 c.c. as
against 705 c.c. of gas. Nos. III. and IV. are duplicates for the first 6
hours, but in IV., gas was evolved much more vigorously at the start, a
result which must be regarded as due to greater initial fermentative
power in fresh yeast of another day 's supply. At the end of 6 hours the
quantity evolved was practically alike in both cases, 1,670 as against 1,661
c.c. But right up to the close of No. IV. there was a considerable and
steady evolution of gas. Nos. V. and VI., respectively containing added
sugar and gelatinised starch, gave about the same amount of gas, 1,820
and 1,827 c.c., the maximum production of gas being greater, however, in
No. VI. In No. VII., to which malt flour had been added, there was con-
siderably more gas than in any of the other tests, 2,320 c.c. This amount
is equivalent to that evolved in No. IV. in about 14^ hours. In No.
VIII., which contained both malt flour and gelatinised starch, the gas
evolved was only about the same as gelatinised starch only, 1,836 as
against 1,827 c.c.

Analyses of Flour and Dough. — In the flour, the gluten was deter-
mined in the usual manner, and dried. The true gluten was estimated by
the Kjeldahl process on the dry gluten. The gliadin is that yielded by
direct extraction of the wet gluten from 10 grams of flour, being 2.8
grams. A measured quantity of 100 c.c. of 70 per cent, alcohol was em-
ployed. The wet gluten and 20 grams of washed and dried precipitated
chalk were placed in a mortar and triturated with a sufficiency of the
alcohol to produce a slack dough. The trituration was continued until
the whole of the gluten was disintegrated, no visible particles being pres-
ent. This dough, together with the remainder of the alcohol, was trans-
ferred to a flask and vigorously shaken. In every case the sediment was
carefully examined in order to see that all the gluten had been thoroughly
comminuted. The contents of the flask were then raised to the boiling
point, and again thoroughly shaken. The flask was then allowed to stand
over night, shaken up once more in the morning, allowed to settle for a
few minutes, and filtered. A direct estimation by weight was then made
by evaporating 50 c.c. of the filtrate and drying off in a tared glass dish.
True gluten, less gliadin, was then reckoned as glutenin. The soluble
extract was obtained by the addition of 500 c.c. of distilled water to 50
grams of the flour, shaking vigorously at intervals during 30 minutes in
the cold and then filtering after 5 minutes' subsidence. A sufficient
quantity of a turbid filtrate was almost immediately obtained, -and this
was filtered bright on a separate filter. Aliquot parts of this solution were
taken for the estimation of reducing and non-reducing sugars and soluble
proteins.

The doughs were first thoroughly mixed and re-kneaded; 50 grams
were then taken, and washed in successive small quantities of tap water
(deep well from the chalk), with separation of gluten. As 50 grams of
dough contain about 21 grams of starch, having a specific gravity of 1.5,
the starch present was assumed to occupy 14 c.c. The washing water was
therefore made up to 514 c.c., allowing 500 c.c. of liquid. To this solu-
tion, 10 grams of thoroughly washed and dried kieselguhr were then
added, and the solution filtered bright. Total soluble matters, sugars,
and protein, were then determined in the filtrate. The gluten was

368

THE TECHNOLOGY OF BREAD-MAKING.

weighed in the wet and dry states, and true gluten and gliadin and
glutenin estimated as before. The moisture was determined direct on a
portion of the dough, and the acidity on another portion direct. The
dough was triturated with distilled water in a mortar and titrated with
phenolphthalein and JV/10 soda, the acidity being calculated as lactic acid.
The results of the analyses are given in the following table, both on
the flour and dough as examined and as calculated on the water-free
solids. The numbers attached to the doughs are the same as before; the
flour is designated No. 0.

COMPOSITION OF FLOUR AND DOUGHS.

f—

No.
As

o. ,

Water

. — —No. ]
As

Water

, No.
As

n. ,

Water

Constituents.

Exd.

Free. .

Exd.

Free.

Exd.

Free.

Moisture

1427

42.11

41.99

Gluten, Wet

28.05

32.72

20.40

35.29

20.70

35.40

„ Dry

10.50

12.14

6.34

10.97

6.50

11.11

„ True . .

8.87

10.33

5.31

9.19

5.84

9.99

Gliadin ex gluten

2.20

2.80

2.26

3.91

2.07

3.54

„ per cent, of True

Gluten

—

27.04

—

42.54

35.43

Glutenin ex gluten

6.67

7.53

3.05

5.28

3.77

6.45

Soluble Extract . .

4.04

4.71

4.07

7.04

5.91

10.11

„ Protein

1.24

1.45

0.34

0.59

0.40

0.69

Reducing Sugars

1.09

1.27

0.63

1.15

0.47

0.80

Non-reducing Sugars . .

0.16

0.19

1.54

2.67

2.56

4.38

Acidity as Lactic Acid

—

0.084

0.144

— No. III. —

No. IV

•t t

. No.

Moisture

43 65

44.49

44.55

Gluten, Wet . .

20.3

35.93

13.78

24.80

19.92

35.86

„ Dry .. ..

6.26

11.08

4.84

8.71

6.10

10.98

„ True .. ..

5.73

10.14

4.29

7.72

5.25

9.45

Gliadin ex gluten

1.81

3.20

1.17

2.10

1.74

3.13

„ per cent, of True

Gluten

—

31.55

—

27.21

—

33.12

Glutenin ex gluten

3.92

6.94

3.11

5.60

3.51

6.32

Soluble Extract . .

3.81

6.73

3.97

7.14

3.50

6.30

„ Protein

0.50

0.88

0.55

0.98

0.40

0.72

Reducing Sugars

0.04

0.07

0.40

0.72

0.20

0.36

Non-reducing Sugars . .

0.58

1.02

0.33

0.60

0.35

0.63

Acidity as Lactic Acid

0.09

0.159

0.09

0.162

0.09

0.162

, — —No. VI. —

, NO. vii. ;

, NO. VIII. .

Moisture

43.68

—

44.35

— •

43.28

Gluten, Wet

19.16

33.91

19.20

34.56

19.88

34.99

„ Dry .. ..

6.02

10.97

5.91

10.64

6.01

10.58

True

5.40

9.56

5.34

9.61

5.41

9.52

Gliadin ex gluten

1.94

3.43

1.96

3.53

2.14

3.77

„ per cent, of True

Gluten

—

35.87

—

36.73

—

39.60

Glutenin ex gluten

3.46

6.12

3.38

6.08

3.27

5.75

Soluble Extract

4.28

7.57

4.63

8.33

4.94

8.69

„ Protein

0.40

0.71

0.34

0.61

0.40

0.70

Reducing Sugars

0.35

0.62

0.86

1.55

0.51

0.90

Non-reducing Sugars . .

0.54

0.95

0.74

1.33

0.67

1.18

Acidity as Lactic Acid .

.0.09

0.159

0.09

0.162

0.09

0.158

BREAD-MAKING. 369

The moisture in the doughs cannot be regarded as absolutely exact,
since there is a difficulty in obtaining a perfectly fair sample : there must
also be a slight loss through continued fermentation in the hot-water
oven. An examination of these results shows that a greater quantity of
wet gluten was obtained from all the doughs, except No. IV., than was
obtained from the flour. In No. IV. there is a very marked diminution.
Speaking generally the dry glutens are slightly lower than in the flour,
thus showing that as a result of fermentation the water-retaining power
of the gluten is increased. As might be expected, the dry gluten also of
No. IV. is much less. The ratios of wet to dry gluten of Nos. 0., I., III.,
and IV., are as follows : 2.70, 3.22, 3.24, 2.85. It will be seen that the
water-retaining power of the gluten has receded under the long fermenta-
tion of No. IV. to practically the same as that of the flour. In all the
doughs there is a diminution of true gluten. The proportion of protein
dissolved from the wet gluten by treatment with 70 per cent, alcohol in
the manner described is much less than that obtained by extraction of the
flour direct by the methods usually adopted. These results are therefore
not comparable with those of gliadin ex flour, but may be compared
among themselves. The most instructive comparison is probably that of
the various percentages of gliadin in true gluten with each other. Of the
flour true gluten, 27.04 per cent, was thus dissolved. In the dough
treated with salt, No. II., this figure had increased to 42.54, while in No.
III. it was also high. In No. III. there is an increase of the soluble gluten
over that in the flour, while with the over-fermentation of No. IV. the sol-
uble portion of the gluten has diminished. A possible explanation of this
is that in washing this long-acted-on gluten some of the gliadin is lost by
washing away. In all the glutens from the more normally fermented
doughs, there is an increase in the proportion which is soluble. Chalk
removes some of the gliadin from solution by adsorption. These gliadin
results are therefore too low, but are nevertheless comparable among
themselves.) In the soluble extracts, that of the flour is 4.71, a figure
materially increased in the salt made dough : it is very probable this
would have been more in a dough made from flour and water only. The
addition of malt flour, as might be expected, caused a still further in-
crease in the amount of soluble matter present. The malt flour used had
a diastatic capacity of 48.6° Lintner, and 31.93° when tested with ordi-
nary starch solution instead of that of soluble starch. Although in all the
fermentation tests there was a destruction of some of the soluble matter
by the yeast, yet that remaining is more than the soluble matter of the
flour itself. In every case there is much less soluble protein obtained
from the doughs than from the original flour. The reducing sugars are
calculated as maltose from the cupric reducing power of the solutions in
each case. It is difficult to see why this should have been less in Nos. II.
and III., but still the fact remains.

In the fermented doughs, hydrolysis of starch and fermentation of
sugar are proceeding together, and except in No. VII., the combined
causes have caused a diminution in the reducing sugars. The solutions
were in all cases inverted in the ordinary manner by the addition of
hydrochloric acid and heating to 68° C. The consequent increased cupric
reducing power was ascribed to the presence of cane sugar and calculated
as such. Here again there are some anomalies, as the flour yielded only
0.19 per cent, of non-reducing sugar. Under the influence of salt, No. I.,
and salt and malt, No. II., this figure increased in these doughs to 2.67
and 4.38 respectively. This treatment can scarcely be expected to have
actually resulted in the production of cane sugar. It is suggested as a

370

THE TECHNOLOGY OF BREAD MAKING.

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BREAD-MAKING. 371

possible explanation that the soluble extract may have consisted in part
of soluble starch or some of the higher and unstable dextrins, and that
these were converted into maltose by the hydrochloric acid, and hence the
considerable increase in cupric reducing power. In the case of all the
fermented doughs, there is an increase in the non-reducing sugars, deter-
mined in the same manner. The acidity results are rather surprising, as
in all, including the very long fermentation, No. IV., the quantity ob-
tained is practically the same.

Further Data on Doughs. — With the aid of the preceding tables some
further data may now be given of these doughs. These follow and are
mostly self-explanatory. The weights of raw materials are given, and also
that of the dough, showing the loss incurred in making. The loss in fer-
mentation is that obtained by direct weighing before and after. The
volume of gas was that read off in c.c. in each experiment. This was con-
verted into grams by multiplying by the factor, 0.00185. As 100 grams
of sugar are required for the production of 46.4 grams of carbon dioxide,
the number of c.c. of gas, multiplied by the factor 0.004, gives the weight
of sugar required for its production. The alcohol produced may be taken
as about one-half the sugar required. The figures obtained in this man-
ner must be regarded as only approximate, but represent with a reason-
able degree of accuracy the results in the particular experiments. The
soluble extract of the fermented dough is calculated from that of its
constituents, while that of the unfermented dough was directly deter-
mined.

There was a certain amount of loss in weight during the time of re-
maining in the fermenting apparatus even with the doughs which con-
tained no yeast. In the fermented doughs, the loss in weight varied from
3.20 to 5.60 grams, or 1.07 to 1.87 per cent. The weight of carbon dioxide
evolved varied from 3.09 to 4.71 grams, and in most cases very nearly
agreed with the loss in weight of the dough. Apparently therefore very
little escapes from the dough during fermentation except the gas pro-
duced, the alcohol remaining in the dough. The determined loss of
weight and calculated amount of alcohol produced together are in close
agreement with the sugar which has disappeared. From the foregoing
data it was possible to arrive at approximately the amount of matter
rendered soluble during fermentation. On subtracting the soluble matter
of the unfermented dough from that found after fermentation, and then
adding on the sugar which has been decomposed into gas and alcohol, the
resultant figure is that required. Except in the case of No. V., where
sugar was added to the dough, the soluble matter of the fermented is
greater than that of the unfermented dough, notwithstanding the con-
tinuous diminution of same by gas production. It will be first of all
interesting to observe the respective amounts of hydrolysis in each case.
With the flour inself there is a noticeable increase, 1.35 per cent, of its
water-free solids having been rendered soluble. As might be expected,
the malt flour in No. II. greatly increased this figure. Fermentation for
6 hours resulted in rather more soluble extract, while the figure was much
more with the longer fermentation. The addition of sugar to the dough
lessened the amount of soluble matter produced by fermentation. That
with gelatinised starch, No. VI., is very nearly the same as the plain
dough, No. III. In No. VI., where malt flour has been added, the produc-
tion of soluble matter has been very high ; in the case of No. VIII., con-
taining both malt flour and gelatinised starch, there is less conversion
during fermentation, but still considerably more than in the dough with
gelatinised starch alone. The amount of residual soluble matter after

372 THE TECHNOLOGY OF BREAD-MAKING.

fermentation affords some guide as to the factors governing the probable
moisture and flavour character of the resultant bread. Comparing Nos.
III. and IV., the much prolonged fermentation of the latter has not
diminished the amount of soluble matter remaining in the fermented
dough, the figures being 3.81 and 3.97 per cent. In other words, the pro-
duction of soluble matter by hydrolysis has more than kept pace with its
removal by fermentation in the longer time. The addition of sugar in
No. V. has not resulted in an increase of residual soluble matter. With
gelatinised starch there is a slight increase. Malt flour shows a high
figure of soluble matter, which is still higher when gelatinised starch has
also been added. Summarising the results under three heads : —

I. Stimulus to Fermentation. — Both sugar and gelatinised starch
cause a slight increase, malt flour alone a very large increase.

II. Stimulus to Hydrolysis (production of soluble matter). —Rather
less when sugar has been added. Much increased by malt flour, and also
increased by same, though to less extent when gelatinised starch is also
added.

III. Effect on Residual Soluble Matter. — Not increased by this
amount of sugar, increased by gelatinised starch, still more by malt flour,
and yet more by malt flour and gelatinised starch conjointly.

523. Further Experiments on Diastatic Action. — In order to study
more closely the exact effects produced in bread-making by the action of
diastase, the following experiments were made : — Diastase was first ex-
tracted from malt by Lintner's process of treating the ground malt in
the cold for 12 hours with 20 per cent, alcohol : this was- filtered off and
precipitated with concentrated alcohol. The precipitate was collected on
a filter, washed first with absolute alcohol, then with ether, and dried over
sulphuric acid in vacuo. This preparation is termed malt diastase. From
a sample of low-grade spring American flour, flour diastase was prepared
in a precisely similar manner. From malt a fresh 10 per cent, cold-water
infusion was prepared and filtered ; this is termed malt infusion. No. 4
preparation is a commercial product sold as ' * diastase, ' ' and obtained by
evaporating a cold-water infusion of malt to the consistency of a syrup
in vacuo. The fifth was a high-class sample of guaranteed pure malt ex-
tract.

Their diastatic value was first determined by Lintner's process on
soluble starch, with the following results : —

Diastatic Value.

No. 1. Malt Diastase 266.6° Lintner.

11 2. Flour Diastase 228.5°

" 3. Malt Infusion 15.6°

" 4. "Diastase" 222.2°

" 5. Malt Extract .. 3.1°

It was decided to make a series of baking tests with these substances,
taking such quantities as would contain throughout the same number of
units of diastatic activity : knowing the diastatic value of each, it becomes
a matter of simple calculation to determine what quantities must be
taken in order to attain this object. Taking the malt diastase as a stand-
ard, the amount of 0.125 gram was fixed on : the equivalent quantities
of the others were as follows : —

No. 1. Malt Diastase 0.125 gram.

" 2. Flour Diastase 0.145 "

" 3. Malt Infusion 21.36 c.c.

" 4. "Diastase" .. , 0.153 gram.

" 5. Malt Extract . . . . . . . . 10,75 grams.

BREAD-MAKING. 373

For baking tests the following quantities were taken : —

Flour, equal quantities of Spring American and English

wheat patents . . . . . . . . . . 140 grams.

Water, in which was included solutions of the equivalent

quantity of each diastatic body . . . . . . 80 "

Compressed yeast . . . . . . . . . . . . 10 "

In one series of tests, a, the diastatic ingredient was in its normally
active state : in a second series, b, precisely similar in every other respect,
the diastatic solution was first placed in a boiling water bath for 5
minutes with the object of destroying the diastase, and subsequently
cooled prior to mixing it in with the flour and yeast. A plain loaf, No.
6, was also made from flour, water, and yeast only.

The doughs were allowed to ferment at a moderate temperature, and
the following observations made on their being ready to go into the oven.

No. 1. Difference between a and 1) very marked; a slacker and more

sticky.
" 2. Very slight difference, if any.

3. a, slightly sticky, difference between it and b not very marked.
" 4. Clearly marked difference between a and b.

" 5. a, fairly stiff, not sticky ; &, tougher than a • both brown in colour

as a result of presence of extract.
" 6. Plain loaf. Compared with all others, stiff.

The loaves were baked in a moderate oven for 45 minutes, and were
of Coburg shape, giving as much facility for expansion and formation of
crust as possible.

The following was the character of the crust : —

No. 1. a browner than b.

" 2. No difference between a and b : both much like No. 6.
" 3. a slightly browner than b.
11 4. a slightly browner than b.

5. Both full brown in colour of surface, and dark in breaks : a

browner than b.
" 6. Plain loaf.

As a rule "the crusts of series a seemed more pliable than those of b.
Throughout the whole series, with the exception of the No. 2's, there was
a distinct difference of flavour distinguishable before the loaves were cut.1

The crumb of each had the following characters : —

No. 1. Good volume: a in centre sticky and gummy; b, better colour.

Flavour in both decidedly sweet, but far more so in a.
2. a, only slightly sweeter than b ; b, better colour, both slightly

darker than No. 6.

" 3. a, sweet and malty; b, ditto in less degree, and slightly better in
colour.

4. a has more flavour than b, and is also very slightly better in colour

than b. Duplicate loaves were baked with No. 4 to see if the
colours were relatively the same. Found b again to be darker
than a, and of considerably less volume.

1 This is a somewhat curious instance of the baker's use of the term "fla-
vour": bakers habitually examine bread in the first instance by the smell of a
loaf, and judge flavour through its subtle association with smell. Such flavour
judgment may be described as "haw the bread tastes to the nose,"

374 THE TECHNOLOGY OP BREAD-MAKING.

No. 5* Both a and & were brown, with very slight difference in colour.
Flavour of & distinctly that of malt extract. Flavour of a
different, being that of malt extract with an additional flavour
of a more purely saccharine character (doubtless the result of
the presence of sugars of conversion).
" 6. Plain loaf, slightly yeasty in flavour.

A portion of each sample of bread was taken, dried to a constant
weight in the hot-water oven, finely powdered, and stored in stoppered
bottles. A soluble extract was prepared from each in the following man-
ner : — 10 grams of the powdered solids were taken during the afternoon,
mixed with 100 c.c. of cold water, and vigorously shaken several times
during the afternoon . and evening. They were then allowed to stand
overnight, and the supernatant-liquid decanted in the morning, without
disturbing the residue, and filtered. A portion of this was evaporated
to dryness for soluble extract, and the maltose determined in another
portion. The following are the results of analysis expressed in percent-
ages on the dried solids : —

ANALYSES OP DIASTASE BREADS.

No. Variety. Soluble Extracts. Maltose.

1 Malt Diastase . . . . 27*24 8.04 7.83 2.90 4?93

2 Flour Diastase .. .. 10.40 9.65 1.61 1.61 0.00

3 Malt Infusion . . . . 17.75 10.55 4.44 3.63 0.81

4 "Diastase" .. .-. 9.20 6.12 2.5 1.13 1.37

5 Malt Extract . . . . 16.04 8.76 5.60 3.23 2.37

6 Plain Loaf . . . . 7.60 1.61

In examining these results, the first noticeable point is that in No. 1,
&, there is a considerable quantity of maltose over that in No. 6. The
same is particularly observed also in No. 3 : it would seem therefore that
the means employed in order to destroy saccharifying action were not
sufficient. As No. 3 was by far the largest amount of liquid solution of
diastatic ingredient acted on, its temperature was taken at the end of the
five minutes in the water-bath, and found to be 198° F%; at the same
time there was an abundant flocculent precipitate of coagulated proteins.
That the maltose in No. 3, &, is the highest of that series also points to
insufficient heating, for the other solutions, which were considerably less
in volume, had apparently much more of their diastatic action destroyed.

The following are the approximate percentages of maltose in each
bread, due to' that actually added in the extract preparation : —

Maltose.

No. 1. Malt Diastase . . . . 0.00

" 2. Flour .. . . 0.00

" 3. Malt Infusion 0.38

11 4. Diastase 0.08

" 5. Malt Extract 5.10

In the last case the maltose thus addejl is very nearly the whole of
that found in No. 5, a, and more than in No. 5, &. The mode of extrac-
tion employed, although giving strictly comparative results, does not
however remove the whole of the maltose in solution from the solids. The
vesicular nature of bread, in which the various constituents are locked up

BREAD-MAKING. 375

within films of coagulated protein matter, makes the entire extraction of
the soluble ingredients a task of considerable difficulty and uncertainty.1

The column headed a-b, gives the maltose due to conversion of starch
though not necessarily the whole of such maltose.

524. Highly Diastatic Malt Extracts. — The preceding experiments
throw a light on the effects produced by highly diastatic extracts during
bread-making. Taking the column, a-h, malt diastase prepared by extrac-
tion and precipitation from the malt as described, effected the produc-
tion of 4.93 per cent, of maltose. Flour diastase, the quantity of which
taken had an equal diastatic value by Lintner's method on soluble starch,
effects no conversion whatever. So also the malt infusion effects com-
paratively little change. It will be remembered that certain forms of
diastase are able to convert starch paste, while others can only act on
soluble starch (see paragraph 267) ; raw grain diastase belongs to the
latter group, and hence, doubtless, its inability to convert the starch of
flour. The diastatic value of any preparation for bread-making depends
not simply on its activity as measured on soluble starch by Lintner's
method, but on its power of converting starch paste, and even the im-
perfectly gelatinised starch occurring in bread.

The commercial "diastase," preparation No. 4, is a compound con-
sisting essentially of the concentrated cold-water extract of malt, so pre-
pared as to retain the diastatic activity of malt in the highest possible
degree. Various samples have given a diastatic capacity on Lintner's
scale varying from about 220° in the lowest to considerably over 300° in
the highest. The following is the result of its analysis : —

ANALYSIS OF "DIASTASE."

Whole Dried

Constituents. Extracts. Solids.

Water 27.90

Mineral Matter (Phosphates) 3.32 4.60

Proteins 13.41 18.60

Dextrin 0.40 8.88

Sucrose 2.20 3.05

Maltose 15.09 20.93

Dextrose and Laevulose 31.68 43.94

100.00 100.00

Cuprous Oxide, Cu20, from 100 grams . . . . 81.75 113.4

Reducing Sugars, calculated as Dextrose and

Ljevulose 41.09 56.99

The effect of this body on bread, when taken in a quantity having the
same diastatic value as the other substances tested, is much less than that
of chemically prepared malt diastase, though much more than the raw
flour diastase. This concentrated cold-water extract is therefore to be
differentiated from both pure malt diastase and raw grain diastase in its

1 The plan of determining soluble extract in dried solids is no doubt respon-
sible for generally low figures. The great advantage of the method is that the
solids can be kept in an unaltered form until a convenient time for their analy-
sis arrives. This is obviously impossible with moist breads. Recently the
author has, in the absence of enzymes (as in bread analysis), used the modifi-
cation of direct -extraction from moist bread. He then simply places the bread
and water together in a flask, adds a few drops of chloroform, corks and shakes,
and sets aside without fear of change occurring during an interval of waiting.
This is particularly applicable to determinations of maltose.

376 THE TECHNOLOGY OF BREAD-MAKING.

effects. Its behaviour indicates the presence of a considerable proportion
of the non-liquefying form of diastase. At the same time the true lique-
fying malt diastase is also present, though not to the same extent as in
the ordinary malt extract, No. 5, which with the same Lintner value on
the quantities taken gave a much higher production of maltose. But
against this must be remembered the quantities actually used : of the
"diastase" there was only 0.153 gram as compared with 10.75 grams of
malt extract. In giving a value to degrees Lintner as a measure of utility
of a malt extract to bakers, it may generally be concluded that an extract
of say 120° Lintner will produce more maltose in bread-making than one
of 60° Lintner, but not so much as double the quantity. The extra dias-
tatic power is probably due in part to liquefying, and therefore sacchari-
fying diastase, and in part to non-liquefying, and therefore non-effective
diastase. The use of 2 Ibs. of the 60° Lintner malt extract will as a gen-
eral rule in bread-making convert more starch into sugar than will 1 Ib.
of the 120° Lintner extract. Further the 2 Ibs. will have imparted to the
bread all the extra sugar, dextrin, etc., naturally present therein. It
must not be forgotten that the flavouring effect of malt extract as a bread
improver is largely due to the empyreumatic products resulting from the
kiln drying of the malt itself. Everything else being equal, with less
malt extract, less of these products will be added to the bread. In addi-
tion, in order to secure a high degree of diastase, the malt is usually low
kiln dried, and so the empyreumatic products are only very slightly de-
veloped. The introduction of a small quantity of a highly diastatic ex-
tract at the dough stage suffices for the conversion of a marked amount
of starch into dextrin and maltose, thus conferring both moistness and
sweetness on the bread. It also exerts a considerable action on the pro-
teins of flour, producing a softening effect on the gluten. In the case
where strong, harsh, and dry flours are in use, the result is to make the
resultant bread approach far more closely in character to that made from
softer arid sweeter flours. One word of caution may be here introduced
as to the employment of these exceptionally powerful extracts; these
preparations are so energetic as to be capable of carrying too far the
changes in starch and other flour ingredients, and thus yielding a wet,
clammy loaf. The obvious remedy is to employ the substance in less
proportion. The precise amount is easily determined by a very few trials.

525. Typical American High-grade Yeast Bread. — Wiley regards
the following as representing the average composition of a bread of this
type :—

Moisture . . . . . . . . . . 35.00 per cent.

Protein . . . . 8.00

Ether Extract 0.75

Starch and Sugar 54.45

Fibre 0.30

Ash 1.50

The ash would approximately consist of 0.50 per cent, derived from
the natural mineral ingredients of the flour, and 1.0 per cent, due to the
addition of salt. The moisture may rise above 40 per cent, in breads
made of flour rich in gluten, or sink to 30 per cent, or under when flour
of an inferior gluten content is employed. The ether extract will vary
according to the amount of milk or other source of fat employed in mak-
ing the bread, or in the case of tin bread, in greasing the baking tin.

526. Analyses of Commercial Breads. — The following table gives the
results of analyses by the authors of a number of samples of bread

BREAD-MAKING.

377

bought for that purpose. They were in all cases ordinary shop prod-
ucts, and were purchased without giving any intimation of the ob-
ject for which they were procured, either to the bakers or the manufac-
turers of the flours. The results of the analyses are given on the whole
breads, and also as calculated on the water-free solids. The energy in
Calories is also given. For this purpose the whole of the carbohydrates,
including cellulose, are reckoned together.

Names of Breads.

No. 1. Best white bread.

11 2. London households.

" 3. Whole-meal bread.

" 4. Bermaline bread.

" 5. Hovis bread.

" 6. Daren bread.

" 1. Veda bread.

" 8. Turog bread.

ANALYSES OF COMMERCIAL BREADS.

, No.

1. ,

, No.

2. ,

No.

3. ,

. No.

4. ,

Constituents.

Water

Bought

Free.

Bought

Free.

Bought

Free.

Bought

Free.

Moisture

38.35

40.00

44.56

42.94

Proteins, Soluble

0.42

0.68

0.57

0.95

0.57

1.03

0.35

0.61

Proteins, Insoluble

6.62

10.73

7.93

13.22

7.13

12.86

6.69

11.72

Starch, Cellulose, etc

45.53

73.86

40.48

67.47

33.20

59.89

32.39

56.69

Maltose

4.44

7.22

3.58

5.96

6.70

12.08

7.03

12.32

Other 'Soluble Matters

2.82

4.57

5.95

9.92

4.29

7.74

7.78

13.63

Phosphoric Acid

0.09

0.14

0.18

0.30

0.46

0.83

0.42

0.74

Other Mineral Matter

0.71

1.15

0.50

0.83

0.89

1.60

0.70

1.32

Acidity as Lactic Acid

0.25

0.40

0.24

0.40

0.45

0.81

0.40

0.70

Fat

077

1.25

0.57

0.95

1.75

3.16

1.30

2 27

Energy in Calories

251.7

243.9

229.*2

234.*5

Li*Lt (

. No.

5. ,

, No.

6. ,

. No.

7. ,

. No.

8. .

Moisture

47.81

45.02

32.57

46.82

Proteins, Soluble

0.35

0.67

1.17

2.12

0.90

1.33

0.58

1.09

Proteins, Insoluble

9.26

17.74

7.83

14.24

8.49

12.59

8.72

16.39

Starch, Cellulose, etc.

27.21

52.15

24.07

43.78

16.38

24.29

36.68

68.97

Maltose

6.46

12.37

6.81

12.40

19.87

29.47

3.40

6.39

Other Soluble Matters

6.15

11.80

12.22

22.22

20.03

29.71

1.78

3.35

Phosphoric Acid

0.43

0.83

0.56

1.02

0.41

0.61

0.39

0.74

Other Mineral Matter

0.60

1.13

0.72

1.31

0.59

0.88

0.53

0.99

Acidity as Lactic Acid

0.43

0.82

0.40

0.73

0.51

0.75

0.50

0.95

Fat

1.30

2.49

1.20

2.18

0.25

0.37

0.60

1.13

Energy in Calories

214.7

—

239.0

—

304.3

215.3

527. Bread Improvers. — In the manufacture of bread, the addition
of certain other substances than flour and water is a recognised and in-
tegral part of the manufacture. When brewer's yeast was the only type
used, some yeast stimulant was absolutely necessary for reasons already
explained (paragraphs 375-8). Potatoes were found exceedingly useful
and convenient for the purpose, and accordingly the potato ferment was
at one time a regular part of the process of bread-making. With the use
of distiller's yeast, the necessity of some stimulant for the yeast no longer
existed, and accordingly potatoes have largely gone out of use. But there
are other functions in bread-making fulfilled by the potato, and these
continue to require attention. Substances added for the purpose of ef-
fecting improvements in bread may be grouped into the following
classes : —

Milk. — Whole, dried, or separated ; improves flavour, appearance and
nutritive value.

378 THE TECHNOLOGY OF BREAD-MAKING.

Butter. — This and other fats improve flavour and shorten crust, thus
preventing toughness.

Moist ness-retaining bodies. — In their pure state, some flours, and par-
ticularly those which are the most nourishing as a result of their high
percentage of proteins, produce a bread which readily becomes somewhat
dry and harsh. To remedy this, an increase in the quantity of gelatin-
ised starch and dextrin removes harshness and makes the bread remain
moist and taste moist much longer.

Potatoes. — The ordinary boiled potato has the effect just mentioned.
As a substitute, it has been proposed to dry potatoes and grind them into
a meal or flour. Such a preparation, however, only adds starch in the
ungelatinised form, and cannot increase the moistness as a consequence.
Whatever soluble constituents the potato contains are thus introduced
into the bread. Recently, preparations have been placed on the market
which consist of thoroughly cooked potatoes, dried and reduced to a fine
powder. These are capable of acting as a direct substitute for the boiled
potato, introducing the same substances and avoiding the mess and dirt
which almost of necessity accompany the cooking of potatoes in a bake-
house.

Gelatinised Starches. — Among members of this group, the use of
scalded flour is pre-eminent. This adds gelatinised starch, which may be
used in a ferment, or if wished may be added to the dough. Scalded rice
and maize also produce the same effects. The employment of all or any
of these has the advantage of greater cleanliness in manipulation than
occurs with potatoes. All are sources of gelatinised starch. Certain
grains and other starchy bodies are now gelatinised, dried off and sold
in the form of thin flakes. These may be used as ready-gelatinised forms
of starch which require no cooking.

Dextrinous bodies. — From its well-known gummy properties, dextrin
serves to keep bread moist. Its principal sources in bread are, starch
which has been converted into dextrin by enzymes, malt extract, and so-
called confectioners7 glucose, which is really almost entirely composed of
dextrin and maltose (see Chapter XXVIII.).

Sweetening bodies. — Sweetness may be conferred by the addition of
pure sugar or by the use of malt extract or " glucose,'7 both of which
contain maltose in large quantities. When gelatinised starch is acted on
by diastase, more or less maltose is formed. Maltose may be thus pro-
duced from the starch of the flour itself, or from that added in the gela-
tinised condition from any other source. In addition to its flavouring
properties, sugar serves the yeast as a source of carbon dioxide gas.

Diastatic bodies. — Various enzymes serve the purpose of converting
starch into dextrin and maltose. Flour itself contains a considerable
quantity of diastase. Carefully prepared malt extract is also actively
diastatic, while certain special forms contain diastase in a very concen-
trated degree. Malt flour, particularly that of air-dried malt, is also rich
in diastatic power. All these substances are used for bread-making pur-
poses. In addition to the starch converting diastase, these bodies may
contain more or less of proteolytic enzymes by which the gluten of flour
is affected. The charges thus produced may be beneficial or otherwise
according to the nature and quality of the gluten.

Mineral bodies. — First among these is common salt, which in addition
to its flavouring properties acts as a binding or strengthening agent on
the dough. Certain other mineral bodies have beneficial effects on bread.
One of these is calcium chloride, which in small quantities serves as a

BREAD-MAKING. 379

strengthening agent, and also may be useful as a source of lime for nutri-
tive purposes. In its general properties calcium chloride falls into some-
what the same category as salt. Magnesium sulphate is at times em-
ployed, more especially it is said in some of the Midland counties of
England. For reasons already given, the addition of phosphates and
phosphoric acid serves to effect some improvements in bread.

Yeast nourishing bodies. — Several of the substances already men-
tioned are of service as direct or indirect yeast foods; among these are
sugars and the bodies from which derived, the diastases which produce
sugar, and some mineral salts. In addition to these some bodies rich in
organic nitrogenous constituents are of value as food and stimulants for
yeast.

528. Malt Extract. — This being one of the substances most largely
used for the improvement of bread, its preparation and properties re-
quire a somewhat extended description. Malt extract is prepared by
evaporating at a low temperature in vacuo the filtered wort from mashed
malt until the resultant liquid is of the consistency of a thick syrup. In
order to investigate the composition of malt extract under different con-
ditions, the following experiments were made : —

A high qualitjr sample of pale malt was finely ground; and of this 500
grams were taken, mixed with 2,000 c.c. of water, and mashed for 2
hours, at a temperature of 60° C., in a water- jacketed pan. The result-
ant wort was then filtered bright, and the "grains" washed, dried and
weighed, their weight being 113 grams, showing that over 75 per cent, of
the malt had gone into solution. This wort was called Preparation I.,
Unevaporated. A portion was reserved for analysis, and the remainder
evaporated in vacuo, the operation being pushed as far as possible : this
constituted Preparation I., Evaporated.

Another 500 grams of the malt were then taken, mixed with 2,000 c.c.
cold water, continually stirred during 3 hours, and then allowed to stand
overnight. The clear liquid was poured off in the morning, the residual
malt drained moderately dry. The liquid was filtered bright, and con-
stituted Preparation II., Unevaporated. A part of this was evaporated
in precisely the same manner as with No. I., and is termed Preparation
II., Evaporated.

The residual malt from No. II. was next taken, mashed with 2,000 c.c.
more water for 6 hours, at 60° C., and then raised to 100° C., and filtered
bright. This constituted Preparation III., Unevaporated. A portion was
evaporated in vacuo as before, and this formed Preparation III., Evapo-
rated.

Each of these was then subjected to analysis, determinations being
made as given in the table of analyses following, in which are also in-
cluded similar analyses of commercial samples of guaranteed pure malt
extract.

Various determinations, as given below, were made on the Unevapo-
rated Preparations.

No. I. No. II. No. III.

Specific gravity at 15.0° C 1,057.5 1,020.7 1,050.0

Dry Solids, grams per 100 c.c. calcu-
lated from gravity . . . . 14.93 5.37 13.00

Dry Solids, grains per 100 c.c. by evap-
oration and weighing . . . . 14.06 4.93 12.78

Dry Solids, weight in percentages . . 13.30 4.83 12.17

The method of analysis employed is that described in Chapter XXIV.,
and is subject to the limitations of accuracy there explained. It should

380 THE TECHNOLOGY OF BREAD-MAKING.

be mentioned that all the figures, both on the liquids and the extracts, are
the results of direct determinations; the percentage composition of
" Dried Solids" being calculated from those obtained in the liquid or ex-
tract with water present. The dextrin was precipitated by alcohol and
corrected for solubility and amount of precipitated protein : it no doubt
contains not only pure dextrin, but also the other gum-like substance?
frequently returned as "indeterminate bodies."

The No. I., or whole extract, contained sucrose in the wort, but this
disappeared during concentration. The glucoses also show a diminution,
while dextrin increases. The dextrin precipitate in the evaporated ex-
tract was much darker, and evidently contained a considerable propor-
tion of products of caramelisation.

The -cold water extracts, No. II., are very interesting. The proteins
and phosphates are very high : so also is the sucrose, which, however,
diminishes on concentration. The quantity of maltose is very small,
while the glucoses represent about half the total weight of the solids
present. The sugars here again diminish during concentration, while
dextrin increases, no doubt for the same reason as in No. I.

In No. III., as might be expected, sucrose is absent, any traces in the
original solution being doubtless destroyed during the prolonged mash-
ing. Glucose (dextrose) and laBvulose are present in very small quantity,
the sugar being almost entirely maltose. As might be expected, the dex-
trin is high, and the act of concentration has produced practically no
alteration in the proportions of the constituents present, the lengthened
period of mashing and subsequent boiling having reduced all bodies pres-
ent to a stable condition.

The above three types of extract are sometimes called —

No. I. Whole extract, being the entire extract of the malt.

No. II. Cold water extract, from the fact of its containing the cold
water soluble constituents only.

No. III. Spent extract, being prepared from the comparatively spent
grains after extraction with cold water. This is also sometimes called a
"split" extract, since the products of the malt are split into two separate
lots in its production.

All three of these are more or less represented in commercial extracts,
the first being the older and purely normal type of the whole malt. With
the demand for extracts of high diastatic power, No. II. type came into
the market. The manufacture of No. II. made the preparation of No. III.
a necessity in order to utilise the very large proportion of residual matter
from making the cold water extract.

In diastatic power, No. I., if properly prepared and carefully concen-
trated, should be of fair quality. No. II. will be of very high diastatic
value, while No. III. will be devoid of any diastatic power whatever.

Modern manufacturing processes are a combination of the various
methods described, mashing being made at various temperatures, or at a
lower than normal temperature in order to retain diastase ; while a good
deal of the purely saccharine extract is sacrificed, or obtained in a further
extraction, when it may or may not be mixed in with the first or more
diastatic extract.

The samples of commercial extract call for but little remark; in the
first, the dextrin is fairly high, and so also is the maltose ; sucrose, dex-
trose, and laevulose being present in small quantity. At the same time,
the sample is well concentrated, but 22.23 per cent, of water being pres-
ent. With any less moisture the extract would be too stiff to pour out of
tins or drums when cold. The second commercial sample affords evidence

BREAD-MAKING.

381

of having been worked at a higher temperature, although the degree of
concentration is less. Both these extracts show all signs of being nothing
beyond pure, normal extracts of malt.

In breadmaking, the addition of malt extract, in the first place, in-
creases, to the extent to which it is used, the quantities present of the
various ingredients of the extract, among which are sugars which impart
sweetness ; dextrin, by which the bread is caused to remain moister ; and
phosphates, which add to the bone-forming materials, and also act as a
yeast stimulant. There is in addition the specific effect on the constitu-
ents of the flour caused by the diastase present in the extract.

ANALYSES OF MALT EXTRACT PREPARATIONS.

No. I., Unevaporated.

No. I., Evaporated.

Constituents.

Water

Whole
Liquid.
86.70

Dried
Solids. .

1.77
6.44
9.95
3.23
68.03
10.58

Whole
Extract.

14.70
1.70
5.27
10.82
Absent
60.97
6.54

Dried
Solids.

1.99
6.18

12.68
Absent
71.48
7.67

Mineral Matter (Phosphates)
Proteins

0.24
0.86

Dextrin
Sucrose
Maltose
Glucose and Laevulose

Cuprous Oxide, Cu^O, from 100 grams
Reducing Sugars, calculated entirely
as Maltose

Water

1.32
0.43
9.04
1.41

100.00
13.99

11.30

No. II.,

95.17

100.00
105.2

84.98

Unevaporated.

6.52
16.56
12.36
9.31
4.20
51.05

100.00
87.50

70.67

No. II.,

22.90
4.80
12.71
13.66
4.79
2.69
38.45

100.00
103.70

82.85

Evaporated.

6.23
16.49
17.72
6.21
3.48
49.87

Mineral Matter (Phosphates)
Proteins . . . .
Dextrin
Sucrose
Maltose

0.32
0.80
0.60
0.45
0.21

Glucose and Lsevulose

Cuprous Oxide, Cu20, from 100 grams
Reducing Sugars, calculated entirely
as Glucose and Laevulose

Water

2.45

100.00
5.11

2.57
No. III.,
87.83

100.00
106.43

53.66

Unevaporated.

1.40
3.61
20.03
t Absent
72.45
2.51

100.00
79.49

40.08

No. III.,

11.20

1.11

3.37
17.40
Absent
66.06
0.86

100.00
103.10

51.99

Evaporated.

1.24
3.79
19.60
Absent
74.40
0.97

Mineral Matter (Phosphates)
Proteins

0.17
0 44

Dextrin
Sucrose
Maltose
Glucose and Laevulose

Cuprous Oxide, Cu:0, from 100 grams
Reducing Sugars, calculated as Maltose

Water
Mineral Matter (Phosphates) ..
Proteins
Dextrin
Sucrose
Maltose
Glucose and Laevulose

Cuprous Oxide, Cu2O, from 100 grams
Reducing Sugars, calculated as Maltose

2.44
Absenl
8.82
0.30

100.00 100.00
11.52 94.67
9.31 76.48
FIRST COMMERCIAL
EXTRACT.
Whole Dried
Extract. Solids.

22.23
1.10 1.42
3.01 3.88
12.90 16.59
3.59 4.61
54.84 70.51
2.33 2.99

100.00 100.00
83.5 94.03
67.44 75.94

SECOND COMMERCIAL
EXTRACT.
Whole Dried
Extract. Solids.
27.64 —

1.40 1.93
4.74 6.55
5.80 8.02
1.92 2.66
53.65 74.14
4.85 6.70

100.00
72.5
58.55

100.00
93.22

75.28

100.00
80.0
64.61

100.00
110.5
89.29

382 THE TECHNOLOGY OF BREAD-MAKING.

THE NUTRITIVE VALUE AND DIGESTIBILITY OF BREAD.

529. Nutrition and Food. — Nutrition may be regarded as the proc-
ess of supplying the materials necessary in order to effect the growth and
development of living organisms, and the maintenance in a healthy con-
dition of those organisms when fully developed. The human organism is
for practical purposes the only being whose requirements need be here
considered. Food may be regarded as that which when taken into the
body provides material for its growth and development, the reparation of
the waste of its tissues, the production of heat, and the energy necessary
both for internal and external muscular work. In other words food com-
prises those substances which are available for purposes of nutrition.

Food substances or " nutrients" are derived from the animal, vege-
table, and mineral kingdom. They belong to the following chemical
groups of substances — proteins and closely allied bodies, as sclero-pro-
teins (gelatin), carbohydrates, fats, and mineral matters, especially those
containing lime, potassium, sodium, phosphorus, and chlorine, also water.
An old classification of nutrients was into flesh formers, as proteins ; heat-
formers, as carbohydrates and fat; and bone-formers, as calcium phos-
phate. A more modern arrangement is into the two groups of tissue-
formers and work arid heat producers as under : —

Tissue-formers. Work and Heat Producers.

Proteins. Proteins.

Mineral Matters. Sclero-Proteins.

Water. Carbohydrates.

Fats.

( ?) Mineral Matters and Water.

The proteins are distinguished from among the other organic constitu-
ents of food by their being capable of exercising both the above-men-
tioned functions of nutrition.

In estimating the nutritive value of foods they are subjected to tests
of three kinds : —

I. Chemical analysis, by which the proportions of the various con-
stituents are determined.

II. The heat produced by their combustion in oxygen, this being a
measure of their heat and energy producing capacity.

III. Physiological tests, in which their degree of capacity for utilisa-
tion by the body is measured.

The general composition as ascertained by chemical analysis need not
be further enlarged on here.

530. Heat of Combustion. — This requires some further description.
Excluding the mineral matters and water, the other food constituents are
all combustible, and each variety evolves a definite amount of heat when
completely burned, depending on its composition. The unit measure of
heat is that which is required to raise 1 gram of water from 0° to 1° C.,
and this is called a 1 1 calorie. ' ' For food valuations a larger unit is con-
venient; and accordingly, that selected is the large or kilo-calorie, which
is the amount of heat necessary to raise 1 kilogram (1,000 c.c.) from 0°
to 1° C. The kilo-calorie or large Calorie is indicated by its being spelled
with a capital C. When burned with an excess of oxygen the whole of
the constituents of any food are completely oxidised ; but when consumed
in the body, they are finally excreted in only a partially oxidised state,
and therefore some allowance must be made for the heat still remaining
unused in these bodies. That having been done, the amount of energy
liberated by any food follows just the same laws as though it were burned

BREAD-MAKING. 383

m the ordinary way. The heat liberated within the body by the follow-
ing substances is, according to Hutchison : —

One gram of Proteins. . . . . . . . 4.1 Calories.

„ „ Carbohydrates . . . . . . 4.1 „

Fat .. 9.3

The energy value of a food is easily calculated from its analysis. If
the percentages of proteins and carbohydrates are multiplied by 4.1, and
that of the fat by 9.3, the sum of these numbers gives the energy in
Calories of the food itself. Thus if a sample of flour gives the following
results on analysis, the heat energy is as shown : —

Per cent. Factor. Heat of Combustion.

Protein . . : 11.08 X 4.1 = = 45.428

Carbohydrates 76.85 X 4.1 = 315.085

Fat .. 1.15X9-3= 10.695

Kilo-Calories per 100 grams 371.208

1 gram 3.71208

Gram-calories per 1 gram . . . . . . 3712.08

Snyder, to whose results a somewhat extended reference follows,
returns his "Heat of combustion" in terms of the complete oxidation
obtained by burning in oxygen, and without any deduction for incom-
plete combustion in the body. He uses therefore the following factors for
calculating the heat of combustion from the analysis. They are applied
to the same analysis of flour.

Per cent. Factor. Heat of Combustion.

Protein 11.08X5.9 = = 65.372

Carbohydrates 76.85X4.2 = 322.770

Fat 1.15X9.3= 10.695

Kilo-Calories per 100 grams 398.837

1 gram 3.988

Ditto determined direct on the flour . . . . 4.032

531. Digestibility. — In making physiological tests this term is used
as meaning the measure of the total amount of the food utilised or
absorbed by the body. The principle of the determination is the weigh-
ing the whole of the food of known composition eaten during a certain
period, and the estimation of the weight and composition of that which is
ejected in the excreta. The difference is the amount absorbed. The more
popular meaning attached to the word digestibility relates to the com-
parative ease or discomfort with which the food passes through the stom-
ach. In view of the use of the word in this latter sense, Hutchison has
proposed to use the word "absorbability" instead of digestibility when
dealing with the proportion of a food which is absorbed or utilised by the
body. But as most writers still employ digestibility as synonymous with
absorbability it will be used in that sense in this work.

532. Amount of Food Required. — To discuss this question ade-
•quately would require much more space than can possibly be devoted to

it here. The student is therefore referred to Food and Dietetics by
Hutchison for full information on this subject. From his most interest-
ing book the following summary is quoted : —

"One may sum up the standard amounts of the different nutritive
constituents required daily thus: —

Protein . . . . . . . . . . . . 125 grams.

Carbohydrate . . 500

Fat 50

384 T&E TECHNOLOGY OF BREAD-MAKING.

These would yield the following amount of energy in Calories : —

Protein 125 X 4.1 = 512.5

Carbohydrate . . . . 500 X 4.1 = 2050.0
Fat 50 X 9.3 = 465.0

Total . . . . = 3027.5 Calories.

Or, in terms of carbon and nitrogen : —

125 grams of Protein = 20 grams N and 62 grams C.

500 „ „ Carbohydrate = 200 „ „

50 „ „ Fat = ' 38 „ „

Total = 20 grams N and 300 grams C.

Such a standard may be regarded as the minimum for a man of
average build and weight, and doing a moderate amount of muscular
work. ... In such standards the ratio of protein to carbohydrates
and fat taken together is of some importance. It is called the nutritive
ratio. If 1 part of fat be counted as 2.25 parts of carbohydrate, the
nutritive ratio . . . is as 1 to 4.9. In this ratio we have an index of
the proportion which the building material of the diet ought to bear to
its purely energy-yielding constituents." For the figure 4.9, that of 5.3
more closely represents the average ratio of a number of authorities. In
the diet of a child the ratio should be approximately as 1 to 4.3.

533. Nutritive Ratio of Wheat Products. — The following figures of
Analysis are taken from those of spring and winter American wheats and
their products : —

Nutritive
Protein. Carbohydrates. . Fat. Ratio.

Spring Wheat .. .. 14.35 70.37 2.74 1:5.3

Baker's Flour . . . . 14.88 69.99 2.00 1 : 5.0

Patent Flour . . . . 12.95 73.55 1.45 1 : 5.9

Bran 16.28 . 56.21 5.03 1:4.1

Germ 33.25 35.19 15.61 1:2.1

Winter Wheat . . . . 12.43 71.67 2.46 1 : 6.2

Baker's Flour .. .. 13.13 71.52 1.77 1:5.4

Patent Flour . . . . 10.18 78.28 1.05 1 : 7.9

For the moment, neglecting the waste through variations in digestibil-
ity, spring wheat and spring wheat baker's flour contain sufficient protein
to comply with the standard nutritive ratio. Bran contains a large
excess of protein, while that in germ is approximately two and a half
times as much as required by the standard. Evidently a mixture of germ
and white flour may be made in such proportions as to comply exactly
with the nutritive ratio. The spring patent is slightly deficient in pro-'
tein, but the deficiency is but small. The winter wheat and its products
are all lower in protein matter. An interesting point is that the spring
patent flour has very nearly the same ratio as the baker's flour from
winter wheat. The baker's flours have a slightly higher nutritive ratio
than the wheats from which they were obtained, while the ratio is defi-
nitely lower in the case of the patent grades. English wheats, and the
general average of wheats milled in England, have a lower protein
content than spring American wheat. From analysis of a number of

BREAD-MAKING. 385

representative English millers' flours the following figures have been
deduced:—

Moisture
Proteins
Carbohydrates

. . 14.0 per cent.

11.0 „ „

72.7 „ „
15

Ash

0.5

Cellulose

0.3 „ „

100.0

Nutritive ratio . . . . . . . . 6.9

Viewed from the standpoint of a perfectly balanced food, such flour is
markedly deficient in fat, and slightly deficient in proteins. In an actual
mixed diet, these deficiencies are made up by the addition of butter to
bread, and the consumption therewith of such substances as lean meat
and cheese.

534. Relative Digestibility of Different Kinds of Bread.— In view
of the fact that most wheats and their resultant flours are, as just stated,
slightly deficient in proteins, the problem of their nutritive value is largely
governed by the extent of that deficiency. American spring wheat, and
consequently the whole meal (i.e., meal from the whole wheat kernel, bran
and all, or "Graham" flour), contain rather more than the standard pro
portion. But, as indicated, weaker wheats (e.g. American winter) and
most wheat mixtures contain less than the standard proportion. Further,
in every case the whole wheat contains more protein than the resultant
flour. This is a necessary consequence of removing the bran, which is
exceptionally rich in protein, during the process of milling. Therefore it
has been and is being urged that whole meal bread is more nourishing
than that from white flour. Obviously such a comparison can only be
made between the products of the same wheat. For example, patent flour
from spring wheat contains 12.95 per cent, of protein as against 12.43 in
whole winter wheat. But as against this, from each variety of wheat, the
whole wheat and the darker coloured baker's flour contain more protein
than does the patent or very white flour. In the case of a food it is of
importance to know not merely its percentage composition, but also what
proportion of it is digested and assimilated by the human alimentary sys-
tem in order to decide its relative nutritive value. This matter has been
made the subject of exhaustive investigation by a number of chemists and
physiologists. The following two lines of experiment have been
adopted : —

1. Bread is made from the different kinds of flour it is wished to
compare. Usually the comparison is between whole meal, and the darker
and lighter flours of the same wheat. At times flours of different lengths
of extraction have been taken, thus these may consist of say 60, 70, 80
or even a higher percentage of the wheat. Standard digestive mixtures
are prepared which resemble as closely as possible the actual digestive
juices of the body. These commonly consist of an acid solution of pepsin,
as representing the gastric or stomach agent of digestion, and, secondly,
an alkaline solution of pancreatin which represents the digestive juices
of the portions of the alimentary canal subsequent to the stomach. The
bread to be tested is rubbed down to a pulp and the pepsin solution
added in measured quantity. A flask containing the mixture is then kept
by means of a water-bath at a constant body temperature (98° F. =
36.6° C.) for a definite time, after which the pancreatic solution is added,

386 THE TECHNOLOGY OF BREAD-MAKING.

and the digestive action continued for a further time. At the close, the
mixture is filtered and the soluble matter identified and estimated. It is
in this way possible to determine what proportion of each bread is thus
dissolved by the digestive juices. Objection may be taken that this mode
of research cannot be regarded as necessarily exactly doing that which
Nature herself does. On the other hand, it does serve to ascertain the
actual solubility of, and changes produced in, a particular food under
definite conditions. If there is uncertainty as to its being an exact copy
of Nature ?s processes, there is the corresponding certainty that irregular-
ities due to the idiosyncrasies of individuals are eliminated.

Among others, Brunton, Tunnicliffe, and Jago have made extensive
investigations in this direction.

II. In the next place digestive experiments have been made on actual
human subjects. The general outline of such tests has been to feed
healthy individuals on a simple diet, of which the breads under examina-
tion form the principal constituent. All the articles of food are carefully
analysed, and the quantities given to each subject weighed. The weight
and composition of the faeces and urine are also determined. Then the
proportion of food digested is regarded as the difference between the total
nutrients of the diet, and those ejected in the excreta. Certain factors
are assumed for the digestibility of the nourishing bodies in the milk or
other extraneous articles, an allowance is made for these, and the digesti-
bility of the bread alone is thus estimated. The methods of arriving at
the amount of these and other allowances which must be made, together
with the precautions necessary in order to ensure accuracy, cannot be
discussed here, but are dealt with fully in the various original reports of
these investigations. The principle of these tests can be made quite clear
by an illustration, which is taken from a series in which the subject was
fed on bread and milk only. Taking the protein figures they are : —

Food Consumed — Bread 67.9 grams + milk 66.2 grams — 134.1
grams.

Excreta — 11.3 grams less from milk 2.0 grams == 9.3 grams, being
estimated excreta from bread.

Total Amount Digested, being consumed less excreted, 134.1 — 11.3 —
122.8 grams.

Milk, Digestible Nutrients of, being consumed less excreted, 66.2 -
2.0 = 64.2 grams.

Bread, Digestible Nutrients of, being total amount digested less
digestible nutrients of milk, 122.8 — 64.2 = 58.6 grams.

This subject, therefore, out of 67.9 grams of bread protein, digested
58.6 grams, or 86.3 per cent, of the bread protein consumed. In one such
test carried out on three subjects the average result was that the follow-
ing amounts of proteins consumed, were digested in the case of breads
made from three grades of flour all from the same hard spring wheat : —
Patent Flour (about 70 per cent extraction) . . . . 85.3 per cent.
Intermediate Flour (about 85 per cent, extraction) . . 80.4 „ „
Whole Wheat Flour (100 per cent, extraction) .. .. 77.6 „ ,,(

The following are the percentages respectively of total protein con?
tained in each flour, and of protein actually digested and assimilated :

TOTAL. DIGESTED.

Patent Flour 13.14 11.2

Intermediate Flour 13.44 10.8

Whole Wheat Flour 13.86 10.7

BREAD-MAKING. 387

In this series of tests therefore, while the protein increased with the
length of extraction, the digestibility simultaneously decreased. In
consequence the whiter the flour, the more available and digestible pro-
tein it contains.

Investigations on these lines have been made by Atwater, Woods and
Snyder by direction of the United States Department of Agriculture, by
Wood of the University of Cambridge, and by a committee of the Royal
Society of England, which, during the period of the late war, issued two
reports, one completed in December, 1916, and the other in March, 1918.

The whole of the results obtained by the two methods, and in all the
investigations referred to, agree in demonstrating the fundamental fact
that in matters of protein nutriment and production of energy, the
longer the extraction of flour from the same wheat, the less nutritive is
the bread, weight for weight.

535. Deficiency Diets. — The exigencies of the recent great war have
caused all the nations participating to consider most carefully the prob-
lem of how to utilise to the best advantage limited and even deficient
supplies of food. In the case of bread this becomes a matter of the great-
est importance, since although weight for weight white bread is the more
nutritious, yet evidently considerably more longer extraction breads can
be made from the same amount of wheat. It is a matter of general scien-
tific agreement that say 100 Ibs. of whole meal bread yields a greater
total amount of digestible nutriment than 70 Ibs. of white bread. As a
war or famine measure therefore, a longer flour extraction may be scien-
tifically justified. Under more normal conditions, the consuming public
elect to eat the more nutritive white bread and to utilise the bran, etc.,
for animal feeding purposes.

536. Mineral Nutritive Value. — This section of the subject has not
been worked out with anything like the completeness that has been
attained with the organic constituents of flour. Even in whole wheat the
ash is not very high, the principal constituents being phosphoric acid and
potash. As stated in Chapter V., the potash and lime are proportionately
more in the fine flour than in the wheat ; so also are the silica and ferric
oxide. Even in the flour, the lime is very little, amounting only to 5.59
per cent, of the total ash, which in itself is very small.

Hutchison (Food and Dietetics, 1900, Chapter XVI.) discusses the
mineral requirements of the body somewhat fully. He finds that the
amount of mineral matters present in an ordinary mixed diet is more than
sufficient for all the needs of the body, and that amount he fixes at about
20 grams per day. As to the form in which they enter into an ordinary
diet, most of them are in a state of organic combination, such as calcium
and phosphorus in milk. "It would appear that such organic mineral
compounds are of special value in nutrition. It cannot be maintained,
however, that it is only in such forms that mineral matter can find access
to the blood. Experiment has shown that even such a substance as car-
bonate of lime is absorbed to some extent." From analyses of human
milk, it would appear that an infant requires about 0.33 gram of lime
daily : the adult requires less, because of the cessation of the growth of
the bones. In the case of pregnant women, the requirements of the foetus
in the way of bone formation increase the demand for lime. A litre of
milk, whether whole or skimmed, contains about 1.5 grams of lime, or
0.86 gram per pint. Hutchison regards phosphorus as a most important
building material of the body, being found in cell nuclei and in abund-
ance in bones and nerve tissue. It is therefore of great importance dur-
ing the development of young animals. Phosphorus is present to a much

388 THE TECHNOLOGY OF BREAD-MAKING.

greater extent in meats than in vegetable products; among the latter,
haricot beans contain a very high proportion. ''The phosphorus con-
tained in foods is for the most part present in an organic form of com-
bination . . . but in part also in an inorganic form as phosphates of
the alkalies or earths. There is reason to believe that the organic forms
are the more valuable for contributing to the growth and repair of tissue.
Examples of these are the chemical substances nuclein, lecithin, glycero-
phosphoric acid, and phospho-carnic acid, all of which are probably val-
uable dietetic sources of the element. The foods richest in these are such
articles as yolk of egg . . . and the germ of wheat. It is doubtful, on
the other hand, whether the inorganic compounds containing phosphorus
are of much value in the body . . . One can, therefore, hardly approve
of the addition to the diet of phosphates in their inorganic form . . .
The recommendation of such preparations is based upon the groundless
assumption that an ordinary mixed diet is too poor in phosphorus to be
able adequately to supply our need of that substance. It may be re-
marked in this connection that we know of no diseased condition which
can be clearly traced to a deficiency of phosphorus in the diet. This is
true, indeed, not of phosphorus alone, but of all the other mineral in-
gredients of the diet with the exception of iron, and possibly also of cal-
cium. A deficiency of iron in the food may, as already remarked, lead to
the development of anaemia, and too little lime in the food may cause the
bones of children to become soft; but with these rather doubtful excep-
tions it may be safely assumed that an ordinary diet will amply provide
for all the mineral matter we require." Hutchison further remarked
that "of the comparatively small amount of mineral matter met with in
bread, one-fourth is excreted unabsorbed. Seeing that this is the case, it
is surely futile to recommend the use of bread containing a larger amount
of mineral constituents. ' '

Brunton and Tunnicliffe regard brown bread as being preferable to
white where mineral ingredients and especially lime salts are deficient in
other articles of food. As wheat is one of those articles in which lime is
very deficient, it is difficult to see where in any case bread, whether brown
or white, can very materially help as a lime food.

537. Importance of the Mineral Constituents of Foods, Ingle. — A

paper on this subject was read at the Leeds Congress of the Royal Insti-
tute of Public Health in 1909. From the analogy of milk, Ingle regards
the most suitable proportions of lime and phosphoric acid (P205) in food
as being about 0.87 of lime to 1 of phosphoric acid. In support of this
view he cites the authority of Weiske, by whom it has been shown that
rabbits fed on oats alone developed thin, fragile skeletons, while similar
animals fed upon oats and meadow-hay produced normal bones; more-
over, that the addition of sodium dihydrogen phosphate to the diet in-
tensified the bad effect upon bone development, while the addition of cal-
cium carbonate to a diet of oats only, greatly improved the development
of bone. Now oats contain about seven times as much phosphoric acid as
lime, while meadow-hay contains 2.5 times as much lime as phosphoric
acid. The writer points out that in seeds generally, among which wheat
is included, there is this injurious excess of phosphoric acid, and although
in wheat there is between three and four times as much magnesia as lime,
yet for bone formation magnesia can only to a limited extent replace
lime, for in the ash of bone only about 1 per cent, of magnesium phos-
phate is usually found, as compared with from 84 to 87 per cent, of
calcium phosphate.

BREAD-MAKING. 389

The writer then proceeds to express himself very strongly as to the
merits, or rather demerits, of bran in the following terms: — "Allusion
may here be made to what the writer believes to be a widespread fallacy —
the impression that bran is well adapted to promote bone formation and
nutrition. Bran is rich in ash, but contains an. overwhelming excess of
phosphorous pentoxide over lime — in some samples the writer found the
ratio to be as high as 1 : 0.055 — and, according to the views here given,
should be extremely unsuited to bone nutrition. This is indeed the case,
for a disease of the bones of horses, known as 'millers' horse rickets' or
'bran rachitis,' is known to be produced by the excessive use of bran as
food." He regards bone diseases, e.g., rickets, as being probably asso-
ciated with the use of a diet containing a preponderance of phosphoric
acid over lime, and suggests as a remedy for deficiencies in mineral con-
stituents of food their artificial addition in the form of inorganic com-
pounds. Thus in the preparation of "humanised" milk from cows' milk,
he recommends the addition of finely divided calcium carbonate. Ingle
regards the preponderance of phosphoric acid rather than the deficiency
of lime in cows' milk as being the cause which renders it more liable than
human milk to induce malnutrition of bone in infants. The same pre-
ponderance of phosphoric acid leads him to regard wheat, flour, and
bread, as not presenting the most favourable conditions for bone develop-
ment. He recognises, however, that cereal grains and their products form
a large proportion of human diet without ill effects, and for adults at
least the excess of phosphoric acid is not injurious. He regards this as
being possibly due to different requirements in man to other animals, and
also to the fact that the phosphoric acid of the ash does not all exist in
the grain as such, but is largely derived from organic phosphorus combi-
nations as lecithin. Such phosphorus is possibly not converted into phos-
phoric acid in the body, and would therefore not act harmfully in bone
nutrition, the really important ratio being that of lime to phosphorus
pentoxide existing as acid in the food. (Jour. Royal Institute of Public
Health, 1909, XVII., 736.)

538, Nutritive Value of Phosphates, Holsti. — Almost concurrently
with Ingle, Holsti points out that experiments on animals in which the
question has been investigated whether the body can obtain its phosphorus
from inorganic sources, have not in the hands of various investigators
yielded concordant results. In the present experiments described by
him, in which organic and inorganic phosphorus were determined in the
food and excretions of man, the result obtained is that it is possible to
supply the necessary phosphorus in large measure from inorganic phos-
phates. (Skand. Arch. Physiol., 1909, 23, 143.)

539. Conclusions. — The balance of evidence is in favour of the view
that ordinary diet contains a more than sufficient quantity of phosphorus,
and therefore that the amount present in bread is of but little or no
importance. Ingle goes further and regards the preponderance of phos-
phoric acid over lime as positively detrimental. There is considerable
divergence of opinion as to the nutritive value of phosphates. Thus
Hutchison looks upon them with doubt, but admits that in certain cases
inorganic salts such as calcium carbonate undergo some degree of absorp-
tion. Ingle evidently agrees with Wieske that oats is a very bad bone-
forming food, and similarly condemns wheat ; they both regard the addi-
tion of calcium carbonate as a definite bone-food. Ingle rather queries
whether the phosphorus of such organic compounds as lecithin is even
converted into phosphoric acid in the body. If not, it evidently cannot
act as a bone nutrient, for which the inorganic calcium phosphate is

390 THE TECHNOLOGY OF BREAD-MAKING.

required. Holsti, as a result of direct experiment, regards inorganic phos-
phates as capable of supplying a large measure of the necessary phos-
phorus of the body. The authors suggest as a probable solution of the
problem that the human body requires phosphorus in two distinct forms :
(1) as organic compounds for the building up of brain and nerve tissue,
which contain such compounds of phosphorus in large quantity; (2) as
inorganic salts for the building up of bone tissue, which consists largely
of calcium phosphate. Lecithin and such substances will naturally go to
the construction of nerve tissue, and inorganic phosphates to bone-for-
mation. When either organic or inorganic compounds of phosphorus are
deficient, the human body is probably able to utilise for both purposes
phosphorus compounds of either type.

In the case of lime, the position is different. Brunton and Tunnicliffe,
Ingle, and to a lesser degree Hutchison, regard lime-starvation as being
within the bounds of possibility. Ingle adduces very strong evidence that
such deficiency may be made up by the use of lime carbonate as a part of
the food. Unfortunately, wheat in any of its forms contains very little
lime. In particular, the use of bran as a food is strongly contra-indi-
cated, as it may very possibly be the cause of actual injury to bone for-
mation and nutrition.

540. Comparative Bacteriological Purity. — Owing to causes over
which the miller has no control some wheats reach him in a very dirty
condition. As a remedy most complete installations of wheat-cleaning
machinery form part of the equipment of every modern mill. The wheat
is dry-scoured, washed most thoroughly and dried; but it is impossible,
owing largely to the crease in the grain, to thus ensure its absolute free-
dom from external impurity. Such impurity is naturally associated with
the bran, and during the operations of milling remains in most part
attached thereto. A portion is rubbed off by the more severe reductions
into the lower grade flours, but the higher grade flours are practically
free from any contamination that may exist on the outer side of the bran.
Among such impurities are found large numbers of bacteria, and some of
these may be very objectionable, and in rare cases even dangerous in
their nature. In consequence, whole-meal and the darker low-grade flours
are much more liable to bacterial contamination than those of the patent
types. The results of these conditions have long been familiar to the
baker, who knows that the darker flours are much more likely to produce
sour bread. In the following experiment a first patent flour and a dark
or low-grade flour from the same class of wheat were taken, and fer-
mented and baken in precisely the same way. Loaves were baked from
each after 3^ hours and 9 hours' fermentation respectively. They
yielded on analysis the following amounts of acidity per cent. : —

White Bread. Dark Bread.

After 3*/2 hours 0.477 1.140

After 9 hours . . 0.491 1.300

The less fermented loaves had the following characteristics: White,
sweet in smell and taste ; Dark, characteristic odour of bread from low-
grade flours, but perfectly sweet in taste and smell. The 9-hour loaves
had shown some further change. The White was darker in colour, had an
incipient sour smell, but no sour taste. The Dark had the colour changed
to dark reddish brown, sour smell, and unpleasant taste, rather of de-
composition than acidity.

Kenwood, in conjunction with one of the authors, has on several occa-
sions made comparative bacteriological examinations of wheat and flours.

BREAD-MAKING. 391

The following are the results of one such test. Three flours were taken : —

A. Highest grade patent flour.

B. Lower grade flour.

C. Stone-milled flour.

These were similarly treated, and preparations of each were incubated
for bacteria on gelatin plates. At the end of 42 hours the following ob-
servations were made : —

A. No growth.

B. Four large colonies and over 100 small ones (non-liquefying).

C. Twenty well-marked colonies, and many organisms (which could
not be enumerated), had liquefied one-third of the gelatin.

At the end of 72 hours : —

A. One non-liquefying colony.

B. One liquefying colony, and quite 200 small non-liquefying ones.

C. The gelatin was entirely liquefied.

In another test, experiments were made with a wheat containing B.
coli communis. The wheat itself yielded twelve colonies of coli. Samples
of highest grade flour, medium grade flour, and bran from this wheat
were examined. Repeated tests on the highest grade flour gave no growths
of coli. In each of separate tests, two colonies of coli were obtained from
the medium grade flour. The bran yielded a growth of coli which cov-
ered the gelatin plate.

High grade flours are practically sterile, and bacteriologically cleaner
than medium and low-grade flours, and far cleaner than whole-meals.
Such organisms as B. coli communis, if present in the wheat, are absent
from the highest grade flour, present in small quantity in that of medium
grade, and abundant in whole-meal. The same differentiation would no
doubt apply to other organisms having the same habitat as B. coli com-
munis, if they happened to be present.

541. Attractiveness and Palatability. — These two factors have im-
mense weight in deciding what shall be the k 3 3:ng type of bread con-
sumed by the community. They are also of th*^ utmost importance. As
long ago as 1857, Lawes and Gilbert recognised that: "It is also well-
known that the poorer classes almost invariably prefer the whiter bread,
and among some of those who work the hardest and who consequently
soonest appreciate a difference in nutritive quality (navvies, for exam-
ple), it is distinctly stated that their preference for the whiter bread is
founded on the fact that the browner passes through them too rapidly;
consequently, before their systems have extracted from it as much
nutritious matter as it ought to yield them. ' ' The fact of this preference
also applies to such districts as some parts of Scotland, where very little
meat is eaten, and also to even the poorest parts of Ireland. In both
cases a very white bread is demanded. But not only does this taste exist
among the poorer and harder physically worked classes, it is also general
throughout the whole community. As recently stated in the daily press,
''there is a popular craving for white bread." If asked the reason why
they preferred a white loaf, the probable answer of the people would be :
"We prefer a white loaf because it is more dainty in appearance, and
because whiteness is instinctively associated with cleanliness. A muddy-
looking loaf may be quite clean, but does not so thoroughly convey that
impression as a .creamy white one. Further, the white loaf has a nicer
taste. ' ' Snyder puts it on record that during the severe monotony of his
digestion tests, in which the subjects were restricted to a diet of bread
and milk only, they keenly preferred the white bread to the brown. In
other words, the general taste regards the white loaf as the more attractive

392 THE TECHNOLOGY OF BREAD-MAKING.

and palatable. Authorities on diet regard both of these as being of
importance. Tunnicliffe writes: "Recent research has distinctly taught
us that, from the point of view of its nutritive value, great importance
attaches to the appetising appearance of food." (Blue Book on the Use
of Preservatives in Food, p. xxxi.). Hutchison is also strongly in favour
of regarding the flavour of food as one of the essential characteristics of
the diet. He sums up his position by the remark: "To persons of jaded
appetite, however, and to invalids and convalescents, the flavouring
agents of the food are very powerful aids to digestion, and no adjustment
of the diet in such cases can be regarded as satisfactory which leaves this
consideration out of account." (Food and Dietetics, p. 274.) On general
dietary principles, therefore, there is a scientific justification for the
popular preference.

542. Complementary Foods to Bread. — In view of the fact that
bread is naturally deficient in protein and fat, amongst organic nutrients,
and in lime among mineral matters, it may be well to indicate those arti-
cles of food which are appropriately regarded as complementary or sup-
plementary to bread itself. Bread is very rarely eaten alone ; meat and
cheese supply its deficiency in protein; leguminous vegetables such as
haricot beans have the same effect. Fat is almost universally added to
bread in the form of butter. Dietetically, jam or other sweets cannot be
regarded as an efficient substitute for butter, margarine, or dripping. In
view of the deficiency in lime, milk is strongly indicated as an accompani-
ment to bread. Here custom anticipates science by causing bread-and-
milk to occupy a prominent position in the dietary of children. May not
the reputation of "the halesome parritch" as a bone-food be largely due
to the milk consumed therewith rather than to the oats from which it is
prepared ?

In improved methods of bread-making, both fat and milk are at times
employed. Both are good; but the latter especially, whether with or
without the cream, serves to increase the lime content of the bread. If
bread be made entirely with skimmed milk, a half kilo (approximately
1 Ib.) will contain about 0.3 gram of lime, or roughly the daily amount
required by an infant. Such bread would be far better adapted to the
requirements of pregnant women than that from whole-meal. Judging
by analogy, the addition of a small proportion of an appropriate lime
salt would be a further advantage. Such salt might possibly be the car-
bonate, which would be changed into the chloride by the hydrochloric
acid of the gastric juice ; or it might be added direct as the chloride, in
which case it would partly replace sodium chloride or common salt.

In some districts a portion of the liquor used in making dough con-
sists of lime-water ; the lime of this is converted into the carbonate, by
the carbon-dioxide gas evolved during fermentation. The use of hard
waters for bread-making, i.e., those containing calcium carbonate or sul-
phate, also adds to the lime content of the bread. Hard water is itself
an important source of lime in the daily income of food, and may under
certain circumstances contribute that substance in excess.

543. Summary. — The foregoing data justify the following conclu-
sions.

Taking breads as supplied by the baker, white bread is weight for
weight more nutritious than whole-meal or ordinary brown breads. The
average best white bread is more nutritious than the second quality or
that made from the darker or low-grade flours.

When from any kind of wheat, standard patent (which is practically
the whole of the flour of the wheat) is compared with "entire-wheat,"

BREAD-MAKING. 393

and graham flour from the same wheat, the white flour yields more nutri^
ment and energy than either of the others.

The addition of finely divided bran to white flour lowers the nutritive
value of the mixture.

The addition of germ in excess of that normally present in wheat,
increases the nutritive value of the bread.

Wheat and all kinds of flour therefrom are comparatively poor in
mineral constituents. The phosphoric acid is largely in excess of the lime.
No diseased condition is known, which can be clearly traced to a deficiency
of phosphorus in the diet. All breads contain more phosphates than are
absorbed by the human digestive system. All wheat preparations are
deficient in lime. Bran is detrimental to healthy bone-formation.

The human body requires phosphorus in two distinct forms, as organic
compounds for the building up of brain and other phosphoric tissues, and
as inorganic salts for the building up of bone tissue which consists largely
of calcium phosphate. In case of deficiency of compounds of either type,
the body is probably able to utilise for both purposes phosphorus com-
pounds of either variety.

Wheat is liable to bacteriological contamination, which conceivably
may be of objectionable or even dangerous character. The whole-meal
will obviously contain the same bacteria as the wheat. The low-grade
flours contain less bacteria than the wheat, but some are still present.
The high-grade or patent flour is practically bacteriologically clean, even
when made from a contaminated wheat.

The bakers' best white bread is more attractive and palatable than
darker coloured or whole-meal breads made from plain flour or meal only.
These in themselves are valuable nutritive assets.

The nutritive deficiencies of bread are best remedied by the addition
of butter, milk, cheese, meat, and leguminous vegetables to the diet. These
supply respectively fat, lime salts, and protein. Hard water, or appro-
priate lime salts added direct, would probably help in correcting the
deficiency of lime in wheat.

No case has been made out for recommending the use of whole-meal
bread by growing children or pregnant or nursing women.

544. Vitamines, or Accessory Food Factors. — In the last edition of
this work reference was made (page 558) to certain experiments of
Hopkins of Cambridge from which he drew the conclusion that young
children would grow and thrive much better on a dietary largely consist-
ing of bread made from 80 per cent, extraction flour than on a dietary
containing a similar proportion of white bread. This view was based, not
on the superior nutritive value and digestibility in the ordinary sense,
but on his opinion that the longer extraction flour contains "certain at
present unrecognised food substances, perhaps in very minute quantities,
whose presence allows our systems to make full use of the tissue building
elements of the grain." Since that date much important work has been
done in this direction. In the briefest possible manner, the present day
knowledge and conclusions are here summarised. The theory of those
physiologists who have given this subject their attention is that there
exists a class of substances provisionally termed "vitamines," which
exercise most important functions in the process of nutrition, and yet
"are present in articles of food in quantities far too small to constitute
any appreciable contribution to the energy supply of the body." The
first step in this research was the discovery that if minute quantities of
certain constituents are removed from a food it, the food, wholly fails to
support nutrition. Further, if these substances are again returned to the
food, health is once more restored. The best known of these cases is that

394

THE TECHNOLOGY OF BREAD-MAKING.

of the rice-eating nations, with whom completely white polished rice
induces a disease known as beri-beri ; while if the husk only is removed,
and the skin of the grain and the germ retained, rice in this condition
not only prevents the disease, but acts as a cure in the case of those
suffering from this complaint. The following "vitamines" have been
more or less separated and identified : —

1. Fat-Soluble A. This substance is probably produced by plants
during growth, and is found both in the green leaves and in the germ of
many seeds. Animals do not seem to possess the power of synthesising
this body ; but store it up in relatively considerable quantities from their
vegetable food. As a result butter and egg-yolk are comparatively rich in
this substance.

It is soluble in reagents which dissolve fats, such as ether, and gen-
erally also in fats themselves. Heat slowly destroys it, and four hours'
exposure to a temperature of 100° C. serves to make butter fat inactive
in this direction.

Fat-soluble A is essentially an agent for developing growth. If young
animals are deprived of it in their food, there are no immediate results,
as a reserve stock is carried in the body. As soon, however, as this is
exhausted, growth ceases and the animals become extremely susceptible
to invasions of disease of a bacterial nature, especially tuberculosis.
Adult animals tolerate a deficiency of this substance for some time, but
ultimately the general state of health is seriously lowered, and the ca-
pacity for resisting disease inroads disappears. In cases where deficiency
conditions have been set up, health to a greater or less extent may be
restored by the use of food containing this body. A shortage of Fat-solu-
ble A as distinct from its absence results in lowered vitality and growing
powers.

DISTRIBUTION IN FOOD STUFFS.

The following table shows how both Fat-soluble A and another body,
Water-soluble B, are distributed among articles of food. The compara-
tive quantities are indicated by the terms, Large, Moderate, Small,
Absent.

Fats-
Butter, Cream ....

Mutton and Beef Fat

Lard

Most Vegetable Oils and Fats

Margarine, animal origin (except lard)
,, (vegetable origin and lard)

Cod-liver Oil

Meats and Fish —

Lean Beef or Mutton ....

Liver, Kidneys, Heart ....

Lean Fish (as cod, haddock) ....

Fat ,, (as herring, salmon)
Wheat-
Germ

Endosperm

Bran

Whole Meal Bread

White Bread

Vegetables —

Cabbage, Lettuce, Spinach
Miscellaneous —

Nuts (walnuts and fatty nuts)

Milk (cows' whole., raw)

" (skim)

Cheese (whole milk)

„ (skim milk)

Whole Eggs (fresh or dried) ....

Egg Yolk

Egg White

Yeast

Extract

Meat Extract (commercial) ....

Fat-soluble A.

Large, moderate.

Moderate.

Absent.

Moderate.

Absent.

Large.

Inconclusive result.
Moderate.
Absent.
Moderate.

Moderate.

Absent.

Inconclusive result.

Small.

Absent.

Moderate.

Small.

Moderate.

Absent.

Moderate.

Absent.

Moderate.

Large.

Absent.

Water-soluble B.
Absent.

Absent.

Small.

Moderate to small.

Very slight, if any.

Large.

Absent.

Moderate.

Small.

Moderate.

Small.

Large.
Large.

Large.
Large.
Absent.

BREAD-MAKING. 395

Water-Soluble B. — This is a substance of vegetable and animal
origin, as shown by its principal sources, which are seed embryos or
germs, and also yeast and egg yolk. It differs from Fat-soluble A in that
it is insoluble in ether, and is soluble in water. Water-soluble B is neces-
sary to promote a satisfactory growth in young animals, and also it is
the special factor in preventing the occurrence of beri-beri and neuritic
diseases in man and animals. So far as the action of heat is concerned,
during the baking of bread the temperature does not rise sufficiently
high to cause any serious diminution in the activity of this substance.

Water-soluble B is also necessary to the growth of young animals;
in addition it is requisite for adults. In both cases, with its deprivation,
there is a fall in body weight, with a fatal termination. Animals do not
seem to build up any reserve of this substance, so that as soon as the sup-
ply ceases, the ill effects are quickly visible. Certain specific diseases, of
which beri-beri is an example, follow from the absence or markedly in-
sufficient supply of Water-soluble B. "Beri-beri is rare though not un-
known where white bread is eaten, because the consumption of this type
of cereal food is usually accompanied by a sufficiency of other food-stuffs
containing the essential principle.7'

Deficiency Diets. — The distribution of vitamines, or accessory food-
factors in an ordinary mixed dietary is so wide that but little or no im-
portance attaches to their comparative absence from white bread. When,
however, famine conditions prevail, as in times of war, the range of
vitamine containing substances may become dangerously narrow and
consequently the conservation of their every source is simply a provision
of safety. Notwithstanding its various disadvantages, actual necessity
may then make the use of long extraction flours or even whole-meal bread
imperative as a measure of getting the greatest possible amount of direct
nutriment and accessory food-factors from a given weight of wheat.

The authors are indebted for the summarisation of much of the above
information to a Report on Vitamines, by the Medical Research Com-
mittee, published by His Majesty's Stationery Office, to which the reader
is referred for a more detailed account of the subject.

CHAPTER XVIII.
BAKEHOUSE DESIGN.

545. Selection of Site. — In determining the site for a bakery, one of
the first matters to engage attention should be to select a locality suitable
from a commercial point of view. A practical baker would at once satisfy
himself whether or not a neighbourhood looked as though it were growing
and improving, or the reverse ; whether it was already over-stocked with
bakeries, or whether there were still openings ; whether full prices were
being obtained, or whether the locality was an undercutting one. The
nature of the roads, whether hilly or level, and all items bearing on the
cost of getting flour into the bakehouse and of delivering bread from the
bakehouse, would be duly noted, and the proper weight given to them in
forming a judgment as to the suitability of the spot. All these may fairly
be termed commercial aspects of the question ; but beyond these there are
considerations which are more intimately associated with the practical
necessities of bread-making.

Among these a leading place must be given to the degree of fresh air
obtainable, and generally hygienic surroundings. The situations best
adapted for selling bread are not necessarily those also best suited for
making the same. A good shop will be naturally where rents rule high
and property is valuable ; as a result, baking operations are of necessity
frequently conducted in a far too limited space for the most efficient and
healthy working. In consequence, the system of having bakeries in more
thinly populated districts, where land is less valuable and a building ca-
pacious enough to accommodate modern labour-saving plant can be
erected, and using the shops as selling places only, is being more and
more adopted. With large firms having abundance of capital this is
comparatively easily managed, but in the case of smaller concerns greater
difficulty exists. But except where really good bakehouses are actually
in use, it is a matter for serious consideration whether the bakehouse
should not be altogether distinct from the shop. However crowded a
locality, there may generally be found at a not unworkable distance a
site where a bakehouse, pure and simple, may be erected. The bread
rounds may be served direct from where the bread is baked, and only
those goods brought to the shop which are requisite for a counter trade.
The difficulty is that this means two places to be supervised instead of
one ; but even when under the same roof the bakehouse is absolutely dis-
tinct from the shop, and the hours of work are by no means simultaneous.
By the use of the telephone, communication between the two becomes
such that orders and messages may be readily transmitted. Granted that
arrangements of this kind mean extra expense, still in the matter of
hygienic requirements the public is master, and will in the long run in-
sist, in no uncertain manner, upon bread-making being carried on under
satisfactory sanitary conditions, and the trader who keeps ahead of time,
reaps a handsome reward for his enterprise.

There is no doubt that a bakery on the ground flour has a far better
chance than one situated underground. No one more thoroughly recog-
nises than the authors the difficulties, in many cases, of finding in old

BAKEHOUSE DESIGN. 397

bakers' shops accommodation for the bakehouse other than below the
shop, and also that many bakeries exist below the street level, and are yet
clean and healthy ; but it is in spite of their situation, and not because of
it, that they are thus clean. To keep them so requires far more effort and
attention than when they are above ground. When a new building is
being erected, it may frequently be an advantage to have a sloping site,
thus permitting two approaches on different floor levels ; this, however,
is not often obtainable. It may further mean that the district is hilly
and, so, difficult for the delivery of bread. The site should be dry and
well drained; also well ventilated, but sheltered as far as possible from
exposure to cold winds, especially on the north and east sides. The top
of a hill has advantage over the bottom for the delivery of bread, inas-
much as the full vans have a downhill journey.

546. Requirements in the Building. — These will be best grouped
under various headings, each of which will be considered in turn.

The following general conditions should, however, be borne in mind in
connection with all that follows, and especially in reference to the de-
scription of typical bakehouses illustrated.

Floors. — Many different types of floors have been tried, but it may
be accepted that the best plan is to select some type of flagged or tiled
floor. Owing to heavy traffic certain parts of the floors wear more than
others, and no homogeneous flooring material that will lend itself to effi-
cient repair in selected places has yet stood the test of hard work. The
heat in bakehouses, together with the short time during which repair
work can be permitted, constitute the great difficulties in this respect. It
is obvious therefore that stone flagging, artificial stone slabs, tiles or hard
bricks, which can all be readily removed in worn places, and relaid effi-
ciently without interruption to work or fear of break up, form the ideal
materials for a bakehouse floor. In certain factories where the wear is
very heavy, floors have been introduced with a surface of cast-iron plates
with hexagonal honeycomb perforations. The plates are laid on cement
and the holes filled with cement to the upper surface.

Walls and Ceiling. — These should preferably be of washable material
(glazed bricks, parian cement, tiles or the like) ; all piers should be out-
side the building ; only plain surfaces should be used inside and no sharp
corners should be employed. Thus, the walls should join one another, the
ceiling or the floor, by a rounded corner with a radius of at least one inch.
Where considerations of expense make such perfection impossible, plain
brickwork walls, kept well lime-washed, are the only alternative which
can be recommended. Upper floors should preferably be ferro-concrete
with girders and joists cased in cement, again avoiding all sharp corners.

Windows and Doors should be placed to avoid draughts as far as pos-
sible; they should be well fitting, especially on walls exposed to strong
winds. Sloping window sills are advisable, as they prevent the accumula-
tion of dust and cannot be used for the storage of odds and ends, which
are not only objectionable, but are often the cause of broken windows.

Chimneys should never be less than 9 in. by 9 in., measured intern-
ally, and should run up outside main walls to above the ridge of roof or
highest building adjoining. Avoid cowls and horizontal connections, and
never put a round chimney pot on a square chimney unless its diameter
equals the diagonal of the square chimney section. One chimney to take
a number of ovens is quite satisfactory if large enough and properly ar-
ranged, but often a number of smaller ones is less costly.

Roofs should exclude draughts as well as wet. If fitted with ventilat-
ors, these should have means for control. Avoid too much glass roofing

398

THE TECHNOLOGY OF BREAD-MAKING.

over the actual doughing room and bakery (in such cases where there is
no floor over) : it is too hot in the summer and too cold in the winter.

General. — Avoid fixtures as far as possible; let all tables, troughs,
bread racks and fittings be on casters or wheels to facilitate transporta-
tion and cleanliness.

Motive Power. — Gas engines are shown in some of the plans on ac-
count of their being the most usually available source of power, and also
the heaviest and most difficult to accommodate, thus showing that lighter
or smaller prime-movers will have ample room. Space and often expense
will of course be saved by adopting electric motors where current is avail-
able. The subject of motive power is fully dealt with in paragraphs 562
to 564.

547. Working Requirements — Compactness. — In natural sequence
there next come forward for consideration the requirements of the baker
in using the building, as these must vitally affect the design. Among
such one of the first to occur is that of compactness: bakeries are not
wanted to be long and straggling, or with the work going on simultan-
eously in more than one place. There is otherwise the inevitable loss of
time resulting from inadequate supervision, and also that necessarily
following from ovens, machinery, tables, etc., being too far away from
each other, and what is more important the difficulty of ensuring the cor-
rect temperature and atmosphere. In the next place, matters must be
so arranged that all approaches and exits are under control, so that the
delivery of flour and raw material, and also the packing up and dispatch
of bread and finished goods, may be easily and efficiently checked. Where
at all practicable, all means of egress and ingress should be through the
one main entrance, or, if through different entrances, the whole of these
should be under control from the office. In the case of a retail trade,
there must be ready means of delivering goods from the bakehouse to the
shop. This necessitates, in the case of bakery and shop being on the same
level, a direct passage from one to the other. With a bakery either under
or over the shop level, the best plan is a simply constructed lift.

548. Ventilation. — As already explained, efficient ventilation is com-
pulsory under the Factory Act, but apart from that the necessities of the
case would lead every baker to ensure his ventilation being as perfect as
possible. With all hot work the comfort and health of the operatives

FIG. 34. — Diagram Showing Ventilating Air-Currents.

require abundance of fresh and pure air. The ventilation of a bakery is
fraught with some difficulty, as it is extremely important that there be no
draughts nor sudden chills through the admission of large quantities of

BAKEHOUSE DESIGN.

399

cold air in a short space of time. Ventilation is usually effected by what
are known as convection currents, the scientific explanation of which has
been given in the introductory chapter. Briefly, air expands as it gets
hot, and consequently is lighter, bulk for bulk, than when cold. As a
result hot (light) air is displaced by cold (heavy) air, and it may be said
that hot air floats upwards, and cold descends to take its place. From
this it follows that in rooms where gas is burning or where there is any
source of heat, the upper part of the room is distinctly the hotter. If
air-flues are led upwards from the upper portion of a room used as a
bakery, the hot air will escape from these, while cold air will stream in to
take its place at the lower levels if suitable openings are provided. This
effect is easily studied in the accompanying figure, No. 34. Immediately
over the ovens is an uptake to which a sliding door is attached; this is
exceedingly simple, and is readily worked by a cord
from the floor level. At the sides in various places
are inlet pipes; the tops of these are so placed that
the cold air cannot strike directly on troughs or other
vessels containing ferments, sponges, or doughs.

A useful form of ventilating flue is constructed
from a compound chimney pipe such as shown in
sketch, Fig. 35. This pipe is made of earthenware,
in lengths of from 12 in. to 18 in., with spigot and
faucet joints like those of an ordinary drain pipe.
But on one side of the flue pipe is formed a cham-
ber; this separate chamber or flue is the air flue.
The heat of the chimney portion warms the air flue,
and so creates a powerful draught through it. Oven
chimneys may, as shown, be constructed of such pip-
ing ; so also in underground bakehouses may the flues
for fires in rooms above, the air flue being carried
down into the bakery. Windows may be used for
ventilating purposes, but it is then a good plan to
place a board on the lower side, so as to cut off any
direct indraught.

ELEVATION.

FIG. 35. — Ventilating
Chimney Pipe.

549. Constancy of Temperature. — Sudden changes in temperature
are of course largely produced by draughts, but also may be due to the
construction and materials used in the actual building of the bakehouse.
Lath and plaster are not the most suitable methods of building bakehouse
walls. These should be constructed either of stone or brick of sufficient
thickness, and if the latter be used a fairly solid brick is an advantage.
Brickwork should be cemented on the surface, or other steps taken to en-
sure its being water-tight. The same reasons which militate against thin
walls also apply to iron. For light sheds corrugated iron may do very
well, but it is not the material for bakery construction. Its ready con-
ductivity of heat causes the bakery to be extremely cold in winter and hot
in summer. For the same reasons open iron roofs are to be condemned.
To prevent fluctuations in temperature there is nothing so effective as
having another room over your bakery, and the common practice of hav-
ing the flour store above is more than justified by its influence in main-
taining an equable temperature in the bakery itself. Suitable roofing
is also important and should receive careful consideration. Slated roofs
are not necessarily the best, but the builder, architect or engineer should
be able to advise as to the best roofing to suit any given locality, if his
attention be drawn to the need for roofing such as will be warm in winter
and cool in summer. Special attention may be here called to suitable

400 THE TECHNOLOGY OF BREAD-MAKING.

specialised roofing felts, which are not only excellent but durable and
cheap. (See also paragraph 584.)

550. Arrangements for Ovens. — It may be taken as a cardinal prin-
ciple of the authors that ovens should be fired from outside the portions
of the building in which baking operations are carried on. In conjunc-
tion with this, one has of course to bear in mind the fact that internal
firing, or firing in some other way from the front, is much preferred by
some bakers; but such reasons as once existed for such preferences can
hardly be said to apply today. Oven constructions are now available
which enable any class of work to be perfectly carried on, and are yet
arranged to be fired from outside the bakery proper. Supposed inap-
plicability of modern externally fired ovens for certain classes of work is
more imaginary than real, and there are now ovens available which, fired
from outside the bakery, do as good quality work as others with the fire
manipulated within the bakehouse proper. This view leads the authors to
suggest the provision in bakeries of a separate stokehole, with means of
access from the bakery, and separate entrances for the bringing in of fuel
and the carting away of ashes. Ovens may be built within the bakery
itself, but where practicable the authors prefer to have them outside, with
lean-to or other roof covering over the ovens themselves only. This sepa-
rate building can then receive independent ventilation, so as to avoid un-
due heating by the oven of the bakery itself. Where there is a row of ovens,
their faces and doors should be flush with, or form part of, one wall, and
this wall should be carried of course right up to the ceiling. This should
be done even if the ovens are within the main building, and have the
upper rooms extending over them. Such a wall may also assist to bear
the superincumbent weight, if desired to do so, but it is well so to arrange
matters that independent pillars or columns are provided between each
oven to carry the weight above. The general work may be faced up uni-
form with these, or the ovens may be slightly recessed, so as to give a
somewhat improved architectural effect, but in either case ovens and
buildings should be separate and distinct from each other.

The design of the bakehouse must depend somewhat on the nature of
ovens selected. These resolve themselves, so far as British practice is con-
cerned, into several types, of which the ordinary oven loaded with a peel
(usually a rectangular chamber) and the drawplate oven, which is nar-
row and elongated, are the most frequent. The particular shape of this
latter variety is determined by the width of plate over which men can
set bread by hand, except for close-set bread and other varieties which
lend themselves to the use of setters. This consideration practically limits
the width of drawplates to six feet, which space can be readily spanned
by reaching from either side.

551. Machinery. — The arrangements in this matter must depend
largely on the space at command and its shape and other characteristics.
The engine should have a separate room provided for it. This is not
often a matter of great difficulty, because in even a small bakehouse the
engine may be screened off with a glass and woodwork partition.

Naturally, in arranging machinery and the bakery generally, provi-
sion will be made for running materials about as little as possible. In
Great Britain, flour store-rooms are generally at the top of the bakery,
and the flour is at once raised there when brought into the building owing
to the convenience of utilising the laws of gravity for the conveyance of
the flour and dough to the lower floors. In countries with more severe
climates, however, where extreme cold and heat is experienced, the flour
is often stored in underground cellars to enable it to be kept at a uniform

BAKEHOUSE DESIGN. 401

temperature. Elevators are then employed for conveying it to the top
floor for distribution as before referred to.

552. Typical Bakery Designs. — Having dealt with general prin-
ciples, an effort will next be made to show how these principles may be
embodied in everyday work. For that purpose the following descriptions,
illustrated by plates VII to IX are given. It must be remembered that
these are not to be taken as complete working drawings; many little de-
tails of construction are omitted, because they do not affect the general
principles of the design.

553. Single Peel Oven Bakehouse. — On Plate VII there is shown a
small bakehouse fitted with one peel oven, which may be of the one-deck
or two-deck type. The outside width is 18 ft. 6 in., windows all in front,
and depth 30 ft. The choice as to which of the two types of ovens men-
tioned shall be decided upon, will be governed by consideration of size
and nature of trade as well as cost ; for guidance in this respect refer to
paragraphs 597 et seq. dealing with ovens. The firing arrangement is
at the side, giving a separate stokehole, fitted with coke bunker. The
assumption is that the oven is not accessible at the back; in fact, that no
facilities for either light or entrance are obtainable from anywhere but
the front. Beyond showing a kneading trough and tempering tank (see
paragraph 577) at one side, no attempt has been made to introduce fix-
tures and utensils ; the places for the latter will suggest themselves to the
baker in looking over the plan. The staircase leading to the flour store
above is arranged so as not to interfere with the lighting of the bake-
house, and to enable the kneading trough to occupy a position in which it
is not exposed to the draught from the entrance doorway. In the flour
loft is shown in outline the position of a sifting machine (see paragraph
576), through which flour is intended to be delivered into the trough be-
low. This machine is readily worked by hand, and should be considered
indispensable as all flour bags contain foreign matter such as oddments
of string, fluff, etc., which may easily escape the dough maker. The oven
portion of the building is covered by a lean-to roof, one storey high, aad
raised and louvred portions should be fitted at the upper part of the roof
to provide ventilation. The top of the oven is separated from the bake-
house by a brick wall, but is open to the stokehole, which is therefore also
efficiently ventilated. A large amount of work could be easily done in a
bakehouse of this type.

Assuming a two-deck oven, the lower chamber should preferably be
reserved for bread and the upper for confectionery, and with a modern
steampipe oven in which each chamber is fired independently of the other
and capable of yielding a batch of 2 Ib. crusty loaves per 1% hours, a
trade of 30 to 35 sacks (280 Ibs.) per week is possible. In addition to
this a considerable output of confectionery and cake will be obtained by
using the oven during the hours in which the bread baking is stopped.
The introduction of proper drainage and sanitary appliances would
render this bakehouse, small as it is, perfect, from a hygienic point of
view — so perfect, at least, as hand-making appliances will permit.

554. Bakehouse for Two Peel Ovens. — The next plan on the same
Plate, VII, is one of a larger bakehouse, in which both front and side
light is obtainable, although it will be seen the latter can be easily dis-
pensed with. This bakery is shown fitted with two peel ovens, which
again would preferably be two-deck. One of the upper ovens may be ar-
ranged as a steam-retaining sloped sole oven for glazed or Vienna bread.
The suggestion here is that the ovens shall be fired at the back, and ac-
cordingly a stokehole extends the whole length of the back ; opening from

402

THE TECHNOLOGY OP BREAD-MAKING.

PLATE VII. Plans of Bakehouses.

With One Peel Oven.

With Two Peel Ovens.

-fe-

30 • O'

REFERENCES.

A. Open Yard.

B. Flour Store.

C. Sifter and Shoot.

D. Bakehouse.

E. Dough Trough.

F. Moulding Table.

G. Tempering Tank.
H. Stoke-hole.

J. Confectionery and Stores.
K. Office.
L. Furnaces.

BAKEHOUSE DESIGN.

403

PLATE VIII. Plans of Single Drawplate Oven Bakery.

REFERENCES.

A. Gas Engine.

B. Dough Divider.

C. Moulding Table.

E. "Single Blade" Kneading Machine.

F. Drawplate Oven.

D. Stoke-hole.

G. Flour Store.

H. Blending Hopper, Sifter and Shoot.

J. Drawplate.

K. Space for Dough Trucks and Proving Dough.

L. Front-fired Drawplate Oven.

404

THE TECHNOLOGY OF BREAD-MAKING.

the passage to the stokehole is a door leading to a small yard, in which
are built a lavatory and men's offices. In order to protect workmen this
passage is roofed over, but left open on side nearest the yard. The
bakery has a table in the centre, while sufficient kneading troughs would
find room against the walls. A sifting machine and tempering tank, as
before described, are shown in a position to which the troughs may be in
turn conveniently movedj All kneading troughs should be on casters to
enable them to be readn^pmoved to suit the work as also to enable thor-
ough cleaning of floors, 1$jJJs an<^ corners. To the right hand of the
bakery is a small office, anifehind is a pastry -room. Over the bakery is
the flour store, arranged as ii^he previous sketch. A bakehouse such as
this woulcrtpave capa^Jy for a kirge trade, and with properly selected
ovens there )|tfpald be ijrx difficuife^in turning out a hundred sacks per
week, and also* tiie corre*sb$)nding aafumnt of small goods, confectionery,
and cake. Of c6*6tee, the a<Jfc>unt or^kehouse space might in such a case
be increased with^Hvantag^p.r the Sw^Qe might be altered in shape to
meet exigencies of*$£e. The^jketch is\^terely intended to indicate the
minimum space requiXfcl for the amount 4Di work wanted. No provision
has been made here fo^feaachiiiery, but such could easily be adopted if
desired. Bread-rooms ai^fenther conveniences should be attached to the
bakery front, or side oppotSje ovens.

555. Single Drawplate (8^n Bakery. — Plate VIII shows plans of a
bakehouse fitted with a split-type drawplate oven, Fig. 60, over which
may also with advantage be built a peel oven, see Fig. 61, in the case of
mixed trades. This arrangement lends itself well to a site where there is
a very narrow frontage and plenty of depth. The sketch has been pre-
pared on this assumption, and shows a bakery standing on a piece of
ground 15 ft. 4 in. in width. This might be still further diminished by
lessening the width of the passage round the stokehole, which in the plan
is 3 ft. wide. By resorting to the plan of having the oven fired at front

FIG. 36. — Oven for Small Bakery.

and within the bakehouse, Fig. 4, Plate VIII, the total width might still
further be reduced to 10 ft. inside and 12 ft. 4 in. external width. Or
even in this case the oven might be fired at the back by arranging a spiral
staircase or step-ladder down into the stokehole from over the oven

BAKEHOUSE DESIGN. 405

through the flour store above. Such very narrow sites are not, however,
likely to often occur, and the staircase arrangement is not recommended.
As drawn, it is assumed that no light is available from the sides, and ac-
cordingly small windows are placed over the ovens into the bakehouse.
This plan shows the position of flour-blending, sifting, doughing, and

FlG. 37. — Interior of Small Machine Bakery.

dividing machinery, arranged in the bakehouse,- and also parts of the
same overhead. The engine-room is in front of the bakery, and beyond
that is the bread-room. A bakery such as this forms an interesting and
fairly complete installation. With this plant, especially where the draw-
plate has over it a peel oven, or is of the two-deck variety, an extensive
and varied trade may be done, and instances are known in which over a
hundred sacks (280 Ibs.) per week have been regularly turned out with
similar equipment, provided sufficient space for dough trucks be avail-
able. The machine plant indicated could very well turn out sufficient
work to warrant the erection of another oven beside that shown, making
of course the bakehouse correspondingly wider. With increased width
rearrangement of space would permit the depth to be reduced. Fig. 36
shows an oven such as this bakery might have and Fig. 37 a view of a
bakery fitted with two-deck draw-plate ovens and machinery on a small
scale.

556, Shop and Overhead Bakery. — The designs given on Plate IX
take into consideration a business which is supposed to be in the main
street of a good neighbourhood where the exigencies of the circumstances
demand both bakehouse and shop to be in close proximity. It is assumed
that the only access to the premises is from the front or street side, there
only being at the back a limited amount of air and lighting space, which
cannot be utilised in any way in connection with the manufacturing op-
erations of the business,.

406 THE TECHNOLOGY OF BREAD-MAKING.

Regarding the shop itself, much must of necessity be left to the nature
of the business and the individual taste of the proprietor. It goes with-
out saying that window space is required for the display of goods; this
is provided by two windows, each about 10 ft. in length. On the one
side of the shop is a counter, and the other is fitted with a table, which
may also be used for counter purposes.- Toward the back of the shop
some small tables are placed, for the purpose of serving light refreshment
—tea and coffee. Descending from the back of the shop is a staircase
leading to lavatories and retiring rooms in the basement. These are in-
dicated by dotted lines on the ground-floor plan. A passage from the
bottom of the staircase leads to one set of lavatories and w.c. 's on the left
hand. Another similar set is reached through the room shown under part
of the bread-room. This basement room, with the adjoining conveniences,
could be retained for the staff, the others being reserved for the accommo-
dation of customers, and both kept separate and distinct from each other.
This basement might also be used for the preparation of light refresh-
ment to be sent up by a small lift fixed by the top of the stairs.

It being assumed that the only approach to the building is from the
front, means of ingress and egress to the bakery have been provided by a
side passage on the right hand of the shop; this goes right through to
the back of the building, and has doors leading into the bread-delivery
room and the office.

As it is no longer possible to have a new underground bakehouse, the
bakery is shown overhead, similarly to the not unusual plan of having
hotel kitchens, etc., at the top of the building. Let us now rapidly run
through the general arrangements of the bakery. As already explained,
the shop is on the ground floor, with lavatories in back part of basement,
opening out in area behind. At the rear of the shop is the bread cooling
and delivery room. On the first floor is the bakery, containing the ovens,
loaf dough divider, and moulding tables. Other machinery and the en-
gine are arranged on the second floor, while the flour stores are on the
third floor. A more detailed examination of the arrangements may be
made by following the flour from its entry into the place to its departure
as bread. Being situated on a main and busy thoroughfare, all flour will
have to be delivered either early in the morning or preferably late in the
evening when the shop business is over. The flour van would be backed
against the side entrance and the flour drawn up at once to the third
floor by the sack hoist some three or four feet in from the door. The
hoist itself is fixed overhead in the flour-room, and draws the sack up
through the trap doors on each landing ; in this way flour or other mate-
rial may readily be brought from a van at the side entrance to any de-
sired floor. Where considered necessary flour-blending machinery will be
fixed underneath the third floor, and arranged so as to be worked from
the flour store (paragraphs 574 to 575). The hopper, through which the
flour passes to the sifter, is also on this floor, the sifter itself being bolted
up underneath the joists, as shown on the sectional drawings. From the
sifter the flour passes into the doughing machine. The sifted flour, to-
gether with water from the tempering tank and yeast or ferment, as the
case may be, is converted by means of the kneading machine into dough.
For ferments and sponges a room has been provided in one corner of the
machinery room, where they may be kept at an equable temperature and
free from draughts. The size of this room may of course be varied to suit
particular requirements. A cake machine and whisk are shown on the

BAKEHOUSE DESIGN. 407

first floor, but these and other machines required could easily be arranged
to suit amended requirements. The doughs are allowed, after being made,
to stay on the second floor until ready, and are then cut out of the
troughs and discharged through a hopper on to the moulding table or
into the dividing machine on the floor beneath. The machinery as shown
is driven by a gas engine fixed in the one corner, from which runs a line
of shafting along the wall.

On the first floor are the divider, cake machine, whisk, the moulding
tables, and the ovens. Although the authors are advocates of drawplate
ovens, they have here shown a series of peel ovens, as these are still
largely used with mixed trades such as this bakery would be suitable for,
but draw-plate ovens could be arranged if preferred. The ovens shown
are two-deck, fired from the back, and should preferably have separately
fired baking chambers giving absolute control of temperatures (see para-
graph 602). The fuel for these ovens is coke, and this, on being brought
as usual to the bakery in sacks, is hoisted direct to the third floor and
taken into the coke store. The ashes are put into a portable closed sani-
tary bin for removal once every twenty-four hours. This bin is sent
down bodily by the sack hoist, and handed over to the dustman on the
occasion of his daily visit. At the far end of the stokehole is fixed a small
vertical boiler for the production of hot water for general purposes. The
flue from the ovens is carried into a chimney stack built against the back
wall, where it cannot become a nuisance to neighbouring property. The
ovens themselves are supported on girders carried between the back wall
and the wall dividing the shop from bread room, and resting with their
front ends upon a girder carried by the pillars and side wall. The baked
bread is packed in portable racks, and taken below by means of a lift into
the cooling and delivery room.

From the cooling-room one would naturally like to be able to load bar-
rows and carts at the back, but this, according to the conditions, is im-
possible. Arrangements have therefore been made for delivering through
the side door. A delivery clerk checks the bread as it goes out. The
bread racks should not exceed 2 ft. in width, so that they may pass each
other in the 5 ft. passage. This passage might be used at night for the
purpose of keeping barrows, as some six or eight could readily be stowed
away in it. A door leads direct from the cooling-room into the shop.
Through this all shop goods would be brought, and, if found absolutely
necessary, bread barrows could also be filled this way in the early hours
of the morning, in addition to the use of the side entrance. On this floor
is placed the office, which, as situated, controls the shop, the side passage,
cooling-room, and delivery clerk's desk. From the cooling-room, through
a door leading into the backyard, are reached the workmen's lavatory
and w.c. With sufficient space at the rear this accommodation might
well be enlarged.

Such, in brief, is the outline of the bakery and shop fitted for a large
and high-class family business in a first-rate locality, but on a severely
restricted site. The exigencies and nature of the business, together with
the actual size and proportions of the premises, must all affect the precise
nature of arrangements in each individual case. Such plans as are here
given can only touch on the general principles involved in the arrange-
ments, which in themselves lend themselves readily to considerable modi-
fication. The following references explain the drawings shown on Plate

408

THE TECHNOLOGY OF BREAD-MAKING.

PLATE IX. Plan of Shop and Overhead Bakery.

BAKEHOUSE DESIGN. 409

IX : A. Blending Hoppers ; B. Flour Sifter ; c. Kneading Machine ; D. Tem-
pering Tank; E. Water Tank; F. Hoist; G. Dough Divider; H. Cake Ma-
chine ; I. Whisk ; j. Engine-room and Gas Engine ; K. Lavatory and Cloak
Room; L. Basement; M. Men's Lavatory; N. Wall supporting Ovens;
o. Side Entrance ; P. Open Yard ; Q. Delivery Checking Clerk ; R. Office ;
s. Counter ; T. Tables ; u. Cooling and Delivery Room ; v. Down to Lava-
tory; w. Shop; x. Lift; Y. Hoist Trap Door; z. Ferments and Sponges;
A.1 Shoot; B.1 Water-heater; c.1 Stoke-hole; D.1 Two-deck Peel Ovens;
E.1 Flour Store; F.1 Dough Room; G.1 Column.

557. Bread and Cake Factory and Automatic Machine Bakeries in
General. — No attempt will be made to describe the buildings and equip-
ment suitable for a very large business, particularly as the equipment is
not very different to that which forms the subject of this paragraph. The
plant in very large bakeries requires to consist merely of more units
rather than units of larger size and capacity. It may be said at once that
modern development in Great Britain tends to replace small bakeries by
others of medium size rather than with very large ones — the latter not
being necessarily at a very great advantage over the former owing to the
difficulty and expense of delivering bread over a very large area. In
large cities it would be better policy to erect several bakeries of medium
size in preference to one large bakery, and with centralised office manage-
ment, and a. good organisation to supervise the various bakeries, there is
the less reason to fear ill effects from decentralisation in regard to manu-
facture; because with the automatic machinery available today it is im-
possible for the output to fall short of the standard, or for the cost to ex-
ceed the same, owing to the automatic machines acting as pacemakers. It
is necessary of course to have efficient foremanship in each bakery, but as
this is requisite in any case, there is no disadvantage in this respect. For
the purpose of our present observations it is necessary to adopt some
classification, in regard to the size of bakeries, in order to convey some
idea of the extent to which the specialisation of machinery and equip-
ment should be carried.

558. When Machinery Pays. — It is one of the most important ques-
tions when designing a modern bakery to determine exactly how far the
provision of machinery should go. At the time of building, when a given
trade has to be provided for, some machines may not be worth installing
which it is essential to have in a few years' time when trade has grown
to proportions making their employment highly remunerative. If, how-
ever, no clear idea of this possibility exists at the time the building is
erected, it may be impossible to provide the necessary space, or to make
suitable arrangements, owing to the later wants not being provided for.

The standard of trade for a medium-sized bakery may today be set
at approximately 500 to 900 sacks (280 Ibs.) per week, because this is the
maximum output of one automatic bread-making plant (see paragraph
594). The size of this unit is determined by technical considerations, but
it may be accepted for our purposes that 1,200, 2,400, or 3,600 2-lb. loaves
per hour is the maximum output of the various sizes of automatic plant
which have been found practicable. If a bakery requires to deal with
greater outputs than these, more than one plant must be installed. The
limit as regards maximum output per week having been definitely ascer-
tained by multiplying the hourly maximum by the weekly working hours
(examples: 2,400 2-lb. loaves per hour =-12 sacks per hour X 6® hours
working per week = 720 sacks ; or 2,400 1 y^-lb. loaves = 8 sacks per hour
X 50 hours working per week - = 400 sacks per week, etc. ) , it may
be asked, what is the lowest output per week, on which such a plant

410 THE TECHNOLOGY OF BREAD-MAKING.

would pay ? The answer to this question is not a simple one — many con-
siderations go to determine the correct course in each individual case, but
it can be affirmed that it would never be advisable to attempt an answer
without the assistance of the bakery engineer who specialises in automatic
machinery. Two bakeries with precisely similar, and on the face of mat-
ters perfectly sufficient outputs, may be very differently placed as regards
the composition of their respective trades. It may pay brilliantly to have
a full installation in the one case and yet not in the other. Such matters
can therefore only be determined after full investigation of the whole of
the circumstances. It will be appreciated that the authors can only lay
down the general rules which should be followed, and that such approxi-
mate facts, as are here quoted, apply to average cases.

The minimum trade for a full automatic plant may be taken at 250
sacks (280 Ibs.) per week of reasonably uniform loaves. On this output
no one need hesitate as to the remunerativeness of the installation, but
it may be here remarked that owing to the uniformly better bread which
would result under tolerably good management in the bakehouse, an in-
crease in the sales may be looked for ; this increase will be all the greater
if the sales are smartly pushed, although that is not what is here meant
—the increase referred to is automatic and due to a better article. To
the uninitiated this may sound * ' too good to be true, ' ' but the statement
is nevertheless based upon a well authenticated fact. Any one installing
a plant on a trade of 250 or 300 sacks will therefore, in all probability,
soon have a larger trade with which to keep it employed, and all increases
will inevitably bring down the cost of production per sack, because no
increase in the number of men working the plant is required for working
it to its fullest capacity.

For bakeries with trades under 250 sacks per week smaller plants are
made, both as regards the actual machines as well as in certain combina-
tions, by reason of fewer machines being employed in conjunction with
intermittent working. Thus, a so-called semi-automatic plant will pay
in the case of a fairly uniform trade of 100 sacks per week and upwards,
and the cost per sack in labour will be only fractionally less good than
that obtained from full-sized installations.

Under one hundred sacks per week the employment of a divider and
a "Flexible" moulder (that is a moulder equally adapted for turning out
tin, cottage or coburg bread as well as smalls) will pay down to weekly
outputs of 60 or 70 sacks. This is contrary to the opinion still very gen-
erally held, but as actual cases exist which prove the statement, the
authors do not hesitate to give it all the weight they can command.

Under 100 (one hundred) sacks per week no up-to-date bakery should
be without at least a divider, provided the machine is designed on the
proper principles, and does not fell or otherwise injure the dough. It is
no use employing a machine merely for the sake of having a machine, and
many a user loses in reduced quality all and more than he can save in
labour. Good modern dividers are very accurate, much more so than any
commercially obtainable hand-scaling, they act as pacemakers, and are
rbsolutely reliable machines if looked after with reasonable care and
kept clean.

Bakers with trades no greater than 25 sacks per week in bread should
by no means assume that a divider will not pay ; even on such compara-
tively small outputs as 25 sacks (280 Ibs.) per week these machines pay
well in many instances. It may be taken that a suitable divider will pay
in any business doing a reasonably uniform bread-trade and employing
three men.

BAKEHOUSE DESIGN. 4H

559. Large Bakeries. — Returning; now to the subject of large
bakeries, and having determined upon the nature of auto-machinery to
be installed, the question of ovens should next engage attention. The
subject of ovens is fully dealt with elsewhere (paragraphs 597 et seq.),
and for factory working, i.e. wholesale production, no type can today be
really seriously considered in Great Britain other than the draw-plate
oven, the continuous travelling oven — or perhaps in Scotland and some
parts of Ireland, the "Coverplate Oven." The size of baking plate for
Drawplate and Coverplate ovens must be determined to suit the style of
loaf. Cottages, coburgs or tins, are most conveniently dealt with in one
sack batches and on plates with a maximum width of 6 ft. "Oven-bot-
tom" or close-set bread, if not in association with any of the first-named
varieties, can be handled perfectly with plates up to 8 ft. 6 in. in width,
as can also "Scotch Bread." Batches may be taken to vary from one
sack cottage to 2^ sack "Scotch" batches, but to illustrate the pro-
cedure, we will adopt the former as a standard. Assuming a full size
auto-plant to be decided upon, this will have an output in 2-lb. loaves of
12 sacks per hour. The batch ovens will bake continuously one batch per
hour — hence 12 one-sack drawplate ovens will be required in such a bak-
ery. Where travelling ovens are in question considerations of too tech-
nical a nature arise to enable the advice of bakery engineers to be dis-
pensed with.

The preceding remarks (in paragraph 558) refer mainly to machines
dealing with the dough after it has left the kneading machine. Naturally,
hoists, sack-cleaners, blenders, storage hoppers, sifters, tempering tanks,
and kneaders have all to be considered; but as these have been longer
on the market and are better understood generally than the automatic
plants, and are also fully referred to in their respective chapters, no spe-
cial reference is here made to them.

The authors have advisedly enlarged upon the auto plants because
they are today the key to successful designs for large bakeries, and
because no architect can be properly instructed as to the nature of build-
ings required, before the bakery proprietor is quite clear as to his require-
ments in regard to machinery. The architect who has had anything to
do with modern machine bakeries, will agree that his clients do best first
to consult the bakery engineer, who will prepare such plans and par-
ticulars as will alone make it possible for him to give his client a per-
fectly designed bakery.

This may be a new order of things, but it is undoubtedly necessary to
prominently advise the above course if mistakes are to be avoided, and
the authors consider no other apology necessary.

CHAPTER XIX.
THE MACHINE BAKERY AND ITS MANAGEMENT.

560. Sanitary Considerations. — The operations of kneading and
working dough involve severe manual labour in a heated atmosphere; it
is impossible to conduct these processes without more or less contamina-
tion of the bread with emanations from the skin of the workers. In the
best conducted bakeries this evil is reduced to a minimum by insistence
on scrupulous cleanliness on the part of the workmen; still, even the
utmost care cannot entirely abolish the evil. For the strongest of sani-
tary reasons, both on behalf of the public and of the workmen, operations
on dough demand mechanical appliances rather than manual labour. So
forcible are these reasons, that the expense of kneading machinery and
its convenience, compared with ordinary manual processes, become
merely secondary considerations.

561. Bakehouse Machinery. — In describing the machines required in
a bakery, some classification will be necessary ; it is therefore proposed to
commence with an account of the various sources of motive power, such
as steam, gas, and other engines. Following on this in natural sequence,
the means of distributing power, embodied under the general term of
"gearing," engage attention. It is then proposed to take the flour as it
enters the bakery and follow its history through each mechanical appli-
ance employed, discussing and describing each in detail. In this latter
connection, hoists, blending, sifting, kneading, and other machinery, as
well as ovens, will be included.

562. Motive Power. — One of the great objects of machinery is to
spare workmen from severe manual labour. There are comparatively few
machines which are profitably worked by hand, and a man must rightly
be regarded as by far the most expensive source of power. For flour-
sifting purposes machines may be obtained which work well by hand
power, the reason being that comparatively little force is requisite to
drive these machines. Various kneading machines are also supplied
which may be driven by hand ; but it is more than doubtful whether any
hand machine can make a mass of dough with the total expenditure of
less force, measured in foot-lbs., than can the baker working direct on the
dough. The worker's task may be lightened by slowing down speed by
means of gearing, but in such cases the compensation is made by the
greater demands on time. In civilised countries hand-worked machines
for the bakery cannot be recommended, as experience proves that opera-
tives strongly object to work the handle of a kneader.

In cases where steam power is available, that of course forms a useful
and convenient mode of driving machines. Thus, if the bakery adjoins
some other building, such as a flour mill, it is economical and convenient
(from the baker's point of view) to take his power from a steam engine
there running, provided it is always available when he wants it. Or if he
can similarly gain access to a boiler arid draw off high-pressure steam
whenever required, it will be well to fix a small steam engine and run it
as a source of power. These conditions are, however, rare in Great
Britain; and certainly the laying down of a steam plant, consisting of

412

THE MACHINE BAKERY AND ITS MANAGEMENT. 413

boiler and engine, is bad economy* for the ordinary baker's requirements.
For these reasons steam engines are comparatively little employed in
bakries except in countries where the severity of the climate demands
steam for heating purposes in any case.

What, then, is wanted is a source of power that can be started at a
minute or two's notice by a man not necessarily trained as an engine
driver, and which can be as quickly stopped, the expense of the source
of power being arrested simultaneously. Further, the motor should not
be, even in case of neglect, of a nature such as would lead it to be a source
of danger to the employes or the building. These requirements are met
most fully by both gas and oil engines, and especially by electric motors.

563. Electric Motors. — Undoubtedly the electric motor is the most
compact as well as the most convenient prime mover. Wherever electric
current is available at a reasonable cost it should be preferred to all other
means of obtaining motive power. A judicious arrangement of motors
will often prove at least as cheap in running cost as that of any other
method. The need for good judgment arises out of the fact that although
a motor, while running at its maximum output, may cost more than some
other source of energy, yet it can be so readily started and stopped that it
proves in the end cheaper than an explosion engine, which is necessarily
left to run throughout the working hours in a bakery. The electric motor
should in fact be in motion only while required to perform actually
remunerative work. To merely replace an engine by a motor to drive a
line shaft would in many cases indirectly involve the waste of much cur-
rent, as the motor would be left running when there would be no need
whatever for it to be in motion. The best plan is to couple such machines
as are required to run simultaneously — say kneader and sifter, or divider
and moulding plant — and let each group be driven by its own separate
motor. As this plan obviates all long lengths of shafting, it frequently
does not prove more costly to instal than one motor with a great deal
of shafting, etc.

Again, the hoisting in of flour frequently takes place at a time when
no other machinery is required to be in motion ; the same holds good as
regards the fewer and much smaller machines required in the confection-
ery department, as compared to the bread bakery.

It will be seen that if the stopping of the machines is dependent
upon the stopping of the motor no waste of current can occur without
malice — a contingency which need not be taken into account in this con-
nection. Illustrations of machines with direct coupled electric motor
drives are given later in this chapter.

Some hesitancy in adopting electric motors existed in the earlier days
of public electric supplies, and not without reason, owing to the apparent
delicacy of much which forms part of electrical machinery ; but no reason
exists today why any one should hesitate to adopt electrical working from
any fear of breakdowns. Electric motors and all pertaining thereto are
today at least as reliable as any other machinery, and types of motors are
now available (notably the totally enclosed machines) which are emi-
nently suitable for bakery conditions. As with internal combustion
engines, it is advisable to have each motor of ample power for its work,
but that is no more necessary in these cases than with any kind of ma-
/ihinery. It is also not so very long ago that certain alternating currents
were the cause of difficulties in motors, but any lingering suspicions in
regard to these troubles may be now confidently dismissed. The authors
know of no current commercially available in Great Britain that cannot
be safely relied on for bakery purposes,

414 THE TECHNOLOGY OF BREAD-MAKING.

Any attempt to explain the principles of the various electric motors
which may have to come under consideration would be of far too tech-
nical a nature to come within the scope of this work; the authors have
therefore confined themselves to the purely practical aspects of their
application to bakeries, and must leave all matters of detail to the local
electricity department or the consulting electrical engineer.

564. Gearing and Power Transmission. — The problem of transmit-
ting power in a bakery is practically confined to the conveyance of rotary
motion from one shaft to another. This transmission of power may
require to take place from a prime mover to a machine, or group of
machines, or it may involve distribution over a building covering con-
siderable distances. In the latter case electrical distribution, as described
in the last paragraph, provides the best solution of the problem, whether
current be available from a public supply, or has to be generated on the
premises. No known means can compare for efficiency and convenience
with electrical driving, if the points at which power is required are
numerous and at all widely separated by distance. The determination of
the best arrangements for electrical distribution cannot, however, be laid
down conveniently within the space available in this work. The power
scheme must, moreover, be entirely adapted to the requirements of each
case, and this is too complicated a matter to be adequately undertaken as
a piece of general advice. The average bakery, however, does not call for
anything very elaborate, and the authors propose to confine their remarks
to the forms of gearing usually required.

565. Shafting. — For driving a group of machines from one common
source of power, a sufficient length of shaft is employed to enable pulleys
to be fixed thereon, opposite to the driving pulleys of the machines which
are to be set in motion. This shaft is commonly called a line shaft. If
subsidiary shafts are required, either to enable a further group of
machines to be supplied with power or for other reasons, such shafts are
called countershafts. The shafting itself is now usually of mild steel, it
should be true in diameter and perfectly straight, and in lengths suited
to the actual requirements. In determining the lengths, it should be
borne in mind that 20 ft. forms the maximum which is practicable ; that
the couplings used for joining up the various lengths forming a line shaft
should as far as possible be close to bearings, and that as few pieces of
shaft as possible should be employed to make one line shaft.

A shaft will, for a given size, transmit power proportionately to its
speed of revolution, hence the higher the speed the smaller the diameter
required to transmit a given power. There are, however, various reasons
why the speed should be kept within limits, among these it is sufficient to
mention the two most important. The first is that bakery machines
require on the whole low speeds, and have therefore to be designed with
considerable gearing in themselves, so that their driving pulleys shall be
capable of running at a reasonably high speed. Too high a line shaft
speed would therefore call for badly proportioned belt drives. The
second reason is that great care is necessary in arranging high speed line
shafts, especially because very careful balancing of all pulleys fixed
thereon is necessary to prevent excessive vibration. It may be taken that
that most suitable speed for line shafts in bakeries is from 140 to 160
revolutions per minute. The diameter of a line shaft must therefore be
proportioned in such a manner that, at this speed it is capable of safely
transmitting the power, it is intended to convey, to all the machines that
will be driven from it,

THE MACHINE BAKERY AND ITS MANAGEMENT. 415

566. Surface Friction Bearings. — A good type of bearing is one
which has a white metal running surface, is fitted with an oil well, and
has ring lubrication. Many makes exist which possess these features, and
the task of selecting the cheapest and most efficient should be considered
to belong to the province of the bakery engineer. "Ring lubrication" is
a fairly modern innovation in spite of its effectiveness and simplicity, and
as it is the best and most automatic device for ensuring the continuous
lubrication of bearings, a short description must here be given. The
bearing is so constructed that under the lower running surface a reser-
voir or chamber is formed which is filled with oil up to a given level. At
each end of the bearing surface, but within the casing, an annular space
surrounds the shaft for the purpose of allowing a ring, usually formed of
stout wire or flat metal strip, to hang on the shaft. The diameter of this
ring is considerably greater than that of the shaft, thus permitting the
lower portion of the ring to dip into the oil contained in the oil well or
reservoir. As the shaft revolves the ring revolves also, and in so doing
conveys the oil from the well to the shaft and over the top in a continuous
supply. The oil thus conveyed is much more than is required by the
oearing, which therefore is always perfectly lubricated so long as the
reservoir contains oil, but as the surplus all flows back to the well, one
charge lasts for a very long time, and there is absolutely no waste.

The bearing described is so good and reliable and withal so inex-
pensive that all older types are now entirely obsolete, and should on no
account be fitted for new installations.

567. Rolling Friction Bearings. — Even better types of bearings are
provided by roller- and ball-bearings. Surface friction being entirely
absent in these, they absorb considerably less power, and are therefore
more economical. Several good makes exist and are absolutely trust-
worthy, and there can be no question that where first cost is not a govern-
ing consideration, their adoption in preference to all others must be
recommended, as the additional cost is undoubtedly more than saved by
the economy effected in power.

568. Bearing Supports. — Bearings are carried in a variety of ways
— in a wall box, fixed in a wall at the end of a line shaft, or where it
passes through a wall ; in a wall bracket which is bolted to a wall ; in a
hanger suspended from a ceiling, or in pedestals supported on a floor,
pier, or girder. A detailed description of these various fittings can
scarcely be necessary, but one essential should be insisted upon with all.
That is, that all bearing supports should be of so-called self-adjusting
type, which means that the actual bearing shall not be rigidly bolted to a
fixed surface, but should be so supported by adjustable screws, that the
exact alignment of the shaft may be readily obtained by the use of the
screws, which are then secured by lock nuts. The alignment of a shaft
should be perfect, otherwise it will absorb infinitely more power in being
driven, and may be even subject to breakage, or seizing in bearings. It
is not sufficient to line up a shaft properly when it is new — a very slight
settlement in the building, or the heavy loading of upper floors may
destroy the original alignment, and ready means for readjustment are
therefore necessary.

For similar reasons, bearing supports should preferably be carried
from the solid walls of a building. A floor may be of ample strength to
carry the weight it has to bear in everyday use, but it can never be abso-
lutely rigid. The floor of a flour store, for instance, may carry many
hundreds of tons of flour, and do so with perfect safety, yet its deflection
will vary according to the load — just in the same way that the best and

416 THE TECHNOLOGY OF BREAD-MAKING.

strongest modern bridge is designed to deflect under its moving load. A
shaft supported in hangers from such a floor will obviously follow its
movements, and can therefore never be in perfect alignment, except pos-
sibly when the load corresponds exactly to that which existed when the
alignment was made. These variations may not and are not likely to be
serious enough to endanger the actual working of the shafting, but they
must cause the absorption of more power than under ideal conditions
would be the case. It follows that hangers and pedestals carried on
upper floors should be avoided as far as possible, although they may be
used quite properly for short lengths of shafting.

Bearing supports should be placed only after careful consideration;
in all cases, either so that they can be quite close to the pulleys, or so that
the machines can be fixed to bring the pulleys close to the supports. This
is very important in bakeries, because owing to the peculiar nature of
bakery machines, high belt speeds cannot be conveniently arranged for,
and the belts have consequently to be kept fairly tight, especially as space
is also of great importance and shaft centres are as a rule not as widely
apart as would otherwise be desirable. For the same reasons, the bear-
ings should not be too far apart — it is advisable to limit the distance of
bearings from one another to 6 ft. in 2 and 21/4-in. shafts, 7 ft. in 2y2 in.,
and 8 ft. in 3 in. shafts. Smaller shafts than 2 in. should not be em-
ployed. Attention is again drawn (see paragraph 546) to the desirability
of avoiding piers on the inside walls of buildings — so that there should
be no hindrance to the fixing of bearing supports on the plain wall sur-
faces in such a manner as to enable unrestricted compliance with the
above considerations.

Each complete length of shaft should be fitted with collars at each
end of one bearing only, in order to suitably limit side play. The collars
should have no projections, so that the danger of attendants7 clothes
being caught up may be avoided. The same remarks apply to couplings
for joining up the several lengths forming one line shaft.

569. Pulleys. — All pulleys, except the fast and loose pair, from
which the line shaft derives motion, should be split — that is to say made
in halves, so that changes and additions can be made without having to
take down or disturb the shafting. The fast pulley should be keyed on
and the loose pulley should be self -oiling and slightly smaller in diameter
than the fast, to reduce the belt-pull when running idle. Except the fast
pulley, no pulley should be keyed on to the shaft ; the use of self-gripping
(preferably ''screw boss") pulleys ensures the shaft remaining undam-
aged and avoids the necessity for cutting key ways. In fixing "screw
boss" pulleys, care should be taken to place these on the shaft in the
correct way, which is of course that which ensures that the belt-pull will
keep the screw boss tightened. For reversing shafts, screw boss pulleys
are useless — other self -gripping pulleys must be used in such cases. For
the speeds above recommended (140 to 160 revolutions per minute) cast-
iron pulleys may be used throughout. All pulleys should be crowned,
except loose pulleys, and arranged to be of as large a diameter as cir-
cumstances will permit. The speeds of shafts are in inverse proportion to
the diameter of the pulleys on each, hence the diameter of pulleys
required to drive one shaft from another at a predetermined speed is
readily ascertained by an ordinary proportion or "rule of three." Ex-
ample : an engine shaft runs at 200 revolutions per minute and the line
shaft is required to revolve at 140. If an existing pulley of 24 in. on the
engine has to be taken into consideration, then as 140 : 200 : : 24 : 40 =
diameter of pulley on line-shaft. If choice can be made without reference

THE MACHINE BAKERY AND ITS MANAGEMENT. 417

to an existing pulley, first decide upon the maximum diameter that
is possible (or desirable) for that pulley which is limited by its surround-
ings, and proportion the others as before.

The reason why pulleys require to be as large as possible is that the
power, which a given belt can transmit, is proportionate to the speed at
which it travels, and therefore the higher the belt speed the greater is
the power the belt can transmit ; or inversely, to transmit a given power,
the higher the speed of the belt the smaller is the belt required. It is
necessary to bear in mind that owing to the greater circumference of the
larger pulley, the belt speed is higher with larger diameters than with
small, in direct proportion to the increase in diameter, the pulley or shaft
speed remaining constant. It follows that, assuming a machine to have
been fitted with a pulley inadequate to absorb the necessary power for
driving it (which will show itself by persistent tendency of the belt to
slip or run off in spite of machine and line shaft being perfectly line-
able), the correct remedy is to increase the size of the pulleys on the
machine and on the line shaft in the same proportions. This alteration
will leave the speed of the machine unchanged, but will at once remedy
the defect, if the increase in belt speed is sufficient. To double the belt
speed will double its capacity for conveying power and so on in propor-
tion.

570. Belting. — For all ordinary purposes leather belting is recom-
mended for bakeries. A good dressing (such as "Clingsurface") peri-
odically applied should be used sparingly and will act as a dressing and
keep the belting in good condition. Resin and other forcible means of
increasing adhesion should be avoided. The best makes of bakery
machines are designed for ample widths of belts, which therefore give no
trouble from slipping, and if reasonably long centres (distance from
shaft to shaft) are allowed, need not be kept unduly tight. For joining
up the ends of belts "Harris" fasteners are very convenient and hold
excellently, if properly put on. The ends of the belt should be marked off
exactly true with a carpenter's square, and cut perfectly clean and at
right angles. Next see that the belt is properly round the pulleys and
shafts which are to be connected. Then turn the belt so that the inside
lies uppermost, and place the joint down on the fasteners with the teeth
upwards without any twists, and place the ends of the belt in exactly
their right places on the same. Get some assistance to hold the belt in
exactly the right position, and drive the leather down on to the teeth of
the fasteners. With the joint properly made there is no danger of the
fastener tearing out.

Do not use the hammer direct, but employ two blocks of wood used
endways to the grain — the one block should form the bed, the other
should be firmly pressed on to the belt close to the joint. Thus the
leather will be driven into the teeth by the agency of the wood, under the
blow from the hammer, without damage to the teeth. Be careful not to
eliminate the curve given to the fasteners by the makers. Drive the
fasteners home with as few heavy strokes of the hammer as possible in
preference to many light taps, which only cause the fangs of the fasten-
ers to be loosened in the leather. Another excellent means of joining
. belts is to use a specially prepared flexible wire — this is sold with suitable
tools for punching the necessary holes in the belt, under the name of
"Malin" outfit. "Harris" fasteners are useless where the belt is bent
in both directions, as, for instance, when taken over guide or "jockey"
pulleys ; in such cases ordinary lacing or wire lacing must be employed.

418 THE TECHNOLOGY OF BREAD-MAKING.

The most common application of a belt for the transmission of power
is found' in the case of two parallel shafts running in the same direction.
In mounting a belt observe the arrangement of the joints, i.e., the places
where the separate lengths of leather from which the belt is made are
connected together. The belt should be put on so that the trailing end
of each piece last reaches the pulley — a moment 's reflection while examin-
ing the belt will make the reason for this plain. When joining up a belt
with leather lacing, the ends should be pared down in order to make a
" scarfed" joint of uniform thickness. This should be arranged so that
the joint follows the same direction as others in the same belt. If double
belts are used it might be difficult to obtain a satisfactory "scarfed"
joint, and the ends should be butted and a separate piece of belt laced on,
jointly to both ends on the outside of the belt, i.e., not touching the pul-
leys ; thus an even inner surface will result. In joining up the ends of a
new belt considerable allowance must be made for stretching: it is not
possible to give exact instructions as to the amount of such allowance,
but a very little experience will provide the necessary judgment. In any
case a new belt will stretch further than can be allowed for in first join-
ing up, and will need "taking up" after it has been at work for a little
while ; with newly installed machinery it is therefore as well to go care-
fully round all belts before starting up the day's work — this precaution
requires but a few moments and will save the inconvenience and loss of a
stoppage during working hours.

It should be, but actually is not, superfluous to here advise that suf-
ficient belting should be kept in stock (not kept in a hot place), together
with fasteners, laces (wire) and tools, to enable repairs to be quickly exe-
cuted when necessary.

If it is desired to drive two parallel shafts in opposite directions, the
belt is put on "crossed," i.e., it must run from the under side of one
pulley to the upper of the other. Shafts at right angles to one another
can be driven by belting quite satisfactorily, if the one is above the other
at a sufficient distance to give a reasonable length of ' ' drive. ' ' The pul-
leys are arranged in such a manner that the belt leaving the "driven"
pulley has a central lead to the "driver," and equally on leaving the
"driver" pulley leads centrally on to the "driven" again. The shafts
and pulleys must be accurately fitted and can only work in just the one
way which ensures correct leads; but the condemnation of such drives
which one occasionally meets with is not justified, and arises out of unsat-
isfactory experiences due to badly arranged gearing. Properly propor-
tioned and erected, the so-called "quarter twist drive" may be as satis-
factory as any other belt drive.

To enable a machine to be driven which has to stand well away from
the wall, or to get into an adjoining room, or for other reasons, a belt
drive may be required to run over guide or "jockey" pulleys. The plan
is not a good one and is unsuitable for considerable powers, but if well
arranged may prove quite satisfactory for light work. It should only be
employed where other means are not available, and should then be so
arranged that the belt is not required to be very tight in order to trans-
mit the necessary power.

Before turning from the subject of shafting, bearings and pulleys, it
may be useful to call attention to a point very commonly overlooked.
The power absorbed by the shafting itself, that is to say, before the brake
horse power or power actually given off by the prime mover can become
available at the machines, is very considerable. One short length of
shafting of course does not require a startling amount, but it may be

THE MACHINE BAKERY AND ITS MANAGEMENT. 419

considered a safe rule not to allow less than 2 to 3 h.p. in fixing upon the
size of the prime mover, when making provision for the requirements of
the average bakery (with, say, 20 to 30 ft. of shafting). In larger estab-
lishments, however, involving shafting in three or four and even more
different places, the power absorbed "on the way" to the machines is
much more considerable and requires to be carefully gone into. There
are many bakeries where the power required for driving the hoist on the
top floor (for getting the flour in during the day, when it is the only
machine for which the engine is being run) is three and four times as
large as the power required by the hoist itself. A similar condition of
affairs can often be found in bakeries when a small whisk or cake machine
in the confectionery department causes an engine and a great deal of
shafting to be kept running for the best part of the day. Seeing that a
better scheme might in many cases avoid this considerable and continual
waste of power, it will be clear that even for matters of quite simple and
everyday practice it may be wiser to be guided by the advice of compe-
tent bakery engineers, rather than ostensibly to save a few pounds by
merely buying individual machines and having the rest of the installation
put together in an amateur fashion.

Cases have been met with where owners have quite erroneously blamed
machines for absorbing a great deal more power than w^as possible, from
no other cause than that stated above. It is the fashion to inquire into
horse powers and weigh all kinds of pros and- cons with much care, but
this is worse than useless if a supposed saving of a little power in a
machine is to be nullified by badly designed accessories or transmission
arrangements. The fact is, that as regards power absorbed by machines,
the user may well leave that subject to the engineers; it will pay him
better to confine his inquiries, when selecting machines, to the question of
their efficiency for his daily work. The machines that will pay him best
are those which produce the finest article — no matter what their price
may be or the horse power they absorb — especially as it is rather in the
nature of things, that the machine which punishes the dough least is also
likely to use the least horse power if proper regard is had to the work
done.

571. Lubrication and Maintenance. — The modern device for ensur-
ing lubrication has already been fully dealt with as regards bearings and
loose pulleys for shafting. The older methods are not referred to, as
modern developments and advice for future conduct alone form the sub-
ject of this chapter on machinery. It may be as well, however, to say
that oil is considered the only suitable lubricant for shafting, at least in
the opinion of the authors, as solid grease lubricant, excellent as it is for
bakery machines proper, involves more constant attention than can be
relied upon where bearings, etc., are out of reach and in inaccessible
places. That no prejudice exists against solid lubricants, will appear
quite clear after a perusal of the description of bakery machines. In
connection with lubrication, special attention requires to be drawn to the
necessity for using bearings from which leakage or overflow is impossible ;
as this is obvious, nothing further need be said.

As to maintenance, it cannot be sufficiently insisted upon that the
only proper course is to appoint two men specially, whose duty it shall
be to carry out certain specified duties periodically. The bakery proprie-
tor should keep a book in which he enters these duties in full — set out
in unequivocal language — he should add further items, as experience
shows up weak spots, so that these may be safeguarded in future, and he
should satisfy himself that the person appointed has attended to his

420 THE TECHNOLOGY OF BREAD-MAKING.

duties at the specified times in a proper manner. The object in appoint-
ing two men is to provide against emergencies. There should then always
be at least one competent person available to do the work, if each of the
two is made to take the duties referred to for alternate months.

The task of preparing the book of instructions is not so formidable as
might appear at first sight. The manufacturers of ovens, machines and
motors provide (or should provide) proper instructions; and if these are
taken as a basis, and common sense, assisted by the engineers, be used,
complete rules will not be difficult of compilation. That the maintenance
of the proprietor's plant should be properly organised by the proprietor
must be evident, because that course is absolutely indispensable in his
own interests. It is no use to blame the men when something has gone
wrong; it would be much better for the proprietor to blame himself for
not having made adequate provision against contingencies. If this
sensible course is followed, the proprietor will soon find a remedy, which
will never be the case if the matter is simply left in the hands of the men.

As regards upkeep of shafting and gearing generally, the authors fear
that the majority of users rarely trouble themselves until defects force
themselves upon their notice. They have already said that spares for
repairs of belts should always be kept handy. It is now suggested that
shafting is as much an essential of an installation as the engine or the
machines, and that it and all its appurtenances, as well as engine and
machines, should be kept 'absolutely clean. If cleaning is properly done
from day to day it is done in an astonishingly short time. If it is neg-
lected until gear has to be "dug out" it is nearly a hopeless task. No
proprietor should be satisfied with his bakery unless shafting and all ma-
chinery be left perfectly clean inside and out at the conclusion of the
day 's work. This is no counsel of perfection ; there are plenty of bakeries
in which this is done, but there are far more in which it is otherwise.
This cleanliness is not only essential for the proper upkeep of the ma-
chinery, but it is indispensable from a hygienic point of view, as well as
from the business standpoint. Let each bakery owner throw his bakery
open to public inspection all day and every day, and if it be kept in the
condition in which it should be, this plan will not only compel the proper
appearance and condition of the establishment, but will prove the best
possible advertisement. In such cases where this plan has been tried, it
has given excellent results and has led to increase of business.

572. Flour Hoisting.— Flour being, for reasons explained in para-
graph 551, usually stored at the top of the building, adequate means for
hoisting are among the primary requirements of a power-driven bakery.
In many cases a covered cartway is formed in connection with the bread-
room either within the four walls of the main building or as an outside
addition.

In the former case square holes are cut vertically above one another
through every intermediate flour, in such a position that the loaded flour
lorry can be conveniently placed immediately under the openings. Each
floor opening should be fitted with hinged flaps, normally completing the
floor and preventing all danger from open holes. These flaps should be
stoutly constructed and made to hinge upwards; a hole is cut in the
centre of the joint between the two large enough to allow the cast-iron
weight-ball, which serves for causing the hoisting chain or rope to
descend, to pass unobstructedly. The trap-doors should be railed off, but
if this is not permanently possible, movable guard rails should be placed
in position each time the hoist is used, to prevent risk of injury to
passers-by. If the flour sacks are to be hoisted outside the main building,

THE MACHINE BAKERY AND ITS MANAGEMENT. 421

the pulley over which the hoisting rope passes is supported on a project-
ing beam or cathead. To prevent the flour from getting wet and to avoid
the admission of cold air into the flour store as far as possible the cathead
should be enclosed, and a continuation of this enclosure should be carried
right down to within a convenient distance of the lorry ; where the lorry
stands in a covered yard, this enclosure or trunking (usually called a
"lucombe") merges into the roof of the yard and is joined to the same
in such a manner as to be watertight. Wherever the lucombe gives access
to a floor, i.e., at each floor to which flour is intended to be hoisted, trap-
doors as described should be fitted, thus practically avoiding all danger
to operatives in * ' landing ' ' the sacks and detaching them from the hoist-
ing rope. The centre of the hoisting rope should be clear of projections
by about 2 ft., and the internal dimensions of a lucombe should not be
less than 4 ft. square.

The Sack Hoist itself, except in such rare cases where it may be direct
coupled to an electric motor, should preferably be of a type employing a
friction drive. There are various hoists upon the market which are quite
satisfactory, but none are simpler, more efficient and reliable, free from
necessity of repair, or easier to work than the one here illustrated, Fig. 38.

The driving pulley will be seen close to the frame to the left of the
illustration, it can be driven in either direction by arranging an ' ' open ' '
or "crossed" belt drive. It usually runs free, and is therefore a loose
pulley. The hoisting drum, grooved to take the highly flexible steel wire
rope, is pressed to the right into the brake drum by a spring contained in
the projection shown to the left of the framing. The drum is there-
fore normally and automatically * ' on the brake. ' ' A slight movement of

FIG. 38.— Sack Hoist.

422 THE TECHNOLOGY OF BREAD-MAKING.

the lever on the right disengages the drum from the brake and allows any
suspended weight (the ball shown is sufficiently heavy) to descend. On
letting go the lever the drum instantly returns to the brake and comes
to a stop. A slightly greater movement of the lever than that referred
to engages the other end of the hoisting drum with the pulley and causes
the hoisting rope to be wound in, thus raising any weight attached there-
to. The action is quick, safe and noiseless and allows of very delicate
handling. These hoists have been in constant use for very many years
and are capable of hoisting hundreds of sacks of flour per week each.
They are made in various sizes, to suit the length of lift and for weights
up to 5 cwts.

The fixing of the hoist is "universal" — that is to say it may be fixed
to suit practically any local requirements. The best plan is to hoist
direct from the drum, as each pulley over which the rope has to run
means wear and tear to the latter. In practice the lever is of course
worked from a hand rope carried to a convenient position.

The hoist shown is fitted with a wire rope, but it can also be supplied
for use with a chain. The rope is, however, rather the safer appliance
because it will not break without warning. The wear of a wire rope can
be readily detected by the gradual breaking of the strands. As the
broken ends stick outwards and are sharp as needles, the occasional pass-
ing of the bare hand along a wire rope will soon draw attention to wear.
A rope is sound so long as the surface is smooth to the touch all along its
length. Chains do not necessarily give any sign of weakness, as this does
jiot arise merely from wear as to thickness of link's; chains harden in use
and may snap from this cause without notice. It is therefore necessary
with all chains at least once annually to dismantle the same and send
them to be annealed. Any ordinary smith or engineer's shop should be
able to perform this very necessary operation, which is not difficult but
requires to be conscientiously done.

The rope pulleys must be properly designed to prevent damage to the
rope — it is best to obtain them from the engineers who specialise in these
hoists ; not only is the shape of groove important, but also the diameter
of pulleys — both must be suitable to ensure a reasonable length of life to
the rope. Hoists should be planned so as to reduce the number of rope
pulleys employed to a minimum. The hoist is fitted with Stauffer solid
grease lubrication, and the same method should be employed for the
pulleys.

Hoisting Speeds must vary according to circumstances; 60 ft. per
minute is quite sufficiently fast for short lifts, such as from one floor to
another, but speeds up to 200 ft. per minute may be employed for long
lifts.

The Hoisting Power varies of course with the speed and weight, but
for the average bakery it may be taken that to provide approximately 2-3
h.p. will be sufficient.

573. Flour Storage and Flour Blending. — There can be no doubt
that the aeration of flour before use in the bakehouse is beneficial as.
regards quality of bread produced, and that if it is carried out efficiently
and in conjunction with judicious blending of different grades of flour,
an advantage can be obtained in regard to quality of the blend over the
market price, or inversely a profit be made if a given quality be taken as
the standard.

To realise these advantages to the full is, however, by no means easy.
and involves a great deal of good judgment. It may be taken that the
process pays only with considerable outputs or exceptional judgment —
or both.

THE MACHINE BAKERY AND ITS MANAGEMENT. 423

Many so-called blending plants are not remunerative, some are even
directly harmful. This principally applies where use is largely made of
worm conveyors, which are most objectionable because they create dust,
due to the friction inseparable from their use. It must be obvious that it
is absurd to spoil good flour in this manner after the miller has gone to
endless trouble and expense to eliminate dust and make his flour as gran-
ular as possible !

With modern developments of milling, blending has not the import-
ance in an average bakery in this country which once attached to it. The
important exceptions are where —

1. The large bakery, properly equipped, specialises in the matter of

blending and really deals with the question on scientific lines.

2. The small bakery where the proprietor or manager possesses special

knowledge and experience, and by personal good judgment, can

ensure that it pays him to blend.

In all other cases, the millers can be relied upon for supplies of good
blends, if judicious selection be made in buying for the requirements of
the business.

FlG. 39. — Special Flour Blending Arrangement.

424 THE TECHNOLOGY OF BREAD-MAKING.

PLAN X. Flour Blending Plant.

THE MACHINE BAKERY AND ITS MANAGEMENT. 425

574. Blending Plant for Large Bakery. — There is no compromise
possible for the large bakery that requires a blending plant. An elab-
orate and somewhat expensive installation alone will serve the purpose,
and headroom is necessary to avoid objectionable conveyors. Plate X
shows a plant for storing three blended mixtures of flour which can then
be used at will ; but owing to limited height a conveyor is employed for
distributing the flour to the storage hoppers. The same plant may be so
arranged that by the partial raising of the roof inclined shoots replace
the conveyors. This second arrangement reduces the use of conveyors to
a minimum ; they are only employed for discharging the flour from the
hoppers to the automatic weighers, and so do a minimum of harm.

575. Blending for Small Machine Bakeries. — An excellent plan,
which reduces the outlay for machinery to a minimum, is to substitute a
hopper feeding direct into the elevator for the blender described in the
arrangement last mentioned. Pen boards placed in the hopper divide the
same into compartments for receiving each one quality of flour. When
the hopper is filled the pen boards are withdrawn and the elevator
started, causing approximately equal proportions of the various flours
forming the blend to be elevated to the sifter. If the kneader is allowed
to run for a few moments previous to introducing the liquor, etc., a per-
fect blend is obtained. Ample time is allowed for obtaining the necessary
output per hour of dough if the kneader is of a sufficient size. It will be
seen that this arrangement has the further considerable advantage, that
an ideal working scheme can be obtained with only two floors. The
ground floor will be equipped with ovens, divider, etc., and the first floor
with kneader, sifter, and elevator. The first floor therefore serves as
doughing-room as well as flour store, and enables the cost of building to
be kept at a very reasonable figure. In view of the considerable cost of
a fully automatic plant and the relatively small advantage obtained by
the use of the same, in comparison with the very simple arrangement last
described, the authors recommend the latter except for really large in-
stallations. The photographic view (Fig. 39) subjoined, illustrates this
arrangement very well.

576. Flour-Sifting Machinery. — Although many attempts have been
made to introduce a sifter with reciprocating sieve or sieves, the rotary
machine is the least troublesome and answers all practical requirements.
The fact is that the reciprocating sieve, although theoretically the ideal
arrangement, is in practice a nuisance because it cannot be made so as to

FIG. 40. — Rotary Flour Sifter.

426

THE TECHNOLOGY OF BREAD-MAKING.

be either noiseless or really durable. On the other hand the rotary sifter
is not only quite noiseless and perfectly trustworthy, but from a commer-
cial point of view does its work perfectly. The illustration (Fig. 40)
shows a machine with a spiral brush roller working against a semi-cir-
cular sieve, which is contained in the lower box-like extension of the
machine.

577. Tempering and Measuring Water. — The introduction of ma-
chinery in general, and of automatic bread-making plants in particular,
calls for more accurate methods in the bakery than were formerly con-
sidered necessary. So long as doughs were made by hand the operative
was more or less a craftsman, who could judge by touch and appearance
as to whether the dough was of the correct consistency or not. The
craftsmen are getting fewer every year, and in any case cannot be relied
upon for sufficiently accurate judgment to suit modern requirements. In
addition, however skilful the workman, he has in modern machinery no
opportunity of controlling the consistency of his dough, other than by
accurately weighing and measuring the materials; therefore if bread is
to be satisfactory and uniform, if automatic dividers, provers, and mould-
ers, are to yield the best results, and ovens are to soak the bread properly
in a given number of minutes at a predetermined temperature, it follows
that the doughs must be perfectly uniform. If they are not so, the
results are either not of the best, or the smooth working of the bakery
must be disturbed by allowing batches to have different periods for prov-
ing and baking. Clearly, then, too much care cannot be exercised in the
making of dough. This subject will subsequently receive further consid-
eration (see paragraphs 578-581) ; it is sufficient for the present purpose to

say that an appliance is neces-
sary, which will enable an ex-
act quantity of water at a pre-
arranged temperature to be
accurately and readily ob-
tained. Needless to say, the
arrangements should also be
such as to enable this result to
be obtained without unneces-
sary waste of water in adjust-
ing the temperature desired.
Theoretically, much might be
said in favour of weighing the
water, as the most accurate
way to obtain a given quan-
tity. In practice, appliances
for weighing introduce many
complications of an undesir-
able nature, and are liable to
derangement, leading to
greater inaccuracies than sim-
pler apparatus involves. The
best and most practical ar-
rangement is the tempering or
attemperating and measuring
tank here illustrated (Fig. 41) .
It is a tank formed of steel
sheets, tinned inside, and sup-
Fic. 41.— Tempering and Measuring Tank. ported on the wall adjacent to

THE MACHINE BAKERY AND ITS MANAGEMENT. 427

the kneader, or on the kneader itself. Hot and cold water are conveyed
thereto in large bore pipes to prevent delay. The hot-water pipe is inter-
nally taken to the bottom of the tank, and the cold-water pipe discharges
at the top. Thus an excellent mixing is obtained by the aid of natural
laws, but, as an extra, a mixing paddle can be fixed with a vertical spin-
dle—this hastens and perfects the process of obtaining a tank full of
water at a uniform temperature, as ascertained by a thermometer which
is immersed, completely and readily visible through the plate-glass front
of the tank.

An internal overflow pipe is fitted and wherever possible (in all new
bakeries, for instance) a sink or gully should be provided immediately
below the position which a tank is to occupy. This gully will not only
take such overflow from the tank as occurs, but is useful for washing
down the floor, the kneader, and for emptying pails, etc. The specially
useful feature about the tank illustrated is the sliding scale (Williams'
patent) seen through the glass front, and readily raised and lowered by
means of the hand-wheel on the left. This scale is plainly marked in
gallons, as seen in the illustration, and facilitates the drawing off of the
exact quantity of water required. In any ordinary tank it is practically
impossible to obtain a pre-arranged level of the water, while tempering
the same to say 96° F., without permitting an overflow, and thereby in-
curring a waste of water. The tank illustrated, however, is larger than
the maximum capacity registered on the scale, and therefore allows suf-
ficient margin for obtaining the correct degree of heat without overflow
or waste. As soon as the water is at the right temperature and thor-
oughly mixed, which is indicated by the thermometer reading remaining
stationary, the scale is moved to the position in which the zero mark
exactly corresponds to the level of the water. The universally-jointed
pipe, shown in an upright position in the illustration, is next placed in
position to discharge the water into the kneader, and then the large draw-
off shown is opened. As the water runs out of the tank and the level
sinks, it is clear that the cock merely requires to be closed sharply when
the water level has sunk to the mark indicating the desired number of
gallons, to ensure that the right quantity of water, at the correct tem-
perature, has been delivered into the kneader. These tanks are made in
various sizes to correspond to the capacity of the kneader.

Attention is here drawn to the fact that certain waters (notably some
moor waters) corrode iron and steel, even when protected by galvanising.
To meet such cases these tanks are also made of copper and gun-metal
throughout, coated with tin internally. These tanks are so cleanly and
useful in saving time and ensuring better and more uniform results, that
their employment, even in hand-worked bakeries, must be recommended.
It is quite a common error to suppose that they are useful only in con-
nection with machinery.

578. Dough Mixers and Kneading Machines. — Of modern dough-
making machines there are three principal types which require to be
considered in detail and which practically cover the entire field. The
first group embraces machines constructed upon the principle of a revolv-
ing drum, the second employs a stationary trough with blades revolving
around their own axes, and the third, arms moving in fixed planes in a
revolving pan.

579. Rotary Mixers. — The idea underlying a rotary mixer is ex-
tremely simple. A drum, of a volume considerably greater than the size
of the batch to be made, is revolved around a horizontal axle, which runs
through the drum. Parallel to the axle are placed a number of metal

428

THE TECHNOLOGY OF BREAD-MAKING.

rods which pass from one side of the drum to the other. A square open-
ing is cut in the cylindrical sheet, which forms the drum and joins up
the two circular castings, which constitute the sides ; the opening is closed
by a removable door. In revolving, the flour, water, etc., are tumbled
about and over the bars until the dough is made. The door is then re-
moved and the drum is revolved, until the opening is at the lowest point
and the dough allowed to discharge itself. It will be seen that the ma-
chine is of a simple nature, does not require much power, and can be
made very cheaply. But there its advantages end, and it is necessary to
say that while its simplicity and inexpensiveness are attractive, the dough
it makes is not kneaded at all in the proper sense, and lacks texture,
volume and colour, while being wet, sticky and inclined to be lumpy
when discharged. It follows that while the machine may answer for slack
doughs, it cannot be recommended for those of a stiffer nature or for
high-class work, or for obtaining a maximum yield. An impartial trial,
with precisely similar flour and other types. of machine, will prove this.

The rotary kneader was first put upon the market under the "Adair"
patents.

580. Kneading Machines with Revolving Blades. — The construction
of these machines is based upon the employment of a cylindrical trough
which encases a revolving blade, with the axes of the two coinciding. The
sheet which forms the trough does not complete the circumference, but
merges above into a rectangular hopper, open at the top. In most ma-
chines two cylinders are employed with parallel axes, apart from one an-
other by a distance rather less than the diameter of each cylinder. In
exceptional cases three blades are employed, but the arrangement intro-
duces undesirable complications and possesses no advantages per se. In
the earliest machines, and many others, the blades were of a haphazard
and of a more or less fanciful design, and although they all made and
make dough, yet the problem of the shape of the blades does not seem
to have been worked out on scientific lines.

The Two-bladed
Kneader may be safely
considered the most typ-
ical and widely - used
dough-making machine
employed in bakeries,
and as such requires to
be dealt with more fully.
The best example of
these is that known as
the "Universal" (Pflei-
derer's patent). In its
original form, this was
the first machine to be
efficiently manufactured
and! introduced to the
bakery trade. It is also
generally acknowledged
to be the most successful,
except only for certain
special types of dough.
Of this machine anillus-

FlG. 42.-"Umversa!" Kneading Machine, tration is given in Fig.

Pfleiderer's Patent. 42, showing the machine

THE MACHINE BAKERY AND ITS MANAGEMENT. 429

nearly tilted over for discharging the dough. The main secret of the
success of this machine lies in the form of the blades, which are con-
structed on highly scientific lines, and ensure that every particle of the
contents of the trough is brought within their action with absolute thor-
oughness. A small model machine on the same lines is sold by the
makers, which constitutes a most useful addition to laboratories generally,
where it is invaluable in many ways, apart from its utility as a dough-
maker for small test batches. This little machine demonstrates the per-
fect mixing action very effectively, if it be charged with dry flour, and
a pinch' of red lead. With a stated number of revolutions it will so thor-
oughly incorporate the two ingredients, which by other means are not at
all easy to mix intimately on account of the great difference in specific
gravity, that a small part of the mixture, placed on a sheet of paper, will
successfully stand the severe test of being "smeared" with a palette
knife to prove the uniformity of mixing obtained.

Returning to the dough kneader, the next point to be mentioned lies
in the arrangements for preventing the escape of liquid from the trough
and for making the entering of grease or dirt impossible. The problem is
not an easy one, but has been solved very simply and effectively. There
are only six bearings in this machine, apart from the two loose pulleys in
connection with the driving gear, and all are fitted with Stauffer solid
grease lubricators. The drive is arranged to be reversible by means of
friction clutches formed between each of the two pulleys and the central
driving disc, which is enlarged in diameter and fitted with a handy rim
to enable the machine to be pulled round by hand when being cleaned.

FIG> 43. — "Universal" Kneading Machine, Single Blade, Fitted with Electric Motor.

The control is from the hand-wheel overhanging the pulleys, which are
driven in opposite directions by belts from the line shaft, one "open" and
one "crossed," thus enabling the blades to be driven in either direction.
The weight of the trough is balanced by counterweights, and the raising

430 THE TECHNOLOGY OP BREAD-MAKING.

or lowering may be by hand or power as desired. The interior of the
trough as well as the surface of the blades are ground and polished, and
the dough leaves these surfaces perfectly clean, on being turned out,
except with very slack doughs.

The machine is fitted, if desired, for driving direct by electric motor,
which is then supplied with a reversing controller to enable the machine
to be reversed. Fig. 43 shows a single -blade " Universal" fitted with a
motor direct. This machine is made with pulley drive also, or the ma-
chine shown in Fig. 42 can also be fitted, self-contained, with electric
motor as here shown (Fig. 44). To prevent the raising of flour dust,

FlG. 44. — "Universal" Kneading Machine Fitted with Electric Motor.

which would result from working the machines without a lid, these
kneaders are either fitted with a sleeve and connected direct to the sifter,
or they can be supplied with a ' ' safety ' ' lid, which is so interlocked with
the driving gear that it is impossible to raise the lid while the machine
is in operation. In certain countries these "safety" lids are made com-
pulsory, as a prevention for accidents to operatives.

581. Kneaders with Rotating Pans. — These are a comparatively
modern product; many are of too light a construction to be serviceable,
and have the serious defect that working parts requiring lubrication are
to be found over the dough, on which grounds their use cannot be recom-
mended. These machines employ a different principle altogether to those
already described, and rely upon the stickiness and plastic and tenacious
qualities of dough for their action, which may perhaps be described as
more akin to sugar "pulling" than anything else.

Fig. 45 shows a diagram of the "Viennara" kneader ("Pointon's"
patent). The arm is fitted with double horns, as shown in Fig. 46, and
describes a curve, which compels the horns to move in a path shown in
dotted lines (Fig. 45). The gearing is so arranged that the speed
throughout this curve is not constant ; it is slowest when the horns are
descending and increases rapidly as the horns sweep the radius between

THE MACHINE BAKERY AND ITS MANAGEMENT. 431

the bottom and side of the pan, being at its greatest during the upward
movement. The pan slowly revolves (about 4^ revolutions per minute),
and being filled with flour to the line indicated, brings fresh material
under the influence of the arm at each stroke (26 per minute) . The effect

FIG. 45. — "Viennara" Kneading Machine. Sectional Diagram.

is to subject the dough, when incorporated, to a combined aerating
stretching and folding action, most admirably adapted to develop it
under ideal conditions and to an extent quite impossible by manual
labour. The operation of the arm is of the gentlest kind, and owing to the
perfectly combined aerating folding and stretching which the dough
receives, it is of a remarkably fine texture, toughness, colour, and volume.
Many claims have been made for devices for increasing the yield, a point
on which bakers have become rightly sceptical ; but certainly the ' ' Vien-
nara" has remarkable properties in the direction of causing the flour to
absorb its proper proportion of water without loss of stiffness or elasticity.
Consequently, the dough produced shows a decided improvement in
colour.

Fig. 46 shows the complete machine with sifter and tempering tank
self-contained. As will be seen, a door is fitted in the pan, which can only
be stopped in the correct position for discharging. This door is inter-
locked with the driving control in such a manner as to make any mistake
impossible. The dough truck runs under the pan, and the dough is dis-
charged automatically by the arm alone being worked, while the pan
remains stationary. The domed lid is a fixture, but the front portion is
hinged and can be raised so that the dough can be inspected. The pan,

432 THE TECHNOLOGY OF BREAD-MAKING.

having no blades, bearings or axles, has a perfectly smooth interior; it is
therefore hygienically perfect and practically keeps itself clean.

In conclusion two important subsidiary advantages in the ' ' Viennara ' '
machine must be referred to. The first is that owing to the extremely
gentle action of the machine, the arm of which can in no wise damage the
dough more than a man's arm does in kneading, it is practically impos-
sible to overwork a batch. Men will leave their jobs and cannot be relied
upon to do exactly as they are told ; it is therefore distinctly an advan-
tage in this machine that by being left longer at work than is necessary it
cannot damage — but will, in fact, rather improve, the dough. The sec-
ond point needing a special reference is that, unlike other machines, this
is a very safe appliance, in using which it is scarcely possible for a man
to receive injury. The arm on its upward stroke will push out a man's
hand, and can never pull him in if he attempts to feel the dough, as is
only too frequently done.

FIG. 46. — "Viennara" Kneading Machine.

THE MACHINE BAKERY AND ITS MANAGEMENT. 433

582. Sponge-making Machines. — Before leaving the subject of
kneaders it is necessary to describe the application of such machines to
the making of "sponges." Although the tendency in machine bakeries
has been for many years to adopt the "straight dough" system, dispens-
ing with sponges and kneading the flour with yeast and salt into a dough
direct, yet the older process holds its own in many countries, and also in
portions of the United Kingdom, notably in Scotland and Ireland. A
very convenient combination is provided by the "Universal" machine
already described, when such a machine is fitted with two speeds to be
used at will. It will be clear that this enables a high speed action to be
used for making light sponges, which when made are turned out into
dough trucks and left to prove. These sponges when ready are then
utilised for making the dough, for which the second or normal slow
speed of the kneader is used.

583. Sponge -Stirrer. — Another form of machine frequently used is
the sponge-stirrer, of which an illustration is given in Fig. 47. A cast-
iron standard carries the driving gear as well as the upright spindle fitted
with suitable blades, which being balanced and arranged to be con-
veniently raised, permits the tub, fitted with casters, to be readily placed

FIG. 47. — Sponge-Stirring Machines

in position. The sliding casting, shown in the illustration above the
stirrer proper, rises and falls with the latter, and acts as a self -centring
guide to the tub, which is automatically locked in position as soon as the
spindle has been lowered. A sifter is fixed above the stirrer (as shown)
and, by means of a canvas shoot enables the flour to pass direct into the
tub. The illustration also shows the kneader, with sifter and tempering

434 THE TECHNOLOGY OF BREAD-MAKING.

tank and the tub lift, with a tub lifted ready for discharging its contents
into the kneader, thus giving a very clear idea of the whole installation
for suitably dealing with doughs in such bakeries as employ the ' * spong-
ing" process.

584. Dough Trucks and Dough Proving. — As has been already
pointed out in paragraphs 546 to 554 dough trucks should always be
movable. They should therefore be of a "handy" size, never exceeding
a capacity for two sacks. They should be fitted with casters, or if pre-
ferred with one caster at each end and an axle in the centre, with two
loose wheels, designed to take the whole load and keep the casters just off
the floor. In England the dough trucks are almost universally of
wood. It is difficult to account for the prejudice, which tenaciously clings
to British practice, against the employment of metal in this connection,
despite the fact that in all other matters pertaining to bakery equipment,
especially as regards large establishments, this country is undoubtedly

FIG. 48.— Steel Dough Truck.

ahead of all others. The common idea is that the metal trough must chill
the dough, but as the dough will be chilled in any case if the bakehouse
cold — and the truck cannot be cold if the bakery is not — the conclusion is
not very logical. Further, the specific heat of iron is low, and the trough
cannot under any ordinary circumstances, affect the temperature of the
dough to a material extent. As a matter of fact the wooden dough truck
has practically disappeared from all modern plants on the Continent, and
as the Continental baker appreciates the importance of not chilling his
dough, at least as much as his British confrere, the statement that there
is no objection to the use of iron or steel in dough trucks, any more than
in kneaders, dividers or moulders, must be held to be proved correct. Of
course every baker will please his own tastes in such a matter as this, but
it is at least worth while to point out that the not inconsiderable wear and
tear, with consequent renewals, occasioned by the use of wooden trucks,
may be eliminated by the employment of the very much more hygienic

THE MACHINE BAKERY AND ITS MANAGEMENT. 435

and durable steel truck, with bright ground interior surface, similar to
that of a kneader. A good plan is to use steel troughs tinned inside, as
being the most suitable surface. An illustration (Fig. 48) is given of
such a trough showing its general construction.

The dimensions of trucks should be suitable for the machines with
which they are to be used, a point sometimes overlooked, and both width
and depth should not be too great, as unduly heavy work is otherwise
thrown upon the operative. Inside dimensions of about 2 ft. in width and
1 ft. 6 in. in depth should not be exceeded.

585. Proving-Rooms. — When bread was almost universally made by
the long sponge system, the employment of separate rooms, kept at an
even temperature, for the storage of sponges during fermentation, was
always regarded as a great advantage. With the advent of automatic
plants, the subject requires consideration in a new light, The fact is that
separate proving-rooms may be responsible for bad results, where auto-
matic plants are in use, unless steps are taken to ensure that the tempera-
ture of such rooms does not vary from that of the machines. Now it
cannot be sufficiently insisted upon that dough must not be subjected to
changes of temperature throughout its different phases ; and, when ready
for dividing (scaling), should not be brought into rooms, or fed into
machines, which are at a different temperature than the dough itself. It
follows that the arrangement of the bakery should be such as to make
this automatic if possible, because the more it is left to the men to ob-
serve such matters and regulate temperatures the more trouble will ensue.
The machine-room, and therefore the machines contained therein, should
be kept at a uniform temperature, equal to that of the doughing and prov-
ing-room, and all should of course be arranged so that they are free from
draughts. If this cardinal principle is adopted and never lost sight of,
and if new bakeries are designed with this clearly in view, much trouble
and constant watching will be saved. Assuming a bakery perfect in this
respect and equipped with automatic plant of the best type, a wonder-
fully high and uniform standard of bread will be obtained, if reasonable
care be used in preparing the doughs at the proper and uniform tem-
perature.

586. Dough Dividers. — These were first placed upon the market in a
commercially practicable form about the year 1896. The introduction of
loaf dough-dividing machinery marks a distinct and very far-reaching
development in the mechanical equipment of bakeries. All subsequent
stages of dough-making and machine-working, however difficult of solu-
tion in themselves, are dependent upon, and secondary to, the problem of
satisfactorily weighing off pieces of dough of given weights from the bulk.
In the course of the last fifteen years three main principles have been
employed in the construction of dividers. Cylinders or boxes with close-
fitting rams, the latter adjustable to give variable volumes provided to
receive the dough necessary to form one piece or loaf, are common to all
three types referred to. It is in the means employed for charging these
cylinders or boxes with dough that the three types principally and mate-
rially differ. A worm, acting as a conveyor at the base of a dough hop-
per— fluted or roughened rollers running in opposite directions, charging
a chamber, communicating with the cylinders — and a weighted ram
acting upon the dough confined in a closed chamber, are the three differ-
ent means referred to. All three principles lend themselves to the con-
struction of machines capable of cutting dough pieces, with sufficient
accuracy for all commercial purposes ; in fact to the production of loaves

436

THE TECHNOLOGY OF BREAD-MAKING.

of much more uniform and accurate weight than is commercially obtain-
able by hand. The effect of such machines upon the dough, and upon the
process of fermentation, is, however, the chief consideration and requires
ro be most carefully taken into account. Dough is not a material which
may be ill-treated with impunity ; it is, or should be, a living mass which
may suffer irretrievable damage if handled with a trifling excess over the
permissible severity. This aspect of the matter is often dismissed with
unpardonable levity, on the plea that "a little more yeast will soon put
that right, ' ' or that ' ' it can be left a little longer to recover ' ' ! There is
no such thing as artificially counteracting actual damage, either by an

FlG. 49. — Two-Cylinder Dough Dividing Machine.

extra allowance of yeast or reviving fermentation, which has unduly suf-
fered, by allowing extra proof. These are palliatives and may mend, to
some extent, the worst effects of undue severity, but cannot' and do not
allow a healthy growth or perfect development to take place.

In two of the systems quoted above there is the inherent drawback
that the force put into the dough (or force with which the dough is han-
dled) cannot be definitely limited in such a manner as to precludo

damage. The action is not positive, and therefore always employs a surplus
of feeding capacity to ensure the filling of the cylinders, which by their
regulated volume give the weights required. On the other hand, the
third type absolutely limits the force employed and is positive in its
action. The pressure to which the dough is subjected by the ram which
causes it to enter the division boxes can never exceed a safe and prede-
termined maximum, since it is due to a weight which in working remains
constant but can be varied to suit the requirements of the class of dough
used, and never forces forward a greater quantity than the measuring
cylinders absorb. It follows that the maximum advantage, when using a
machine of this type, will be obtained by employing a minimum weight to
give sufficiently accurate loaves.

Correct Weights. — It will be opportune, at this point, to call attention
to the relative value of weighings, more or less accurate. It is a fact that
it is possible to insist upon too much accuracy, especially in view of the
very natural tendency to scale as closely as possible and obtain the maxi-
mum saving in dough. Everything, however, may be carried to excess,
and a baker may easily lose more in quality, and therefore in texture,
bulk, and general attractiveness of loaf, than he gains in dough by very
close weighing.

Extreme accuracy is inseparable from punishment, and in turn pun-
ishment is inseparable from loss in legitimate selling qualities of the loaf.
So long as a divider gives more accurate weighings than can be commer-
cially obtained by hand-scaling, a business will be more benefited by good
quality, due to avoidance of punishment, than from an insistence on the
maximum economy in dough.

The sound plan therefore is to choose the divider which is limited in
its punishing effects, and then adjust the machine to work with the mini-
mum weight required to ensure sufficient accuracy for commercial pur-
poses.

The illustration (Fig. 49) shows a two-cylinder deadweight divider,
suitable for small bakeries, which has a maximum output of 1,400 pieces
per hour. For guidance as to proper proportions of output, remu-
nerativeness, etc., see paragraphs 555 and 557. Larger machines, with
outputs up to 2,400 and 3,600 pieces per hour, are referred to in para-
graph 594 under Automatic Plants. Both machines are made right and
left handed for belt, or direct electrical, driving.

587. Moulding" Machines. — When the newly-kneaded dough is
turned out into the dough truck, it requires to be left undisturbed at a
proper temperature in order to ferment, and as a result of the generation
of gases the original volume of the dough is much increased. It is here
that the value of a good kneading machine becomes apparent, because if
thorough aeration has been combined with a maximum of stretching and
folding, the result will be a dough which excels in bulk, toughness, fine-
ness of texture, and good colour.

To obtain the best results it is essential for the development of fer-
mentation to be as uniform throughout the whole mass of dough as possi-
ble, and for the gluten to be toughened, so as to resist the gases uniformly,
causing an evenness and silkiness of texture not otherwise obtainable.
Judicious and efficient "cutting back" assists uniformity for the same
reason, and when finally ready for scaling or dividing a good dougli must
be uniform all over. It will be apparent that in cutting the dough, when
scaling or dividing into pieces of a size suitable for loaves, these condi-
tions are disturbed, inasmuch as fermentation will, from that moment,
take place under totally different circumstances. Apart from this, the

438

THE TECHNOLOGY OF BREAD-MAKING.

cutting produces wounds, which form portions of the surfaces of the piece
intended to become a loaf. It is therefore necessary to re-work each
piece, with the two-fold object of closing the wound by forming a com-
plete skin all over the dough-piece, and of working the interior, so as to
cause fermentation to continue under conditions which will be uniform
and suitable throughout the newly detached piece of dough intended to
become a loaf. This process is called moulding.

Hand Moulding has hitherto been performed in such a manner that
the piece was rolled on a table, against the palm of the hand, as a more
or less pear-shaped mass, causing the central portions to be worked out-
wards, and vice versa. It was essential to preserve the skin, which was
'formed in this process, from rupture while tightening up the interior,
which of course had the effect of stretching the skin simultaneously. The
tail of the loaf, similar to the gradually contracting and tube-like lower
extremity of an inflated balloon, sealed the skin and was worked into the
loaf-piece at the- conclusion of the operation, when each piece should
become as nearly spherical as possible. The loaf was placed tail down-
wards on boards or in drawers to undergo a further period of proving,
protected from chills. It is needless to say that good moulding could
only be performed by a craftsman, and that the quality of workmanship
varied to a very great extent. The labour was monotonous, and also
arduous, if carried on indefinitely, while effective supervision and a
maximum speed were not easily obtained. From a hygienic point of view
also it was objectionable.

FIG. 50. — Dough Moulding Machine.

THE MACHINE BAKERY AND ITS MANAGEMENT. 439

Machine Moulding. — To find a satisfactory solution of the difficult
problem of moulding dough by mechanical methods proved by no means
easy. The experience of several years' working, however, conclusively
shows that the task has been accomplished. The principle adopted is to
impart to the dough-piece a continuous, rotatory, and screw-like motion
("Pointon's" patent) by feeding it into a spirally shaped trough
arranged upon a revolving cone-shaped table (see Fig. 50).

The spiral trough is stationary, with its finished (ground) surface on
its under or working side ; it is supported by arm-rods, and brackets from
above by means of the column, around which the table revolves. The
table is grooved to afford grip to the dough. It is obvious that if the
trough were merely arranged to encircle the table horizontally a pure
rolling motion would be imparted to the loaf. A skin might thus be
formed, although it would be wrinkled and not in any way stretched, but
the dough itself would only be squeezed about and in no sense truly
moulded. The illustration, however, shows that the trough, after a short
horizontal length, to enable the dough-piece to start rolling, gradually
ascends the cone table, causing the loaf to be forced against it. The result
is that the dough-mass does, in fact, undergo a screw-like motion, sys-
tematically displacing and methodically rearranging the whole, of its
bulk, while stretching the skin continuously from the head of the loaf
tailwards in every direction. At its upper or delivery end the trough
again "eases off" its rate of mounting the conical table, and thus ceases
to form the tail, which is "tucked in,'7 and enables the finished loaf to
roll off the table in as nearly a spherical condition as is necessary for all
practical purposes. The proper accomplishment of this process is essen-
tial to the obtainment of "build," ensuring not only a tough and highly
stretched skin and a thoroughly worked interior to the loaf, but also that
orderly and regular rearrangement of the cellular structure which, by
means of proper subsequent proving, compels the growth of that much
desired and beautiful texture of the perfectly developed loaf of bread.

From the description given, it will be seen that the "pitch" of the
trough, which governs the rate at which it ascends the table, will regulate
the degree of "working" imparted to the dough. If too much "work-
ing" is put into the dough, the skin of the loaf will be overstretched and
yield under the strain; and if too little, then the "build" will not be
sufficient. It is necessary also to point out that the capacity of the trough
must be suitable approximately to the size of the loaf to be moulded. In
consequence of these two important considerations a number of troughs
are required for each such moulder, if various sizes of loaves — or if bread
made from doughs of widely differing consistency — are required to be
moulded. In practice the cone-table or "umbrella" moulder is now only
employed in businesses with uniform outputs.

588. Flexible Moulder. — In order to provide a moulder which shall
be capable of ready and instantaneous adaptation to all the varying re-
quirements of average bakeries, the inventors of the previously-described
machine have recently put upon the market an improved and perfected
form, illustrated in Fig. 51, which they term the flexible moulder. The
principle underlying the construction of this machine is exactly the same
as that of the "umbrella" type. A flat moving table is formed by close-
fitting metal laths connected by chains which constitutes an endless iron
belt running over axles, whose axes are steeply inclined from the hori-
zontal. The moulding troughs are thus enabled to be" made perfectly
straight and therefore adjustable for capacity by the simple and instan-
taneous movement of a single lever ; they can consequently mould dough-
pieces of widely differing weights, found in practice to vary from Y^ Ib.

440 THE TECHNOLOGY OF BREAD-MAKING.

to 4 Ib. pieces. Being suitably supported by bridges spanning the entire
width of the moulding surface, the angularity of the troughs upon the
table can also be adjusted at will, so that doughs of widely differing con-
sistencies can be dealt with. This machine is provided with the following
fittings — two parallel troughs, a " splitter," which cuts the 2 Ib. piece of
dough into suitably proportioned pieces for forming the "tops" and

FlG. 51. — Flexible Moulding Machine.

'bottoms" of cottage loaves, and a tin shaper for suitably shaping tin
loaves to fit the particular "pans" in use. It may therefore be fairly
claimed for this machine that it is universal in its scope, and solves all the
requirements connected with the ' ' balling up ' ' type of moulding.

589. Another Mode of Machine Moulding. — An alternative means
to those described above has recently been introduced for giving a very
complete stretching action without risk of damage to the dough, which is
proving very successful on the very slack and sticky pan bread doughs of
Northern England, made from exceedingly weak flour. It is the outcome
of much experimenting, owing to the failure of the "rolling out" and
"coiling" type of moulder to deal with slack doughs made from weak
flour. This failure is due to the punishment inflicted upon the slack
doughs from weak flours almost universally employed in Great Britain
and prevents that full recovery of fermentation afterwards necessary for
obtaining a really first class loaf.

The principle of the new method is that of using a fluted spindle,
making a pre-determined number of revolutions for each loaf treated for
coiling the dough-piece and thereby causing internal compression within
it. The spindle speed requires to be suitable and the revolving piece of
dough has applied to its outer surface suitable pressure by means of yield-
ing rollers or bands to give just the compression required. On comple-
tion of the correct number of revolutions the spindle reciprocates rapidly

THE MACHINE BAKERY AND ITS MANAGEMENT. 441

in an axial direction, and thereby withdraws itself from the dough-piece,
allowing the latter at once to fall clear. It is found that the mechanical
* ' rounding up " or " moulding ' ' of even the most delicate dough can by
this means be performed with the very best results, and that the finest
possible development of volume, texture, colour and flavour are secured.

The application of this principle to Automatic Bread Plants for
rounding purposes takes place immediately after the dividing stage, and
the rounders of this type are built essentially as an adjunct to the divider
itself. The dough-pieces fall directly upon their discharge from the
divider boxes on to the spindles of the rounder, and on their return from
the spindles directly into the pockets of the prover trays. It follows
that the number of division pockets, rounder spindles and prover tray
pockets employed as one series are the same, the whole forming a con-
tinuously moving series of links in a chain of elements, ultimately deliv-
ering the loaves to the moulder.

In considering the actual work performed by each spindle it would
not be correct to say that it stretches the dough into sheets in the classical
manner of making up a pan loaf by hand, or that it then coils up the
sheet thus obtained, but it does in fact perform an operation which yields
an identical result in the finished loaf, since by another method it sub-
jects the structure of the dough-piece to the treatment which is required
.to ensure uniformly even distribution of the gases, while putting the
"interior" under compression within a suitable skin which is under
tension.

In this as in all similar processes, it is not a question of reproducing
mechanically a method which has established itself as the result of the
exigencies of hand working, but of substituting therefor a process which
lends itself to mechanical operations, while yielding the same or a better
result.

590. Quality of Machine-Moulding. — It is perhaps natural that
scepticism should be felt in regard to the degree of good workmanship
attainable by such machinery as has been described, when the difficulty
of getting good moulding by hand is borne in mind. Flexible moulders
are of such recent introduction that the number of bakers who have as
yet had the opportunity of seeing such machines at work is comparatively
limited. For the guidance of those who may remain unconvinced, the
authors' personal experience is that the machine above described will
mould as well as the journeyman, with this important point in its favour
— that it reaches the same standard of perfection with every single one of
the 3,000 loaves which it is capable of turning out per hour. The jour-
neyman's average workmanship will be much below the best he can do,
but the flexible moulder will never fall below its best. Hence, moulding
machinery should be carefully investigated on behalf of every progressive
machine bakery.

591. Handing-Up and Proving. — If a loaf is moulded directly after
having been scaled off it will lack development and cannot possibly be
either of as good texture or bulk as it should be. It is therefore necessary
to give each dough-piece a preliminary moulding after being scaled off, so
that it may have a period of rest in which to recover or prove before being
finally moulded into shape ready for baking. This preliminary process is
called "handing-up" or "balling-up." The above remarks apply to
ordinary hand-made bread, notwithstanding the fact that there are a good
many bakeries, especially in certain districts, where the loaf is finally
moulded directly after having been scaled or divided. When considering
the question of machine-moulding, it is very necessary to appreciate

442 THE TECHNOLOGY OF BREAD-MAKING.

accurately the different conditions under which the dough is then han-
dled. When hand-moulding is employed there is always a considerable
number of dough-pieces on the table which have been scaled or divided ;
which means that there is always a short period of rest before moulding
actually takes place. Slight as this rest may be, it is essential, and gives
the dough an opportunity of recovery before being moulded. This it
cannot possibly have if fed automatically from a divider into a moulder,
as under such conditions the moulding takes place the instant the piece
has been divided. In hand-working there is no reason why this accumu-
lation of loaves and consequent rest should not be allowed to take place,
as it involves no extra labour and is beneficial to the dough. With ma-
chinery, however, unless the divider feeds directly into the moulder, an
additional man would be required to feed into that machine. The neces-
sity for handing-up, although always present if a good loaf is required, is
all the more pronounced in the case of machinery ; excepting only in spe-
cial cases such as with very slack tin doughs, which may go direct from
the divider to the moulder with reasonably satisfactory results. It will be
understood, however, that these remarks apply only to cases in which the
aim is only an average quality of workmanship ; there can be no doubt
that, where a really good loaf is desired, handing-up is indispensable and
remunerative. Assuming then that handing-up must be included as an
essential operation in the process of making a good loaf, it becomes neces-
sary, for businesses with an output sufficiently large to necessitate con-
tinuous running of machines during working hours, to instal two mould-
ing machines for every divider.

592. Hander-Up. — The first of these machines is coupled direct to
the divider and is called a hander-up. In principle, the hander-up is
exactly similar to the moulder ; but as the newly divided loaf is of smaller
bulk than when it comes to be finally moulded and also requires less
action put into it, the hander-up is a smaller machine than the finishing
moulder. Businesses with outputs up to one-half the capacity of the
divider installed, need not instal two moulders, but by employing a finish-
ing moulder only may, by arranging for the machines to be worked inter-
mittently, get as good and as economical work as the full equipment
yields to the business with a large output. In either event, that is to say
whether handing-up and moulding are done in separate machines or on a
finishing moulder only, a period of rest, averaging about 20 minutes, is
necessary between the two operations, and provision has to be made for
proving the loaves under suitable conditions as to temperature and pro-
tection from draughts. To use any of the older devices in this connection,
such as drawers or proving racks, etc., entails the separate handling of
each loaf into and out of the accommodation provided, apart from the
labour in feeding the loaves into the final moulder. It also involves
possibilities of bad organisation and careless marshalling of the racks,
while the men may not take the batches in their proper consecutive order
and may thus give some less and others more than their proper period of
proof. Considerable space for racks, etc., and for moving them about
would be required.

593. Automatic Prover. — To obviate the foregoing objections and
dispense with all labour between the hander-up and moulder, and ensure
the best possible development of the loaf, the automatic prover has been
introduced. This machine receives the loaves from the hander-up, and
discharges them, fully proved, in perfect condition to the moulder; the
whole process, from the feeding of the divider to the discharge of the
finished loaf ready for the oven, thereby becomes perfectly automatic.

THE MACHINE BAKERY AND ITS MANAGEMENT. 443

The auto prover ("Pointon V patent) is essentially a conveyor suitably
regulated as to speed (with provision to vary the latter if required) and
thoroughly enclosed to exclude draughts. Further, it is capable of being
heated, and in any event is supplied with moist vapour so as to prevent a
dry skin from forming on the loaves, which are consequently proved
under perfect conditions.

594. Auto-Dividing, Proving, and Moulding Plant. — Fig. 52 shows
diagrammatic representations of two modifications of an entire plant of
this description. The loaves coming from the divider fall direct into
troughs on the hander-up and, having been "balled up," are deposited on
trays (eight pieces on each tray, in the full size machine), which are car-
ried on chains, traversing the interior of the prover by a circuitous
course in such a manner as to effect as great a saving of floor space as
height of ceiling and other circumstances permit. The trays move inter-
mittently, and of course at a speed suitable to give the length of proof
required, which normally is from 15 to 20 minutes. Stepped pulleys are
provided for running these trays, so that the rate of speed can be con-
trolled within certain limits. By the time a tray has travelled round the
prover and has allowed the loaves deposited upon it from the hander-up
to undergo the correct period of proof, it reaches a position directly over
the delivery band and by engaging with a suitable gear is turned upside
down, depositing its load of eight loaves on the delivery band. The latter,
travelling out sideways, delivers the loaves singly on to a further con-
veyor which feeds them (in the case of cottage loaves through the splitter
already referred to) into the finishing moulder.

The lower diagram in Fig. 52 shows a form of prover in which much
greater variations in length of proof can be obtained at will. By con-
venient mechanical arrangements the long conveying band can be "short
circuited" at desired points and the loaves at once passed direct to the
finishing moulder.

The prover is so designed that it can be arranged in a variety of ways
in order to suit varying local conditions. It normally occupies a floor
space of about 12 ft. X 10 ft-» but; can be suspended under the ceiling to
partly overhang the moulder ; or it may be fixed, together with the
hander-up and divider, on an upper floor and deliver to the moulder
below. The best arrangement, however, to suit any given place must of
necessity be decided in consultation with the engineers. On the face of
matters it might be thought that a prover arranged under the ceiling
would be best with a view to the saving of floor space thus effected, but
as a matter of fact there are a number of serious objections to this plan,
which should only be adopted in conjunction with proper safeguards to
meet the following points. Every one, with experience of bakery work-
ing, well knows the difficulty of ensuring cleanliness in odd corners and
inaccessible places. A prover, with its damp heat, is peculiarly liable to
get into an insanitary condition, and thus calls for rigid cleanliness and
scrupulous attention. Being, therefore, of all the machines employed in
the bakery to-day the one most needing conscientious inspection, it is the
last which should be so constructed as to render efficient daily examina-
tion difficult.

The prover, illustrated and described, thoroughly meets these require-
ments ; it is fitted with large doors, so that it can be opened out every day,
and thoroughly ventilated. Readily removable cloths are fitted to the
trays, so that their frequent washing is facilitated. A permanently fitted
light in the interior is recommended, so that it may be impossible for any
part of it to get into an unhygienic and objectionable condition without
instant detection.

444

THE TECHNOLOGY OF BREAD-MAKING.

THE MACHINE BAKERY AND ITS MANAGEMENT. 445

The whole of the trays in the prover can be easily removed (they are
only hung upon pegs) and should be periodically scrubbed. When the
trays are removed, the interior of the prover can be entered and examined
without difficulty — the reader may imagine himself standing in it, as in a
small room. The result of five or six years' continuous working, in actual
bakehouse use, is entirely satisfactory ; it may therefore be safely stated
that the apparatus is now entirely beyond the experimental stage. The
prover is really free from any wear and tear, as the speed of the running
parts is low, and the load on the trays is practically balanced.

FlG. 53.— Semi-Automatic Plant.

The power required for driving the complete installation, consisting
of dough divider, hander-up, auto prover and finishing moulder, is only
about 8 h.p. The plant, when once installed, is therefore not expensive
to run, since the whole of the operations indicated are carried out with
one man for feeding the dough into the divider. When the dough has
been thus fed, a maximum output of finished loaves from the moulder is
obtained at the rate of 2,400 pieces per hour, in the case of a plant with a
4 cylinder divider, or 8,600 where a 6 cylinder divider is the primary
unit. For bakeries requiring intermittent working a semi-auto plant is
available, of which a view is shown in Fig. 53.

595. "Setters."-— The appliances hitherto in use in modern bakeries
for receiving the moulded loaves, and for conveying them to the ovens, in
so far as they have been specially adapted at all, have all been modifica-
tions more or less of the type introduced in the early days of drawplate
ovens under "Price's" patent. An upright framing, mounted centrally
upon a bogie fitted with casters, carries rods or brackets projecting on
either side. Upon these brackets rest trays, open upon one of the longer
sides only. The loaves are set upon these trays, which fit the width of the

446

THE TECHNOLOGY OP BREAD-MAKING.

drawplate, and are slid off upon the latter, as shown in the illustration,
Fig. 54.

Cloths, fixed to the central upright of the setter rack, are spread over
the loaves while proving. On another plan, the setter boards come close
together, and with closed sides to the rack, are kept protected from
draughts; the trays are then placed upon the rack with their open side
inwards (see Fig. 55).

FlG. 54. — Loading Drawplate from Setter.

FIG. 55. — Improved Setter.

THE MACHINE BAKERY AND ITS MANAGEMENT. 447

596. Final Prover. — Something more than the above is required,
especially for dealing quite satisfactorily with cottage or other loaves that
are made from two pieces, which are "topped," i.e., placed on top of one
another. It is necessary, in order to get the best results, to give the two
pieces which are to form the loaf a further rest, after coming from the
finishing moulder, and to meet this requirement a secondary or final
prover is now being placed upon the market. Fig. 56 shows a longi-

FiG. 56. — Final Prover.

tudinal section of this machine, from which it will be seen that the dough-
pieces are placed upon trays similar to those used in the first automatic
prover, and moving intermittently. The loaves are given a maximum
proof of 10 minutes, while the capacity of the machine is equal to the
output of the full automatic plant. The loaves are removed from the
prover by hand, ready to be placed on the setters.

597. Ovens. — This subject is still one of the most vital importance
to the baker, and although the oven is obviously the oldest item in the
equipment of his business, yet it has undergone greater developments
during the present generation than in all the previous history of the bak-
ing trade.

If dealt with exhaustively, the subject of ovens would occupy a large
volume by itself, and therefore only so much of it can be treated here, as
applies to the average modern requirements and as specially affects large
separate interests in this country. Among general types it is necessary
to discriminate between ovens heated (1st.) internally, (2nd.) in part in-
directly, and (3rd.) by purely mechanical means, i.e., quite externally.

598. Internally Heated Oveng. — These may be dismissed very
shortly. They consist merely of a masonry or brickwork chamber, com-
municating with a chimney and heated by fire direct, applied in various
ways. The heat thus stored is utilised, after the oven has been swept out,
for baking the bread. During all known history until modern times this
was practically the only principle applied to ovens for bread-baking pur-
poses, and it is undeniable that if the manipulation of such an oven is
properly understood and attended to, perfect results as regards baking
can be obtained, for at any rate the great majority of the loaves of each
baking. The principal objections are want of fuel economy, loss of time
in re-heating, utter dependence upon skill, and absence of hygiene.

448 THE TECHNOLOGY OF BREAD-MAKING.

599. Hot Air Ovens. — These are subject, more or less, to the same
objections. Their construction differs from that of internally heated
ovens by the furnace or fireplace being independent of the baking cham-
ber. The heated gases from the fire are conducted through flues placed,
as far as possible, in such a manner as to enable the baking chamber to be
heated by the tiles, which form the covering or walls of these flues. The
waste gases are, or may be, also admitted eventually to the baking cham-
ber itself. Dampers are introduced with the object of regulating the
heat, but are not invariably successful. Provided that such ovens are
well designed, they bake well, and are more nearly continuous than in-
ternally fired ovens. Against this must be set the drawback that most
ovens of this kind consume considerable amounts of fuel. Unless exceed-
ingly well built, the obviously numerous flues render frequent repairs of
this type of oven necessary.

600. Mechanically Heated and Electric Ovens. — These represent
the modern development, and lend themselves to specialisation in aston-
ishing variety, of which the leading examples will be reviewed after a
short general survey of the ' ' mechanical means ' ' available for heating the
ovens. This class of oven may be fairly described as externally fired, but
internally heated, the significance of which characterisation will in due
course become clear.

Ovens heated electrically would certainly fulfill the most exacting re-
quirements in every respect, were it not for the fact that the electrical
generation of heat absorbs far too much energy to allow of working costs
which are commercially practicable. Apart from miniature ovens, for
laboratory work, a few electrically heated ovens have been built, but the
amount of current consumed, about 80 kilowatts per one sack batch, is so
enormous that, however low a price per B.T. unit be assumed, the cost
will be seen to be quite prohibitive.

Some startling revolution of the means for producing electrical cur-
rent, or some equally wonderful invention for the conversion of electrical
energy into heat, must therefore be awaited, before electrical heating of
ovens can become a question of practical politics.

601. Perkins' Tube or Steam Pipe Ovens. — As a matter of fact,
Perkins' invention of the closed circuit system, and the subsequent im-
provement thereon embodied in the " Perkins7' sealed-end tube, was the
epoch-making departure from the accepted notions of his day, which has
brought about the revolution in ovens effected in recent years. It is an
interesting testimony of the value of Perkins' invention that the first
man to employ ovens of his make, Mr. H. W. Nevill, built up in compara-
tively few years an enormous business. The Perkins' invention is based
upon scientifically correct principles: The boiling point of all liquids
bears a definite relationship to the pressure to which the liquid is at the
time subjected. The higher the pressure the higher is the temperature.
The following is the principle of Perkins ' apparatus : — A system of
hermetically sealed pipes, completely filled with a suitable liquid, is pro-
vided, and at its highest point an expansion vessel is attached in order to
accommodate the extra volume of the liquid when heated. By exposing
a suitable proportion of this system of piping to the action of a fire the
pressure in the apparatus was enabled to rise to the point corresponding
to a temperature adequate for the baking of bread. Obviously the greater
portion of this apparatus was arranged to be within the oven chamber,
while the portion exposed to the fire, arranged as a coil in a brick-lined
iron furnace, was placed at any convenient point, as in a stokehole or
room adjoining the bakehouse. Many ovens were constructed in this

THE MACHINE BAKERY AND ITS MANAGEMENT. 449

manner, and remained successfully at work for many years. Perkins,
however, soon concluded that it would be better to dispense with any
form of joints for connecting up the various lengths of pipe, from which
his apparatus was constructed. (The joint which he invented was never-
theless remarkably efficient, and is the only one used to this day for this
class of work, including the "loop-tube" ovens referred to later on.) He
therefore adopted the plan of using a large number of single straight
tubes, welded at each end, and with a portion of each tube projecting into
a furnace constructed at the back of the oven and fired from a stokehole
separate from the bakehouse. These tubes were set in two rows, the low-
est of which acted as firebars, and upon them the fire rested. To this day
this oven is the prototype, arid apart from improvements in details and
adaptations to particular requirements remains unaltered. These single
sealed tubes possess a practically unlimited life — they have been tested
carefully after forty years of hard continuous service, and have been
found absolutely intact and fit to continue their work indefinitely. They
obviously avoid the risk inseparable from joints, and, unlike tubes ar-
ranged in complicated coils and intricate loopings, are readily and in-
expensively replaced, should occasion arise, without interruption or dis-
turbance of working. The so-called loop-tube ovens are a half-way stage
between Perkins' earlier and later systems. The tubes, instead of being
sealed at either end, are endless ; that is to say, have their ends jointed
up to form a continuous tube, just as is the case in Perkins ' first construc-
tion. While each loop-tube is therefore much longer and more compli-
cated in shape than Perkins' later straight tube, it is shorter than the
circuit employed in Perkins' first oven. The loop-tube has nearly all the
faults of the first Perkins' oven, but lacks the best points in the stopped
end tube; yet experience proves that the Perkins' sealed-end tube ac-
complishes everything required of it by the baker, and is not excelled by
the loop-tube in any single direction. Claims have been made on behalf
of the loop-tube, in that ovens employing it are more economical in fuel
than are ovens fitted with sealed-end pipes. This is not borne out by
facts, if ovens of modern construction are compared under equal condi-
tions; what gave a certain amount of colour to these statements is that
the long narrow furnaces peculiar to earlier Perkins' construction need
considerable care to ensure that the consumption of fuel be kept to a
minimum. As workmen are careless, and mostly fire in the manner in-
volving least trouble to themselves, the fuel consumed in ovens with these
long narrow furnaces usually exceeded considerably the amount actually
required. The "Perkins" ovens have, however, for some years been
equipped with furnaces which make this impossible, and practically
restrict the consumption of fuel to the amount actually required.

It follows that the sealed-end tube is considered preferable, and the
reasons, in so far as they affect the baker, may be shortly stated thus : it
lends itself to constructions which are as economical, as uniform in bak-
ing, and as continuous as any that are possible with any other system. In
addition, it is more durable, involves less risk, avoids all possibility of an
oven being put temporarily out of use, and if replacements are required,
enables these to be carried out at a nominal expense. As the original
patents for these various systems referred to have now expired, they are
all equally available for oven manufacture.

602. Oven Types. — The withdrawable baking plate was the subject
of practicable proposals by Perkins. At a later period ' ' Wieghorst 's "
early productions made their appearance ; following upon these the draw-
plate proper (Pfleiderer's patent) was actively introduced into this country

450 THE TECHNOLOGY OF BREAD-MAKING.

towards the end of the last century, and has since spread largely over
the civilised world. The drawplate proper, with plate travelling inde-
pendently upon the drawplate carriage, employing only rolling bearings
inside the oven, and leaving the bakehouse floor entirely unobstructed
when not drawn out, has since the beginning of this century certainly be-
come the standard bread oven for batch working. Replacing old ovens in
existing bakeries, and nearly always being installed in all new bakeries
with any pretence to being abreast of modem ideas, the drawplate has
long ago demonstrated the fact of its entire suitability for all baking re-
quirements. Fig. 57 shows a battery of one-deck drawplate ovens, and
Fig. 58 a battery of two-deck ovens, coke fired. Fig. 59 gives a view in
the stokehole of a coke-fired battery, from which the smallness of the
modern furnace will be noticeable. Drawplates are made in many dif-
ferent sizes, to suit requirements of trade as well as to conform to restric-
tions in regard to space. It may be taken that the plate should not ex-
ceed 6 ft. in width in all cases where setting has to be done by hand
(conf. paragraph 556), but when only bread is baked which may be
handled with setters, the width may be as much as 8 ft. 4 in. Greater
widths should be avoided, as leading to difficulties in setting, on account
of the heavy weights to be handled.

Split Drawplates. — Fig. 60 shows a very useful modification (Poin-
ton's patent) of the standard arrangement, enabling a drawplate oven to
be adopted in bakeries possessing only a very limited floor space. The
plate is cut transversely into two equal halves, and when drawn out, the
special gearing shown enables the first half to be lowered, so that the back
half can be drawn forward over it. After setting the batch on the back
half the process is reversed. These ovens are in actual use and answer
admirably ; it will be seen that they not only enable a drawplate to be
used where it would be otherwise impossible to do so, but that a plate.

FlG. 57. — One-Deck Drawplate Ovens.

THE MACHINE BAKERY AND ITS MANAGEMENT. 451

FlG. 58. — Two-Deck Drawplate Ovens

FIG. 59.— Stokehole of Coke-Fired Ovens.

452

THE TECHNOLOGY OP BREAD-MAKING.

about 11 ft. long, can be used in a 6 ft. space : in less space therefore than
a similar size peel oven could be worked.

Fie. 60. — Oven with Split Drawplate.

Combined Drawplate Peel Oven. — Fig. 61 shows this very useful com-
bination. The carriage of the drawplate carries a chequered iron plate
platform (barely visible in the illustration because almost entirely hidden
by the drawplate itself) from which the peel oven is conveniently worked.
The step just above the car wheel gives easy access to this platform.
With regard to the firing of this oven refer to "furnace arrangements"
further on.

FIG. 61. — Combined Drawplate and Peel Oven.

THE MACHINE BAKERY AND ITS MANAGEMENT. 453

Portable Draivplatc Ovens. — A useful small oven, very suitable for
caterers, is shown in Fig. 62 (Ih lee's patent). The fact that the special
design of running gear employed dispenses with all outer supports,
makes this oven quite self-contained and truly transportable.

FlG. 62. — Portable Drawplate Oven.

Peel Oven. — The standard peel oven, although made in any size to
suit requirements, does not call for lengthy description. Fig. 63 shows a
typical arrangement of two-deck ovens with pits for working the bottom

ovens.

II
1

FIG. 63.— Double-Deck Peel Ovens.

454

THE TECHNOLOGY OP BREAD-MAKING.

Portable Ovens.— Fig 64
shows a very excellent two-
deck specimen, with prover
and hot-water tank.

Field Ovens, as shown in
Pig. 65, are mounted on
platform waggons and en-
able baking of the very best
type to be carried on for
trpops in camp or on the
march. This two-deck oven,
although only weighing 22
cwt., bakes rations for over
2,000 men per day : a very
good indication of the effi-
ciency of the steam-pipe
principle. It may be fired
with coke or can be heated
with wood ; even green
wood cut on the march an-
swers the purpose. The in-
sulation on these ovens,
despite their elegance and
lightness, is so excellent

FIG. 64.— Portable Oven.

FIG. 65.— Field Oven.

THE MACHINE BAKERY AND ITS MANAGEMENT. 455

that baking has been carried on with 3 in. of unmelted snow lying on
the top of the oven.

Ship Ovens. — War ships and merchantmen are now as well equipped
as any establishment ashore, and carry fully equipped bakeries with
kneading machines, mostly driven by electric motor direct, and steam-
pipe ovens. Fig. 66 shows one of the large size and substantial two-deck
ovens carried by our large liners.

FlG. 66. — Ship Oven.

Hotel Ovens. — Large hotels and businesses with dining accommoda-
tion for large staffs frequently provide themselves with modern equip-
ment, and Fig. 67 shows a typical case of this kind. In this the oven seen
on the left-hand side is a "Vienna" oven with sloping sole, powerful
steam generating apparatus, steam valve for drawing off vapour, and
patent oven-light to protect the gas jet from the effects of steam. This
type of oven is fitted with the Monier sole, referred to in a subsequent
paragraph, and admirably bakes rolls of the true Vienna style — that is
to say, rolls with a thin "egg-shell" crust and perfect bloom and gloss
for consumption within a few hours of baking. Vienna rolls, as more
often required in this country, require an oven somewhat differently ar-
ranged, and are better produced by the aid of steam from a boiler as they
must be soaked more thoroughly and require a heavier crust so as to keep
brittle for a longer period.

456

THE TECHNOLOGY OF BREAD-MAKING.

FIG. 67.— Hotel Oven.

FIG. 68. — Coverplate Oven with Cover Lifted.

THE MACHINE BAKERY AND ITS MANAGEMENT. 457

Coverplate Oven. — A very special type of oven has been quite lately
produced, which cannot be classified either as a peel or drawplate, and to
which the name of "Coverplate" oven (Ihlee's patent) has been given.
It is essentially a hot plate, fitted with a removable lid or cover, in which
is arranged a system of pipes to give top heat. The idea is to give a large
batch capacity (40 dozen 2 Ib. loaves) in a minimum of working space,
with the least possible weight and expense. The oven is designed to deal
with Scotch batch bread, but might also suit similar classes of goods much
made in Ireland. The furnace gases can be taken over the tops of the
loaves to give the "flashing" effect required in Scotland. Fig. 68 shows
the oven as fitted in a Glasgow bakery, where the work done appears to
be excellent and to meet the high standard demanded there. When the
cover is lifted, as shown in Fig. 68, the method of procedure is of course
exactly the same for setting and drawing a batch as would be the case
with a drawplate. For the many existing bakeries in Scotland, with flats
on upper floors, the scheme, if practicable, would appear to possess
marked advantages because of the great saving in weight, combined with
economy in floor space.

Arrangement of Furnaces. — All the ovens referred to can be built to
be fired from the front, back, or at either side, but of course preference
must be given to back firing in all cases where exigencies of space do not
make this impossible. One furnace to two baking chambers, as in two
deck ovens, should be avoided because, notwithstanding any claims to the
contrary, effective control of e^ch chamber is only possible when each
chamber has its own furnace. The drawback to having a furnace to each,
in two-deck ovens, has hitherto been that this construction entailed having
the sole of the upper oven at an inconveniently great distance from that
of the lower one. Beanes' patent construction avoids this difficulty, and
enables the soles to be kept at the same minimum distance apart as in the
two-deck oven with one furnace. For the purpose of these observations
it is assumed that each chamber has at least two rows of tubes, as in
some cases ovens are built with two decks and only three rows altogether.
This is bad practice, and does not lead to a saving at all commensurate
with the loss in efficiency, durability, and continuity of the oven.

603. Oven Fittings. — Drawplate ovens are commonly equipped with
a ' ' dummy ' ' clock to each chamber for marking up the time at which the
batch should be drawn. There is also a mercurial thermometer and
means for injecting steam, while efficient steam generators may be ar-
ranged for if required. Peel ovens are fitted with a thermometer, and
either a gas bracket or patent oven-light as may be desired. The latter
has the advantage of lighting up the oven without being affected by the
steam; oil lamps are supplied where gas or electricity is not available.
Doors, arranged to slide vertically, should be fitted for Vienna ovens, or
where small goods require setting in a bath of steam, as the doors may
then be readily adjusted to a convenient height, while retaining the steam
at a lower level than would otherwise be the case.

Pyrometers are quite out of date in steam-pipe ovens, as the tempera-
ture can never rise to a point which would endanger a thermometer,
which is, if of good make, absolutely reliable and will always read ac-
curately. Good working instructions should be insisted upon with new
Covens, and kept in a conspicuous place in the stokehole. Their observance
should be rigidly insisted upon by the proprietor or manager.

As regards oven soles, all ordinary styles of bread current in this
country will be baked satisfactorily on iron soles. A very useful method
of indelibly marking each loaf with the name or trade-mark of its maker

458 THE TECHNOLOGY OF BREAD-MAKING.

is possible with drawplates, by having the plate divided into suitable
squares, in each of which the desired mark is cast, so that it is positively
baked into the loaf. The plan is in use in many places and answers ad-
mirably. For Vienna rolls, etc., a sole of earthenware material is often
preferred. "Monier" soles, as manufactured by Perkins, have proved
entirely satisfactory in these cases, and can be strongly recommended as
having now stood the test of over fifteen years ' continuous working. Tiles
must be condemned, as they tend to interpose too great a resistance to the
transmission of heat from the tubes, the safety of which is thereby en-
dangered.

The cases where iron soles do not fully over all requirements are, how-
ever, comparatively few and far between.

604. Automatic Travelling Ovens. — Travelling ovens of the type
used in biscuit manufacture are not directly suitable for bread-making.
For the production of modern thin-crusted loaves with a rich bloom, ade-
quate bulk and for baking with a minimum loss of weight in the loaf,
special constructions ensuring the retention of an atmosphere suitably
charged with steam are essential. Of types specially adapted for the pro-
duction of high class bread there are now quite a number of travelling
ovens working successfully in Great Britain and elsewhere, both on the
single tunnel plan and with chains operating on a circuitous route con-
veying the loaves on swinging trays in combination with direct heating
internally by coke or high pressure gas and by Perkins' tubes. Some of
the swinging tray ovens have their chains integral with those of the final
provers and are therefore automatically charged, as are others which
have provers operated by separate sets of chains. This subject is, how-
ever, so complicated by technicalities and dependent upon conditions in
individual bakeries, that no detailed descriptions can be included here.

605. Oven Firing. — It is not possible to give any detailed instruc-
tions on this subject, as the treatment must necessarily vary considerably
for different makes of ovens. It may, however, be said that where pos-
sible in regard to cost, coke is much the cleanest and most satisfactory
fuel to use. It saves much trouble and dirt and avoids all risk of creating
a nuisance by the emission of smoke. With every kind of fire, and espe-
cially with ovens, "little and often" should be the golden rule in adding
fuel. The saving of trouble by filling furnaces to their fullest capacity,
and often beyond that, is pernicious : it literally wastes an enormous per-
centage of the fuel and leads to exceedingly bad results in the bargain.
Avoid burning rubbish, an oven furnace is not a destructor, and avoid
offal — egg shells, remains of meat, etc., especially if an oven be fitted with
a copper boiler, as gases are formed which are detrimental to the copper.
Do not use coke in large unbroken lumps — pieces about the size of a
duck's egg are quite the maximum that should be allowed. Keep the
flues clean by regular periodical sweeping, and remember that the tube
ends should also be kept clear of dust. For the rest it is necessary to fol-
low the directions supplied by the oven builders.

606. Nature of Coke Combustion. — This subject is of great practical
importance in connection with the whole question of the firing of oven
furnaces, and so merits a somewhat careful examination. First of all,
coke has the advantage of producing an absolutely smokeless fire, and
so soot deposits and their inconveniences are practically obviated. On
the other hand, the flameless combustion of carbon produces heat which
is not only intense but also very local, so that the furnace itself is very
hot, in eomparison with flues at some little distance. This necessitates
careful designing, so that due provision shall be made for the ready

THE MACHINE BAKERY AND ITS MANAGEMENT. 459

transmission of this local heat ; granted proper arrangements, however,
this localisation of heat in no way interferes with the perfectly efficient
working of coke-fired ovens, it in fact constitutes an advantage.

Although coke itself burns flamelessly, yet one usually sees more or
Jess pale blue flame over the surface of a coke fire. This is due to a
process similar to that which is utilised in a producer and arises from the
formation and subsequent combustion of carbon monoxide, according to
the following equations. The air, in passing up through the red-hot coke
of the fire, forms carbon monoxide thus : —

2C + 02 2CO.

Carbon. Oxygen. Carbon Monoxide.

The gas rises to the surface, and there, on meeting with excess of air,
undergoes combustion, thus : —

2CO + 02 2C02.

Carbon Monoxide. Oxygen. Carbon Dioxide.

In this way the production of carbon monoxide indirectly causes a
flame combustion from coke, and thus produces heat in such a form as to
be more readily conveyed away, so far as the flames will reach, from the
furnace into the flues. But unless complete combustion of the carbon
monoxide occurs, there is a very serious loss of heat. This is readily seen
by studying the thermal effect of the burning of carbon and carbon mon-
oxide respectively. One gram of the former evolves during combustion
8,080 heat units, while the same quantity of the latter produces 2,634 heat
units. From the equations above given it is readily calculated that 1
gram of carbon produces 2.33 grams of carbon monoxide. And further,
this quantity of carbon monoxide must produce in burning
2.33 X 2,634 = 6,146 heat units.

But as the gram of carbon only evolves 8,080 heat units, we have 8,080
- 6,146 — 1,934 heat units produced in the burning of 1 gram of carbon
to monoxide.

Heat Units.

Summing up : —

Heat produced by 1 gram of carbon burning to monoxide 1,934
Heat produced by the combustion of the carbon monox-
ide yielded by 1 gram of. carbon . . . . . . 6,146

Total .... . . 8,080

Whatever quantity of carbon monoxide, therefore, that escapes com-
bustion, means a loss of over three-quarters of the heat-producing power
of the carbon it contains. To prevent this loss, air should gain access to
the coke gases after they leave the coke. In practice this end is sometimes
attained by letting the furnace doors be slightly open — it is possible, how-
ever, by having the opening too large, not only to cut off the draught
from the fire, but also to absolutely cool the oven by the admission of ex-
cess of cold air into the flues. Theoretically, the right thing might ap-
pear to be to keep the furnace closely shut, and thus favour the produc-
tion of carbon monoxide, providing for its combustion, beyond the fire,
by admitting air on the flue side of the "bridge" or back wall of the
furnace. Such an opening would need to be regulated so as to admit the
exact quantity of air with the utmost nicety, as too little would mean im-
perfect combustion, and too much a direct cooling of the oven. In prac-
tice there would be considerable difficulty in carrying out this idea.

607. Water Heating. — The problem of heating water for a bakery
requires more careful consideration than it usually receives. The widely
current notion that nothing could be simpler or better than a boiler over
the oven furnace is perhaps not unnatural; especially bearing in mind

460

THE TECHNOLOGY OF BREAD-MAKING.

that such an arrangement ensures a good supply of warm water directly
on commencing work after a period of rest. As a matter of fact, how-
ever, there are serious objections to this plan, and an independent appar-
atus must be recommended as preferable. In the first place, it is wrong
to suppose that there is any
saving in fuel by having a
boiler over the furnace ; assum-
ing of course that in comparing
such an arrangement with an
independent heater both are
properly constructed. Nature
never gives anything for noth-
ing, and water cannot be heated
in an oven boiler without a
corresponding amount of fuel.
There are of course ovens which
part with their waste products
of combustion at so high a tem-
perature that they can be util-
ised for heating water in ade-
quate quantities; but these can
not be here considered as we
are dealing with modern ovens,
which, if properly constructed,
do not waste heat to this extent.
In the second place, it must
always be remembered that a
boiler constitutes a local de-
mand for heat, at such times
especially when much hot water
is drawn off, and this necessa-
rily tends to rob the oven of
heat in an uneven manner, be-
sides checking the temperature
generally at times which bear
no relation whatever to the
legitimate functions of an oven.
Further, a boiler buried in
brickwork is much subject to
deterioration, while being at

the same time inaccessible to inspection; the result is therefore usually
that the time comes when it gives out without warning, drowns the fire
and spoils the bread by interfering with the baking, to say nothing of the
inconvenience caused and the probable disturbance of work while repairs
and renewals are effected.

Excellent independent heaters are now available, and a very good
type is illustrated in Fig. 69 (Perkins' patent). The boiler proper, con-
sisting of a cylindrical vessel, with a domed lid which is removable, will
be seen to be mounted upon a cylindrical furnace. Perkins' tubes, ar-
ranged in a circle, pierce the bottom or tube plate of the boiler, and con-
vey the heat from the fire, which lies within the basket of pipes formed
by the tubes, to the water above. The fire therefore lies on a small circular
fire-grate, and is walled in on all sides by the vertical tubes. Thus no
firebrick lining is necessary, and renewals are confined to the fire-grate,
a very small affair; whereas the boiler top can be readily lifted for the

FlG. 691— Water Heater.

THE MACHINE BAKERY AND ITS MANAGEMENT. 461

removal of scale. -This scale can only form on the tubes as these consti-
tute the only heat ing1 surface for the water, and owing to the fact that ex-
pansion and contraction of the tubes takes place, the brittle scale auto-
matically chips off as soon as it has accumulated to any appreciable thick-
ness and collects at the bottom of the boiler ready for removal.

The boiler must always be kept full of water, and this is readily
assured by a supply being provided by means of a ball-cock supply tank
(as shown in illustration) under a sufficient head to drive the water to
the highest point at which it is desired to draw off.

Before leaving this subject it is necessary to point out the importance
of always selecting materials suitable to the nature of the local water
supply. Hard waters are usually neutral to galvanised surfaces, and in
all such cases therefore galvanised pipes and boilers meet all practical
requirements. Naturally, hard waters deposit the greatest amount of
scale, and the apparatus described above is then the best, as no trouble
will ensue so long as the scale deposited at the bottom of the boiler is
periodically cleaned out. Soft waters, especially moor waters derived
from areas with large deposits of peat, corrode iron and steel very rap-
idly, especially when hot; and galvanising also proves no protection in
such cases. To meet these conditions, the independent heaters are sup-
plied in copper, as regards all surfaces which come in contact with the
water, or, to avoid undue expense, with copper-coated surfaces. As entire
destruction through pitting and corrosion may take place in so short a
time as 12 or 15 montM where galvanised iron or steel are used, the im-
portance of this point w ill be appreciated.

608. Complete Automatic Bread Bakeries. — Before leaving the sub-
ject of bakery equipment it may be of interest shortly to refer to bakeries
which dispense entirely with skilled labour ; excepting always, of course,
the need for good judgment and expert knowledge required in making
dough by the aid of the machines and regulating properly its subsequent
growth and development. Such bakeries are entirely within the range of
practical politics for the production of uniform loaves which are within
the scope of the machinery employed and have in fact to some extent al-
ready come into everyday use and can be multiplied -indefinitely where
the output required is sufficiently large (say 500 sacks per week and up-
wards). Assuming a trade of 500 sacks per week consisting of nothing
but 2 Ib. tin bread (or of the cottage or coburg varieties), eight men
would be sufficient to take the flour from the flour store and deliver the
finished bread on to trucks in the -bread-room, and of these only three
men would need to be bakers. It will be clear that the cost of production
is thus brought down to a minimum, and as the baked bread is discharged
into the bread-room by the automatic oven, transportation throughout the
whole process is carried out by mechanical means.

609. Scotch "Chaffing"' or Moulding Machine. — Another special
adaptation to local requirements is represented by a machine for per-
forming the final operations required in "Scotch" batch bread (Poin-
ton's patent). In the manufacture of Scotch bread, although the dough-
making process follows entirely different lines to those generally adopted
in England, the machines used, as far as dividing, handing-up, and prov-
ing are concerned, are exactly similar to those described in paragraph
.587 et seq. But the final operation of moulding the loaf is on an entirely
different principle to that of the balling-up type so far referred to. In-
stead of working the dough-piece up into a ball shape as described in
paragraph 587, the Scotch practice demands that the piece be pressed out
into a flat sheet, stretched, folded over, pressed again, and finally folded

462 THE TECHNOLOGY OF BREAD-MAKING.

into an oblong packet ready to be placed on the setter. These operations
are very difficult to accomplish mechanically, especially as they are of a
non-consecutive nature, but would appear to be perfectly accomplished
by Pointon's Patent Chaffing Machine.

610. Bakery Registers. — An almost integral part of the economy of
a machine bakery, and in fact any bakery of modern pretensions, is a
register of particulars of the making of each batch of the day's work.
This should be in book form, and affords, when properly kept, a most
valuable record of work done, and also gives the means of checking same
from day to day. The authors have had printed a register in which the
following is the heading of the day 's work : —

BAKEHOUSE REGISTER. TEMPERATURE.

Day. Night.

19 Highest

Lowest ....

Temperature of bakehouse at time of setting 1st sponge or dough

There then follow the various column headings, arranged right across
two pages of the book, in the following order : — Number and kind. Water
(quantity). Temperature. Yeast, kind and quantity. Salt. Flour.
Flour temperature. Sponge when set. Temperature when set. When
taken. Remarks. Time when taken. Water. Temperature. Salt.
Flour. Dough temperature. Oventime. No. of Loaves. Remarks.

Such a register may be amplified, simplified, or modified, according
to the requirements of any particular mode of working. The system of
testing the temperature of a sponge when set, and when taken, often gives
useful information as to its condition. With any uniform method of
working, the amount of rise in temperature is very nearly a constant
quantity. When the rise is excessively low, the sponge is likely to have
been starved or the yeast to have been weak. If, on the other hand, there
is an abnormally high rise, the fermentation will have been too vigorous,
and have proceeded beyond its proper limit. In either case a useful diag-
nosis of the condition of the sponge is afforded at a time when it is pos-
sible to take steps toward remedying either evil. Subject to certain limi-
tations, the same remarks apply to straight doughs.

CHAPTER XX.
ANALYTIC APPARATUS.

611. Commercial Testing and Chemical Analysis of Wheats and
Flours. — As a matter of convenience, the various analytic operations
involved in the testing and examination of wheats and flours are divided
into two classes : first, those which are more readily performed, and which
afford information having the most immediate bearing on the actual value
of these bodies ; and second, those determinations which are more purely
chemical in their nature. The operations of the first class are comprised
under the heading of "Commercial Testing of Wheats and Flours";
their nature is such that they may be performed personally either by the
miller or baker. The second series of tests requires rather more chemical
knowledge and experience : they consequently appeal more particularly
to the students of milling and baking who have had the advantage of a
course of chemical training in a properly appointed laboratory.

A description of the laboratory, and of the principal analytic appar-
atus used in weighing and measuring, will now be given as an introduc-
tion to analysis.

612. The Laboratory. — For the benefit of any millers and bakers
who may wish to fit up a laboratory for themselves, the following few
hints as to utilising a room for the purpose are here inserted. If any
work is to be done beyond the roughest experiments, a balance and micro-
scope will be Tequisite ; these delicate instruments must be kept free from
dust, and so cannot be exposed to the ordinary atmosphere of the mill ;
they should therefore be placed in either a private office or study, and
covered over when not in use. For the other purposes of a chemical lab-
oratory, almost any room, or part of a room, can be made to answer. A
working bench or table should be fitted in as good a light as possible, at a
convenient height. Gas, when obtainable, should be laid on to this bench
by means of a pipe terminating in a nozzle, over which a piece of india-
rubber tubing can be slipped. There should be near at hand a drain,
over which is fixed a tap, with a good water supply. This tap should also
have a small side tap, with nozzle for india-rubber tubing, in order to
lead water into any apparatus in which it is required. These are almost
the whole of the necessary fixings. There must of course be a few shelves
on which bottles and the various apparatus may be kept. "With time and
money to spare, many additional fittings might be suggested. These can,
if wished, be added afterward.

613. The Analytical Balance. — It is presumed that the student be-
fore attempting the following work, will have made himself familiar with
the simpler chemical apparatus by their actual use in the laboratory.
Quantitative analysis, as its name implies, is that species of analysis by
means of which the quantity or amount of each ingredient in any partic-
ular body is determined. For purposes of analysis, quantity is measured
and expressed either by weight or by volume. Accordingly, the chemist
first of all requires some accurate means of determining with exactness
both weight and volume.

464

THE TECHNOLOGY OF BREAD-MAKING.

For purposes of weighing, an accurate balance and set of weights are
necessary. Of these there should be in a laboratory at least three of dif-
ferent degrees of sensibility. Taking the most delicate first, let us de-
scribe what may be termed the ' ' analytic balance proper. ' ' This instru-
ment requires to be made with the utmost care and accuracy, and is
illustrated in Fig. 70. The specialty of this particular variety is that
the beam is very short ; it is claimed for it that, as a result, the delicacy
of the balance is increased, while the time in which a weighing is per-

FlG. 70. — Short Beamed Analytical Balance.

formed is lessened. On referring to the figure it will be noticed that the
balance is enclosed in a case; the bottom of this consists of a stout slab
of glass, fixed on levelling screws. The front, back, and sides of the case
are glazed ; and all open, the front and back by sliding up, the two sides
on hinges, as doors. The beam is suspended on a pillar, which in turn is
screwed down to the bottom of the case. The beam carries at its centre a
knife-edge made of agate ; this rests on a plane of the same material ; on
each end of the beam there are similar knife-edges, and from these

ANALYTIC APPARATUS. 465

depend the scale pans. When the balance is not in use, the beam, instead
of bearing its weight on the knife-edge, rests on a sort of cradle ; so, too,
the end hooks carrying the pans are likewise supported by the cradle.
Underneath each pan there is also a small support on which the pan rests
until it is required to set the balance in action. In the centre of the front
of the balance, and immediately underneath the glass base, is fixed a
large brass milled head; this, on being slowly turned by the operator,
first lowers the supports from beneath the pans, then drops one portion
of the cradle, and so suspends each scale pan from the terminal knife-
edges of the beam, and next lowers the central knife-edge on to its agate
plane, and permits the balance to swing. On turning the milled head back
again, the opposite of these movements takes place in reverse order, and
each knife-edge is gently lifted from the agate plane. The object of this
is to prevent wear of the edges by their being continually in contact, par-
ticularly as a balance would soon be seriously injured by the jarring
caused to knife-edges and planes by putting on and removing weights
while these were in contact. It must be borne in mind, as a golden rule
of weighing, that nothing must be added to or removed from either pan
of the balance when the instrument is in motion. In order to show the
movement of the beam, there is a long index finger descending from its
centre and moving in front of an ivory scale at the bottom of the pillar.
A description of the mechanism employed to effect these various move-
ments is unnecessary, as they can readily be understood by a few
minutes' careful inspection of the instrument itself. Some other attach-
ments of the balance will be better understood when we come to describe
the operation of weighing. It a student is working in a laboratory under
the direction of a teacher, he will find balances there, and already prop-
erly adjusted ; in case that he happens to have purchased one for his
private use, all the adjustments will have been made by the maker, and
should not be interfered with by him unless he is thoroughly acquainted
with the mechanism of a balance. It should always be borne in mind
that a balance must on no account be altered or re-adjusted except by
some responsible person ; there may be several persons working with the
balance, and the one, by altering it, and possibly setting it wrong, may
upset the work of all the others. Suppose a student has procured a
balance for his own private use, let him place it in its permanent posi-
tion, which should be on a stout bench or table in a dry room, and at a
height convenient for weighing when sitting down. The light should, if
possible, be from a window behind the balance; that is, the balance
should be so placed that the operator is facing the light, which should
not be glaring, while it should be good. Occasionally, in a balance so
placed, the ivory scale at the base of the pillar is in such deep shadow as
to be scarcely readable. This may be remedied by foldi^& a piece of

white cardboard at right angles and placing it in front oftfje scale. It
will be below the range of the eye, and acting as a reflecwfc will
ciently illuminate the scale. A light coming from a high window b
the operator also answers, but a strong light from either side*5 not s
able for weighing. The first thing to do is to get the pillar of tfe bala
vertical. In the balance, a plummet hangs from the back of "Jfre pilla
immediately over a corresponding index point on the base ; the two
-iing screws in front of the balance must be turned in one directi
other until the plummet is directly over the index point ; the ba
balance will then be horizontal. In the next place carefully
beam and the pans with a camel's hair brush. Then turn the mill
which actuates the balance, and allow the beam to vibrate; it

466 THE TECHNOLOGY OP BREAD-MAKING.

likely swing one way or the other immediately the beam is liberated, but
if not, open the right-hand side door and waft a very gentle current of
air down on the one pan with the hand. Close the door again, and watch
the vibrations of the index finger ; it should be explained that all the sides
of the case must be kept closed as much as possible during the operation
of weighing. The little ivory scale has its zero in the centre, the divi-
sions count each way from it, and are usually ten in number on each side.
Should the balance be correctly adjusted, the index finger will swing the
same number of degrees each side of the zero, and after a time, as each
vibration becomes shorter, will come to rest over the middle of the scale.
Strictly speaking, the distance travelled on each side must be slightly less
than that of the other : thus, supposing the index travelled to 9 on the left
hand, it would, when the balance is correct, swing slightly less than 9 to
the right, say 8.9, and then back to 8.8 on the left. With a good balance
this diminution is so little for one or two vibrations that practically we
may say that it should swing equally on both sides.

Such a balance as that described is capable of weighing to the tenth of
a milligram, with a weight of two hundred grams in the pan. In addi-
tion to this instrument a coarser balance is also necessary ; this should be
capable of carrying a kilogram, and weighing to the hundredth of a
gram.

614. Adjustment of Balance. — In case when testing the balance the
index does not swing to the same distance on either side of the zero of the
scale, first of all again dust the balance most carefully, and test once
more. In the event of this not removing the error, the beam must be re-
adjusted ; there will be seen two little balls, one on either side of the top
of the beam, and running on two slender horizontal screws attached to
the beam — on the side which is the lighter, screw the ball very slightly
from the centre of the beam, and again test. Repeat this until the two
sides of the beam exactly counterpoise each other. When once adjusted,
a balance, if kept clean, needs no alteration for a considerable time, pro-
vided always that it be carefully and delicately handled. In different
makes of balance the modes of adjustment vary ; the maker will, however,
in every case either give directions or see to the proper adjustment of the
instrument before it leaves his hands in case of its being a new one. For
a very clearly written and most interesting chapter on the mechanical
principles and management of the balance, the student is referred to
Thorpe's Quantitative Analysis, published by Longmans & Co.

615. Analytic Weights. — After the balance, the next thing required
by the chemical student is an accurate set of weights. As a rule the
chemist returns his results in percentages; it is not therefore of very
great importance to him, from that point of view, what unit of weight he
adopts. In England, chemists either use grain weights or else those of
the French metric system. When grain weights are employed, the set
contains pieces varying from the 'hundredth of a grain to 1,000 grains.
From its much greater simplicity, weights of the metric system are now
used to a much greater extent than grain weights. Not only is there this
advantage of greater simplicity, but, in addition, they have become the
international system for scientific purposes ; for this reason, as well, it is
highly advisable that all chemists and students of chemistry should learn
to work with these weights. Whatever weights are employed a few very
simple factors suffice to convert those of the one denomination into those
of the other. In Chapter I. is given a table of the most important metric
weights and measures, together with their English equivalents.

ANALYTIC APPARATUS.

467

The set of weights employed for analytical purposes must be of the
greatest possible accuracy. They usually range from 50 grams to a milli-
gram. The heavier weights are made of brass and then electro-gilded;
the fractions of a gram are made of stout platinum foil. In shape, the
brass weights are made slightly conical, and are each fitted with a small
handle at the top, by which they must be lifted; for the same purpose
each of the platinum weights has the top right-hand corner bent at right
angles to the weight. These weights are arranged in a box, each being
placed in a separate compartment, those for the gram weights being lined
with velvet; the smaller weights are further protected by an accurately
fitting cover of glass. For the purpose of lifting the weights a pair of
forceps is provided; this has its place in the box. Analytic weights
must on no account be touched with the fingers. Most sets of analytic
weights contain the following pieces arranged in the box in the order
shown below : —

50 20 10 10 5

1112
0.2 0.1 0.1 0.05

Rider.

0.005

0.01

0.02

0.5

0.0011

0.001 1

0.001J

The student will require to learn, not only the denomination of each
weight, but also its place in the box. He must be quite as well able to
read the weights he has placed in the balance pan from the empty spaces
as from the weights themselves. As soon as the weights are done with
they should always be returned to the box; this should be further pro-
tected by being kept in a case made for it of wash-leather. The accuracy
of all analysis depends on that of the weights ; too great care cannot,
therefore, be taken to preserve them from injury.

In giving the denominations of the weights above there is a place
marked " Rider"; the nature and use of this particular weight remains
to be explained.

The arrangement of the weights, as shown in Fig. 71, corresponds
with the table just given of their value. Special attention must be
directed to the * ' Rider, ' ' which is drawn to its full size at A.

The student must now
refer again for a moment
to the figure of the balance
previously given; he will
there notice, at the top
right-hand corner, a milled
head; this actuates a rod,
at the other end of which,
from a little hook, depends
the rider, as shown just
over the left-hand pan.
From end to end of the
beam itself there also runs a
graduated scale; this scale

is divided into twenty equal parts, the centre is marked zero, and the
other graduations numbered 1-10 from the centre towards each end.
Each of these units is still further subdivided into 5 or 10 equal parts.
This scale is the exact length of the beam, measured from one to the other
of the terminal knife-edges. An inspection of the balance itself shows
immediately that, by means of the milled head and rod attached thereto,

FIG. 71.— Box of Analytic Weights.

468 THE TECHNOLOGY OF BREAD-MAKING.

the rider can be placed astride the scale at any part of its length. The
weight of the rider is one centigram, consequently, if placed in the pan
of the balance, or at 10, the extremity of the scale, the effective weight of
the rider is the same as its absolute weight. But if it be placed some-
where intermediate between the centre and end of the beam, its effective
weight is between 0 and 1 centigram. The effective weight is governed
by the well-known principle of the lever, namely, that the force exerted
by any weight is directly proportional to its distance from the fulcrum.
As each side of the beam is divided into 10 equal parts, the weight of the
rider at each division is the number of tenths it is from the centre : thus,
at 5, its weight is equal to 5/10 of a centigram, or 5 milligrams, and so
for each graduation and intermediate fraction. The employment of the
rider in actual weighing will be gathered from the next paragraph.

616. Operation of Weighing. — In performing this operation, let it be
supposed that the student has balance and weights in readiness, and
requires to obtain the weight of some particular piece of apparatus ; this,
whatever it is, must be thoroughly cleaned and dried, and then placed on
the left-hand pan of the balance. For this purpose the front of the case
of the balance may be raised, or if working with a balance with side-
doors, that on the left hand may be opened. Two rules of weighing
are: 1st, always place substance in left-hand pan, and weights in the
right; 2nd, keep the doors of the balance case closed whenever possible.
Let the weight of the piece of apparatus in question, say a crucible, be
17.8954 grams ; by the following method this figure will have been ascer-
tained. First take the 20 gram weight from the box by means of the for-
ceps, and place it in the right-hand pan, release the beam from its sup-
port by turning the milled head: notice whether the left or right-hand
pan of the balance is the heavier. In this case the weight will be too
much, and the index finger will swing to the left. Bring the balance to
rest by turning the milled head, and take out the 20 gram weight, and
replace it by the 10 gram, try whether sufficient — not enough, add 5
grams — still too little, add 2 — too little, add 1 — too much. Do not forget
that every time before a weight is added or removed the beam must be
brought to rest on its supports ; this is always to be done gently and care-
fully. After the addition of each weight the beam will have swung over
more slowly ; with the 18 grams in the pan the swing of the index to the
left will have been much slower than any preceding it, showing that the
actual weight of the crucible is being closely approached. Return the 1
gram weight to its place in the box, and next try 0.5 gram — not enough,
add 0.2 — not enough, add 0.1 — not enough, add 0.1 — too much. Replace
the 0.1 and try 0.05 — not enough, add 0.02 — not enough, add 0.01 — not
enough, add 0.01 — not enough. The weight has now been ascertained
within a centigram, because the addition of another centigram would
bring the weight up to the 0.1 gram, which has already been tried and
found too much. The conclusion of the weighing should now be done
with the rider. Place the rider on the 5 on the right-hand end of the
beam, lower the supports, cause the beam to vibrate, and shut the door of
the case. If nec'essary, waft with the hand a gentle current of air on to
one of the pans in order to set the beam in motion. Count the number
of graduations which the index moves on either side of the zero ; it will
be found to vibrate slightly more to the right than to the left. Next try
the rider on the 6th division; this is found too much. Try the rider at
intermediate distances until it is found that the beam swings through an
equal number of graduations on either side of the zero scale ; the weight
in each pan is then the same. Let us now see how the weights are to be

ANALYTIC APPARATUS.

469

read ; this should be done from the box, reading the empty spaces. In
the case in point these are 10 -f- 5 -f- 2 == 17. Against "weight of cru-
cible," write this number in the note book. Next read off the decigram
weights; there are empty, 0:5 + 0.2 + 0.1 = 0.8; write .8 after the 17.
The centigrams come next, they are 0.05 + 0.02 + 0.01 -f- 0.01 = 0.9 ;
write 9 after the 8. The milligrams and fractions of a milligram are to
read off from the rider ; in the present instance the rider stands at 0.0054
grams, 54 must therefore be written after the 9. The whole figure will
then read : —

"Weight of crucible = 17.8954 grams."

Having thus read the weight from the empty spaces in the box, next
take the weights out and check the reading off as they are returned to
their places. This double reading greatly reduces the chances of error in
recording the weight of the substance. After a little experience in weigh-
ing, and thus getting to know the capacity of the particular balance used,
the student should test his balance in order to ascertain the value of each
graduation of the index scale. To do this put the rider on the 5 milli-
gram mark, cause the beam to vibrate, and notice how far on either side
of the zero it swings. Alter the position of the rider until the beam
swings from the zero to the 10 on the one side ; note the position of the
rider. Suppose it to be on
the 5, then 10 divisions of
the index scale ==5 milli-
grams, and 1 division = 0.5
milligram. This value will
only be approximately the
same when the pans are
loaded, but still sufficiently
near to save the time of
weighing. Thus, suppose
3.5 grams have been placed
in the pan, and the index
vibrate 10 to the right and
8 to the left, there is no
need to successively try the
0.2 and other weights down
to the 0.01, but the rider-
may at once be put on the 1
milligram mark, and will be
found to be very nearly in
its right place. One or two
trials will then find the ex-
act weight. The 1 is found
in this case by taking half
the difference between the
vibrations on each side ;
this will often apply, even
though the balance does not
swing quite to the ten ; thus, the distances indicated might be 9 and 7.
The beam should, however, be always caused to swing freely, as it makes
.a long oscillation in the same time as a short one. It will be noticed
that, so far, the right-hand side only of the rider scale has been referred
to; the left is also frequently convenient. Supposing that, with the 3.5
grams just mentioned, the index had vibrated the two extra degrees to
the left, this would have indicated that the substance weighed about 1

FlG. 72. — Various Measuring Apparatus.

470

THE TECHNOLOGY OF BREAD-MAKING.

milligram less than 3.5 ; to put this weight in would require the removal
of the 0.5, and the placing of the 0.2, 0.1, 0.1, 0.05, 0.02, 0.01, 0.01, on the
pan, and the rider at the 9 milligram mark. The same result is pro-
duced by placing the rider on the 1 milligram mark to the left. When
the rider is on the left side of the beam, the weight it represents must
be subtracted from that in the right-hand pan.

The operation of weighing has been described at full length, because
it is the foundation of all quantitative analysis ; these operations are,
however, much shorter in practice than they appear on paper. The gen-
uine chemical student will never forget that his balance should be care-
fully, intelligently, and even lovingly used.

In addition to the two balances and set of weights already described,
the student will need another set of weights, ranging from 10 milligrams
to 200 grams.

617. Apparatus Employed for Measuring Purposes. — These include
measuring flasks, burettes, and other appliances.

618. Burettes and Floats. — Fig. 72 on page 469, is an illustration of
various forms of measuring apparatus. The instrument marked a is
termed a burette, and is used for the purpose of accurately measuring
small quantities of liquid when delivered. There is at the bottom a glass
stop-cock; the tube is graduated throughout. The most useful size of
burette is that holding 50 c.c. ; such an instrument is graduated in 500
divisions ; these are numbered at each c.c., from the top downwards. In
using the burette it is first cleaned, and then rinsed with a little of the
solution with which it is to be filled, then filled up almost to the top.
When a long and narrow tube, such as a burette, contains a liquid, the

top is not exactly level, but is
always slightly curved, with,
in the case of water and aque-
ous solutions, the concave sur-
face upwards. It is custo-
mary, in comparing the height
of a liquid with the gradua-
tion marks, to read from the
bottom of this curve, or "me-
niscus," as it is termed. The
next thing is to run the liquid
out through the stop-cock un-
til the zero mark is reached.
Fix the burette upright in the
burette stand, and place the
eye level with the zero gradu-
ation, then turn the stop-cock
carefully, and let the liquid
run out until the bottom of
the meniscus exactly coincides
with the zero line. The bu-
rette is generally used for the
purpose of running a liquid
into a solution until some
particular change takes place,
then the height of the reagent in the burette is again read off, and
the quantity that has been used determined. So when the change,
whatever it may be, is complete, again bring the eye level with the bottom
of the meniscus, and read off the graduation with which it coincides.

FIG. 73.—

ELrdmann's

Float.

FIG. 74. — Mohr's
Burette, with Spring
Clip.

ANALYTIC APPARATUS. 471

Accurate reading of the burette is much assisted by the use of "Erd-
mann's Float"; this little piece of apparatus, which is shown on pago 470,
(Fig. 73), consists of a piece of glass tubing of such a size as to be able
to slide readily up and down within the burette. The tube is closed at
both ends, so as to form an elongated glass bulb, which contains a small
quantity of mercury. Around the float a single line, a, is marked with
a diamond. When using the float it is dropped in the burette, and the
line around it brought to agree with the zero mark at starting, and after-
wards the height is read from the line on the float. A form of burette
very convenient for general use is that known as Mohr's; it differs
slightly in shape from that figured in the preceding illustration. Mohr's
burette is made either with a glass stop-cock, or else with a glass jet
fastened on with a piece of india-rubber tubing, and so stops the burette.
The flow of the liquid is regulated by means of pressing the two buttons,
shown, between the finger and thumb. The figure shows only just the
lower end of the burette. The glass stop-cocks of burettes and other
instruments should always be slightly greased, so as to prevent their
sticking. If a burette is likely to be put aside for some time, it is well to
withdraw the stop-cock altogether, and put it away separately, or a small
slip of paper may be inserted between the plug of the stop-cock and its
casing.

619. Pipettes. — Turning once more to Fig. 72, there are two instru-
ments marked ~b, ~b ; these are pipettes, and are used for delivering a defi-
nite volume of any liquid ; the capacity of the two figured is respectively
50 and 100 c.c. In the tube just above the bulb there is a mark (not
shown in the figure), which indicates the point to which the pipette must
be filled. When using the instrument, place the lower end in the liquid
to be measured, and suck at the upper until the liquid rises above the
graduation mark, then stop the upper end with the tongue ; next quickly
substitute the tip of the finger for the tongue, without allowing the liquid
to run out. This requires some little practice, but repeated trials over-
come any difficulty at first experienced. Next raise the finger very
slightly until the liquid begins to run from the lower end ; let it do so
until the bottom of the meniscus coincides with the graduation mark,
then hold the end of the pipette over the vessel into which the liquid is to
be poured, take away the finger and let the tube drain. When the highest
degree of accuracy is required, the pipette should always be emptied in
precisely the same manner. A good uniform method consists in holding
the pipette vertical and allowing it to discharge its contents by gravity.
When the main stream has stopped, hold the instrument in the same posi-
tion until three drops have fallen, and then remove it. The pipette, if
correctly graduated, will thus deliver the exact amount of liquid marked
on it. The following are convenient sizes for pipettes : 2, 5, 10, 20, 25, 50,
and 100 c.c. One 10 c.c. pipette will be required graduated throughout
its whole length, somewhat like a burette; it is, in fact, used for very
much the same purpose.

620. Measuring Flasks. — The only other piece of apparatus that
need be explained at present is the graduated flask, d, Fig. 72 ; this has
also a mark round the neck showing the graduation line. The same
remarks apply to its use as those already made in reference to the other
pieces of measuring apparatus.

Other pieces of apparatus required, with the methods of using them,
will be described as occasion for their employment arises.

CHAPTER XXI.
COMMERCIAL TESTING OF WHEATS AND FLOURS.

621. Wheat Testing. — The simplest and most direct commercial
tests that can be made on whole wheat are its weight per bushel, weight
of 100 grains of average size, and percentage of foreign seeds, dirt or
other extraneous matter. Other tests are best made on the finely-pow-
dered whole meal of the grain.

622. Weight per Bushel. — This operation is so familiar to all millers
that an explanation of it is scarcely necessary. As is well known, there
is a special piece of apparatus sold that is made for the purpose. A
cheap and efficient substitute for this may easily be prepared and used
where a strident has such a balance as the coarser one previously
described. Get a coppersmith to make a cylindrical measure about 3 in.
in diameter and 3 in. deep. Procure from a dealer in chemical apparatus
a counterpoise box ; these are brass boxes with lids which screw on. Put
the empty measure on the one side of the balance and the counterpoise
on the other, fill with shot until it exactly balances the measure. Next fill
the measure exactly full of distilled water, level with the brim, and again
weigh, always placing the counterpoise on the weight pan. The weight in
grams of the water held by the measure represents its capacity in c.c.
Now the weight of a bushel of water (== 80 Ibs.), and that of the water
contained in the little vessel, are always constant ; and, as the weight of
the water the vessel contains is to the weight of the wheat that is being
tested, so is the weight in pounds of a bushel of water to that in pounds
of a bushel of the wheat. Expressing this in the usual way we have —
As weight of water held by vessel : weight of wheat held : : 80 : Ibs. per

bushel ;

80 X weight of wheat held __ weight of wheat in
weight of water held ~ pounds per bushel.

Now for any particular vessel the weight of water it holds is always con-
stant, so that 80 in the upper line, and the weight of water in the lower,
may be reduced to a single factor, and the weight in pounds per bushel
at once determined by multiplying the weight of grain, held in the meas-
ure, by that factor. Suppose that the capacity of the vessel is 200 c.c.,

80
then •— =0.4 is the factor, and the weight of wheat in grams held by

the vessel would simply have to be multiplied by that figure. In taking
weights per bushel the little measure should be carefully filled, and then
struck level by means of a pencil or other round piece of wood.

623. Weight of 100 Grains. — For this estimation it is important that
the grains selected shall represent the average sample : if they are simply
picked up one by one out of a heap, the weight is almost certain to be in
excess of the true average ; for a person under these circumstances almost
invariably unconsciously selects the largest grains. To obviate this, fold
a strip of paper so as to form a V-shaped gutter ; take a handful of the
wheat and let it pour in a small stream along the length of this gutter.

472

COMMERCIAL TESTING OF WHEATS AND FLOURS. 473

Then commence at the one end and count off the 100 grains, taking each
as it comes. Weigh on the pan of the balance arid enter the weight in
the note-book.

624. Percentage of Foreign Matter. — The foreign matter in a
sample of wheat may consist of other seeds, or possibly dirt or stony sub-
stances. Where it is only the former, a portion of the grain may be
weighed off, and foreign seeds separated by hand-picking, and again
weighing. The methods adopted for the removal of dirt must depend on
the character of that present in the particular sample. Light, dusty, non-
adherent matter may be removed by sifting or winnowing by means of
an air current, and then weighing the residual grain. Adherent dirt will
probably require washing of the wheat, and with this operation, the
absorption of water by the grain comes in as a disturbing factor, for
which provision must be made. The following is a convenient method of
estimating dirt by the process of washing. From a fair sample of the
wheat a convenient quantity is weighed off for the estimation; 20 grams
is usually a good workable quantity. A duplicate 20 grams is weighed off
and placed in the hot-water oven in order to determine moisture (see
subsequent paragraph 627). The lot to be washed is put in a wide-
mouthed bottle, and shaken up with water ; the water is then poured on
a fine sieve. This operation is repeated until the grain is clean. The
wheat is then poured on to the sieve and examined in order to see whether
there are any pieces of stone or other matter which ought to be picked out.
Finally the drained wheat is transferred to a dish and also placed in the
hot-water oven. Both it and the portion for moisture determination are
allowed to remain until the weight is constant (say over the night),
which is then noted. The difference between the two figures is the
amount of dirt removed by washing. An example will make this clear.

Wheat taken for moisture, 20 grams,

Weight after drying . . . . . . 17.54 grams.

Wheat taken for washing, 20 grams ;

Weight after washing and drying . . 16.06 „

Weight of dirt removed . . . . . . 1.48

Multiply by . . . . . . . . . . 5

Amount of dirt in samples . . . . . . 7.40 per cent.

625. Grinding of Samples. — The fine whole meal for other determi-
nations is best obtained by passing the wheat through a combined grind-
ing and cutting mill, of which a very convenient form is that known as the
' ' Enterprise ' ' drug mill. An ordinary coffee mill might answer the pur-
pose, but most likely would not cut up the bran sufficiently fine. The
process adopted is as follows : — The mill is set as fine as it will run with-
out clogging. (It need scarcely be mentioned that every part must first
be thoroughly cleaned.) The wheat is then poured in the hopper and run
through as rapidly as possible. The grist is next put into a fine sieve,
about 20 or 24 meshes to the inch, and sifted. The bran is returned to
the mill, and run through and again sifted ; this operation is repeated on
the coarser particles until the whole of the meal has been thus sifted.
Care must again be taken at the end to clean every particle out of the
.mill and add it to the meal ; this is essential, because the latter particles
are more branny than the former. The meal is next stirred up thor-
oughly, and then stored in a tightly corked or stoppered bottle. In this
way a whole meal is obtained, which of necessity is an exact representa-
tive of the grain. It may be asked whether the wheat should be cleaned

474 THE TECHNOLOGY OF BREAD-MAKING.

in any way previous to grinding for analysis. The answer to such a ques-
tion is that this must depend on the purpose for which the analysis is
required. An analysis made for the purpose of buying1 or selling by
should be performed on a sample representing the bulk of the parcel of
grain in question ; it should therefore be in no way cleaned or washed.
When a miller requires to know the analytic character of a variety of
wheat in the cleaned state, the analysis would obviously be made on the
sample after cleaning. Undoubtedly the safest plan is to analyse the
sample exactly as collected, unless the analysis is made for some special
purpose. If a clean wheat is analysed the weight of cleaned wheat
obtained from a definite weight of the uncleaned wheat should first be
ascertained.

626. Experimental Test Mills. — The best general mode of testing
wheats is that of first reducing the same to flour, and then testing the
flour. With this end in view, the larger mills are frequently fitted with
small reduction plants by which an experimental quantity of wheat may
be reduced to flour, and this tested before the whole of the wheat is
ground. The plant for this purpose may be of various sizes, from a fairly
complete small roller mill installation to a specially made machine for
reducing purposes, the different separations being made by hand. In
this connexion see the description of Tattersall's special milling plant in
Chapter XXVII on Routine Mill Tests. On the flour thus obtained,
determinations may be made of such kinds as are employed on flour pro-
duced during the ordinary course of manufacture. It does not follow
that the experimentally-made flour will be equal in every respect to that
obtained in practice on the larger scale ; but usually the results are suf-
ficiently nearly comparative with each other to afford valuable informa-
tion. The practical miller will naturally make allowances for the milling
peculiarities of the wheats he may be thus examining.

With a mill of this kind, the percentage yield of straight flour, bran,
and other offal, obtainable from each particular sample of wheat may be
determined.

627. Moisture Determinations. — These may be made either on the
ground meal from grain or the dressed flour. They are sometimes made
on the whole wheat, but with this there is the objection that the unbroken
grains lose moisture somewhat slowly. In view of the wide extension of
the use of conditioning and analogous appliances and processes in modern
milling, a check on the moisture of the wheat and also on the flour, bran,
and other products has become of considerable importance. The per-
centage of water or moisture is usually found by weighing out a definite
quantity of the flour or meal in a small dish, and then drying in the
water oven until it no longer loses weight. When a number of samples
have to be assayed, some regular method of procedure is necessary. The
following method may be adopted : —

Procure from the apparatus dealer one dozen selected glass dishes,
2 1/2 in. diameter. Mark these with the numbers 1 to 12 on the sides with
a writing diamond. Have a little box made in which to keep these dishes.
The box should have a shelf, supported a little way from the bottom, con-
taining a series of separate holes, one for each dish, so that they may be
kept without danger of breakage. Clean and dry each dish, and then
weigh it carefully; enter the weights in the note-book, and, previous to
using each dish, test its weight. This may be done very quickly, as the
weights are already approximately known. It will be found that, if used
with care, the weight of the dishes will remain constant, within some four
or five milligrams, for a considerable time. Time may be still further

COMMERCIAL TESTING OF WHEATS AND FLOURS. 475

economised by having a series of counterpoises made for the set of dishes.
These consist of little brass boxes in the shape of weights, the tops of
which can be unscrewed. Brass counterpoises of this description can be
readily, obtained. Have engraved on the top of the counterpoises a series
of numbers corresponding to those on the dishes ; clean the counterpoises
and dishes thoroughly, and balance the one against the other in the fol-
lowing manner : — Place No. 1 dish in the left-hand balance pan, and the
corresponding counterpoise in the other, together with its cover. Fill up
the counterpoise with shot until it is as nearly as possible of the same
weight as the dish, then add little shreds of tinfoil until the two exactly
counterbalance each other; finally screw the lid and box part of the
counterpoise together. Proceed in exactly the same way with all the
dishes. In this case the shelf of the box for the dishes should also have
little holes cut in it for the counterpoises, so that each may be kept im-
mediately in front of its particular dish. Having a set of counterpoises,
before using each dish test it on the balance against its counterpoise, and
if necessary adjust the weight with the rider. As the dishes gradually
become lighter through use, the rider will have to be placed on the left-
hand or dish side of the balance. In case the balance is one which is only
fitted with the rider arrangement on the right-hand side, the dish may, if
wished, be placed on that side, and the weights on the left in weighing ;
this, however, is liable to lead to confusion and mistakes in reading the
weights. As the dishes grow lighter, their weight against the counter-
poise is really a minus quantity, and should be entered as such in the
note-book. For a long time the difference between the two is inappreci-
able, but still, for the sake of accuracy, the test should always be made.
When the dish and counterpoise differ more than .005 gram, the latter
should be readjusted. Having a number of determinations to make,
weigh out exactly 10 grams of each flour in a dish, then place them in the
hot-water oven and allow them to dry for 24 hours; at the end of that
time the water will be expelled. Take out the dishes, allow them to cool
in a desiccator, and weigh as quickly as possible. As the weight of each
is approximately known, put the larger weights on the balance pan before
taking the dish from the desiccator. After weighing, return the dishes
to the oven for another hour, and again weigh ; the two weighings should
agree within a milligram. Dry flour is very hygroscopic; that is, it
absorbs moisture with great rapidity. This is noticeable during weigh-
ing, for a sample will often gain while in the balance as much as five
milligrams. The student will at first, for this reason, get his weights too
high. The best plan is to put on the rider at a point judged to be too
high, and then at each trial bring it to a lower number until it is found
to be at one at which the dish is the heavier. Then take the lowest figure
known to be above the weight of the dish, for if the rider now be moved
upwards, the dish will often be found to gain in weight just as rapidly
as the rider is moved upward. Before the dish is removed from the desic-
cator for the second weighing, put in the pan the lowest weights before
found to be too heavy. After a time the student will find that he can get
his two weighings to always practically agree; he may then, but not till
then, dispense with the second weighing: It is evident that the flour
after being deprived of its moisture will weigh less; the weight taken,
therefore, less the weight of dried flour, equals the moisture, this, when
10 grams are employed, multiplied by 10 gives the percentage.

There are now made flat porcelain numbered dishes for milk analysis,
and these may if wished be used instead of glass dishes for moisture
determinations. Another convenient form of dish is that of polished

476 THE TECHNOLOGY OF BREAD-MAKING.

nickel made in the flat shape ; these latter possess the advantage of being
unbreakable.

628. Hot-Water Oven. — These ovens are usually made of copper,
and are of the appearance and shape shown in Fig. 75. The oven con-
sists of an inner and outer casing, with a space between them about an
inch in thickness; the top, bottom, two sides, and back, are therefore
double. This space for about half the height of the oven is, when in use,

filled with water, which is kept
boiling by a bunsen flame placed
underneath. Anything placed in
the oven is thus kept at a tem-
perature of from 96-100° C., but,
while there is any water within
the casing, never above the latter
temperature. In order to prevent
the oven boiling dry, a little feed
apparatus is a convenient attach-
ment. This usually consists of a
copper vessel open at the top,
and communicating by means of
a pipe with the water space of
the oven. Through the bottom

FIG. 75. — Hot-Water Oven. of this vessel is passed a piece of

glass tubing, the top of which

reaches to the height at which it is desired that the water shall remain in
the oven. This glass tubing is kept in its place by a piece of india-rubber
tubing, which, while making a water-tight joint, allows the tube to be
slidden up or down as wished. A small stream of water is led into the
feed apparatus ; this feeds the oven, and the overflow passes out through
the glass tube, which should either stand over, or be led into, a drain.

Another very good plan is to have fitted to the top of the water oven
an inverted Liebig's condenser, through the outer casing of which a
stream of cold water is passed. The steam from the boiling water in the
casing is then condensed by the condenser, and returned to the oven. The
oven, having been once filled, will not need replenishing for a consider-
able time, as the loss of water is very little. The condenser should be
made of brass or copper tubing ; the inner tube about % in. in diameter,
and the outer 1*4 in. : the length should be from 24 to 30 in. The cold
water should enter the jacket at the bottom. When a condenser is used,
the oven should also be fitted with a glass water gauge, to indicate the
height of the water as shown in the figure. With this arrangement the
oven may be filled with distilled water, and so loss of heat by the forma-
tion of crust be prevented.

Where time is an object, it is convenient to use an oil oven instead of
one filled with hot water. The oven is similar in construction, but the
jacket is filled with oil, and the temperature raised for wheat or flour
drying to 105-110° C., being regulated by adjusting the burner, or by
means of an automatic regulator.

629, Vacuum Oven. — In estimations of moisture for milling pur-
poses, speed is almost always of the utmost importance ; the authors have
therefore designed and used with success a special form of vacuum oven
for such determinations. The oven, Fig. 76, is of circular shape with flat
bottom, and consists of an inner casing, a, a, and an outer jacket b, b, of
copper. The diameter of a, a, may be from 10 to 12 in., arid the internal
height about 5 in. The space between the casing and jacket should be not
less than 1 in. At c is attached a small water gauge. A return condenser

COMMERCIAL TESTING OF WHEATS AND FLOURS. 477

is fixed as shown at d, d. By means of a burner fixed under the oven the
temperature of the water in the jacket is maintained at 100° C. Or if
wished, a solution of potassium carbonate may be employed ; this boils at
a temperature above 100° C. and depending on the degree of concentra-
tion of the solution. A drawback is that the salt slowly attacks the metal
of the oven. Or an organic liquid such as toluol, boiling at 107° C., may
be used. With this, however, care must be taken, as the boiling liquid is
inflammable. The advantage of the higher temperature is the more rapid
drying capacity of the oven. At e is fixed a pipe leading to a Korting
or other efficient vacuum pump. The open end at e is turned up so as to

FlG. 76. — Vacuum Oven.

prevent the inrush of air from impinging on the contents of dishes in the
oven. At / a tap is placed, by which air can be admitted into the oven ;
on the opposite side g is shown a small Bourdon vacuum gauge. The
upper part of the oven is drawn into an opening about 6 in. internal
diameter, terminating in a flange the face of which is turned and ground
perfectly true at h. On this rests a gun-metal lid, i, also faced true. At
j, j, are hinged screw clamps by which the lid is securely screwed down
to make an air-tight joint with the upper flange of the oven. In use the
oven is made hot by a burner arranged underneath, preferably of the

478 THE TECHNOLOGY OF BREAD-MAKING.

ring type. Flat nickel dishes are most suitable for the flours or meals.
These are placed in the oven and then the lid is fixed in position. ' In
order to make the joint, the faces of the flanges are smeared with a luting
mixture of rubber dissolved in naphtha, such as is used for repairing
pneumatic tyres, or a rubber ring may be used. In this latter case the
ring and the faces of the flanges should be well blackleaded. The top at /
is closed and the vacuum pump started, and kept at work so as to main-
tain a good vacuum as shown by the gauge. Drying is exceedingly rapid
and thorough with the flat dishes in immediate contact with the flat bot-
tom of the oven. The minimum time for complete drying should be
ascertained by an actual test; after which, provided the vacuum is kept
up, the dishes with their contents may simply be dried for the requisite
time and then weighed. To reopen the oven the pump is turned off, and
then the tap / carefully opened to admit air. The clamps are then un-
screwed and the lid slid off.

630. Effect of Humidity of Air on Moisture of Flour.— Flour is ex-
ceedingly hygroscopic and absorbs or loses moisture, according to whether
the atmosphere is damp or dry, with great readiness. Richardson exam-
ined a series of flours immediately on coming from the mill, and again
after being exposed to the atmosphere for a day, with the following
results : —

Original Gain Second

Moisture. or Loss. Day.

No. 1 9.48 .. +0.65 .. 10.13

,,2 7.80 . . +2.15 . . 9.95

,,3 7.85 .. +2.30 .. 10.15

,,4 7.97 .. +2.15 .. 10.12

,,5 13.69 . . —3.28 . . 10.41

It will be seen that, notwithstanding the wide differences in per-
centage of moisture on the first day, they had, at the end of the second,
become practically equalised. Richardson next allowed these flours to
remain exposed to the atmosphere for 16 days, making during that period
15 determinations of moisture. In one and the same flour during that
time variations of nearly 5 per cent, were observed. In the following
table the results are expressed in weight in Ibs., which 100 Ibs. of the orig-
inal flour would have assumed under the conditions: —

No.
1.

2.
3.
4.
5.

No. 1 of these flours was the well-known brand, Pillsbury's Best; it
will be of interest to give the weight of this each time determined, and
also the relative humidity of the air each day.

Relative

Weight of Humidity

Date. Flour. of Air.

March 17 . . 100.38 Ibs. 42.2

„ 18 . . 101.88 „ 59.5

„ 19 .. 102.03 „ 60.1

„ 20 .. 102.48 „ 55.6

„ 21 .. 101.43 „ 51.8

„ 22 .. 101.68 „ 51.1

24 102.88 66.9

Original

Highest Weight

Lowest Weight

Amount of

Weight.

Moisture.

during 16 days.

Variation.

100 Ibs.

9.48

102.88 Ibs.

99.53 Ibs.

3.35 Ibs.

100 „

7.80

104.87 „

100.00 „

4.87 „

100 „

7.85

105.20 „

100.00 „

5.20 „

100 „

7.97

105.95 „ '

100.00 „

5.95 „

100

13.69

100.00

95.35

4.65

Relative

Weight of Humidity
Date. Flour. of Air.

March 7 . . 100.00 Ibs.

8 .. 100.65 „ 46.4

„ 10 .. 99.53 „ 35.0
„ 11 .. 101.73 „ 59.0
„ 12 .. 102.68 „ 60.1
„ 13 .. 99.88 „ 34.0
„ 14 .. 101.08 „

15 101.53 48,2

COMMERCIAL TESTING OP WHEATS AND FLOURS. 479

It will be observed that with an increased dampness of the air, the
weight of the flour is also increased. Of course, in strictness, the weight
of the flour is governed by the degree of humidity prior to the moisture
determination, rather than that at the time the determination is actually
made.

On exposing a sample of patent flour to an atmosphere kept absolutely
saturated with water, it absorbed more than 26 per cent, of ij;s original
weight in 64 hours. The following table gives the weight at different
intervals :— -

Weight of flour taken . . . . . . 1.0000 grams.

after 35 minutes . . . . 1.0285 „

„ 18 hours 1.0930

„ 22 „ 1.2005 „

„ 42 „ 1.2405 „

„ 64 „ 1.2670 „

These variations in weight of which flour is capable go far toward
explaining discrepancies in wafer-absorbing power, and yield, of labora-
tory samples.

631. Gluten Determinations.— The strength of flour has been amply
discussed in a previous chapter, in which it is shown that it largely de-
pends on the quantity and character of the insoluble proteins contained
in the flour. In a crude form these are obtained in the well-known wash-
ing process for gluten. One great objection to the gluten test is the diffi-
fulty of knowing precisely when the whole of the starch has been
removed, and then stopping short of washing away any of the gluten
itself. In many flours the gluten begins to disintegrate and wash away
before the whole of the starch disappears. With some little experience
the same worker can get concordant results, but this is not invariably the
case with two workers testing against e-ach other ; one will then frequently
Throughout a whole series uniformly get higher results than the other.
As, therefore, considerable differences may exist in the percentages of
crude gluten obtained, both in the wet and dry state, it is recommended
that in addition the "true gluten" or protein matter be also determined
by a direct nitrogen estimation. Even when there are marked dis-
crepancies in the crude gluten as obtained by washing, the true gluten
varies only within comparatively narrow limits.

As an index of strength, it is recommended that the following estima-
tions be made : — Percentage of gluten wet and dry by the washing-out
process, and of true gluten by nitrogen determination on the dry gluten ;
all of these to be calculated on the whole flour. Appearance and physical
character of the gluten to be noted. Percentage of total proteins in the
whole flour.

632. Gluten Extraction. — One of the most important points is that a
uniform method is always adopted. The following is a very convenient
mode of working. Thirty grams of the flour should be accurately
weighed and transferred to one of Pfleiderer's small doughing machines
(made especially for the purpose). To this should be added in the
machine 15 cubic centimetres (= 15 grams) of water from a graduated
pipette. The whole should then be thoroughly kneaded, receiving 100
revolutions by the counter after the flour and water are first roughly

- mixed. (While the machine is exceedingly convenient, the dough may as
an alternative be made by hand.) From the resultant dough one or two
portions of exactly 15 grams each should be accurately weighed and then
transferred to a small glass containing sufficient cold water to keep them
entirely submerged in which they must be allowed to remain for exactly

480 THE TECHNOLOGY OF BEE AD-MAKING.

an hour. (The second piece is only to be weighed off in event of a dupli-
cate being required.) The weighed portion of dough contains exactly 10
grams of flour, and should be washed in the following manner : — Prepare
some water at a temperature between 70° and 80° F., and partially fill
a clean bowl with same. For reasons before given the water must be
ordinary tap water, and not distilled water. Wash the lump of dough
by kneading it gently between the fingers in the water, using no muslin
or other enclosing substance. The starch is gradually washed away, and
the remaining dough acquires the consistency and characteristic feel of
gluten. Take care that no fragments are washed off the main lump ; and
after the gluten is approximately freed from starch, place it aside on a
clean surface of glass or porcelain: let the washing water settle, and
decant it very carefully through a fine hair sieve. Should there be any
fragments of gluten on the sieve, pick them up with the main piece and
do the same with any remaining in the basin. Take some more of the
tepid water and repeat the washing some little time longer; change the
water about two or three times, with the same precaution against loss as
before. The last washing water should remain almost clean. The gluten
may now be taken as pure, freed as far as possible from adherent mois-
ture and weighed.

In the case of Hungarian and certain other flours of very high water-
absorbing power, it is sometimes advisable to make a slackrr dough for
gluten extraction than that just described. For this purpose add 20 c.c.
of water to the 30 grams of flour, and take 16.66 grams of the dough for
each estimation. This weight contains, as before, exactly 10 grams of
flour. If preferred, 10 or 20 grams of flour may be weighed off and made
up into a dough with water direct for this estimation.

When it is intended to determine the gliadin in the gluten, 30 or 33.33
grams of dough should be taken for washing purposes instead of 15 or
16.66 grams. The washing operation should be conducted as before. The
whole mass of gluten is then weighed and registered as wet gluten, after
which it is separated into two halves by weight. One is dried for dry
gluten, and the other is used for the gliadin estimation (see paragraph
677).

For the drying of the gluten, pieces of paper should be prepared
beforehand in the following manner : — Take a sheet of cartridge or other
stout paper and cut it up into small pieces 3 inches square. Place these
in the hot-water oven and dry at 212° F. for two days. Take them out
and allow to cool in a desiccator, and weigh them off rapidly to within a
decigram. Mark the weight in pencil on the top left-hand corner of the
paper . Keep a store of these in a clean box. If preferred, these may be
obtained ready cut from a printer. They will then be found to be of just
the same weight ; and if two pieces be equally dried in the hot-water oven
they will still counterbalance each other. This should be verified by an
actual trial. When any number of glutens are being simultaneously
determined, a blank piece of paper may be put in the oven with the
glutens, and used throughout as a counterpoise when weighing them. If
for any reason special accuracy is required, the paper should in each
case be dried and weighed for each estimation.

Having weighed the gluten as above described, mould it between the
fingers and notice its physical condition, whether tough and elastic, soft
and flabby, or " short" and friable. Make a note of same. Mould it into
a ball and place it on the centre of one of the weighed papers. On the
one corner mark the date, and below, the name or number of the flour,
with the weight of the wet gluten. Next place the gluten in the hot-water

COMMERCIAL TESTING OF WHEATS AND FLOURS. 481

oven and dry at 212° F. until the weight is constant; then weigh to the
decigram, subtract the weight of the paper, or weigh against the counter-
poise piece, and express the result in percentages. The gluten adheres to
the paper, and thus may be kept as a record of the flour.

To determine the true gluten, break up the crude dry gluten into
coarse fragments, and estimate nitrogen by the Kjeldahl method, as
described in Chapter XXIII. The percentage of the true gluten should
be returned on the whole flour, and should be at least 80 per cent, of the
crude gluten.

By means of the same process (Kjeldahl) determine the total proteins
in the flour.

633. Extraction of Gluten from Wheat-Meal.— The meal may be
weighed and made into a dough precisely as with flour ; or if wished, 10
or 20 grams only may be weighed off and transferred to a basin, and then
mixed with sufficient water to make a somewhat slack dough. This is
allowed to stand as before for one hour under water. Instead of washing
the dough direct in the bowl, it is preferable to first enclose it in a piece
of either fine muslin or, preferably, millers' bolting silk. This must be
held securely in order to prevent any loss of the dough, which must be
held under water in the bowl and kneaded between the fingers until a
fresh lot of water is no longer caused to become milky by the escaping
starch. On opening the silk, it will be found not only to contain the
gluten, but also the bran of the wheat, and these have to be separated
from each other. With the harder wheats this is done without much diffi-
culty, but in the case of those that are softer it is sometimes almost impos-
sible to recover the whole of the gluten. After having washed out the
starch, squeeze the water from the silk, and then open it out on a piece of
glass. There will usually be one fairly sized lump of gluten ; take this out
and rinse it moderately free from bran in a basin of clean water, next
squeeze it well together, then pick off any tolerably large pieces of gluten
that remain on the silk, and add them to the main lump. After each addi-
tion again squeeze the piece together and rinse off any loose bran. The
difficulty is now to gather together any particles remaining in the bran—
these are often so small as to be scarcely visible. Take the mass of toler-
ably clean gluten and add to it a portion of the bran, roll them together
with considerable force between the palms, and then wash off the bran.
This process of rubbing together the main lump of gluten and the bran
effects the removal of any little fragments of gluten by their sticking to
the larger piece ; which, in virtue of its adhesive property, picks them out
from the bran, just as a magnet picks out iron filings from among those
of brass. Treat the whole of the bran remaining on the silk in this man-
ner; the result will be a lump of gluten still containing a little bran.
With a hard wheat, however, the whole of the gluten will have been thus
recovered; with the softer ones it is sometimes advisable to drain the
water off the bran and again rub it all up with the gluten. In every case
inspect the bran most carefully before throwing it away ; the bran should
also be rubbed between the fingers; this will often detect fragments of
gluten that escape the eye. Having got the whole of the gluten together,
wash it time after time until free from bran. This is a tedious operation,
but one that can be performed by vigorous and careful treatment. Pour
every lot of water on to the muslin in order to see that no gluten is lost.
The washing must be continued until the gluten yields no turbidity to
clean water.

The subsequent processes are performed on the wheat gluten precisely
as with that from flours.

482

THE TECHNOLOGY OF BREAD-MAKING.

634. Water-Absorbing Capacity. — One of the best methods of deter-
mining the water-absorbing capacity of a sample of flour is by doughing
it, and then judging by the consistency of the dough. The dough may be
tested in this manner shortly after being made up, and again after an
interval of some hours. A more or less accurate judgment is thus formed
of the water-absorbing power of the flour when, first made into dough,
and also its capacity for resistance to the changes which take place in the
constituents of flour while standing for some time in a moist condition.
The unfortunate point about such determinations is, that judging by the
appearance and stiffness of a dough is exceedingly uncertain: one per-
son's own judgment is not at all times alike, and the difficulty is multi-
plied infinitely when an attempt is made to compare that of several per-
sons. Again, there is the fact that for all purposes of exactitude it is
essential that some means shall exist for expressing results in actual
figures.

Finding the problem in this state, one of the authors devised appa-
ratus, which had as its object the determination of water-absorptive
power, and giving a numerical expression of the result. The starting
point was to decide on some mode of expressing yield: the first idea was
to make use of the number of quartern loaves of bread that could be pro-
duced from a sack of flour. But here the difficulty occurred that differ-
ent bakers are in the habit of weighing their bread into the oven at differ-
ent weights, to say nothing about the possibilities of different weights

when the bread leaves the oven. Further,
the use or non-use of "fruit" renders this
method of considerable uncertainty. There
is again the fact that some bakers work with
slacker doughs than do others.

After considering several possible modes
of expression, the decision arrived at by the
authors was to give the quantity of water
that a specific weight of the flour took, in
order to produce a dough of definite arid
standard consistency. By almost universal
consent the standard of weight of flour
would, in England, be the sack of 280 Ibs.,
while water can be conveniently expressed
in quarts. The quart being the quarter of
a gallon, and the gallon weighing 10 Ibs.,
render it easy to convert quarts into either
gallons or Ibs. It will be noticed that the
adoption of this standard does not touch on
the contested question of loss of water in
the oven. If preferred the tests may be
made, and the results expressed in c.c. per
100 grams, i.e., parts per hundred, or if
wished Ibs. of water per barrel, 196 Ibs. of
flour, may be adopted.

635. Water-Absorption Burette.— The
operation of doughing resolves itself into
taking any convenient quantity of flour and
adding sufficient water to it to make a
dough of -normal stiffness and then calcu-
lating out the water employed into the pro-
portion of quarts per sack. The simplest

FIG. 77. — Burette, Arranged
with Reservoir.

COMMERCIAL TESTING OF WHEATS AND FLOURS. 483

way of doing this is to fix on the quantity of flour, and then make
a measuring instrument for the water ("burette" or "pipette"), which
shall be graduated so that each division represents a quart of water
per sack. Such a measuring instrument is the first part of the apparatus
described ; in using it, the flour is weighed out, and the quantity of water
run in is at once read off, without any calculation whatever, as quarts per
sack. The practical advantages of this method are evident, as from a
small doughing test a baker can at once direct how much water is to be
added per sack of any particular flour. The strength burette, together
with the viscometer, is shown in Fig. 78 : at the top of the instrument is
the zero mark, between which and "40" there are no graduations; the
tube is then graduated in single quarts down to 80 at the lower end. At
the bottom a glass jet is attached by means of a piece of india-rubber
tubing ; this is normally kept closed by the spring-clip, but may be opened
at will by pressing the two buttons shown, one on either side. In use, the
burette may be held in the hand, but is preferably fixed in a burette
stand. It may be filled either by pouring in water at the top, or by open-
ing the clip and sucking it up through the jet.

It is important to bear in mind that if great exactness is required in
doughing tests, the dough, when made, should have a definite tempera-
ture. It is recommended that for this purpose that of 70° F. be adopted.
If possible, a flour-testing laboratory should stand permanently at as
nearly as possible that temperature. Before starting a series of tests, the
water should be adjusted to 70° F. : and the flours, if cold, allowed to
stand in a warm room sufficiently long to give the same temperature when
tested by the thermometer.

Where a number of flours are being tested, it is an exceedingly con-
venient plan to have a water reservoir attached to the burette ; the whole
apparatus will then appear as shown in Fig. 77.

In the lower part of the figure the burette is seen fixed in a stand. At
a is a second tube opening into the burette above the clip ; by means of
india-rubber tubing, this second tube, a, is attached to a glass reservoir,
A, which stands on a shelf above the level of the top of the burette. By
means of a spring-clip at a the liquid in the reservoir is shut off from
the burette. The burette being empty, open the clip a; the water flows
from A upward into the burette ; when the level coincides with the zero
mark close this clip, and proceed to deliver the desired quantity of water
by pressing the clip at the bottom of the burette. In this manner the
instrument may be filled with great convenience and rapidity.

To test a flour, weigh out as exactly as possible one and a half ounces
of the sample, and transfer it to a small cup or basin. Next fill the
burette with water until the level exactly stands at the top graduation
mark. Then place the cup containing the flour under the burette, and
press the clip, allowing the water to run out until down to as many
quarts as 'it is thought likely the flour will require. Then, by means of a
stirring rod, or bone spatula, work the flour and water into a perfectly
even dough ; try, by moulding it between the fingers, whether it is too
stiff or too slack : if so, dough up a fresh sample, using either more or less
water as the case may be. Having thus made a dough of a similar con-
sistency to that usually employed, read off from the burette how much
• water has been used. The figures will express, without any further cal-
culation whatever, how many quarts of water the flour will take to the
sack. It is well before judging the stiffness of the dough to allow it to
stand for some time. The authors allow their doughs to remain an hour
before testing them.

484 THE TECHNOLOGY OP BREAD-MAKING.

It is not safe to state from the doughing test alone how many loaves a
certain flour is capable of yielding per sack, because different bakers, by
working in different manners, do not get the same bread yield from one
and the same flour. Each baker should therefore ascertain for himself by
means of a baking test, working according to his own methods, how many
loaves he obtains from a sack of any particular flour. He can then in the
following manner arrange for himself a table showing the bread equiva-
lent of the "quarts per sack" readings of the burette. To make this test,
take a sack of flour and measure the quantity of water requisite to make
a dough of the proper consistency. Then count the number of 2-lb. or
4-lb. loaves it yields on being baked. Suppose that the flour takes 70
quarts of water : then dough up a sample with the burette, using water to
the 70 quart mark, and take dough of that stiffness as the standard. Any
other flour of the same character which takes the same quantity of water
to make a dough of similar consistency will turn out about the same yield
of bread. Suppose another sample of flour takes 72 quarts of water, then
it will make, neglecting the slight loss in working, 5 Ibs. more dough (one
quart of water weighs 2^ Ibs.). Weighing the bread into the oven at

4 Ib. 6 oz. per the 4-lb. loaf, every two quarts more water per sack means
rather over another 4-lb. loaf produced. In exact figures the additional

5 Ibs. of dough yield 4 Ibs. 9 oz. of baked bread, or practically 4!/2 Ibs.

In this easy manner, by this instrument, a baker may determine for
himself, without any but the simplest mental calculation, and working
according to his own processes, how much bread a particular flour yields.
It is advised that every baker should for himself construct a table of re-
sults, based on his own method of working. To do this, let him, as sug-
gested, make a trial baking, and find out how many quarts of water a
sack of any one flour takes, and how many loaves it produces. Enter
those figures in the table, then for every two quarts more add on 4^ Ibs.
of bread or 1% 4-lb. loaves : for every two quarts less subtract the same
amount.

636, The Viscometer. — In order to carry the water absorption prob-
lem a step further, it is necessary, not only to have made the dough, but
also to devise means for mechanically determining its consistency. This
is the more difficult, as different kinds of flour produce doughs of dif-
ferent character. Thus, a spring American flour will yield a dough whose
essential characteristic is rigidity; a Hungarian flour yields a soft dough,'
but one which, nevertheless, possesses most remarkable tenacity. Any
instrument for measuring the consistency of dough must take into ac-
count these two somewhat opposite characters, giving each its proper
value. The resistance of the dough to being squeezed, and its resistance
to being pulled asunder, must both be taken into account. The second
part of the flour-testing apparatus consists of an instrument for definitely
measuring the viscosity of dough. This is effected by forcing a definite
quantity of dough through a small aperture, and measuring the time
taken in so doing, the force being constant. The machine for making
this measurement is termed a ' ' Viscometer, ' ' literally, a measurer of vis-
cosity. It is so arranged that, in doing the work of forcing the dough
through the aperture, both the stiffness and tenacity of the dough are
called into play as resisting agents. The consequence is that a very soft
and tenacious dough may prove its viscosity to be as great as that of a
stiff dough with comparatively little tenacity. Undoubtedly this is in
keeping with the observed facts of baking, for, as is often said, certain
flours will bear being made much slacker than others ; that is, their tenac-
ity as dough more than makes up for their comparatively little stiffness
or rigidity.

COMMERCIAL TESTING OP WHEATS AND FLOURS. 485

£,

The viscometer consists essentially of a cylinder, having a weighted
and graduated piston, and an aperture through the bottom for the exit
of the dough; the stiff er the dough, the more slowly does the piston de-
scend. Since the first instrument was made a number of alterations and
refinements have been introduced with the object of diminishing certain

causes of error which were revealed on ex- ^ ^ ^

periment. In its present form the instru-
ment is affected in its working by the condi-
tion of the dough, and that only ; further, it
takes cognizance both of the tenacity and the
rigidity of the dough. It is claimed for the
viscometer that it affords a means of absolute
measure of these two qualities of stiffness and
tenacity. In certain cases where two doughs
have been submitted to the judgment of
bakers, and then tested by the viscometer,
that judged the softer to the touch has been
registered by the viscometer as the dough of
greater consistency. The very simple expla-
nation is that it is difficult to form an accu-
rate judgment of tenacity by handling a
small piece of dough. Flours which exhibit
this particular combination of softness and

tenacity are just those which bakers would
say require to be worked slacker than others.

Consequently, even in these instances, the

viscornetric measurement affords a valuable

indication of the working water-absorbing

capacity of the flour. Millers and bakers

who have seen the apparatus at work endorse

this opinion. In using the instrument, the

dough is first put into the viscometer, and

the time which the piston takes to travel be-
tween two of its graduations is noticed.

Fig. 78 is a sectional drawing of the vis-
cometer, about one-third the actual size of

the instrument. The lower part, a l>, is a

cylindrical base, through which are two

lightening holes, marked y z. The cylinder,

e /, and flange, c d, are cast in one piece ; c d

has a collar, turned down to fit inside a ~b, the

edge of c d is milled. Through the bottom of

the cylinder is a hole, marked t; the upper

edge of this hole is rounded off, in order that

no cutting edge will be presented. This

aperture may be opened or closed at will by

the cover, u, which slides between a pair of

guides, and may be drawn in or out by the

rod and milled head, v. The piston, m n,

consists of a disc of gun-metal, the lower

edge of which is rounded; this piston is

attached to the bottom of a trunk, m o, the diameter of which is about

one-sixteenth of an inch less than that of the piston. This piston trunk

passes through the cylinder cover, g h: in the top of this cover is screwed

a tube, i j, carrying at its upper end a collar k I. Both this collar and

FlG. 78.— Viscometer and
Strength Burette.

486 THE TECHNOLOGY OF BREAD-MAKING.

the cylinder cover, g h, are bored to exactly fit the trunk of the piston.
The cylinder cover tube, i j, and collar, k I, therefore together act as a
guide for the piston, allowing it to slide steadily up and down with the
minimum of friction. The bottom of the cylinder cover fits over the top
of the cylinder, and is secured in its place by a pair of studs and bayonet
catches, s h. On the upper part of the trunk are three lines, p q r, the
distance between each pair being three-eighths of an inch. This trunk is
loaded inside in order to give it the requisite weight. With the exception
of the piston, m n, the instrument is throughout constructed of brass.

637. Method Employed in Using the Viscometer. — It is first neces-
sary to fix on a standard of stiffness for doughs: that adopted by the
authors is such as allows the piston of the viscometer to fall from mark
p to mark r in 60 seconds. As such doughs are slacker than those em-
ployed for many purposes, a stiffer standard may, if wished, be selected ;
in such a case the readings may be taken, if desired, when the piston has
made half its stroke, that is, has travelled from r to q instead of the whole
distance, r to p. Each individual user of the instrument may thus deter-
mine on a standard for himself.

Whatever standard is selected, whether the 60-seconds' standard em-
ployed by the authors, or another, weigh out one and a half ounces of
flour, add water from the strength burette, and dough up the sample as
before described, using a quantity of water, which, as well as can be
judged, shall give- a dough of standard consistency. The dough may be
mixed by hand in a basin, but the authors strongly recommend the use of
one of Pfleiderer's small doughing machines made specially for testing
purposes : these have the great advantage that they mix the dough thor-
oughly, and with absolute uniformity. The machine is made with water-
tight bearings, and is fitted with a revolution indicator by which the
number of turns given to the handle are registered. Place the flour and
water direct in the machine, and turn the handle so that the upper edges
of the blades approach each other. When the flour and water are roughly
mixed, scrape down the sides of the machine by means of a small spatula :
note the position of the revolution indicator, and give the dough fifty
revolutions. When sufficiently mixed, take the dough from the machine
and set it aside in a small glass tumbler, or other vessel, for one hour.
Cover over with a glass plate in order to prevent evaporation. When
examining a number of samples, dough them up one after the other for
an hour, and then come back to the further testing of the first one, and
take them in rotation.

Having thoroughly cleaned the cylinder and piston of the viscometer,
fill the cylinder with the dough to be tested ; to do this, slightly open the
bottom aperture and push in the dough through the top, by means of a
stout spatula. In this way fill the cylinder completely, taking care that
there are no air spaces; shut the aperture, t, and then, holding the
cylinder horizontally in the left hand, put on the cylinder cover, the
piston being at the top of its stroke. Secure it by means of the bayonet
catches, and stand the cylinder squarely on the base, a Z>. Arrange a
vessel, w x, to receive the dough as forced through the instrument. Next
have ready a watch with seconds' hand (a chronograph is the most con-
venient thing, if one happens to be in possession of the worker) ; pull out
the milled head, v, the piston begins to descend. As soon as the line r
coincides with the top of k I, note the time, or start the chronograph :

COMMERCIAL TESTING OF WHEATS AND FLOURS. 487

note again when the line p descends to k I, and observe how long the
piston has taken to travel this distance. If exactly sixty seconds, or what-
ever other standard has been selected, the dough is of the standard
consistency, and the quantity of water used is that required by the partic-
ular flour to make a dough of the standard stiffness. Feel the dough with
the fingers and see, especially, whether it seems hard or soft. A soft
dough, which nevertheless goes through the machine slowly, must possess
great tenacity. Such flours have almost invariably high water-retaining
power. The tests having been made, turn back the bayonet catches, and
withdraw the cylinder cover, piston, and guide from the cylinder. Re-
move the dough from the piston, and clean out the cylinder by means of
a spatula. In handling the piston be careful not to hold it with the cover
end uppermost, as the piston rod then slides backwards, and is stopped
by the piston coming violently in contact with the cover. The piston
being thin is liable by rough usage in this way to be forced off the rod.
When the instrument is done with, the cylinder should be soaked in
water, so as to remove any traces of dough that might clog the valve at
the bottom.

Having described the mode of using the instrument, its action on the
dough may now be examined. In the first place, the lower edge of the
piston and the upper one of the aperture through the cylinder bottom
are both rounded, therefore the dough is not subjected to any cutting
action. In the next place, the piston during its descent meets with no
resistance whatever except that due to the dough itself ; as it passes down
through the hole in the cylinder cover it is impossible for the dough to
find its way up through that opening against the downward movement
of the piston ; consequently, there is no clogging whatever of the moving
parts of the apparatus. The dough, in order to make its way out, has to
alter its shape so as to pass through the small hole at the bottom, conse-
quently its rigidity is here taken into account. At the end of the stroke,
the piston is found to have pushed out a plug of dough from the centre
of the cylinder, leaving a ring of dough standing round its outside. To
force out this plug, the piston must have torn away these particles of
dough from the aiinulus (ring) of dough left standing. Hence it is that
this apparatus registers so thoroughly the tenacity of the dough as well
as its rigidity. By shading the dough in the figure an attempt has been
made to indicate the probable lines of movement of the dough as the
piston passes downwards. An inspection of the drawing of the visco-
meter, and a study of its principles, show that it is the condition of the
dough, and that only, which can possibly affect the speed at which the
piston descends.

In practice it is well to have at least two tests made on the same flour
with the viscometer. When the approximate water-absorbing power is
known, these may well be taken at 2 quarts below and 2 quarts above this
point respectively. Having obtained a pair of piston readings, one above
and the other below the sixty seconds (or other predetermined) stand-
ard, the actual quantity of water corresponding to the standard may be
calculated in the following manner : — For entering the tests it is recom-
mended that a book be procured ruled both ways of the page : the water-
absorption results should then be entered as shown in Fig. 79, page 489.
Supposing 70 quarts to have run through in 90 seconds, and 72 quarts in
50 seconds, then on drawing a line connecting these two points, the place
where it crosses the horizontal line marked 60 in seconds, will give the

488 THE TECHNOLOGY OF BREAD-MAKING.

water absorption in quarts. Thus referring to Flour No. 2, Fig. 79, the
72 quart dough ran through in 86 seconds, and the 74 quart dough in 43
seconds : on these points being joined by a line, it cut the 60 seconds line
at very nearly midway between the 72 and the 74 quart lines, therefore
the water-absorbing capacity was taken as being 73 quarts. In this way,
the absorptive power of various flours for intermediate points between
two readings was arrived at. An inspection of Fig. 79 shows that the
upper portions of these lines, graphically representing absorbing capac-
ity, are very nearly parallel to each other. The authors find if the first
test made gives a viscometer reading between 45 and 90, that the water
absorption may be deduced with sufficient correctness for most purposes
in the following manner : — On a page, properly ruled both ways, set out
two or three lines similar to those in Fig. 79 representing the water-ab-
sorbing power of different flours. Then, supposing a flour under exam-
ination has run through the viscometer in 87 seconds, with 68 quarts of
water, make a mark at that point, and draw from it a line across the 60
seconds line, and parallel to the lines of other flours previously set out.
Reckon the water absorption from the point where it cuts the 60 seconds
line. Such a flour would probably absorb about 69.5 quarts of water.
Judging from a number of flours that have been tested in this manner,
the single test gives results that very seldom are more than 0.5 quart oft
from those obtained by doughing the flour with two different quantities
of water.

Examples of a few detailed viscometer tests are given in the table on
this page. The heavier figures are the calculated quarts per sack for 60
seconds.

RESULTS OF VISCOMETER TESTS ON FLOURS.

No. Names and Description of Flours.

1. Patent Flour, from American Hard Fyfe Wheat.

2. Bakers' Flour, from American Hard Fyfe Wheat.

3. Hungarian Flour, First Patent.

4. English Wheat Flour.

TIME ALLOWED TO REMAIN IN DOUGH— ONE HOUR.

*0.

Quarts per
Sack.

Seconds. No.

Quarts per
Sack.

Seconds.

215

223

193

200

107

52 2

—

255

183

170

120

38 4

—

COMMERCIAL TESTING OF WHEATS AND FLOURS. 489

56 9 60 Z 4- 6 S 10 2 4 6 8 80 2

56 S 60 Z * f, 8 70

Fie. 79. — Diagram of Water-Absorption Results.

638. Colour. — This is probably at the same time one of the most
difficult and most important tests to be made on flour. The great diffi-
culty is that the colour of the flour itself is not necessarily a criterion of
that of the bread produced. For example, some lower grade winter wheat
flours look very white and even better coloured than harder spring wheat
flours, whereas the bread made therefrom is exceedingly dark and ill-
coloured. Further, the colour of the bread is dependent not only on that
of the flour, but on the mode of working, and other factors which vary in
themselves.

Unless tests are made for no other purpose than the comparison of
flours placed side by side, it is absolutely necessary to have some means of
measuring and registering colour. The most familiar, and on the whole
the most successful, instrument for this purpose is that known as Lovi-
bond's Tintometer or colour-measurer. As this appliance has been ex-
tensively employed in the following investigations, a description of it at
this stage is necessary.

639. Lovibond's Tintometer. — The instrument itself is an optical de-
vice, Fig. 80, by means of which a sample of flour, bread, or other body
may be viewed side by side with a prepared surface of the purest white
obtainable. With the instrument is furnished a set of transparent stand-
ard tinted glasses. These are numbered from 0.01 upwards to 5.0, or
higher if wished, so that any degree of depth of tint may be built up from
these glasses, proceeding upwards by intervals of 0.01 at a time. For
flour-testing purposes three series of such tinted glasses are employed.
One of these is a Yellow, the second a Red, and a third Blue.

The base, A, carries a stand, A1, which is supported in an oblique
position by the strut. A3. On this stand is placed the optical instrument
itself, B. This consists of a tube, blackened on the inside, and having

490

THE TECHNOLOGY OF BREAD-MAKING.

FlG. 80. — Lovibond's Tintometer.

apertures on the upper end, G,
through which one looks in using
the instrument. These openings
are three in number, the outer
ones being intended for use with
both the eyes simultaneously,
while that in the middle is for
the purpose of one-eye examina-
tion. At the lower end of the
tube, H, provision is made for
the reception of two small cells,
fitted with slits into which the
standard glasses, J, are to be in-
serted. At F the coloured slabs
under examination are placed
for purposes of measurement.

The spongy texture of bread gives it a mottled appearance when
viewed through this instrument, and so a special device is necessary by
which the sponginess may be transformed into an even and uniform tint.
This is shown in Fig. 81, which is a plan of the tintometer arranged for
this purpose. K M is a flat stand, on which the tintometer, B, is fixed.
At L L, between the cell;, for standard glasses, and H, are placed two
lenses such as those employed for spectacles. At W the standard white
comparing surface is arranged, and the slice of bread under examination
is fixed at Y. On looking through the eye-pieces at G, the lenses throw
both the white surface, W, and the bread, Y, out of focus, so that they
appear as even coloured, structureless surfaces.

To use the tintometer, the standard white comparing surface must
first be prepared. Fill one of the little trays supplied with the instru-
ment with some specially prepared plaster of Paris, also supplied : press
down with a piece of clean glass until a smooth uniform surface is ob-
tained : if for bread, fill the cavity in the stand at W in the same way.

FlG. 81. — Tintometer Fitted for Use with Bread.

When using the first arrangement of the instrument, stand it in a
convenient position facing a window looking toward the north, and, if
possible, so that the light is from a white, cloudy sky, rather than when
the sky is perfectly blue. In this latter case it is well to place a piece of
white paper or white opal glass between the light and the surfaces being
examined. On the one side of the field, F, place the tray of white, and
the flour on the other. On looking down through the tintometer the flour
will look much the darker. In the cell over the white surface put in some
of the standard colour glasses already referred to — say, for example, 1.0
Y. (yellow) and 0.50 R. (red). The white light from the prepared sur-
face passes up to the eye through these, and gives that surface an ap-
parent yellowish red tint. Note whether the tint as a whole is lighter or
darker than the flour, also whether too red or too yellow. If too dark
and too red, remove the red glass and substitute a lighter one, and again

COMMERCIAL TESTING OF WHEATS AND FLOURS. 491

compare. If too light and too red, add a little more yellow, leaving the
red undisturbed. Very quickly it is possible to get the tint matched ap-
proximately : it is in getting an exact match that the difficulty occurs. It
is .well to try one or two modifications of the standard glasses, and see
which comes the nearest. If the eye is uncertain, it is often an assistance
to place a dark glass, say 5.0 Y., in front of the eye-piece, and look
through the middle aperture at both the flours ; they appear much darker,
but minute shades of colour are thus more readily distinguished. Having
got the tint which so closely as possible matches the flour, a register
should be made of the numbers of the glasses composing it.

The bread form of the instrument should be arranged horizontally on
a stand, so that it is at a comfortable height fo-r the eyes of the observer
when sitting, and so that the light comes from a window, over the
shoulder, as shown by the arrow, P, Fig. 81. (If necessary, the instru-
ment may of course be arranged for the light to fall from the right in
stead of the left.) Care must be taken that neither the surface, W, nor
that of the bread has the shadow cast on it of any part of the apparatus.
The use of the standard glasses in measuring is the same as before.

It is scarcely necessary to say that colour judgments are difficult, and
to point out that different persons' eyes appreciate colours differently.
One difficulty with the tintometer is, the comparison is being made be-
tween an opaque coloured surface in the case of the flour, and a tint im-
parted to a beam of light in the case of the test-surface — there is a dif-
ference in qualit}^ which makes comparison difficult. A desideratum is
some form of permanent, graduated, tinted surface which can be com-
pared with the flour.

The great value of the tintometer is for from time to time perma-
nently measuring and checking the colour of standard flour samples : this
is well worth any trouble taken in so doing. The standards being thus
kept verified, it will be sufficient for ordinary purposes to check and com-
pare flours side by side with the standards.

640. Colour Investigations. — In obtaining the readings made in con-
nection with the following research, the judgment of four persons was, in
many instances, utilised, while every reading was checked by at least two
persons, and always, where the slightest doubt was felt, by three.

Among methods of judging the colour of flour the most obvious is
that of testing the flour itself in the normal dry condition. To this there
is the objection that the colour of dry flour depends not merely on the
nature of the wheat and the flour constituents, but also on the compara-
tive coarseness or fineness of the particles of the flour. Further, on ex-
posure to air flour very quickly bleaches, although this of course does not
effect the validity of a test made on a sample taken from bulk. The
bleaching of flour is commonly ascribed to light, but this is not essential,
for in the following experiment the samples were kept during the in-
terval between readings in a dark cupboard. The following three dry
samples gave tintometer readings as under, being simply pressed into
smooth slabs and examined: —

Immediate. After standing one Day.

Yellow. Red. Yellow. Red.

American Spring Bakers . . 0.27 0.06 . . 0.25 0.04
Ditto, another sample . . 0.34 0.11 . . 0.30 0.09
American Winter Bakers . . 0.20 0.02 . . 0.11 0.02

Pekar's Test. — A second and well-known method of testing colour is
to dip the compressed slabs into water, so as to wet the surface, then
allow the same to dry off, and read or compare the colours. The tint is in

492 THE TECHNOLOGY OF BREAD-MAKING.

this instance darkened considerably as a result of the action of oxydase
in the presence of air, coloured oxidative products being formed. In this
case, again, the degree of granulation of the flour affects the depth of
colour — a coarse flour absorbs more water, and becomes darker through
taking longer to dry, while the surface has more or less "grain" as a re-
sult of roughness of the surface before Wetting.

A third method consists of making the flour into dough, working it
until perfectly smooth, and then examining and comparing. One objec-
tion to this method is that the colour of the dough darkens rapidly on the
outside, and hence, if an attempt be made to read off the colour, or even
compare a series of three or more at a time, a new dough surface darkens
visibly while the comparison is being made. To obviate this, the pellet
of dough may be placed on a* sheet of colourless glass, and the colour of
the dough observed through the glass — in this way the colour of the
dough proper is seen as distinct from that of the outer skin. It is no
uncommon occurrence to take two flours from the same variety of wheat,
the one very fine and the other granular, and compare them either dry
or wetted in compressed slabs. The granular flour under both tests looks
the darker, but on working them into dough, as just described, the
coarser flour often produces the more "bloomy" dough; bakers will at
once form their own judgment as to which of the two will under similar
conditions make the best loaf. Also, of course, the outer skin of the same
samples may be compared and read if necessary.

Investigation shows that the colour of dough is influenced by its de-
gree of stiffness. Thus, a spring bakers' flour was made into dough with
different quantities of water, and the following readings taken at the ex-
piration of one hour. At the end of thirteen hours, in which the doughs
were kept in a water-saturated atmosphere, the colour of the outer skins
was also read : —

Colour of Dough. Colour of Skin.

Yellow. Red. Blue. Yellow. Red. Blue.

1. Doughed with 50% of water 1.50 0.68 0.08 3.55 2.10 0.86

2. Doughed with 55% of water 1.42 0.63 3.75 2.10 0.56

3. Doughed with 60% of water 1.19 0.54 3.15 1.90 0.48

The colour both of dough and skin is darker in the tighter doughs;
also this relation of colour holds good for some time, for at the end of
eighteen hours the order of colour of the dough was the same as at the
end of one hour.

In order to eliminate so far as possible the differences due to varia-
tions in tightness of doughs, the whole of the flours were in the subse-
quent tests treated with the quantity of water sufficient to make doughs
of uniform stiffness. For this purpose each flour was tested by the visco-
Lieter in the manner previously described. The next step was to investi-
gate the influence of the length of time the dough had stood on the depth
of colour; this, be it remembered, always being read through colourless
glass. The following results were obtained : —

Winter Winter Spring Spring

American American American American

Time. Patent. Bakers. Patent. Bakers.

1 hour after mixing 0.92 0.29 1.37 0.94 1.02 0.64 1.34 1.10

2 hours after mixing 1.02 0.36 1.49 0.97 1.09 0.64 1.49 1.00

3 hours after mixing 1.08 0.40 1.50 1.00 1.25 0.75 1.52 1.07

4 hours after" mixing 1.10 0.43 1.51 1.00 1.20 0.65 1.47 0.97
22 hours after mixing 1.08 0.58 1.50 1.02 1.20 0.75 1.46 1.07

COMMERCIAL TESTING OP WHEATS AND FLOURS. 493

It may be well here to explain the precautions taken in order to get
as exact readings as possible. First of all, every series of tests to be read
were arranged in order of colour as apparent to the eye ; then they were
read in succession, commencing with the lightest. After matching No. 1,
No. 2 was placed against its (No. 1's) standard tint glasses and seen to
be darker, then measured. In all cases where there was any apparent
discrepancy the reading received a checking by three persons. When
making time measurements the following method was adopted : — First of
all, at the expiration of the time, the colour glasses of the preceding read-
ing were again placed in the instrument, thus taking, for example, the
two hours' reading on the first flour just given, the one hour glasses, Y.
0.92 ; R. 0.29 were inserted, and the dough compared with them. It was
definitely ascertained that a distinct darkening had occurred ; its meas-
urement then followed. Each reading was thus compared with that pre-
ceding throughout the whole series. It will be observed that a slight but
steady darkening occurs throughout the whole series, the increasing red
or- foxy tint "saddening" the bloom of the yellow. Unless otherwise
stated, future readings were made on doughs after standing one hour.

The authors have also adopted another method of preparing the flour
for examination, which is really a modification of the Pekarised slab
method. The testing Pfleiderer doughing machine is thoroughly cleaned
by making a stiff dough in it, and thus removing anything that would
injure the colour. A dough is made by taking 30 grams of flour and 15
grams of water, and then pinning it out into a thin sheet — say three-
sixteenths of an inch thick — on a piece of glass. This is allowed to dry
off in a dark place and then read just like the Pekar slab. It has the
advantage of giving a smooth surface with all errors due to the ' ' grain ' '
of the flour eliminated; but has the disadvantage that the degree of
darkening depends somewhat on the thickness of the sheet.

The next and final test is that made by baking the loaf and then
observing the colour of the bread. It is scarcely necessary to point out to
bakers that colour is influenced by the kind of yeast used and mode of
working; but using the same yeast, it was thought well to register the
effect produced by the mode of fermenting employed, and especially the
time of fermentation. A spring American bakers' flour was first made
into an off-hand dough in the following manner : —

10 Ibs. flour,
5 Ibs. water at 90° F.,

1J/2 oz. compressed yeast (Delft Pure), and
1*4 oz. salt,

were taken and made into dough at 5 p.m. The dough was then main-
tained at a temperature of 80-82° F. during the whole time of the ex-
periment. At intervals a 2 Ib. piece was taken, moulded, and baked. On
the next morning the loaves were cut, the colour examined, and also the
total acidity, reckoned as lactic acid, determined. On the second day also
the colour was read, a freshly-cut surface being used for that purpose.
The following table gives the results obtained. The first column gives the
number of hours after setting the dough until the loaf was placed in the
oven; the first day's colour readings follow in the second column, the
next days in the third, and the acidities in the last.

494 THE TECHNOLOGY OF BREAD-MAKING.

TESTS ON BAKERS ' FLOUR — OFF-HAND DOUGH.

First Day's Colour. Second Day's Colour. Acidity.

No. Hours. Y. R. B. Y. R. B. per cent.

1 4 2.11 1.41 0.30 1.85 1.25 0.16 0.57

2 6 1.75 1.25 0.18 1.91 1.10 0.26 0.63

3 8 1.75 1.00 0.10 1.85 1.10 0.26 0.66

4 10 1.75 1.20 0.10 1.75 1.30 0.26 0.69

5 12 1.70 1.15 0.05 1.66 1.20 0.24 0.73

6 13/ 1.70 1.20 0.30 1.75 1.40 0.30 0.79
Fermentation had not proceeded sufficiently far to properly raise the

first loaf, which was somewhat close and heavy, .and also dark in colour;
but it should be borne in mind its texture could scarcely be in fairness
compared with that of the other numbers of the series. The last showed
signs, but only slight, of darkening — due doubtless to the commencement
of those changes which accompany sourness. The loaves Nos. 2 to 5" do
not vary greatly in colour, but there is a slight diminution of the depth
of tint. Taken as a whole, this series darkened before the second day.

In another series of tests two doughs were worked with a flour fer-
ment. The one was from a spring American patent flour; the second
from a bakers' grade from the same wheat. The following quantities
were in each case employed : —

34 Ib. flour ]

3 .oz. compressed yeast j- Ferment.

5 Ibs. (2 quarts) water at 102° F.J
9^4 Ibs. flour Dough.

The ferment was allowed to work 45 minutes from the time of being
set ; then the dough was made, and one loaf immediately taken. This was
allowed to prove, and at once baked. Loaves were taken at intervals as
shown in the following table, in which is also given the colour and acidity
both on the first and second day after baking. It should be added that
the first loaf was baked at about 9.15 p.m.

TESTS ON BAKERS' FLOUR — FLOUR FERMENT AND DOUGH.
(Same sample as used in previous series.)

No.
1

First
Hours. Y.

Immediate 1.80

Day's Colour.
R. B

1.15 0.50

Acidity
per cent.

0.65

Second Day's Colour.
Y. R. B.

1.40 0.96 0.06

Acidity
per cent.

0.59

2 hours

1.65

1.20

0.40

0.73

1.48

1.00

0.04

0.71

4 "

1.65

1.30

0.40

0.72

1.42

1.00

0.04

0.90

6 "

1.90

1.80

0.60

1.05

1.60

1.40

0.05

1.12

7/2 "
9/2 "

2.20
2.22

2.08
2.15

0.75
0.75

1.17
1.10

1.60
1.65

1.45
1.40

0.08
0.08

1.27
1.34

REMARKS.

No. 1. Very close. and heavy.

No. 2. Sweet, good loaf.

No. 3. Colour slightly worse, odour faulty.

No. 4. Decidedly sour, rapid darkening in colour commenced.

No. 5. These changes intensified.

No. 6. These changes still more marked.

The colour here distinctly fell off, with increase of acidity, a distinct
difference being observed even between Nos. 2 and 3. The off-hand
doughs were, as a series, whiter than those prepared with a ferment, but
this is probably due to the excessive fermentation in the latter series,
which was intentionally pushed to an extreme. Taken as a whole these
loaves were distinctly less coloured on the second day.

COMMERCIAL TESTING OF WHEATS AND FLOURS. 495

The following are the results of the corresponding series of tests on
patent flour : —

TESTS ON PATENT FLOUR.

First Day's Colour.

No.

Hours. Y.

Immediate 1.45

2 hours

1.40

;>,

4 "

1.30

6 "

1.75

7/2 "
9/2 "

1.70
1.70

0.70
0.62
0.60
0.98
1.01
1.02

Acidity
per cent.

0.29

Second Day's Colour.
Y. R. B.

1.40 0.72

Acidity
per cent.

0.32

0.35

1.60

0.73

0.05

0.37

0.50

1.32

0.65

0.06

0.52

0.63

1.60

1.01

0.68

0.70

1.40

0.90

—

0.73

0.75

1.48

0.93

—

0.82

REMARKS.

No.
1.

Second Day.

Sweet.
Sweet.

Both 2

4.
5.
6.

Incipient sourness.

Sour.

Very sour.

First Day.

Close and heavy — Sweet

Bright and good bloom — Sweet

Greyer, very little different — Sweet,
and 3 good volume

Smaller, darker, slightly sour . .

Smaller, darker, sourer

Very small, dark, very sour . .
Again, with an increase of acidity, there is also a darkening of col-
our; and in the earlier numbers of the series also a darkening t on the
second day's reading as compared with the. first. There is a property of
bread colour to which attention has already been drawn by Abercromby,
which property renders comparison difficult both to the eye and also the
tintometer. That property is " a silky texture in the bread, which, by
reflecting the light, gives an appearance of better colour. ' ' To this char-
acteristic the authors venture to apply and appropriate the term
"sheen. " The difficulty is that a loaf looks more "sheeny" in one posi-
tion than another ; not only may two observers, the one looking over the
other's shoulder, get a different impression, but the sheen may be af-
fected even by slightly turning or altering the position of the loaf. One
reason why the patent flour breads suffer in colour on the second day is
the loss of brilliance or sheen.

641. Effect of Age on Flours. — The experiments set forth in the
table on page 496 were made in order to determine the effect of age on
American flours. All the tests were made at various times on 14-lb. sam-
ples, stocked meantime in close textured canvas bags. The first tests were
made on the arrival of the flours in this country in October ; the second
series after the lapse of three months, in January ; and the third after the
expiration of another two months, in March. The colour on dry flour,
wet gluten, and water absorption by viscometer were in each case deter-
mined.

With increase of age a slight, but only a slight, amount of bleaching
is observed. In connexion with this, it will be of interest to note the dif-
ference in colour between a sample of flour by which purchase was made
on Mark Lane, and the colour of bulk when delivered some weeks later.
The seller alleged that the difference in colour between bulk sample and
selling sample was due to bleaching of the latter in the interval between
date of purchase and arrival of the flour.

Colour of Sample.

Dry Flour . . . . 0.10 Y. + 0.01 R.
Pekarised Flour . . 1.32 Y. + 0.50 R.

Dough, through glass . . 1.10 Y. 4- 0.60 R.

Bulk.

0.32 Y. 4- 0.90 R.
2.20 Y. + 0.90 R.
1.50 Y. 4- 0.90 R.

Comparing the above results with the
authentic samples, comment is unnecessary.

amount of bleaching on

0.30

0.21

0.27

0.22

0.20

0.07

0.18

0.06

0.07

0.04

0.06

0.03

0.02

0.03

0.02

0.29

0.22

0.27

0.22

0.16

0.06

0.16

0.08

0.07

0.02

0.06

0.04

0.03

0.02

0.01

0.28

0.21

0.26

0.22

0.16

0.06

0.14

0.06

0.07

0.02

0.04

0.03

0.02

0.01

496 THE TECHNOLOGY OF BREAD-MAKING.

The amount of gluten and also water-absorbing power by viscometer
show generally signs of slight diminution.

EFFECT OF AGE ON FLOURS. .

No. 1. Bakers' Flour from Duluth Wheat.

„ 2. Patent „

„ 3. Bakers' „ Manitoban Wheat.

„ 4. Patent

,, 5. Bakers' „ Indiana Winter Wheat.

„ 6. Patent

„ 7. Bakers' „ Ohio Winter Wheat.

„ 8. Patent

Colour.

New

Three months old

Five months old

Wet Gluten.

New 44.0 42.0 44.5 39.0 37.0 28.9 33.7 31.8

Three months old . . 43.7 41.7 37.4 36.2 30.6 29.1 33.3 30.2

Five months old .. 43.2 41.2 35.7 35.0 30.1 28.9 32.7 30.3
Water Absorption.

New 69.5 68.0 66.0 63.5 59.0 53.0 56.0 57.5

Three months old . . 68.5 67.0 67.5 66.0 60.0 55.0 56.0 55.5

Five months old . . 66.0 62.0 66.0 63.0 55.0 51.0 56.0 55.0

642. Baking Tests. — In comparing the relative value of baking tests
with those made by analytic methods, it should be borne in mind that the
latter are obtained by processes in which all disturbing influences are so
far as possible eliminated, whereas in baking tests the quality of the
yeast, temperature of working, etc., are all disturbing elements. As seen
by preceding results quoted, the colour and other characteristics of the
bread are affected by differences in the mode of performing baking tests.
In baking tests, again, the individuality of the baker must largely come
into play, as he will naturally treat the flour in the manner most nearly
comparable with his own general mode of working. As no two bakers
work exactly alike, one set of results may not quite agree with those
obtained by another baker working in a somewhat different manner, and
with not altogether the same objects in view.

643. Baking Tests, Thatcher. — Thatcher has recently summarised
the various methods proposed for the testing of flour, and describes those
tecomm ended and adopted by him in the laboratory of The Washington
Agricultural Experiment Station, U.S.A. The following is a description
of his mode of making baking tests : —

Quantities taken.

Flour . . . . . . . . . . . . 340 grams.

Yeast 10 „

Sugar 12 „

Salt 5 „

Water . . . . . . . . . . . . A Sufficiency.

COMMERCIAL TESTING OF WHEATS AND FLOURS. 497

These were then kneaded in a special machine for twenty minutes, so
arranged as to maintain the dough at a temperature of 90° F. for that
time. The dough was then transferred to a greased tin, and placed in a
proving box or cupboard maint led at 90°. Here it was allowed to rise
until it just touched a tin strip laid across the top of the tin. The tin was
then transferred to an electric oven heated to 400° F., and baked for
forty minutes. The bread was allowed to cool for thirty minutes, after
which the weight and volume were determined. The latter was effected
by measuring in a cylindrical box with seeds. Thatcher concludes that it
is impossible to form final conclusions as to the baking quality of a flour
from the results of a chemical analysis alone. Further, he is of opinion
that no single test which was tried is capable of giving conclusive evi-
dence as to the baking quality of flour. Any such processes as have yet
been suggested must be supplemented by a baking test if final and
accurate conclusions are to be reached. (Jour. Amer. Chem. Soc., 1907,
910.)

644. Baking Tests, Method Employed by the Authors. — The quan-
tity of flour taken for a baking test may vary according to the custom
and requirements in any particular district. Usually, however, it is
desirable to keep the quantity as low as practicable, so that a test may be
made on a small sample : at the same time the loaf should be of a fair
size, so as to compare as well as possible with the bread made for com-
mercial purposes. The authors employ the following quantities, whicli
answer well for general purposes.

Quantities. — Flour .. .. 560 grams = 19. 71 oz.

Water as per Viscometric Absorption, or otherwise

determined.
Salt . . . . . . 6 grams

Compressed Yeast . . 10 grams

The metric system of weights is adopted because of its greater sim-
plicity and the readiness with which exact weights can be determined.
The quantity, 560 grams, is 2 grams for every Ib. of flour in the sack, so
that one half the weight of any constituent or product is without any
further calculations the weight in Ibs. that would be obtained proportion-
ately by treatment of the sack of flour.

The resultant loaf of bread usually weighs from \l/2 Ibs. to 1^4 IDS->
and although less than the weight of a 2-lb. loaf, is yet sufficiently near
to enable a comparison to be instituted.

Bearing in mind that the proportions of water used vary very consid-
erably in different parts of the United Kingdom, the authors, for general
tests, have adopted the plan of making where possible three separate bak-
ir.-gs on each flour, distinguished respectively as a, &, c. For fc, what is
believed to be the best quantity of water is employed. This may be deter-
mined by a water-absorption test, controlled by the viscometer or other-
wise. It will be remembered that that instrument gives results in quarts
per sack; and as a quart weighs 2^ Ibs., the number of quarts X 5 gives
the weight in grams or volume in cubic centimetres of water that must be
taken to the 560 grams of flour. For a, 20 grams (equivalent to 4 quarts)
less water is taken than in "b : while in c, 20 grams more water is added
than used in &. The three tests, therefore, represent quantities of water
with differences of a gallon to the sack between each, and cover all varia-
tions in quantities for ordinary bread-making. Another advantage of
testing in this manner is that it provides for those flours which fall off
very much during fermentation. In other words, some flours will not in
reality take as much water as might be judged from the tightness of the

498 THE TECHNOLOGY OF BREAD-MAKING.

dough when first made. Conversely, other flours fall off less than the
normal in fermentation, and evidently require more water than is indi-
cated by the character of the dough at the moment of preparation.
Where one test only is made, a very frequent comment is — this flour
would have been better with a quart or two quarts more [or less] water.
If a series of tests is made, one of them is likely to closely agree with
the quantity of water best suited to the flour throughout its whole fer-
mentation. If thought preferable the difference between each test may
be taken at some other figure than the gallon.

Mode of Fermentation. — First weigh out the flour, and put it in a
pan of sufficient size (for which purpose an ordinary white pudding-
basin, 8 or 9 inches internal diameter, answers well). Next take the tem-
perature of the flour, and if anything below 70° F., carefully warm it
until that temperature is reached. A convenient method in the testing
laboratory of doing this is to stand the basin containing the flour in hot
water, and stir the flour continually with a spatula until sufficiently
warm. A "ferment" is next made with the whole of the water to be
used. This water may be either measured or weighed ; if the former
course be adopted, the measures should be specially graduated to deliver
grams of water at 100° F. It has been found convenient to have the fer-
ment, when set, at 90° F. ; the initial temperature of the water should be
go adjusted by experiment as to give this temperature at the finish ;
Lsually about 10° is lost in this operation, and therefore the water may
be taken at 100° F. Make a hole in the middle of the flour (bay), and
having the water in a measure, break down the previously weighed yeast
into the water, and pour the whole into the bay. Work carefully a littlo
of the flour into the liquor so as to form a ferment of the consistency of
a thin batter: this ferment, as above stated, should have a temperature
of 90° F. For the fermentation there should, when practicable, be pro-
vided a proving cupboard, so arranged as to just take, on a series of
shelves, a number of these basins, all of which must be labelled and
marked. By some convenient means the temperature of this cupboard
should be maintained at about 85° F. ; this may be done either by the
injection of a jet of steam, or the well-known plan of a small atmospheric
burner at the bottom of the cupboard, with a vessel of water over it. The
temperature of this cupboard should be under control, and must be kept
uniformly at the desired degree.

Cover the basin containing the ferment with a light linen cloth, and
place it in the proving cupboard for one hour ; at the end of that time the
ferment will be "ready," and should have nicely dropped. Add the
finely-powdered salt, and stir in the flour and salt into the ferment with
a bone spatula. Knead thoroughly either by hand, or preferably in one
of Werner and Pfleiderer's small doughing machines, taking care that
no loss occurs during the operation, and that the dough is made perfectly
smooth. Return to the proving cupboard, and after one hour well "knock
down ' ' the dough : place again in the cupboard for half an hour, and then
weigh the dough accurately. The bread may be baked in a tin, or for
most purposes, preferably, as a cottage loaf. Mould, and allow to stand
for a few minutes if necessary. Moulding should, if possible, be done
without dusting flour ; when any is used, a quantity should be weighed,
and that remaining after -the moulding of each loaf again weighed, and
note made of the quantity used. This should not exceed 2 grams per
loaf. Bake in an oven, the temperature and behaviour of which is known,
and, if possible, together with loaves of a familiar flour, so as to be able
to judge the comparative tendency of the flour to take the fire. When

COMMERCIAL TESTING OF WHEATS* AND FLOURS. 499

baked, allow the bread to stand twelve hours — say over night — and then
weigh. Notice whether the bread happens to be burned at the bottom,
and if so make a note, as the weight will thereby be affected.

Note the character of the loaf, compared with a standard or known
cample; whether of good volume, bold 'and well shaped, twisted or flat;
also the colour of the outer crust, and likewise in the partings between
the top and bottom of the cottage.

If wished, the volume of the loaf may be determined by means of a
cylindrical measure sufficiently large to hold it completely. The loaf is
placed in this, and rape seed or other small seed added to fill the measure,
the upper surface of which is then "struck." The quantity of seed used
is then measured, preferably in a vessel graduated in cubic centimeters,
and also the quantity of seed similarly required to fill the measure with-
cut the loaf. The difference gives the volume of the loaf.

Compare the appearance of the three loaves side by side, and decide
which represents the bread from the best size or stiffness of dough. Note
also whether there is a great difference between each, as some flours stand
an excess of water over the normal far better than others.

Next cut the loaf in the direction of greatest outline, and observe the
colour, texture, pile, and sheen of crumb ; also moistness, odour, and
flavour of crumb. (It should be borne in mind that the flavour of a small
baking test is not an absolute criterion of that of bread regularly made in
full-sized batches.) The colour may be measured and registered when
thought desirable by means of the tintometer modified by the addition of
de-focussing lenses.

If wished, a system of giving marks for colour, texture, flavour and
other characteristics may be adopted. In fixing these a maximum and
minimum should be decided on, and then the loaf being tested should
have its intermediate position indicated as accurately as possible by the
number of marks given.

If it is desired to keep a permanent record of its size, the cut loaf
may be placed on a sheet of paper, and marked round with a pencil. This
may be done on a leaf of a note-book, and the other data placed on the
opposite page.

The following are given as an example of how baking tests may be
entered in the note-book, together with deductions made therefrom : —

Description of Flour — High-Class English Patent.

Water absorption by Viscometer — 60 quarts per sack.

(I f) C

Flour in grams 560 560 560

Water „ .. 280 300 320

Yeast „ . . 10 10 10

Salt „ 666

Uiifermented Dough in grams . . . . 856 876 896

Ibs. per sack . . 428 438 448

Fermented Dough in grams . . . . 827 850 860

Ibs. per sack . . . . 413.5 425 430
Fermented Dough calculated into loaves

of 4 Ibs. 6 oz. per sack 94.5 97.1 98.3

Weight of Bread, 12 hours old, in grains . . 707 737 760
Weight of Bread, 12 hours old, in Ibs. per

sack 353.5 368.5 380

Loaves of 4 Ibs. each per sack . . . . 88.4 92.1 95.0

Colour of bread by Tintometer— Yellow . . 1.35 1.35 1.35

Ked 0.70 0.75 0.75

500 THE TECHNOLOGY OF BREAD-MAKING.

In the above results the mode of determining Ibs. per sack is self-
evident : quantities in grams are simply divided by 2. Calculated loaves
per sack from dough are obtained from Ibs. per sack by reducing to
ounces and dividing by 70 (ounces == 4 Ibs. 6 oz.). The readiest way of
performing this calculation is to multiply in grams by 8 and divide by
70, thus :

827

= 94.5 loaves per sack.

The results obtained as yield in bread by calculating at 4 Ibs. 6 oz. on
the dough are more trustworthy than those by direct weighing of the
bread itself, as single sample loaves will vary more in weight from the
normal than does a full batch calculated on the weight of dough.

645. Special Apparatus for Baking Tests. — When baking tests are
being conducted on a large scale, certain special appliances enable results
to be obtained not only with greater speed, but with more exactitude.

For water measuring purposes it is very convenient to employ a large
burette and reservoir similar in character to that figured No. 77 for
making viscometric determinations. The burette should have a capacity
of 400 c.c., and should be provided with a large way tap. The reservoir
should be open at the top, but provided with a cover : a number of tests
having to be made, sufficient water should be in one operation adjusted
to the right temperature, and used for the whole series that are started off
together.

Where it is possible to bake sample loaves with a batch of ordinary
bread, that forms one of the best modes of procedure. It has the great
advantage for crusty bread that a better shaped loaf is produced than
when single loaves, or some two or three only, are baked in a small oven.
For laboratory work, however, a special oven is usually necessary. For
this purpose the authors have for some time used a specially constructed
electrically-heated oven. The top and bottom heats are under separate
control and very satisfactory results are obtained, the bread being well
and evenly baked.

646. Alternative Scheme for Baking Tests. — For the convenience of
those who prefer to work entirely with English weights the following
directions for making a baking test are given : the quantity of flour used,
3 Ibs., produces from 4 Ibs. to 4^ Ibs. of bread. This may be baked
either in tin or cottage loaves.

First determine the water-absorbing capacity of the flour either with
burette alone, or in conjunction with the viscometer. Make a dough
either of full viscometric strength, or as much tighter as may be neces-
sary to suit the requirements of the district. This can readily be done by
deciding once for all on a constant deduction from the water-absorbing
capacity according to the sixty-seconds standard.

With 7 Ibs. of flour, each ounce of water used is equivalent to one
quart per sack. For tests 011 3 Ibs. of flour the water in ounces, equiva-
lent to quarts per sack, is obtained by multiplying by 3/7 ; thus 50 quarts
per sack equal 21.4 ounces per 3 Ibs. of flour. The following table gives

COMMERCIAL TESTING OF WHEATS AND FLOURS. 501

the proportionate quantity of water for 3 Ibs. of flour, from 50 to 81
quarts per sack : —

50 quarts

— 21.4 ounces.

21.8

22.3

22.7

23.1

23.5

24.0

24.4

24.8

25.3

25.7

26.1

26.6.

27.0

27.4

27.8

66 quarts

= 28.3 ounces.

28.7

29.1

29.6

30.0

30.4

30.8

31.3

31.7

32.1

32.6

33.0

33.4

33.8

34.3

34.7

Quantities. — Flour 3 Ibs., water as per table, salt */2 oz., yeast ^4 oz.
Weigh all ingredients as accurately as possible.

First, weigh out the flour, and put it in a pan of sufficient size ; take
out about an ounce of the flour, and put it aside in a small cup. Counter-
poise a jug on the balance, and weigh out the requisite quantity of water,
warmed to a temperature of about 85° F. Weigh the salt and rub it with
the hands into the flour ; add the weighed yeast to the water and mix it
thoroughly, taking care to break down any lumps with the fingers. Make
a hole in the middle of the flour, and pour in the yeast and water ; stir it
sufficiently to work enough of the flour into the water to form a thin
sponge : cover this over by drawing up a little of the flour from the sides.
Let this stand for an hour in a warm place, covered over with flannel.
Then knead the whole into a dough. Clean all fragments of dough from
the hands, and rinse them in a little of the reserved flour ; let the rinsings
go into the dough. Let the dough ferment for from 3 to 4 hours. In the
meantime, grease and weigh a 4-lb baking tin. Dust a perfectly clean
kneading-board with a little of the reserved flour, and turn out the dough
from the basin, cleaning it as thoroughly as possible with the fingers.
Mould the dough into a loaf, using up in so doing the remainder of the
reserved flour. Transfer the loaf to the tin, taking care that as little as
possible is lost. Notice to what extent the dough has become slacker dur-
ing fermentation, also whether elastic or possessing very little tenacity.
Let the dough prove in the tin for about an hour, then weigh. Next
bake for an hour, or an hour and ten minutes, according to the heat of the
oven. Remove the loaf from the tin and allow it to cool ; in an hour
weigh the loaf. Note the colour of the crust, odour of the bread when
warm, etc. Next, with a sharp knife, cut the loaf across its highest part ;
note the colour, texture, flavour, and degree of moisture of the interior.
Keep for a day or two and repeat these observations.

If it is desired to keep a permanent record of the test, a good plan is
to place the cut loaf on a sheet of paper, and mark its size round with a
pencil. A large-sized exercise book, without lines, answers this purpose
very well. The other data may be so arranged as to come inside the
outline of the loaf.

502 THE TECHNOLOGY OF BREAD-MAKING.

Another convenient method of making a baking test is by taking a
definite quantity of water, and adding flour to the same until a dough of
the right consistency is obtained. The dough is then weighed : the weight
of water, yeast, and salt used always being a constant, that of flour is
simply obtained by difference from the weight of the dough. A table is
easily calculated giving equivalent yields per sack from weight of dough
in each case.

General Interpretation of Results. — This it is hoped has been rendered
sufficiently clear by the explanatory remarks on the different constituents
and properties of flour, by which the description of each is accompanied.
It must be remembered that baking tests on small quantities of flour are
only to be viewed as comparative ; because, as in all operations conducted
on a commercial scale, the results obtained in practice fall below those
yielded by direct tests on small amounts of material. Consequently, it
must not be assumed, because 7 Ibs. of flour yield a certain weight of
bread when baked, with every precaution taken against loss, that the sack
of 280 Ibs. will yield 40 times that weight of bread. Still it is well, from
time to time, to gauge the theoretical yield by a small test, as information
is thus obtained as to how closely the practical and theoretical yields
agree with each other. By keeping a closer watch on this point, many
bakers could lessen considerably various sources of loss which now occur,
and are almost unnoticed. In case it is wished to make the baking test a
means of estimating how much the actual working yield of flours is, a
careful comparison must first be made between the results obtained by a
small baking test, and one on a sack of the same flour. Divide the yield
of bread from the sack by that from the quantity used for small test : then
the quotient may be used as a multiplier in order to convert the small
test yield into working yield per sack. Thus, suppose that this quotient
is, in the case of a 7 Ib. test, 39 : then whatever weight of bread is yielded
by a 7 Ib. baking test, that quantity multiplied by 39 gives the approxi-
mate yield per sack. But the figures thus obtained must not be relied on
too absolutely, as disturbing elements occur when working on the large
scale which are avoided when making experimental tests. It is on the
whole safer to view experimental tests as affording information on the
comparative merits of flours, rather than as an indication of absolute
yield by the flours when baked in large quantities.

CHAPTER XXII.

DETERMINATION OF MINERAL AND FATTY MATTERS AND
HEAT OF COMBUSTION OF WHEATS AND FLOURS.

647. Determination of Ash. — To determine ash, weigh a small plati-
num or silica dish, and then add five grams of the flour or meal ; place the
dish on a pipeclay triangle resting on the ring of a retort or tripod stand,
and burn the flour by gently heating with the bunsen. The volatile mat-
ter burns off readily, and leaves behind a cake of ash mixed with carbon ;
the heat must be continued until the carbon has disappeared, leaving only
the ash, which must be white, or of a greyish tint. The heat must not be
raised too high ; the burning off of the carbon may be facilitated by occa-
sionally stirring it with a fine platinum wire. Take care that when this
is done none of the ash is lost by being removed with the wire. When
the burning is complete allow the dish to cool in the desiccator, and weigh.
When wheat. or flour is burned in this manner, the resultant ash is gen-
erally infusible at the temperature employed. The more than usually
ready fusibility of the ash is an indication of the addition to flour of some
readily fusible salt. With a very fusible ash there is a difficulty in burn-
ing the flour or other substance completely, since the fused salts enclose
particles of carbon and protect them from the oxygen of the air. In the
case of such an ash, the carbonaceous mass may be extracted with succes-
sive quantities of hot distilled water. This may be done either in the dish,
or the partly burnt ash may be transferred to a clean mortar and first
reduced to a fine powder and then treated with the water. The solution
is filtered, and the carbon returned to the platinum dish and carefully
dried, after which it is again heated with the bunsen. The carbon will
then usually burn off freely. The filtrate is next evaporated to dryness
in the same dish and heated. A carbon-free ash is thus obtained. It
sometimes happens that an ash encloses just a few particles of carbon
somewhat obstinately. A small quantity of hot water to dissolve soluble
matter should then be added, and the solution distributed by giving a
circular movement to the dish. The contents are evaporated to dryness
and again ignited. This very simple treatment will frequently secure
the elimination of the last traces of carbon.

Instead of heating over a bunsen flame, a muffle may be employed with
advantage in ash determinations. This piece of apparatus consists of
what is really a very small oven- made of fire-clay and contained in a
muffle-furnace. By means of a powerful gas burner the whole muffle is
heated to dull redness, and in a current of air, flour and similar sub-
stances burn readily to a carbon-free ash. If wished, the muffle may be
arranged for heating by means of a specially applied electric current.

648. Ash Estimations, Snyder. — Snyder attaches great importance
to the determinations of ash in flour. He finds that the percentage amount
of ash in different wheat crops varies but little from year to year. The
ash determination is of value in establishing the grade of a flour. The
more completely the bran, shorts, and germ particles are removed, the
smaller is the ash content. There is a definite relationship between the
ash content and the grade of the flour. The ash is more constant in

504 THE TECHNOLOGY OF BREAD-MAKING.

amount and composition than any other class of compounds found in
wheat, consequently the ash content of the different grades of flour is
quite uniform. The patent grades of flour almost invariably contain less
than 0.50 per cent. ash. The range in ash content of the different grades
of spring wheat flour is approximately as follows : —

Per cent. Ash.

First Patent 0.35 to 0.40

Second Patent 0.40 to 0.48

Straight Grade 0.48 to 0.55

First Clear 0.60 to 0.90

Second Clear 0.90 to 1.80

Flour made from fully matured wheat has the minimum ash content,
because high maturity is usually accompanied by a low ash. The ash
determination cannot be used to establish the comparative value of two
samples of flour belonging to the same grade ; for example, if two sam-
ples of flour contain respectively 0.36 and 0.40 per cent, ash, the one with
the lower per cent, is not necessarily the better flour. If, however, two
samples of flour contain respectively 0.42 and 0.55 per cent, ash, the
former is a patent grade and the latter a straight grade flour. In grading
Hungarian flours, the ash determination has been used successfully by
Virodi. When making comparisons, however, too strict an application of
the results is not admissible, particularly when the ash determinations are
made in different laboratories and by different analysts, as the results
then are not always strictly comparable. When the ash determinations
are made under similar conditions, the results are of much value in deter-
mining the grade of a flour. (Bull. No. 85, Agric. Expt. Station, Univ.
of Minnesota, 1904.)

Should the ash of any flour be higher than would be expected from
comparison with that of a flour of corresponding colour of the same char-
acter, the addition of mineral substances may be expected. An analysis
of the ash would then show whether or not its composition was normal
for flour, or whether some foreign ingredient was present.

649. Determination of Phosphoric Acid, P205, and Potash, K20, in
Ash. — When it is desired to estimate both these constituents, take 50
grams of flour, and heat in a platinum dish until the whole of the volatile
matter, and most of the carbon, is burned off, then moisten with concen-
trated hydrochloric acid without removal from the dish. Evaporate to
complete dryness, first over the water-bath and then by gentle ignition
with the bunsen. This operation renders the silica present insoluble ; add
warm dilute nitric acid to the ash, and filter from silica and any un-
burnt carbon : wash the filtrate with the warm acid. The solution thus
obtained contains the phosphoric acid, together with the iron, lime, and
other bases. This solution must now be made up to a definite volume in
a measuring flask, say 250 c.c. ; 100 c.c. may then be taken for the phos-
phoric acid estimation, and a similar quantity for the determination of
potassium.

650. Phosphoric Acid Estimation. — For the purposes of this estima-
tion two special reagents are required, known respectively as "Molybdic
solution" and "Magnesia mixture."

651. Molybdic Solution. — Dissolve 150 grams of ammonium molyb-
date, Am.,MoO4, in a litre of water. Make up a litre of nitric acid of
about 1.20 specific gravity; this may be obtained sufficiently near by
taking 500 c.c. of commercially pure acid of 1.4 sp. gr., and adding
thereto an equal quantity of water. Pour the molybdate solution into the
nitric acid (the mixture must not be reversed). The solution thus ob-
tained must be kept in the dark.

DETERMINATION OF MINERAL AND FATTY MATTERS. 505

652. Magnesia Mixture. — Dissolve 110 grams of magnesium
chloride, MgCl2, and 140 grams of ammonium chloride, AmCl, in 1300 c.c.
of water ; dilute this mixture down to two litres with the strongest liquid
ammonia.

653. Mode of Analysis. — By means of a pipette draw off 100 c.c. of
the solution of ash (made up as before directed), and pour it into an
evaporating basin. Concentrate by evaporation over a water-bath until
the volume is reduced to about 30-40 c.c., transfer to a beaker, carefully
rinsing the basin with distilled water in small quantity. Add to the solu-
tion thus obtained about 100 c.c. of molybdic solution, and allow the mix-
ture to stand for at least three hours at a temperature of about 50° C.
Tbe top of the hot-water oven is a very good place on which to put the
beakers during this time; the solution may, if it happens to be con-
venient, be allowed to stand a longer time — all night, for instance —
without injury. A bright yellow precipitate forms, which contains all the
phosphoric acid, together with molybdic acid; but as the composition of
the precipitate is not constant, it cannot be weighed for the purpose of
determining phosphoric acid. The bases remain in the filtrate. Bring
the precipitate on to a small filter, and there wash with a solution of
ammonium nitrate until the washings no longer redden litmus paper.
Test the first portion of the filtrate by adding a drop of sodium phos-
phate solution to a very small quantity, and warm gently — a yellow pre-
cipitate shows that the molybdate has been added in excess. Should
there be no precipitate, some more molybdic solution must be added to
the main portion of the solution, which must then be allowed to stand as
before in a warm place. Next dissolve the precipitate in the least possi
ble quantity of warm ammonia solution (one part strong ammonia to
three parts of water). This operation is best performed by pouring the
warm ammonia on to the filter. When this has passed through, if any
more of the precipitate remain on the filter, return the filtrate to the filter,
and repeat this operation until the whole of the precipitate is dissolved.
While pouring the filtrate back on the filter, place another beaker in order
to catch any drops of the filtrate. Wash out one of the beakers, and
also the filter, with the warm ammonia solution. This solution contains
the phosphoric acid as ammonium phosphate; to it add about 10 c.c. of
magnesia mixture, and one-third of the total volume of strong ammonia,
set aside in the cold for three hours, or a longer time if wished. Test a
small portion of the filtrate for excess of magnesia mixture by adding a
drop of sodium phosphate solution ; in the event of there being no pre-
cipitate formed, some more magnesia mixture must be added to the solu-
tion in order to completely precipitate the phosphoric acid. Filter and
wash the precipitate with dilute ammonia, dry, and then ignite in a
weighed platinum crucible, and weigh. Before ignition separate the pre-
cipitate as thoroughly as possible from the paper ; burn the latter sepa-
rately, and let the ash drop into the cover of the crucible. The precipi-
tate, after ignition, consists of magnesium pyrophosphate, Mg2P207. The
magnesia mixture precipitates ammonium magnesium phosphate, thus : —

Am3P04 + MgCl2 = MgAmP04 + 2AmCl.

Ammonium Magnesium Magnesium Ammonium

phosphate. chloride. ammonium chloride.

phosphate.

On ignition, the precipitate is decomposed, undergoing the following
change : —

2MgAmP04 = Mg2P2O7 + 2NH3 + H20.

Magnesium Magnesium Ammonia. Water.

ammonium pyrophosphate.

phosphate.

506

THE TECHNOLOGY OF BREAD-MAKING.

The reason for completely detaching the precipitate from the filter
paper is that the carbon of the paper reduces the phosphate to phos-
phide, thus lessening its weight.

Magnesium pyrophosphate, Mg2P2O7, contains anhydrous phosphoric
acid, P2O5, combined with two molecules of magnesia, MgO. The mole-
cular weight of the salt, compared with that of the acid, is
Mg2 P2 02 P2 05

48 + 62 + 112 = 222. 62 + 80 142.

As 222 by weight of the pyrophosphate contain 142 by weight of phos-
phoric acid, the weight of the precipitate, whatever it may be, must be
multiplied by 142/222 — 0.64 ; this gives the phosphoric acid in the quan-
tity taken, and when that quantity has been two-fifths the total solution
from 50 grams, the result, on being multiplied by 5, gives the percentage
of phosphoric acid.

654. Washing and Ignition of Precipitates. — In all quantitative esti-
mations it must be remembered that none of the substances being worked
on must be lost; therefore when transferring a solution or precipitate
from one vessel to another, rinse out all remaining traces of the body.

Thus, with the yellow precipitate pro-
duced by the molybdate, first carefully
pour the supernatant solution down a
glass rod, 'as shown in Fig. 82, without
disturbing the precipitate Then fill the
beaker with the washing solution and
commence filtering. In order to remove
the precipitate from the beaker, a small
brush made of a quill is very useful.
Cut the stem of a quill across near the
bottom of the feather end, so as to leave
the fibres of the feather projecting be-
yond the stump. Next cut off all the
feather except about an inch at the bot-
tom; then with one cut of a sharp scis-
sors or knife cut the remaining feather
part to a width of about a quarter inch.
In this way a little brush is made, which
readily finds its way round the edge of
the bottom of the beaker. For washing
purposes the chemist uses a "wash-
bottle," as shown in Fig. 83.

To make a wash-bottle, fit a good cork (india-
rubber is preferable) to a 20 or 24-ounce flask. Bore
through it two holes, through which pass pieces of
glass tubing bent, as shown in the figure ; the ends of
these tubes must be rounded off; to the left-hand one
is attached, by means of india-rubber tubing, a fine
glass jet. The length of the tubes must be so arranged
that the direction of this jet can be controlled by the
forefinger of the hand holding the wash -bottle. To
obtain a large stream of water, pour it from the
shorter tube; on blowing through the shorter tube a
fine stream of water is projected from the jet on the
end of the other tube.

The precipitate is usually dried by placing it together with the
funnel in the oven. The operation of transferring the precipitate from

FlG. 82. — Precipitate Washing.

FIG. 83.— Wash-
Bottle.

DETERMINATION OF MINERAL AND FATTY MATTERS. 507

the paper to the crucible requires great care. First thoroughly clean, and
ignite, the crucible and cover; allow them to cool in the desiccator,
and weigh. Crucible and cover must always be weighed together.
While the crucible is cooling get ready a sheet of glazed paper; this
should be black for light-coloured precipitates, and yellow for any black
precipitates. Trim this paper with either a sharp pair of scissors or
knife, so as to produce clean cut edges. Also have in readiness a piece of
platinum wire about a foot in length. Clean the bench and spread out
the sheet of paper, place on it the crucible and cover. Take the filter
paper out of the funnel, fold it together at the top, and very gently rub
the sides together so as to detach the precipitate. Hold the paper all
this while over the glazed sheet; next open the filter and pour its loose
contents into the crucible. Having cleaned the paper as thoroughly as
possible, fold it into a strip about three-quarters of an inch wide; then
roll it up into a coil, and wind the platinum wire tightly round it. Hold
the burisen burner at an angle of 45 degrees over the crucible cover, and
burn the paper to an ash in it: the paper will readily leave the wire
when burned.

In order to ignite crucibles, they are suspended in triangles; the
older form consisted of pieces of common clay pipe, threaded on iron
wire, the ends of which were twisted together. Triangles are now very
frequently made of fused silica. A clean triangle is placed on the ring
of the retort stand, and then the crucible placed on it : the crucible is
first gently heated by the bunsen, and then more strongly by the foot
blowpipe. (For most purposes, a mekker burner may be substituted for
the foot-blowpipe). After ignition the crucible is allowed to cool in the
desiccator, and then weighed. The weight of the precipitate is obtained
by deducting from the gross weight that of the crucible and the filter ash.

655. Weight of Filter Ash. — This determination is usually one of the
first made by the chemical student. The best filters hitherto have been
those of Swedish make, but now other houses supply filters almost if not
quite as good. The most convenient sizes for quantitative work are 2%,
3l/2, and 4^ inches diameter. Several packets should be ordered at a
time, and it should be stipulated that they shall be from the same parcel
of paper. To determine the weight of the ash, take twenty filters, fold
and burn them one or two at a time, allowing the ash to drop in a
weighed crucible; ignite until a perfectly white ash remains, and again
weigh. One twentieth of the weight is taken as that of the ash of a single
filter. Provided the various sized filters are of the same paper, the ash
of one size may be calculated from that of another. The areas of circles
are as the squares of their diameters, consequently the ash of a 4-inch
paper would weigh four times as much as that of a 2-inch paper ; other
diameters could be calculated in the same manner. The weight of ash of
filter papers of the better quality is now generally declared on the pack-
age. Such weight is usually so small that it may be neglected in ordi-
nary analyses. ,

656. Potash Estimation. — To a second portion of 100 c.c. of the solu-
tion already prepared, add ammonia and pure ammonium oxalate in
slight excess ; filter off the precipitated iron and lime compounds. Evap-
orate the filtrate to dryness, and ignite gently in order to expel ammo-
nium salts. Dissolve the residue in a small quantity of hot water, filter
if necessary, add hydrochloric acid in slight excess, and evaporate to
dryness. Dissolve the residue in a very small quantity of water, add
some platinum chloride solution and a drop of hydrochloric acid, and
evaporate to a sirupy consistency. If the solution lose its orange tint

508 THE TECHNOLOGY OF BREAD-MAKING.

during evaporation, more of the platinum chloride solution must be
added. Treat the moist residue with strong alcohol, of a strength of at
least 80 per cent., filter off the precipitate on a small counterpoised or
weighed filter ; wash with alcohol until the washings are colourless. Dry
at 100° C, and weigh. The precipitate consists of K2PtCl6 : 487.7 parts
by weight of this body are equivalent to 94 parts of K2O (potassium
oxide). Owing to the great expense of platinum salts, other methods are
now frequently adopted, for particulars of which the student is referred
to standard works on analysis.

657. Counterpoised and Weighed Filters. — When working on pre-
cipitates that are decomposed by a red heat, it becomes necessary to
adopt some method other than ignition in a crucible before weighing. It
is usual under these circumstances to either weigh or counterpoise the
filter beforehand. If the filter is to be weighed, prepare first of all a
test-tube shaped stoppered weighing bottle (these can be procured of the
apparatus dealer). Dry this in the hot-water oven, cool and weigh. Fold
the filter, insert it in the bottle, and dry in the hot-water oven until the
weight is constant. The best plan is to set the filter drying over night ;
the bottle must, of course, be open while in the oven ; in the morning
stopper it, allow it to cool in the desiccator and weigh. Return to the
oven for an hour, and then again weigh; the two weights should agree
within a milligram ; if not, the drying must be continued until they do.
The washed filter and precipitate must first be dried in the oven in the
ordinary manner, then transferred to the weighing bottle, and treated
exactly as was the original filter. The weight of filter and precipitate,
less that of the filter, gives the weight of precipitate. Where the greatest
possible accuracy is required this method is to be preferred.

But when speed is an object, a counterpoised filter may be used. Take
two Swedish filters, and trim one of the pair until they exactly counter-
poise each other when tested on the analytic balance. In this case they
are simply to be weighed direct on the pans. Place the one of the papers,
folded but unopened, on one side of the funnel, and then put in the other,
opened in the usual way. Filter and wash, then dry both filters, and
when weighing, again use the empty paper as a counterpoise, placing it
on the weight side of the balance. In this method of working, the assump-
tion is that the two papers being of the same weight to start with, and
taken from the same lot of filters, will contain the same weight of mois-
ture. Further, that as they are subjected to the same treatment, they
will also counterpoise each other at the final weighing. The use of
counterpoised filters effects a great saving of time, and yields results of
sufficient accuracy for most technical purposes.

658. Determination of Fat. — The fat of meal and flour is estimated
by treatment with either ether or rectified light petroleum spirit. Either
of these reagents, especially if warm, dissolves fat, together with any
traces of resinous matter, with readiness, while none of the other con-
stituents of wheat is soluble, in these compounds. In order to offect the
estimation, a weighed quantity of the sample is first dried in the hot-
water oven, and then treated with repeated quantities of ether or petro-
leum spirit until a small quantity of the reagent leaves no greasy stain on
being evaporated on a piece of white filter paper. If ether be used, that
known as "methylated" may be employed. Rectified light petroleum
spirit, distilling entirely below 80° C., and leaving no weighable residue,
can be purchased from dealers in chemicals for analysis. Both ether and
petroleum spirit are extremely volatile and inflammable ; both give off at
ordinary temperatures an inflammable and explosive vapour. The great-
est care must therefore be observed in working with these substances.

DETERMINATION OF MINERAL AND FATTY MATTERS. 509

-659. Soxhlett's Extraction Apparatus.— As ether and petroleum
spirit are so volatile and inflammable, special forms of fat extraction
apparatus have been devised for this estimation. Their object is to keep
the liquids out of contact with the air of the room, and also to make a
small quantity of the reagent suffice by repeatedly doing duty. Among
the most effective of these apparatus is that devised by Soxhlett, and
illustrated in Fig. 84, in which the complete apparatus is shown in
section.

Directions will first be given for the fitting up of the apparatus, and
then its use and the principles involved therein will be described. The
apparatus proper, known familiarly as a "Soxhlett," is that portion a c;
this is to be procured from the apparatus
dealer. Fit the lower end by means of a
well-fitting cork into a good Bohemian flask,
n, preferably one with a rounded bottom,
and about four or six ounces capacity. To
the top of the Soxhlett, a, fit another cork,
and through it bore a hole for the tube of a
Liebig's condenser, j k. The body of this
condenser should be from 18 inches to 2
feet in length ; the inner tube must have an
internal diameter of half an inch, and must
not be constricted at the end— these direc-
tions are of considerable importance. Fit a
cork and bent leading tube to k. Fit up a
four ounce flask, m, with a cork through
which passes a leading tube and two-bulbed
thistle funnel, I. Pour sufficient mercury in
this funnel to just fill the space between the
two bulbs. Instead of this flask and funnel,
m I, a small U-tube, about ^ inch diameter,
and with limbs 5 inches long, may be em-
ployed. By means of a piece of glass tub-
ing bent to shape, this U-tube may be
corked direct to the top of the condenser, k,
and then sufficient mercury added to just
cover the bend. The whole apparatus is
then self-contained, which is a decided advantage. With a condenser of
ample length this mercury arrangement may be entirely dispensed with,
and the top of the condenser tube simply covered with a test-tube or
small beaker. The more modern spiral worm condenser may with advan-
tage be substituted for the older straight tube Liebig. A small water
bath, o, is also required,

Dry 10 or 20 grams of the meal or flour for one or two hours in the
hot-water oven, taking as much as can conveniently be placed in the ap-
paratus. Take a square piece of Swedish filter paper, big enough to fold
up into a little cylindrical case, i ~b. Fold this so that no liquid can es-
cape through the case except through the pores of the paper, even when
full. This specially folded filter is easily prepared by taking the end of a
ruler, or other flat-ended cylinder, placing the end in the middle of the
paper, then doubling it across the diagonals, and folding the corners
round the ruler. Transfer the meal to the filter, and drop this into the
Soxhlett.

For flours, instead of this folded filter, it is convenient to use a small
glass percolator : this is easily made by taking a piece of glass tubing of

FlG. 84. — Soxhlett's Extraction
Apparatus.

510 THE TECHNOLOGY OF BREAD-MAKING.

such a size as to drop easily into the Soxhlett, and cutting it to about the
same length as the case, i b. A piece of filter paper is then tied securely
to the lower end. Ether percolates through flours with extreme slowness ;
and consequently, when a paper case is used, much of the ether simply
finds its way through the sides of the case, without penetrating the in-
terior of the mass of flour. Attach the Soxhlett to the flask, n, and place
it on the bath. Next see that all lights are extinguished within 10 or 12
feet of the apparatus. Bring the ether or petroleum spirit from an outer
store-room, and pour it in the Soxhlett through a funnel until the level
of the liquid rises to g ; it will then syphon over into the flask n. Next
pour in about an ounce more of the liquid, and at once, before doing any-
thing else, carry the ether or spirit back to the store-room. Next attach
the condenser, j k, and push in the corks as tightly as possible. Support
the apparatus by means of a retort stand, p q r, and ring. If using the
flask, m, place it on a shelf conveniently near and connect the leading
tube at k to that of the flask by means of a piece of india-rubber tubing.
Connect the lower end of the condenser to a water tap by means of india-
rubber tubing, and arrange another piece to the upper end to take the
waste water to the drain. Bring a water supply to the bath, and also fix
an india-rubber tube leading to the drain. Arrange a bunsen under-
neath the bath. Before going further, once more examine each cork and
joint, to see that all are air-tight. Turn on a stream of water through
the condenser. Next light the bunsen, and keep it going with a gentle
flame. The ether will soon boil ; when it does so, arrange the flame so as
to keep it boiling steadily, but not too violently. The ether vapour as-
cends through d e, and drives the air before it up through the condenser,
and out of the flask, m, through the mercury in the funnel, I. As soon as
the ether vapour reaches the condenser, it is condensed and runs back in
a small stream, dropping into the filter, i &. The complete condensation
is furthered by the use of the mercury funnel, which offers a slight re-
sistance, and thus prevents the escape of ether while still allowing a pas-
sage for air. As the condensed ether drops, the body of the Soxhlett fills
up to the level of g ; the ether then returns to the flask by means of the
syphon, / g h. It carries back with it the fat it has dissolved out of the
meal ; as the ether continues boiling in n, pure ether is continuously dis-
tilled over the fat remaining in the flask. By this treatment one quantity
of ether can be made to act on the same meal an indefinite number of
times. If all the joints are in good condition, no odour of ether will be
observed during the whole of the time the apparatus is in work. The
apparatus may be allowed to remain in action for an hour or more. Turn
out the bunsen underneath the bath, and also all other lights in the vicin-
ity. Take the apparatus to pieces, cork up the lower flask ; test a drop of
the ether remaining in the Soxhlett, in order to see if it contains any fat
by allowing it to fall on a piece of white filter paper, when it should pro-
duce no stain.

The ether solution requires next to be evaporated to dryness and the
fat weighed.

660. Treatment of Ethereal Solution. — Having obtained an ethereal
or petroleum spirit solution, containing all the fat in the sample being
analysed, filter if not perfectly clear. It will be next necessary to drive
off the solvent, and thus procure the fat in a suitable state for weighing.
Take, for the purpose of evaporation, one of the counterpoised glass
dishes, and tare it in the balance, making a note of its weight against the
counterpoise. It must here again be mentioned that ether vapour is not

DETERMINATION OF MINERAL AND FATTY MATTERS. 511

only inflammable, but also highly explosive when mixed with air. In de-
fault of special apparatus for the purpose, heat the water-bath to boiling,
and then take it into a room in which there are 110 lights. Partly fill the
dish with the ether solution, place it in the bath, and allow it to evapo-
rate spontaneously, refill from time to time from the flask, and finally
rinse the flask with a little pure ether, pouring the rinsings into the dish.
If necessary, heat some more water and replace that in the bath as it be-
comes cool. When most of the solvent, whether ether or petroleum spirit,
has been thus driven off, place the dish in the oven, heat for two or three
hours, and then weigh until constant. Well ventilate the room before
any lights are brought in. By this method the whole of the ether used is
lost ; but if wished the greater part may be recovered by connecting the
flask by means of a cork and leading tube to a condenser and distilling off
most of the ether, after which the concentrated fatty solution may be
poured from the flask into. the dish, and then the flask rinsed out with
successive very small quantities of ether. Some operators prefer to use
instead of the flask n, a small conical flask, which is itself weighed. The
whole of the ether is then distilled off, and the residue dried off to con-
stant weight in the flask itself.

CHAPTER XXIII.
SOLUBLE EXTRACT, ACIDITY, AND PROTEINS.

661. Soluble Extract. — The proportion of a meal or flour soluble in
cold water is of importance in judging of the character of a sample. This
soluble portion is termed the "soluble extract," or "cold aqueous ex-
tract," and consists of the soluble proteins, sugars (maltose and sucrose),
gum (dextrin), soluble starch, and soluble inorganic constituents of the
grain, principally potassium phosphate. The solution made for the purpose
of this estimation is also available for the determination of the acidity and
soluble proteins. On the addition of even cold water to a flour or meal,
chemical action immediately commences, the soluble starch being dis-
solved out of any abraded or ruptured starch granules, and acted on by
any diastase present. As a consequence, the soluble extract varies with
the time the solution is allowed to stand in contact with the flour or meal ;
absolute uniformity must therefore be adopted in the method employed
for making this soluble extract. The following is a convenient standard
method : — Weight out 25 grams of the flour, and transfer to a clean dry
flask of from 500-700 c.c. capacity, add 250 c.c. of cold distilled water,
cork the flask with a clean cork, and shake up vigorously for five minutes
by the clock. One or two minutes' shaking is sufficient to break up any
little balls of flour, but in order to ensure perfect solution the longer time
is recommended. Next, let the flask stand for 25 minutes, making half-
an-hour from the time of commencement. In the meantime arrange a
10-inch coarse filter paper, in a funnel 5 inches in diameter, both being
quite dry, and place a clean dry beaker or flask to receive the filtrate.
At the end of the half-hour most of the insoluble portion of the flour will
have subsided ; remove the cork and carefully decant as much as possible
of the supernatant liquid on to the filter without disturbing the sediment.
The filtrate will at first be cloudy ; return it to the filter until quite clear,
then collect for analysis. By working in this way, there being practically
none of the solid matter of the flour on the filter, any subsequent changes
in the wet flour do not affect the results. As the speed of filtering varies
with different filter papers, it was often found, when both flour and
water were placed on the filter together, that a higher extract was yielded
by the same flour, simply as a result of a slower filtering paper ; there is
a further disadvantage in that, when any of the solid matter of the flour
was allowed to get on the filter, it greatly impeded the rapidity of filter-
ing. Twenty-five c.c. of this clear filtrate must next be evaporated to dry-
ness in order to ascertain the amount of matter it holds in solution. The
glass dishes that were used for the moistures are also well adapted for
this purpose. Having tared a clean dish against its counterpoise, and
noted any difference in weight, pour 25 c.c. of the filtrate into the dish,
and evaporate to dryness over the water-bath.

For all practical purposes, any soluble extract obtained by the above
process may be regarded as pre-existing in the soluble state in the flour,
as in baking operations there can be no difference between matter already
soluble and matter rendered soluble by other agents present in the flour
during the period elapsing before filtration.

512

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 513

In case it is required to differentiate between the soluble and readily
rendered soluble matters of flour, the diastase of the flour may first be
destroyed by boiling the flour with 95 per cent, alcohol. The moisture in
the flour must first be determined, as it has to be allowed for in arrang-
ing the strength of the alcohol employed. The operation may be carried
out in the following manner : — Weigh out 25 grams of the flour, contain-
ing say 12 per cent, of moisture ; 25 grams must obviously contain 3
grams of water. As 5 c.c. of water will reduce 95 c.c. of absolute alcohol
to 95 per cent, strength, then the water present in 25 grams of flour will
reduce a proportionate quantity,

As 5 : 3 : : 95 : 57 c.c. absolute alcohol.

In a clean dry flask add 57 c.c. of absolute alcohol to the flour, or
other quantity as calculated from the moisture. This alcohol will then
be of 95 per cent, strength. Next add a further 100 c.c. of previously
prepared 95 per cent, alcohol, and boil for an hour, after fitting to the
flask a return condenser so as to restore the alcohol. Next filter and air-
dry the flour, then transfer to a flask and determine soluble extract as
previously directed.

662. Water-Bath. — This consists of a vessel, usually of copper, about
4 inches deep, and of other dimensions varying with the number of
dishes for which it is made. In case of a bath specially prepared for flour
extracts and similar work, one to hold 12 dishes is a convenient size ; its
actual dimensions would then be 12 in. X 15 in. X 4 in. The top con-
tains a series of holes about 2^ ins. diameter, one for each dish; to each
of these is fitted a cover. A water supply apparatus, similar to that used
with the hot-water oven, is attached to the side of. the bath. It is very
convenient to have a series of flanged glass rings to drop into these holes,
on which the dishes are placed ; they are thus prevented from coming in
actual contact with the metal. These rings are similar in shape to the
top of a beaker, and are about an inch deep ; in fact, the tops of broken
beakers are often cut off and utilised for this purpose. They must be of
such a diameter that they just fit in the holes of the bath, being sup-
ported by their flanges. The reason for their use is that the outsides of
the dishes are liable to pick up foreign matter from the metal of the bath,
and so have their weight increased. When the dishes are allowed to
eome in contact with the metal of the bath, they must be carefully wiped
clean before being dried. In use, the hot-water bath should have its feed
apparatus so regulated as to mairtain the water in the bath at a depth of
about half an inch ; the water must be kept boiling at a moderate rate
by means of a bunsen burner. The evaporation of the fluid in the dishes
then proceeds by the action of the steam.

663. Soluble Extract, continued. — On the contents of the dish hav-
ing evaporated to dryness, place it in the hot-water oven for 24 hours,
and then weigh. In order to calculate the percentage of soluble extract,
it must be remembered that by adding 250 c.c. of water to 25 grams of
flour a 10 per cent, filtered solution has been prepared. It follows that
25 c.c. of the solution contains the soluble extract of 2.5 grams of flour ;
the weight must therefore be multiplied by 40 in order to give the per-
centage. It ought to be mentioned that in strictness this is not quite cor-
rect, as no allowance is made for the moisture of the flour, so that, as 25
grams of flour contain about 3 grams of water, we really have more
nearly 253 c.c. than 250 of water present. As, however, the results are
only used for comparative purposes, this is not of practical importance.
If wished, the soluble extract may be calculated out to the exact quantity,
when the percentage of moisture has been ascertained.

514 THE TECHNOLOGY OF BREAD-MAKING.

664. Acidimetry and Alkalimetry. — The measurement of the
amount of either free acid or free alkali in a solution is often an opera-
tion of considerable chemical importance. Thus, in flours or meals, the
acidity is occasionally determined ; the measure of acidity being often a
useful help in deciding whether or not a sample of flour or wheat is un-
sound. Flours which contain bran or germ develop acidity much more
rapidly than those thoroughly purified from the offal. This developed
acidity is caused usually by the presence of lactic acid, and is produced,
as has been previously stated, by the action of the lactic ferment. This
organism is always found in greater or less numbers on the bran and
germ of the grain, and acts by converting the sugar into lactic acid.
This action is much favoured by damp and warmth.

665. Normal Solutions: Sodium Carbonate. — The progess of acid-
imetry (acid measuring) belongs to the department of volumetric an-
alysis, and hence it becomes necessary to explain some of the terms used
in that branch of analytic work. There is required a set of standard
acids and alkalies ; that is, solutions of known and definite strengths, and
an indicator. The standard solutions are usually made up to normal
strength. It is requisite that the exact meaning of this term normal
should be understood. Normal solutions are prepared so that one litre at
16° C. shall contain the hydrogen equivalent of the active reagent,
weighed in grams. It follows that normal solutions of acids and alkalies
are all of the same strength, and that equal quantities exactly neutralise
each other. Decinormal solutions are prepared by diluting normal solu-
tions to one-tenth their original strength, and are shortly designated at
N/10 solutions. The acid and alkali most commonly used are sulphuric
acid, H2S04, and sodium hydroxide (caustic soda), NaHO. Both these
substances are extremely deliquescent, and so cannot be easily weighed
with accuracy. It is customary, therefore, first to make up as a starting
point a normal solution of sodium carbonate, Na2CO3. Directions follow
for starting from this point and making up the necessary solutions.

Normal sodium carbonate contains 53 grams of the dry salt to the
litre ; as this solution is seldom employed for any other purpose than that
of preparing other solutions, a quarter of a litre only need be made. Take
about 18 to 20 grams of the pure dry salt, heat to dull redness in a plat-
inum dish or crucible for about 15 minutes, allow to cool under the desic-
cator, and then weigh out exactly 13.25 grams. Transfer this weight to a
250 c.c. flask, and two-thirds fill with water, shake up until the whole of
the salt is dissolved, and then fill up the flask to the graduation mark.
Keep the solution in a clean dry stoppered bottle.

666. Indicators. — The next step is, with the aid of this solution, to
make up a solution of normal sulphuric acid. From a study of elementary
chemistry, the student already knows that it is usual to determine
whether or not a substance is acid or alkaline by observing its action on
litmus. Acids turn a solution of that body red, the blue colour being
restored by excess of alkali ; when the solution is neutral its colour is
violet. Bodies such as litmus, which are used in order to determine the
completion of any particular action, are termed " indicators. ' '

Litmus. — To prepare the litmus solution, take some litmus grains and
boil with distilled water ; let the liquid stand for some hours, and decant
off the clear supernatant solution. Let this solution again boil, and add
nitric acid, drop by drop, until it assumes a reddish-violet colour; boil
for a time, and the colour once more becomes blue. Continue this treat-
ment with nitric acid until a violet tint is obtained that remains perma-
nent after boiling. The reason for this boiling is that the litmus contains

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 515

some earthy and alkaline carbonates; the carbon dioxide liberated, on
addition of an acid, gives the litmus a reddish tint, and so requires to be
expelled by boiling. The litmus solution should be kept in an open bottle
supplied with a small dropping pipette, by which a small quantity can be
removed when wanted. If this litmus solution be kept in a closed bottle
it is apt to become colourless ; the colour may be restored by pouring the
solution in an evaporating dish, and thus exposing it for a short time to
the action of the atmosphere.

Phenolphthalein. — Another indicator, much more delicate than lit-
mus, is phenolphthalein ; this body, however, possesses the disadvantage
of being unsuitable in the presence of carbon dioxide or ammonia. Phe-
nolphthalein is a white or brownish powder, of which one part is dis-
solved in 30 parts of 90 per cent, alcohol, and one or two drops of the
solution employed for each estimation. The addition of phenolphthalein
to an acid solution produces no colour, but with the slightest excess of
alkali an intense magenta red is produced.

Methyl Orange. — Under this name is prepared another body, also
most useful as an indicator. It is a yellowish brown powder, one part of
which may be dissolved in 30 parts of 90 per cent, alcohol, and two or
three drops employed for each estimation. In alkaline solutions methyl
orange has a yellow tint, which changes to pink or red with the slightest
excess of acid. Methyl orange is absolutely unaffected by carbonic acid,
and also by organic acids. On the other hand, it is sensitive to the action
of ammonia, and is well adapted for titrating that body. A curious re-
sult of the action of these last two indicators is that water from chalk or
limestone formations containing calcium carbonate in solution reacts
alkaline to methyl orange and acid to phenolphthalein. The dissolved
carbonate affects the methyl orange, which is insensible to the carbonic
acid, while the phenolphthalein is caused to give an acid reaction by the
excess of carbonic acid present.

667. Normal Sulphuric Acid. — Of normal and decinormal acids and
alkalies, two litres of each is a convenient quantity to prepare ; these sol-
utions are best kept in stoppered Winchester quarts, which hold just over
the two litres. Normal sulphuric acid contains 49 grams of H2S04 to the
litre. Take about 65 to 70 c.c. of pure sulphuric acid of 1.840 specific
gravity (i.e., strongest acid of commerce), mix this with four or five
times its volume of water, allow to cool, and then make up to exactly two
litres with distilled water. With acid of full strength the solution will now
be too strong ; it must next be tested against the normal sodium carbonate.
Fill a 50 c.c. burette with the acid solution ; with a pipette pour 20 c.c.
of the normal sodium carbonate into a porcelain evaporating basin, and
add two or three drops of methyl orange. Note the height of the acid in
the burette and proceed to add it cautiously, little by little, to the car-
bonate in the dish. Wait between each addition until the effervescence is
over. Continue adding the acid until the neutral tint between yellow and
pink is reached. Read the height of the acid in the burette, deduct the
first reading ; the difference is the amount of acid required to neutralise
the 20 c.c. of normal sodium carbonate. Let us suppose that this amount
is 18.65 c.c., then as with normal solutions equal quantities should exactly
neutralise each other, it is evident that the 18.65 c.c. require to be made
up with distilled water to 20 c.c. ; that is, 20 — 18.65 — 1.35 c.c. of water
must be added. Measure the total quantity of acid solution there is, and
add water to it in the above proportion. Suppose that there remain 1950
c.c., then as 18.65 : 1950 : : 1.35 : to the quantity of water that must be

516 THE TECHNOLOGY OF BREAD-MAKING.

added. Add the proper amount of water to the solution, shake up thor-
oughly, and once more test by filling the burette and titrating against 20
c.c. of the normal sodium carbonate, exactly as before described : 20 c.c.
of the one solution should exactly neutralise 20 c.c. of the other. It
should be explained that the term titrating is applied to the operation of
testing a solution by adding to it a volumetric reagent.

668. Normal Sodium Hydroxide. — The next step is to prepare a
solution of normal sodium hydroxide ; this solution contains 40 grams of
pure NaHO to the litre. Weigh out about 120 grams of pure caustic soda
of commerce, and dissolve up in a beaker in the smallest possible quan-
tity of hot water. Allow the solution to stand for some time, in order
that any sediment present may subside; cover the beaker during this
time with a glass plate. By means of a pipette, draw off as much as pos-
sible of the clear solution, and dilute it down to two litres. Run in this
solution from a burette into 20 c.c. of the normal sulphuric acid using
phenolphthalein as an indicator. With the quantity directed the solu-
tion will be too strong. Calculate the amount of water that must be
added to bring the solution to its normal strength, and proceed exactly
as was directed with the normal acid. After dilution, again titrate acid
against alkali, when 20 c.c. of the one must exactly neutralise 20 c.c. of
the other.

669. Decinormal and Centinormal Solutions. — Having succeeded in
preparing with accuracy the normal sulphuric acid and sodium hydrox-
ide, decinormal solutions of these reagents must be made. Measure out
by means of a 100 c.c. pipette, 200 c.c. of the normal acid, and pour it
into the litre flask; fill up to the graduation mark with distilled water,
and pour into a clean dry * ' Winchester quart, ' ' next add another litre of
distilled water, and two litres of decinormal acid are prepared. In the
same manner make up two litres of decinormal soda. Titrate 20 c.c. of
one of these against the other ; these, too, should become exactly neutral
when mixed in equal quantities.

Centinormal solutions are occasionally required for certain purposes
of analysis. They may be readily prepared by taking 100 c.c. of deci-
normal solutions, and diluting down to a litre with distilled water free
from carbon dioxide.

670. Water Free from Carbon Dioxide. — In addition to the reagents
already described, it is necessary to have, for determinations of acidity
in flours or meals, some distilled water free from carbon dioxide. This is
readily obtained by first rendering some water alkaline with caustic soda,
and then distilling; the first portion of the distillate should be rejected.
The caustic soda combines with the carbon dioxide that may be dissolved
in the water ; and so by this treatment the gas is prevented from coming
over with the condensed steam. The water should be tested in order to
see that no soda has been carried over mechanically by too violent boil-
ing. The water must give no colouration on the addition of two or three
drops of phenolphthalein to 100 c.c., but should strike a distinct and
permanent pink on the addition of a drop of N/W soda.

For many purposes it is sufficient to boil ordinary distilled water for
some ten or fifteen minutes before use, by which most of the carbon diox-
ide is expelled.

671. Acidity of Meals or Flours. — When it is desired to make this
estimation, the aqueous infusion should be made with the water free from
carbon dioxide. Pour 100 c.c. of aqueous infusion into a white porcelain

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 517

dish, add two or three drops of phenolphthalein solution, and proceed to
titrate with N/W soda. The burette must be read before the soda is run
out, and then again at the completion of the reaction. After the addition
of each drop of soda, stir the liquid thoroughly ; the reaction is complete
when the slightest pink shade remains permanent after stirring. It need
scarcely be said that the dishes and other apparatus must be perfectly
clean ; the burette should first be rinsed with clean water, and then with a
few c.c. of the soda solution ; this should be allowed to run away, and
then the instrument should be filled. Soda solutions tend to cause glass
stopcocks to set fast ; the burette must therefore be washed after use, and
before being put away the stopcock should be withdrawn and wrapped
round with a small piece of paper, and again put in its place; this pre-
vents its sticking. It must of course be seen that it is not so placed as to
drop out by an accident and get broken. For soda solutions it is prefer-
able, however, to use a burette with an india-rubber tube and spring clip.
Assuming that the acidity of meal or flour is due to lactic acid (see re-
marks on page 331 as to causes of acidity and sourness in flour and
bread), then as 1 c.c. of N/W NaHO is neutralised by 0.009 gram of
lactic acid, the No. of c.c. used X 0-009 gives the weight of lactic acid in
100 c.c. of the infusion. This quantity of infusion contains the acid of
10 grams of the meal or flour, therefore No. of c.c. of N/W soda X^.009
X 10 = percentage of acid in the sample — in other words, with the quan-
tities directed the percentage equals 0.09 times the No. of c.c. of N/W
soda used.

Balland, who has devoted much attention to the acidity of flours, finds
that, on exhausting a good flour with alcohol and titrating the solution
with turmeric paper as an indicator, the normal acidity represented as
sulphuric acid varies between 0.015 and 0.040 per cent. But working
with the whole flour a higher percentage of acidity is obtained. Planchon
took 5 grams of the flour and gradually mixed same with 50 c.c. of cold
distilled water, and added, when perfectly homogeneous, two or three
drops of alcoholic phenolphthalein solution and titrated with N/2Q solu-
tion of sodium hydrate. He used 0.0245 as a factor, and multiplying the
number of c.c. of soda by that figure, got what was in his opinion the ac-
tual acidity of the flour. He finds that this does not increase during the
time necessary for the estimation ; but on the contrary, that no variation
occurs during the first two hours. Taking the same flour, and maintain-
ing it in contact with water for varying times, he got the results which
are appended. A corresponding series of tests was made with the filtered
aqueous extract of such flours : the results obtained are given in the fol-
lowing table as soluble acidity.

Percentage of acidity reckoned as H2SO4.
Total. Soluble.

Titrated immediately 0.110 0.0107

after 1 hour 0.110 0.0225

" 2 hours 0.110 0.0230

" 4 " . . .. .. 0.113 0.0250

" 7 " 0.115 0.0275

11 24 " 0.126 0.0425

11 48 " .. .... 0.145 0.0830

The same flour, when extracted with alcohol (rectified spirit) for 24
'hours, showed after filtration the presence of 0.03 per cent, of acid-
ity soluble therein. Flour does not give up the whole of its acidity imme-
diately to either water or alcohol. Planchon, therefore, recommends in-
stead the titration of the whole flour in the presence of water, and gives

518 THE TECHNOLOGY OF BREAD-MAKING.

the following as the results of such tests, still reckoning total acidity as
sulphuric acid : —

Acidity per cent.

Nine Roller Milled samples of fresh flour . . from 0.105 to 0.122

Stone Milled sample of fresh flour . . . . . . 0.119

Second sample of do. . . . . . . . . 0.133

Damaged flour unfit for use . . . . . . . , 0.160

Second sample of do. . . . . . . . . 01565

The authors may state that they have for some time independently
adopted the method of titration of the whole substance for both flour and
bread testing, and confirm the conclusions arrived at by Planchon.

The mode of titration of the mixed flour and water is performed in
just the same way as wi-th the filtered aqueous extract.

672. Estimation of Proteins. — For technical purposes, proteins are
now determined by what is known, after the name of the inventor, as
Kjeldahl's process, (or some modification thereof). This method depends
on the fact that, when an organic substance is heated with a mixture of
concentrated sulphuric acid and potassium sulphate, its nitrogen, if any,
is (with very few exceptions) converted into ammonia, and retained by
the acid as ammonium sulphate. The residuum is subsequently rendered
alkaline by excess of soda, and distilled. The ammonia comes over and
is collected in a known volume of decinormal acid, which is titrated, and
then the amount of ammonia determined. From this the percentage of
protein matter is readily calculated. A detailed description follows of
the mode of performing an organic nitrogen estimation by Kjeldahl's
method.

Reagents and solutions required. — Pure concentrated sulphuric acid,
as free as possible from nitrogen compounds.

Concentrated solution of caustic soda. Take 3 Ibs. of commercial
sodium hydrcxide, either in powder or sticks, and dissolve in as small a
quantity of water as possible ; let the solution cool, and make up to suffi-
cient to fill a Winchester quart (about two Imperial quarts). Store in a
Winchester fitted with india-rubber stopper.

Powdered potassium sulphate. Heat this for some time in an iron
vessel, and stoie in a stoppered bottle.

Decinormal sulphuric acid and sodium hydroxide.

Methyl orange solution.

Apparatus. — Special long-necked heating flasks of Jena toughened
glass, of 300 or 500 c.c. capacity. Wrought-iron stand to hold four of
these flasks for heating purposes. This stand should consist of a stout
sheet iron plate, 15 inches long by 4y2 inches wide, supported on four legs
for ordinary bunsen burners, and with four holes, each 2 inches diameter,
through the plate. On the one long edge of the plate an upright back
should be fixed about 4 inches high, and with round notches cut out so
that when the flasks are resting in the holes in the plate, the necks may
lie in the notches in the back. The flasks are thus supported when in use
in an oblique position.

Distilling Apparatus. — If 500 c.c. flasks are used, these may be em-
ployed direct for the distillation. If not, a 500 c.c. flask of the same kind
should be used for this operation. To this flask, a, in Fig. 85, fit a rubber
cork and splash-head, b. This latter is attached in turn to a condenser, c,
fitted with a condensing tube of pure tin. The lower end of the con-
denser, d, is passed through a rubber cork, and thus fixed to the Kjeldahl
bulbs, e f.

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 519

FlG. 85. — Kjeldahl Distilling Apparatus.

Mode of Analysis. — To estimate total proteins on flours or meals,
weigh off 1 gram of the sample and transfer it to a clean, dry heating
flask. The weighing is best done with a pair of counterpoised horn dishes
for the balance. Obtain a wide-mouthed glass funnel that will just fit
the flask, and pour into it the flour or meal, carefully brushing every
particle in by means of a brush kept for the purpose. Or if preferred,
make a V-shaped gutter out of glazed paper that will pass right into the
neck of the flask and down into the bulb, and introduce the substance by
means of this. In any case all particles must be brushed right down into
the flask. By means of a pipette add 20 c.c. of the concentrated sulphuric
acid and about 10 grams of the potassium sulphate. This latter may be
conveniently measured, using for that purpose the end of a test tube, or
what answers very well, a sewing thimble of the right size. (This may
be obtained once for all by weighing out the quantity.) Rinse the acid
gently round inside the flask, so as to thoroughly wet it, taking care that
there are no dry patches of flour between the acid and the flask. Occa-
sionally one gets a small patch which obstinately refuses to mix with the
acid, which must then be provided for in the heating. Arrange the flask
stand in a stink cupboard designed so as to carry off the fumes produced,
and stand the flask obliquely in one of the holes, with its neck lying in the
notch. Should there be any adherent dry patches of flour, turn the flask

520 THE TECHNOLOGY OF BREAD-MAKING.

so that they are out of the liquid and on the upper side of the flask. Turn
on a very small bunsen flame ; as the acid gets hot it carbonises the flour,
which froths up and gradually subsides into a tarry looking liquid. The
steam of the boiling acid attacks any flour patches on the upper part of
the flask, and speedily brings them down into the solution. Continue to
apply heat so that the acid is just below the point of ebullition, a bubble
of steam escaping only occasionally : the black liquid gradually loses its
colour, and in about 45 minutes has usually become colourless. As soon
as this stage is reached it is allowed to cool.

When perfectly cold the next step is to arrange for the distillation :
this, however, must be preceded by a blank experiment, made in order to
determine the amount of ammonia present as impurity in the reagents
used. Add 20 c.c. of the concentrated sulphuric acid to the contents of
the 10 gram measure of potassium sulphate in a round-bottomed flask
precisely as before: heat so as to melt the sulphate, and allow to cool
Measure off 200 c.c. of water in a graduated jar, and pour it into the flask
containing the acid and sulphate — the liquid becomes very hot, but does
not spurt if sufficient water is added. Next add a drop of methyl orange,
and give the flask a shake round so as to mix the contents. Then by
means of a funnel pour some of the strong soda solution from a 100 c.c.
graduated measure into the flask until the acid is neutralised, and add an
extra 5 c.c. Make a note on the label of the bottle of the total quantity
thus used. (The object of adding methyl orange is to determine once for
all how much soda is necessary ; this quantity is then used in the estima
tions until a fresh quantity is made up, when it should be again titrated.)
Introduce a few fragments of coarsely granulated zinc in order to pre
vent bumping, and cork up the flask to the splash-head, &. By means of
a pipette, introduce 25 c.c. of decinormal sulphuric acid into the bulbs,
e /, and connect to the condenser. Turn a current of cold water through
the condenser, and light a bunsen underneath the flask; its contents
speedily come to the boil, and the steam and ammonia together are con-
densed, and retained in the Kjeldahl bulbs, / e. Continue the distilla-
tion until about 200 c.c. have come over ; turn out the lights, disconnect
the bulbs, and pour their contents into an evaporating basin, and titrate
with decinormal soda and methyl orange. In the blank experiment, the
quantity of ammonia evolved amounts usually from 0.3 to 0.5 c.c. of deci-
normal ammonia : make a note of this quantity, and repeat the blank with
each new lot of concentrated acid and soda. So far as possible make
these up each time in about equivalent quantities.

Returning to the clear solution obtained by treatment of the flour or
meal with acid and sulphate as previously described, if a 500 c.c. flask
has been used, add water to it in the same way as to the blank, and then
the quantity of strong soda solution as ascertained, then the granulated
zinc and distil as before. If the burning down with acid and sulphate
has been carried out in a 300 c.c. flask, the cold contents must first have
150 c.c. of water added to them, and then be transferred to a 500 c.c.
flask. With the remaining 50 c.c. of water give the 300 c.c. flask several
rinsings, which must be added to the main portion in the larger flask,
after which the requisite quantity of soda is poured in. As soon as the
soda is added, the ammonia is set free and therefore no time should be
lost in corking the flask to the splash-head in order to prevent any escape.
At the close of the experiment thoroughly wash out the distillation flask
and place it bottom upwards in a rack so as to drain. Preserve the
washed zinc in a small bottle or flask of water for use in the next test.

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 521

Calculation. — As 25 c.c. of acid are taken for the determination in the
bulbs, that quantity, less the amount required for its titration, represents
the amount of decinormal ammonia evolved, thus : —

25 c.c. — 13.3 c.c. AyiO soda == 11.7 c.c. TV/10 NH3.
(According to blank experiment, the correction is 0.4 c.c.)
then 11.7 — 0.4 = 11.3 c.c. from nitrogen of flour.
As 1 c.c. of JV/10 NH3 equals 0.0014 of nitrogen as ammonia, then
11.3 X 0.0014 = 0.01582 of nitrogen.

Osborne and Voorhees find that gliadin contains 17.66 per cent, of
nitrogen, and glutenin 17.49 per cent. As these two proteins constitute
the main portion of the proteins of flour, they assume wheat proteins to

100
contain 17.60 per cent, of nitrogen. As - _-£ — 5.68, they multiply the

quantity of nitrogen found by 5.68, as a constant factor in order to con-
vert the percentage of nitrogen into that of proteins. Proteins as com-
monly separated contain a quantity of water of hydration which is not
driven off at 100° C., and therefore multiplication by 5.68 does not give
the quantity of hydrated proteins. The figure formerly employed for
calculating of nitrogen into hydrated proteins was 6.33, but this is now
regarded as being more correctly expressed by 6.25. As this last factor,
6.25, has been very extensively employed, it is still most commonly used
so as to make results comparable with those already on record. In re-
turning analytic results, the actual quantity of nitrogen found, and also
the factor used for calculation into proteins, should be stated.

Returning to the 0.01582 gram of nitrogen obtained in the experi-
ment, then

0.01582 X 5-68 = 0.0898 gram of true proteins.
0.01582 X 6.25 = 0.0989 gram of hydrated proteins.
These are the quantities in 1 gram of flour, and therefore these quantities
X 100 = 8.98 per cent, of true proteins, and 9.89 per cent, of hydrated
proteins respectively.

As 0.0014 and 5.68, and 6.25, respectively are constants, their respec-
tive products, 0.00795 and 0.00875, may be used as factors. Therefore
the number of c.c. of decinormal acid neutralised by the evolved am-
monia X 0.00795 gives the weight of true proteins, and X 0.00875 gives
the weight of hydrated proteins, in the quantity taken for analysis.

673. True Gluten Estimation. — For this purpose take about 0.15
gram of dry gluten, weigh it accurately, and treat with acid and 'sulphate
as with the whole flour. Conduct the whole estimation precisely as be-
fore ; then, number of c.c. of NH3 evolved X 0.00875 = weight of true
gluten (hydrated proteins) in the quantity of dry gluten taken. The
following data show the mode of calculation : —

Flour yields 13.10 per cent, of dry crude gluten.
Taken for true gluten estimation — 0.152 gram.
Ammonia evolved, less correction, 14.6 c.c.
14.6 X 0.00875 = 0.12775 gram true gluten.
As the whole flour contained 13.10 per cent, of true gluten, then :
As 0.152 : 13.10 : : 0.12775 = 11.01 per cent, of true gluten.

Therefore :
Percentage of crude gluten X true gluten found in estimation

Crude gluten used for estimation
percentage of true gluten in whole flour.

522 THE TECHNOLOGY OF BREAD-MAKING.

In order to test the "True Gluten" determinations the following ex-
periment was made : — Four glutens were extracted from the same flour,
one being washed, as well as could be judged, to the right degree of
purity; two of the others were purposely underwashed, and the fourth
overwashed. The following were the results in wet and dry glutens : —

Wet Gluten. Dry Gluten. True Gluten.

No. 1. Washed correctly . . 53.0 per cent. 16.1 per cent. 15.0 per cent.
No. 2. Insufficiently washed 63.0 " 20.0 15.1

No. 3. Would pass for be-
ing washed suffi-
ciently .. .. 56.7 16.8 15.1
No. 4. Lost weight beyond
No. 1 with very

great difficulty . . 48.5 15.1 14.7

Note No. 4 was weighed when at 51 per cent., and again washed in
clean water; this water on testing gave starch colouration with iodine
solution, showing that even at 51 per cent, starch was still present. Not-
withstanding the wide differences in crude gluten between Nos. 1, 2, and
3, the true gluten is practically identical in all. In No. 4, however, the
protein itself is being lost. This was an exceptionally tough, hard, gluten-
ous flour, or doubtless there would have been an appreciable difference in
true gluten between Nos. 1 and 2. In true gluten estimations it is recom-
mended that where the true gluten does not amount to 80 per cent, of the
crude gluten, another estimation be made of the crude gluten and the
first one rejected.

674. Estimation of Soluble Proteins. — To make this estimation, take
50 c.c. of the filtered solution as prepared for soluble extract, and evapo-
rate to dryness in one of the acid flasks. For this purpose the flask should
be placed in the hot-water oven, as, unless the whole flask is kept hot re-
condensation occurs. Even in the hot-water oven evaporation proceeds
but slowly ; it may be considerably hastened by immersing the flask in a
bath composed of water with a large excess of potassium carbonate. This
easily maintains a temperature of 110-115° C. Treat the dry residue in
the flask with acid and sulphate, and proceed in the usual manner. It
should be remembered that 50 c.c. contain the soluble proteins of 5 grams
of the flour.

675. Gliadin Estimations; Classification of Methods. — Serious objec-
tions have been taken to gluten estimations on the ground that they can-
not afford a true determination of the total protein content of the flour ;
and therefore it is urged that they should be dispensed with and instead
a determination made of the nitrogen of the flour and the percentage of
protein obtained by calculation. Most of the investigations on this mat-
ter have been conducted with reference to the strength of flour, and ac-
cordingly the various researches and conclusions based thereon have been
fully described in Chapter XIV. dealing with that subject. That chapter
should be carefully read as an introduction to the whole question of
gliadin determinations. If gluten determinations cannot yield a true in-
dication of the protein content of flour, it follows that the protein con-
tent cannot yield a true indication of the gluten content of the flour.
From what has preceded, it will be seen that the authors regard that ag-
glomerate of various flour constituents, which is called gluten, as being
the factor which in virtue of its quantity and quality largely dominates
the properties of a flour. That body can be determined with considerable
accuracy by a simple physical operation, and possesses well-marked phys-
ical characteristics. They therefore attach importance to its estimation.
It being known that gluten is largely composed of glutenin and gliadin,

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 523

and that these bodies may roughly be compared to the sand and lime in a
sample of mortar, oiie being the component which gives substance and the
other the constituent which acts as a binding agent, it would seem that
the relative proportions of each must exert a considerable effect on the
qualities of gluten. Accordingly, the effect of such relative proportions
has received most careful examination. Certain earlier observers, as for
example Guthrie and Fleurent, attached considerable importance to the
proportions of each, and have suggested the bearing which they have on
the character of flour. Others, among whom are included Snyder and
Wood, have arrived at the conclusion that flours cannot be differentiated
in quality according to the proportions of gliadin and glutenin. Thus
Snyder finds that gliadin may range from 45 to 70 per cent, of the total
protein, without the flour being affected in any but a minor degree. Al-
most every one of those who have investigated the problem has adopted a
different method of determination, and therefore no very direct compari-
sons can be made. Further, from time to time, each operator has modi-
fied his own methods as possible improvements have suggested themselves.
The methods adopted divide themselves into (1) direct estimations on the
flour, and (2) estimations made on the washed out gluten. Each of these
merits some little examination in detail.

676. Gliadin Estimations on Flour. — On treating flour with 70 per
cent, alcohol, the gliadin, together with some portion of the water-soluble
proteins, as well as the soluble carbohydrates and soluble ash, is dissolved
out. It is therefore not possible to estimate gliadin by direct weighing
of the residue from the evaporated filtered solution, but instead, recourse
must be had to a nitrogen determination on the filtrate by the Kjeldahl
process. As an example of American methods the following description
by Teller is given : — * ' Two grams of the flour are put in a flask of about
150 c.c. capacity, 100 c.c. of dilute alcohol, specific gravity 0.90, are then
added to the flour, care being taken to mix the flour well with a small
quantity of the alcohol before the entire amount is added. The flask is
then set aside at room temperature for 24 hours, shaking occasionally to
assure thorough extraction of the gliadin. The liquid is then filtered and
50 c.c. of the clear filtrate taken for determination of nitrogen. The al-
cohol should be evaporated off on the steam bath before the sulphuric
acid is added to avoid charring of the alcohol. The nitrogen obtained is
then multiplied by the factor 5.7, or, as we find it more convenient in our
laboratories here, the number of c.c. of decinormal acid obtained for each
gram of flour is multiplied by the factor 0.8. This gives the per cent, of
gluten or gliadin direct. In our commercial work here we determine the
gluten by the Kjeldahl method, using 1 gram of flour and multiplying
the titration of ammonia obtained by the factor 0.8 as given above. We
find this to give as nearly the true amount of gluten in the flour as can
be done by the most careful hand washing, and it is much more reliable
when the work is done by different operators on different days." — (Per-
sonal communication, May, 1910.)

The method adopted by the authors is substantially the same as that
of Teller, except that, following more closely on the lines of Chamber-
lain, they use hot 70 per cent, alcohol, and take 400 c.c. to 4 grams of
flour, (a quantity which may be somewhat in excess of that absolutely
necessary.) They shake frequently during the 24 hours, or preferably
shake continuously in a shaking machine, a description of which is subse-
quently given in paragraph 677. After filtration, 200 c.c. of the clear
filtrate are placed in a 500 c.c. long necked Jena flask. This is immersed
in a bath of potassium carbonate and water, and connected to a spiral
condenser. The alcohol is distilled off, and then the flask is disconnected

524 THE TECHNOLOGY OF BREAD-MAKING.

and the heating continued until the solution is evaporated to dryness.
This takes place rapidly with the bath at 110-115° C. The Kjeldahl de-
termination is then made on the residue, and the results calculated in the
usual way.

In a paper, previously quoted, Teller has shown that alcohol of 0.90
specific gravity, i.e., 57 per cent, strength, dissolves more nitrogenous
matter from flour than does 70 per cent, spirit. This points to the
fact that the dilute alcohol takes up some of the water-soluble proteins
in addition to gliadin proper. Chamberlain also states that hot alcohol
dissolves out less protein than does cold, and therefore recommends the
latter. This again is an indication that other protein than gliadin is
being dissolved, since gliadin is more readily dissolved on the applica-
tion of heat than in the cold : on the other hand proteins of the albumin
type become less soluble because of coagulation. It is important also to
consider the bearing of the length of time of extraction in view of the
nature of the solvent, a dilute solution of alcohol not being capable of in-
hibiting proteolytic action. Air-dried gliadin is "very soluble'7 in 70
per cent, alcohol, and must be at least equally soluble in the finely divided
condition in which it naturally occurs in flour. With the use of a very
large excess of the solvent, it would seem that the increase of protein
dissolved by greatly prolonged extraction is not merely gliadin, but con-
tains in addition alcohol soluble protein produced by proteolytic action
on protein matter, which at the outset is insoluble in the dilute alcohol.
Corroboration of this is afforded by the fact that when dough is allowed
to stand under conditions which favour proteolytic action, there is a
marked increase in the quantity of dilute alcohol soluble protein. The
method employed must be regarded as a measure of the amount of pro-
tein dissolved in dilute alcohol under certain definite conditions, but
evidently is not a measure of gliadin only. Another point which has to
be considered is that according to Chamberlain, of the total gliadin and
glutenin contained in the wheat and flour, only about 85 per cent, can
be obtained as gluten by the washing process. On this the question arises
whether this balance of 15 per cent, is a loss due to inherent faultiness
of the gluten washing process, or whether it is the result of some of the
gliadin and glutenin being in a non-adhesive condition and therefore not
functioning as gluten. This matter has been already discussed (see para-
graph 439), and if the authors' view be correct, then flour contains some
gliadin which would be determined as such in a direct estimation on the
flour, and yet is not contributing to its strength.

677. Gliadin Estimations on Wet Gluten. — The foregoing considera-
tions have caused the authors to incline to determinations made on the
wet gluten itself as being more likely to have a direct bearing on the
problem of the quality of gluten and its effect on the strength of flour.
In gluten-washing those bodies which do not go to the building up of that
india-rubber like body are eliminated. The soluble carbohydrates and
ash have been more or less removed, and also such soluble proteins as are
not retained by the absorptive power of the gluten- proteins. If there-
fore the alcohol solvent be applied to this body it can only extract what
is practically soluble protein and the small amount of mineral bodies
which is inherently associated with this substance.

From its physical nature, gluten is a difficult body to treat with a
solvent. As the result of a • long series of experiments the authors
adopted the method of triturating with starch and then extracting the
gliadin. The following is a description of the method employed :

Quantities, 2.2 grams wet gluten, 11 grams of spirit-washed starch,
400 c.c. of 70 per cent, alcahol.

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 525

In order to obtain a fairly pure wheat starch, 1,000 grams were taken
and washed with about 4 litres of hot 70 per cent, alcohol in the shaking
machine for 24 hours. The starch was filtered from the spirit, pressed
fairly dry, and again washed with a similar quantity of hot 70 per cent,
alcohol for another 24 hours in the machine, and filtered and pressed.
A third washing was then given with 95 per cent, alcohol in the same
way, after which the pressed starch was carefully air-dried in a warm
room. This is termed spirit-washed starch.

After measuring the alcohol, 10 c.c. were reserved, and the remainder
raised to the boiling point. In practice, this was done by connecting the
flask to a return spiral condenser, so that there was no loss on the spirit
commencing to boil. The weighed gluten and about half the starch were
then placed in the mortar and ground up with a few drops of the
reserved alcohol into a thin dough. This was stiffened by the addition of
A little more starch, and the grinding continued, a little more alcohol was
then added, and so as again to make a thin dough, and then a little more
starch. By this alternate addition of starch and alcohol, the gluten was
rapidly disintegrated, and finally was obtained as a perfectly smooth
dough. This was carefully transferred into a shaking bottle of 1 litre
capacity. Any cold alcohol remaining was added, and then the alcohol
from the flask, which by that time will have got to the boil. The bottle
was then at once introduced into the shaking machine, where in practice
it remained about eighteen hours.

FlG. 86. — Shaking Apparatus.

526

THE TECHNOLOGY OF BREAD-MAKING.

The following is a description of illustration, Fig. 86, of the installa-
tion of shaking apparatus employed by the authors. When electricity is
available, the most convenient source of power is a small electric motor A.
This is started and regulated by the graduated switch, B. In order to
slow down the speed, the motor is geared up with a countershaft, C ;
which in turn drives the main pulley, D, of the shaking machine. The
machine is made to hold six or ten bottles, each of which stands in a
socket, E, of the right size. The sliding cap, F, is then placed down to
hold the bottle securely, and screwed in position by the screw, G. The
switch must be turned on so as to give the machine about sixty revolu-
tions per minute. As the machine revolves, the contents of the bottle fall
from the bottom to the top, and back again, about once a second.

At the close of the shaking period, the bottle is removed, and the
liquid poured on to a dry 10-inch filter. It filters very quickly and runs
through quite bright. If 364 c.c. of the filtrate be taken, that quantity is
equivalent to 2 grams of wet gluten. In order to save the spirit, the
filtrate is boiled down in a flask connected to a condenser until the whole
of the alcohol has distilled off. For this purpose the flask should be im-
mersed in a hot bath of potassium carbonate solution ; in this the spirit
boils rapidly, and the gliadin does not stick to the flask. The remainder
in the flask is then transferred to a weighed glass basin and evaporated
to dryness. The necessary starch correction is made and the results cal-
culated as gliadin ex gluten. The weight of residuum thus obtained is a
very convenient one (about 0.30 to 0.35 gram), but lesser quantities may
be taken if wished. For example, 1.1 grams of gluten, 5.5 grams of starch,
and 100 c.c. of alcohol may be used for each test. Then, on evaporation
of 91 c.c. of the filtrate, the gliadin ex 1.0 gram of gluten is obtained.

678. Application of Gluten and Gliadin Tests to Commercial Flours.
—In order to illustrate the application of the various gluten and other
tests to modern flours, the authors obtained a range of commercial sam-
ples from the same millers, which are numbered according to grade, No. 1
being the highest.

The following are the results of analysis : —

PROTEIN AND OTHER ESTIMATIONS OF VARIOUS COMMERCIAL FLOURS.

Numbers—. 1. 2. 3. 4. 5.

Percentages on Flour.
Wet Gluten
Ratio of We
Dry Gluten
Non-Protein
True Gluten
Gliadin ex Gluten
Glutenin ex Glut

Percentages on Dry Gluten.
Non-Protein Matter in Dry Gluten

Gliadin ,

Glutenin ,

Percentages on Flour.

Total Proteins ,

Gliadin ex Flour

Non-Gliadin Proteins (Glutenin, Albumin, etc.

Percentages on Total Proteins.
Gliadin ex Flour
Non-Gliadin Proteins
Recovered as True Gluten
Not recovered as True Gluten

Percentages on Flour.

Moisture

Ash

Water absorption, Quarts per Sack . .

. . 32.83

34.36

35.47

34.67

34.77

; to Dry

Gluten . .

.. 3.0
. . 10.72

3.0
11.28

3.0
11.72

3.1
11.09

3.0
11.56

Matter i

n Dry Gluten

. . 2.19
. 8 53

3.12
8.16

3.39
8.33

3.20

7.89

3.26
8.30

uten . .
Gluten

. . 5.30
. . 3.23

5.45
2.71

5.41
2.92

5.41

2.48

5.54
2.76

20.43
49.44
30.13

9.53

5.29

) 4.24

55.51
44.49
89.51
10.49

14.56
0.38
60

27.66
48.31
24.03

9.80
5.20
4.60

53.06
46.94
83.26
16.74

14.52
0.36
62

28.92
46.16
24.92

10.06
5.38
4.68

53.48
46.52
82.80
17.20

14.38
0.42
62

29.76

48.78
21.46

9.71
5.25

4.46

54.07
45.93
81.25
18.75

14.40
0.44
63

28.20
47.92

23.88

10.58
5.40

5.18

51.04
48.96
78.45
21.55

14.06
0.52
63

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 527

In these flours the total gluten increases as the colour goes down, and
keeps pace with their strength, but in true gluten No. 1 is slightly higher
than any of the others. The gliadin in No. 1 is rather a higher propor-
tion of the dry gluten than in any of the other flours. Looking at the
total proteins as determined direct on the flour they run closely parallel
to the dry glutens. The gliadins as obtained from the flour run very
closely to each other, being highest in No. 1 and lowest in No. 5. The per-
centage of proteins not recovered as true gluten steadily increases as the
flours diminish in quality. It would seem therefore that a comparison of
the total proteins with the proportion thereof recoverable as true gluten
has a close connection with the grade of flour. The ash in all the flours
is low, and precludes the possibility of mineral additions to the flour. The
flours likewise gave no reaction when tested for the presence of bleaching
agents. As might be expected with flours from the one mill, there is a
close general resemblance between the whole of the grades.

679. Gluten and Gliadin Tests on Special Flours and Wheats.— The
various gluten and allied tests were also applied to a series of single
wheat flours, and typical wheats, with the following results. The wheat
determinations were made on the finely ground meal of the whole grain,
but in order to make the data obtained somewhat more comparable with
those on flours, they have also been calculated to amounts present in 70
per cent, straight-run flours from such wheats.

SINGLE WHEAT FLOURS.

6. From strong spring American wheat.

7. „ French wheat, grown in England, 1910 crop.

8. „ Karachi wheat, 1910 crop.

9. „ Taganrog wheat, 1909 crap.

10. „ Bar-russo wheat, 1910 crop.

11. „ New Russian wheat, 1910 crop.

12. Fourteen years old strong American flour.

PROTEIN AND OTHER ESTIMATIONS ON SINGLE WHEAT FLOURS.

Numbers—. 6.
Percentages on Flour.

Wet Gluten ...... 42.30

Ratio of Wet to Dry Gluten . . 2.8

Dry Gluten ...... 15.02

Non-Protein Matter in Dry

Gluten ........ 4.25

True Gluten ...... 10.77

Gliadin ex Gluten . . . . 7.36

Glutenin ex Gluten . . . . 3.41

Percentages on Dry Gluten.
Non-Protein Matter in Dry

Gluten ........ 28.29

Gliadin ........ 49.00

Glutenin ........ 22.71

Percentages on Flour.

Total Proteins ...... 12.95

Gliadin ex Flour ...... 6.43

Non-Gliadin Proteins . . . . 6.52

Percentages on Total Proteins.

Gliadin ex Flour 49.65

Non-Gliadin Proteins . . . . 50.35

Recovered as True Gluten . . 83.16

Not recovered as True Gluten. . 16.84
Moisture, per cent, of flour
Water Absorption, Quarts per

Sack . 70

29.90 23.47
3.0 3.4
9.75 6.77

1.95

7.80
4.98

2.82

1.40
5.37
3.75
1.62

25.73
3.0

8.52

0.90
7.62
3.49
4.13

37.70

3.3

11.34

2.07
9.27
6.91
2.36

32.90
3.3
9.98

1.63

8.35
5.75
2.60

47.27
5.1
9.20

6.13
3.07
2.84
0.23

20.00 20.68 10.56
51.07 55.38 40.96
28.93 23.94 48.48

10.19
5.25
4.94

51.52

48.48
76.54
23.46
12.86

8.14 13.78
3.82 7.63
4.32 6.15

46.93
53.07
65.97
34.03
12.14

55.37
44.63
55.30
44.70
12.00

18.25
60.93
20.82

11.46
5.64

5.82

49.21
50.79
80.89
19.11
12.70

16.33 .
57.61
26.06

12.12
6.34
5.38

52.31
47.69
68.89
31.11
12.60

66.63
30.87
2.50

13.15
5.75
7.40

43.72
56.28
23.34
76.66
12.46

67.0 71.0 69.5 70.0 68.5 —

528

THE TECHNOLOGY OF BREAD-MAKING.

WHEATS.

13. Old Odessa, 1909 crop.

14. New Odessa, 1910 crop.

15. Manitoba.

16. Northern Plate (Rosario Santa Fe).

17. American Durum.

18. English Rivetts.

19. "Azima" (Russian).

20. "Ulka" (Russian).

PROTEIN AND OTHER ESTIMATIONS ON TYPICAL WHEATS.

13.

Numbers —

Percentages on Meal.
Wet Gluten
Ratio of Wet to Dry

Gluten 3.0

Dry Gluten . . . . 10.96
Non-Protein Matter in

Dry Gluten . . . . 1.96
True Gluten . . . . 9.00
Gliadin ex Gluten . . 4.64
Glutenin ex Gluten . . 4.36
Percentages on Dry Gluten.
Non-Protein Matter in

Dry Gluten .. .. 17.88

Gliadin 42.33

Glutenin 39.79

Percentages on Meal.
Total Protein . . . . 13.24
Gliadin ex Meal .. 5.07

Non-Gliadin Proteins . . 8.17

Percentages on Total

Proteins.

Gliadin ex Meal . . 38.29

Non-Gliadin Proteins . . 61.71
Recovered as True

Gluten

Not recovered as True

Gluten

Calculated on 70 per cent.

Straight Flours.
Wet Gluten
Dry Gluten
Non-Protein Matter in

Dry Gluten
True Gluten
Gliadin ex Gluten
Glutenin ex Gluten

16.

14. 15.

33.27 25.50 34.65 35.70

17. 18. 19. 20.

28.85 18.50 31.35 40.50

2.7 2.9

9.49 11.88

2.04 2.54

7.45 9.34

3.68 5.54

3.77 3.80

21.49 21.38

38.78 46.63

39.73 31.99

12.11 13.41

4.11 5.60

8.00 7.81

33.94 41.76
66.06 58.24

67.97 61.52 69.65
38.48 30.35

3.0
11.86

2.23
9.63
5.73
3.90

2.9
10.00

2.40
7.60
4.68
2.92

3.0
6.21

1.26
4.95
2.81
2.14

3.1
10.07

1.94
8.13
4.98
3.15

32.03

47.53
15.66

2.80

12.86

6,63

6.23

18.80 24.00 20.29 19.26

48.31 46.80 45.25 49.45

32.89 29.20 34.46 31.29

13.73 13.70 8.81 11.22

5.99 4.15 2.97 4.76

7.74 9.65 5.84 6.46

43.63 30.29 33.71 42.42

56.37 69.71 66.29 57.58

70.21 55.47 56.18 72.46

29.79 44.53 43.82 27.54

36.43 49.50

13.56 16.97

2.91 3.63

10.64 13.63

5.26 7.91

5.38 5.72

51.00 41.21
16.94 14.28

26.43 45.00
8.87 14.38

3.18 3.43 1.80 2.77

13.76 10.86 7.07 11.61

8.18 6.68 4.01 7.11

5.58 4.18 3.06 4.50

3.1

12.98

3.30
9.68
6.07
3.61

25.42
46.76
27.92

13.86
5.38

8.48

38.82
61.18

69.69
30.31

57.86
18.54

4.71

13.83

8.67

5.16

• On examining the results 011 single wheat flours, excluding No. 12 for
the moment, No. 6 gave the highest percentage of wet gluten, while Bar-
russo,' No. 10, was the next highest. The spring American was also
highest in dry gluten, while No. 8, Karachi, was the lowest. In this par-
ticular flour the ratio of wet to dry gluten is very high ; Wood 's re-
searches (paragraphs 430 et seq.) go to show that the more water there
is in the gluten the nearer it is to actual disintegration. The absolute
amount of gliadin ex gluten was high in both Nos. 6 and 10, while low in
No. 8. But the relative proportion of the whole dry gluten which con-
sisted of gliadin was comparatively high in No. 8. Comparing the total
proteins with the dry gluten, No. 9 was the highest in the former and
almost the lowest in the latter. Taganrog, No. 9, was very difficult to
wash for gluten ; there was considerable frothing, and the wet gluten was

SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 529

very friable throughout the whole operation of separation. This flour is
from a very hard wheat, and one which alone does not make a good loaf.
The gliadin ex gluten content was very low. On the other hand the
gliadin ex flour was high. Taking Nos. 6 and 9, protein and gliadin
determinations on the flour would place No. 9 the higher ; but gluten and
gliadin ex gluten estimations at once show the marked superiority of the
spring American flour.

No. 12 sample, called "Fourteen Years Old Strong American Flour,"
is of rather special interest. A number of years ago, one of the authors
made some experiments on the feasibility of compressing flour into solid
blocks by hydraulic pressure of several tons to the square inch. Among
flours thus tested was a sample of strong American flour, of which several
blocks were preserved. These, after 14 years, were quite free from any
mould or visible signs of decomposition, and a portion was accordingly
subjected to this series of tests. On washing for gluten the dough broke
down into a flocculent non-coherent deposit, and evidently was physically
quite unfitted for bread-making. By repeated washings on a hair sieve,
and squeezing and coaxing the particles together, a flabby and scarcely
coherent mass of wet gluten was obtained, which gave the unusually high
percentage of 47.27. However, most of this was evidently water, the
ratio being 5.1, and the total quantity of dry gluten 9.20 per cent. Pur-
suing the investigation of the dry gluten a step further, it contained only
3.07 per cent, of true gluten, 6.13 per cent, consisting of non-separated
starch. Nearly all the true gluten was composed of gliadin, the whole
of the glutenin having disappeared. On turning to the direct determina-
tions on flour, the proteins are high and are very nearly the same as in
the strong American flour, No. 6 ; 13.15 against 12.95 per cent. The
gliadin ex flour is very nearly as much as that of No. 6, 5.75 against 6.43
per cent., and would in ordinary analysis call for no very special remark.
It shows up rather more in percentages on total proteins, where the figure
is 43.72 against 49.65 in the No. 6 flour. But, according to Snyder (para-
graph 426), this difference lies almost within the normal range since the
same type of flour may have variations of proteins soluble in alcohol from
45 to as high as 70 per cent, with only minor variations in the bread-
making value of the flour. The importance of these comparisons lies in
the fact that the ordinary protein and gliadin ex flour tests scarcely serve
to differentiate a spring American flour of the highest quality from a
flour of the same origin, but so profoundly altered by fourteen years age
as to have completely lost the physical properties so essentially character-
istic of wheaten flour. On the other hand the abnormal character of this
fourteen-year-old flour is at once revealed by an ordinary gluten test,
and is in evidence throughout the whole series of subsidiary tests on the
wet gluten. This is in striking contrast with Chamberlain's conclusion
that "the determination of gluten is not able to yield any information
that cannot be gained either from the determination of total proteins or
that of the alcohol-soluble and insoluble proteins. " It is submitted that if
what may be called the purely chemical tests (i.e., protein and gliadin
determinations on the flour direct) fail so signally to indicate such
remarkable differences as there are between these two flours, then they
can be even less depended on as a means of gauging and estimating minor
differences in character and quality. The gluten tests and their develop-
ments, on the contrary, afford exceedingly valuable information as to the
general baking properties of the flour.

The wheats range from the strongest Manitoban to one of the weakest
of English wheats, Rivetts. The first pair, Nos. 13 and 14, consist of

530 THE TECHNOLOGY OF BREAD-MAKING.

Odessa of two successive years ' crops. The old was very satisfactory, but
the new wheat was the reverse. The former was higher in wet, dry, and
true gluten. Also the relative proportion of gliadin ex gluten was higher
in the older wheat. The total proteins and gliadin ex meal were in gen-
eral accordance with the gluten series of tests. The calculated per-
centages on 70 per cent, straight flours are introduced with the object
of showing approximately the composition of the flours from the wheats,
and permitting same to be compared with other flours. The Manitoba
wheat, No. 15, is high in wet and dry gluten, and also in true gluten. The
gliadin is high both absolutely, 5.54 per cent., and relatively, 46.63 per
cent., of the dry gluten. On the meal, the total proteins, 13.41, and
gliadin, 5.60 per cent., are also high. Throughout the whole series of
tests the Rosario Santa Fe very closely resembles Manitoba wheats. The
American Durum, No. 17, refuses to come into line with any of the oth-
ers. The wet and dry glutens are low, so also is the true gluten, 7.60 per
cent. But the gliadin ex gluten is relatively high, being 46.80 per cent,
of the dry gluten. Gluten testing would reveal the fact that this wheat
was extremely hard; and this, coupled with the low gluten, would indi-
cate thorough conditioning of same before grinding. The total proteins
of this wheat are high, 13.70, while the proportion recovered as true
gluten was low, being only 55.47 per cent. The gliadin ex meal is very
low. The extreme hardness of the grain very materially affects all esti-
mations made by solvents direct on the meal, and therefore gluten and
gliadin ex meal are both abnormally low. If the wheat be softened by
standing some time after the addition of water, these soluble constituents
would show an increase. Similarly, the great hardness of the wheat
would react adversely on the flour if untreated, whereas effective condi-
tioning would very materially improve the flour. The English Rivetts,
No. 18, is almost the antithesis of the preceding flour. Its gluten
throughout is low, 18.50 per cent, wet, but contains a fairly high propor-
tion of gliadin, 45.25 per cent. The total proteins agree, being so low as
8.81 per cent., while the gliadin ex meal is down to 33.71 per cent, of the
total proteins. The Azima, No. 19, has a fair gluten, with a relatively
high percentage of gliadin ex gluten. The total proteins occupy a
medium position, while the gliadin ex meal is also fairly high. The Ulka
wheat, No. 20, is distinguished by a very high percentage of wet gluten,
of a soft and what is sometimes called ' ' pappy ' ' character. The ratio of
wet to dry gluten is high, 3.1, but the dry gluten is nevertheless the high-
est of the series, 12.98 per cent. The true gluten, 9.68, is also the highest
of those in the table. The gliadin ex gluten is high absolutely, 6.07, and
medium relatively, being 46.76 per cent, of the dry gluten. In total pro-
teins this wheat is also the highest of the series with 13.86 per cent., while
relatively the gliadin ex meal is rather above the average with 38.82 per
cent.

CHAPTER XXIV.

ESTIMATION OF CARBOHYDRATES, AND ANALYSIS OF BODIES

CONTAINING SAME.

680. Estimation of Sugar by Fehling's Solution. — The composition
and properties of the sugars are fully described in Chapter VI. It is
there shown that maltose is capable of forming a red precipitate of copper
sub-oxide in the reagent termed Fehling's solution, while dextrin and
starch cause no precipitate. (See, however, Brown and Millar's conclu-
sion that dextrin has a reducing power of about R. 5.8, paragraphs 180
and 263.) This reaction is not only of service in testing for maltose and
certain other sugars, but also serves the purpose of quantitatively deter-
mining the amount of sugar present in a solution.

As before, directions are first given for the preparation of the re-
agents, and then for the performance of the analytic operation.

681. Fehling's Standard Copper Solution. — Powder a sufficient
quantity of pure re-crystallised copper sulphate, and dry it by pressure
between folds of filter paper. Weigh out 69.28 grams, dissolve in water,
add 1 c.c. of pure sulphuric acid, and make up the solution to 1 litre.

682. Alkaline Tartrate Solution. — Weigh out 350 grams of pure
Rochelle Salt (potassium sodium tartrate), and dissolve so as to make
about 700 c.c. of solution. Filter if necessary. Next dissolve 100 grams
of sticks of pure caustic soda in 200 c.c. of water. If the solution is not
clear, it must be filtered through a funnel fitted with a plug of glass wool.
Mix the two solutions together, and make up the volume to 1 litre.

When required for use, these solutions must be mixed together in
equal proportions; they then form the original Fehling's solution. This
solution possessed the disadvantage of changing in character by being
kept ; and hence the modification in which the Rochelle salt is only added
to the copper sulphate immediately before the solution is required for
use. Each c.c. of the mixed solution contains 0.03464 gram of copper
sulphate, and was formerly considered equivalent to exactly 0.005 gram
of pure dry glucose.

683. Action of Sugars on Fehling's Solution. — A careful investiga-
tion has been made by Soxhlett of the action on Fehling's solution of
specially pure specimens of the various types of sugars : he finds as a
result that the amount of precipitate formed depends not only on the
quantity of sugar present, but also on the degree of concentration of the
solution, the temperature at which the determination is made, and other
conditions. Hence great care must be taken to work always in precisely
the same manner, as it is only by so doing that comparative results are
obtained.

Sugar may be determined by Fehling's solution either gravimetrically
or volumetrically. A description of the gravimetric method is first given.
The student should commence by practising the estimation on cane
sugar, as this substance is easily obtained in a condition of purity. Cane
sugar has no action on Fehling's solution, but when heated gently with

531

532 THE TECHNOLOGY OP BREAD-MAKING.

dilute acid is changed, by hydrolysis, into a mixture of glucose and fruc-
tose in equal quantities, viz. : —

CuH^On + H20 = C,H1206 + C6H1200.

Cane Sugar. Waver. Glucose. Fructose.

Glucose and fructose both act on Fehling's solution, precipitating copper
sub-oxide Cu20, in definite quantity.

684. Gravimetric Method on Cane Sugar. — Procure some of the
sugar known as coffee crystals; this is the variety of sugar sold by the
grocer for use with coffee, and consists of large, colourless, well-defined
crystals of almost pure cane sugar. Select some of these free from extra-
neous matter, powder them, and dry for a short time in the hot-water
oven. Make up a one per cent, solution by weighing out 1 gram of the
pure dry sugar, dissolving it in water, and making up the volume to 100
c.c. Take 50 c.c. of this solution, and add to it 5 c.c. of pure fuming
hydrochloric acid. For this purpose it is best to use a flask graduated at
50 and 55 c.c. Place the flask* in a water bath, and heat until it reaches
the temperature of 68° C. ; this operation should be arranged so as to
occupy about 10 minutes. Next pour the contents of the flask into a
100 c.c. flask, and dissolve in it dry sodium hydroxide in small quantities
at a time until the solution is slightly alkaline, testing after each addi-
tion with a small strip of litmus paper. Cool the flask and make up the
contents to 100 c.c. with water. The flask now contains a 0.5 per cent,
alkaline solution of cane sugar converted into glucose and fructose. Add
25 c.c. of Fehling's standard copper solution to the same quantity of
alkaline tartrate solution, and mix the two thoroughly. Take two beak-
ers of about 6 ounces capacity, and pour into each 25 c.c. of the mixed
Fehling's solution. Next add to each 50 c.c. of boiling distilled water
that has been boiling for about half an hour. Stand the beakers in a
water bath, the water of which is kept boiling by a bunsen ; allow them
to stand for 7 minutes, and then look to see that no precipitate has
formed. Should a precipitate occur, the Fehling's solution is impure,
and is consequently no longer fit for use. Next add to each beaker 20 c.c.
of the 0.5 per cent, sugar solution and replace in the water bath for 12
minutes. The precipitated cuprous oxide is best weighed on a counter-
poised filter ; prepare, therefore, beforehand, two pairs of small Swedish
filters, trimmed until each one of the pair exactly counterpoises the
other, when tested in the analytic balance. Fold one of the pair of coun-
terpoised filters, and filter the copper oxide rapidly from the solution ;
the filtrate should still be of a deep blue colour. Collect the filtrate in a
porcelain evaporating basin, and examine carefully in order to see if any
traces of the precipitate have found their way through the paper ; if so,
pour away the supernatant liquid from the basin, and wash any precipi-
tate back on to the filter. Moisten the other of the pair of counterpoised
filters with some of the filtrate, and wash both the filters rapidly with
boiling water, and dry both in the hot-water oven. The reason for treat-
ing the second paper with some of the filtrate is to cause each to be in
as nearly as possible the same condition, so that it (the second) shall
still counterpoise the first paper after being washed and dried. The fil-
ters should be dried for 12 hours and then weighed, the counterpoise
paper being placed on the weight side.

If wished, the cuprous oxide may be converted into cupric oxide and
weighed as such. Or the oxide may be reduced to copper, either by the
action of hydrogen or by electrolytic processes, and weighed in the
metallic, form. For these and other methods, consult Allen's Commer-
cial Organic Analysis, vol. i.

ESTIMATION OF CARBOHYDRATES. 533

In order to understand the calculations involved in the estimation of
sugar by Fehling's solutions, it will be necessary for the student to make
himself thoroughly acquainted with the properties of the sugars as
already described.

The glucose and fructose produced by the action of dilute acid on cane
sugar, as shown in the equation in a preceding paragraph, are sometimes
grouped together as glucose, or grape sugar ; it is then said that one
molecule of cane sugar (sucrose) produces, when inverted, two molecules
of glucose. From the equation it will be seen that the molecular weight
of cane sugar is 342, while that of the glucose formed is 360. It was for-
merly supposed that an exact number of molecules of CuO of the copper
sulphate was reduced to Cu20 by the sugar ; hence we find the statement
that two molecules of glucose reduce 10 CuO to 5 Cu2O. Soxhlett's re-
searches, however, show that the reaction is not so simple, but, as before
stated, varies, being dependent on the degree of the dilution of the re-
agent and other conditions. Different kinds of sugar, too, under the same
conditions, reduce, weight for weight, different quantities of CuO to
Cu20. Working in the manner directed, the reducing power of sugar on
Fehling's solution is, according to determinations by 0 'Sullivan and
others : —

Cane Sugar has no reducing action. i CTam produces and reduces

Glucose 1.983 grams of Cu20 2.205 of CuO.

Cane Sugar after inversion . . 2.087 ,, ,, 2.315 ,,

Maltose 1.238 „ „ 1.378 „

The reason why the inverted cane sugar produces more Cu20 than
does glucose is, that 1 gram of cane sugar, on inversion, yields more than
a gram of glucose, the exact quantity being 1.052 grams. When only the
one variety of sugar is present in a solution, the following factors may be
used for calculating the amount of sugar from the weight of precipitated
Cu,O.

Glucose .. .. .. 1/1.083 = 0.5042

Cane Sugar after inversion . . . . 1/o.087 = 0.4791

Maltose Vi-238 = 0.8077

Thus, suppose that in the analysis made with the 0.5 per cent, solu-
tion, the weight of the precipitated Cu.,0 was 0.2075 grams, then
O.2075 X 0.4791 = 0.0994 of cane sugar.

Theoretically, in 20 c.c. of the 0.5 per cent, solution there is 0.1 gram
of sugar ; the results of the analysis give 99.43 per cent, of chemically
pure sugar. If the estimation were made with perfect accuracy, this
would show that the sugar contained 0.57 per cent, of moisture or other
impurity; the deficiency is doubtless in part due to error of analysis.
The duplicate estimations made should agree closely.

When making an analysis of a substance, the composition of which is
known approximately, a quantity should be taken that contains as nearly
as can be calculated 0.1 gram of inverted cane sugar, or 0.2 gram of
maltose. In case the estimation shows that the amount of sugar differs
widely from these quantities, a second determination must be made in
which more or less of the substance is taken.

In the presence of other carbohydrates capable of inversion by hydro-
chloric acid, O 'Sullivan recommends that cane sugar be inverted by
means of invertase, which is without action on the other sugars, etc.,
which may possibly be present. The method is described in detail in
connection with the analysis of malt extract.

685. Volumetric Method on Cane Sugar. — When Fehling's solution
is intended only to be used gravimetrically, its exact strength is not a

534 THE TECHNOLOGY OF BREAD-MAKING.

matter of great importance, but when employed for volumetric estima-
tions, its strength must first be accurately determined by titration with
a standard solution of sugar. For this purpose the 0.5 per cent, solution
of inverted cane sugar already described may be used. The sugar must
be added to the Fehling's solution, and not the Fehling's solution to the
sugar. The sugar solution is therefore placed in a burette, and in order
that its contents may not get heated during the operation, the glass jet
is attached by means of a piece of india-rubber tubing about 8 or 10
inches long. The burette may then be placed so as not to be vertically
over the basin in which the Fehling's solution is being heated.

Measure out 5 c.c. each of the standard copper and alkaline tartrate
solutions into a white porcelain evaporating basin ; add 40 c.c. of well-
boiled boiling water, and heat the liquid quickly to the boiling point by
means of a small bunsen flame. In order to test the purity of the Feh-
ling's solution, boil for 2 minutes; there should neither be a precipitate
nor any alteration of colour. Next add the sugar solution in small quan-
tities at a time, boiling between each addition. As the operation pro-
ceeds, the deep blue colour of the solution disappears ; towards the end,
add the sugar more cautiously, and after each boiling allow the precipi-
tate to subside. Tilt the dish slightly over, note whether the clear super-
natant liquid is still of a blue tint by observing the white sides of the
dish through it. When the colour has entirely disappeared, the reaction
is complete. The exact point may be determined with more exactitude by
means of a dilute solution of potassium ferrocyanide, acidulated with
acetic acid. With a glass rod put a series of drops of this reagent on a
white porcelain tile ; wash the rod, take out a drop of the clear liquid from
the dish with it, and add it to one of the drops of the ferrocyanide ; the
slightest trace of copper produces a reddish-brown colouration.

The results of the first estimation must only be looked on as approxi-
mate, but having thus gained an idea of about how much sugar is re-
quired, the succeeding ones may be made more quickly, as almost all the
sugar may be added at one time. Thus, if 9.6 c.c. of sugar solution were
required in the first trial, then in the second from 8.5 to 9.0 c.c. may be
run in at once, and then the solution added more carefully as the end of
the reaction is reached.

Provided the Fehling's solution is of normal strength, then
10 c.c. =: 0.0500 grams of glucose or invert sugar.
10 c.c. = 0.0475 ,, ,, cane sugar (after inversion).
10 c.c. = 0.0801 „ „ maltose.

The difference between the cane sugar and glucose is here again ex-
plained by the fact that cane sugar produces on inversion more than its
weight of glucose ; 0.0475 gram of cane sugar yields 0.05 gram of glucose.
Working with a 0.5 per cent, solution of cane sugar, each c.c. contains
0.005 gram, and 9.5 c.c. contain 0.0475 gram of sugar ; 10 c.c. of the Feh-
ling's solution should therefore require for its complete reduction 9.5 c.c.
of the sugar solution.

As the Fehling's solution is rarely of the exact strength its equivalent
in cane sugar must be noted so as to be used in each determination. Sup-
pose the 10 c.c. of Fehling's solution required 9.3 c.c. of the sugar solu-
tion, then we know that 10 c.c. is equivalent to only 93/95 = 0.9789 of
the respective quantities of different sugars given above. The exact
strength of the Fehling's solution should be noted on the bottle, together
with the date when the titration was made ; the solution should be fre-
quently tested against the solution of pure sugar. The quantity of sugar
found must therefore be multiplied by 0.9789. An example will make

ESTIMATION OF CARBOHYDRATES. 535

this clear. A 0.5 per cent, solution of a commercial sugar was tested vol-
umetrically, when 11.4 c.c. of the sugar solution were required to com-
pletely reduce 10 c.c. of the Fehling's solution. By titration 10 c.c. of
the Fehling's solution are known to be equivalent to 0.9789 of 0.0475-
0.0465 of pure cane sugar ; that quantity is therefore present in 11.4 c.c.
of the 0.5 per cent, solution. A 0.5 per cent, solution contains 0.005 gram
of sugar, so that 11.4 c.c. contains 0.0570 gram of the sugar. As 0.0570
gram of the sample contains 0.0465 gram of sugar, the percentage of pure
sugar in the specimen is 81.58. The analysis would appear in the note-
book thus : —

"Volumetric determination of pure sugar in a commercial sample of

cane sugar.

Inverted and made up to 0.5 per cent, solution.
11.4 c.c. required to reduce 10 c.c. of Fehling's solution,

which = 0.0465 gram of pure cane sugar.

0.0465 X 100

"11.4 X 0.005 = 81.58 per cent, of pure sugar."
686. Estimation of Maltose in Wheats or Flours. — The method of
procedure is much the same as with cane sugar. The principal point is
to obtain a solution of the right strength. Assuming that an aqueous
infusion of wheat contains an average amount of 2.5 per cent, of maltose,
then 100 c.c. of a 10 per cent, solution of the meal or flour contains 0.25
gram of maltose, so that 80 c.c. of the 10 per cent, solution are required
in order to furnish an approximate amount of 0.2 gram of maltose. For
each quantitative estimation, take 25 c.c. of Fehling's solution, 10 c.c. of
water, and 80 c.c. of the clear 10 per cent, solution of the meal or flour.
These quantities give the same degree of dilution as those directed to be
used in the estimation of cane sugar ; proceed exactly as in the determi-
nation of that substance. Having weighed the precipitate of Cu20, mul-
tiply by the factor 0.8077 ; the result is the quantity of maltose in 80 c.c.
of a 10 per cent, solution of the meal or flour. As 80 c.c. of such a solu-
tion contain the soluble portion of 8 grams of the meal, the percentage is
obtained by multiplying by 100/8 = 12.5.

In making this estimation the soluble proteins of the grain are kept
in solution by the alkali of the Fehling's solution. They may, if wished,
be removed by boiling and filtering the 10 per cent, solution. Put about
100 c.c. of the solution in a beaker, take the weight, and then boil for
about five minutes; replace on the balance and make up to the original
weight with distilled water. Filter off the coagulated proteins by passing
the liquid through a dry filter; the filtrate is a 10 per cent, solution,
minus the proteins coagulated by boiling.

If maltose is to be determined volumetrically, the solution should
always be first freed from coagulable proteins in the manner just de-
scribed. Take 10 c.c. of the mixed Fehling's solution, add 20 c.c. of
water, and run in the clear 10 per cent, solution of the meal or flour until
the reaction is complete, exactly as was done with the inverted cane sugar.
The less quantity of water is added because of the maltose solution from
the meal or flour being so very dilute.

In case the estimation of maltose is being made in a much stronger
solution than that obtained by treating a meal with 10 times its weight
of water, dilute the solution down until it contains approximately about
one per cent, of maltose, and then work with exactly the same quantities
as were directed for the inverted cane sugar 0.5 per cent, solution.

The estimation of maltose in wheats and flours is principally of value
as a means of judging the amount of alteration which the starch has
undergone; that a sugar analogous to cane sugar is also present is

536 THE TECHNOLOGY OF BREAD-MAKING.

demonstrated by the experiment quoted in the early part of Par. 370, in
which an additional precipitate is obtained as a result of treatment with
hydrochloric acid. It must be remembered that with such an aqueous infu-
sion there is always some change due to enzymic action on the starch of
the wheat. If necessary, this action is obviated by destruction of the en-
zymes as a preliminary to the test. This may be done by boiling the flour
with 95 per cent, by volume alcohol for one hour, filtering and air-drying.
687. Estimation of Dextrin. — Most substances which contain
maltose contain also dextrin ; thus the two are both found in wort pro-
duced from malt, and also in starch solutions that have been subjected to
diastasis. Dextrin has no action (or but little) on Pehling's solution, but
by prolonged treatment with an acid is converted into maltose, and ulti-
mately into glucose. When maltose and dextrin are simultaneously
present in a liquid, other carbohydrates being absent, the maltose is
estimated in a portion as already described; another portion is treated
with acid, by which both dextrin and maltose are converted into glucose.
A second estimation of the copper oxide reducing power is then made.
The weight of precipitate will be found to be considerably more than in
the first estimation. This is due, in the first place, to the fact that glu-
cose precipitates more Cu20 than does maltose. The maltose originally
present must be calculated into glucose, and the amount of precipitate
due to it subtracted from the weight found in the second estimation : the
remainder is reckoned as glucose produced by the hydrolysis of the dex-
trin ; the percentage may be then obtained by calculation. Unfortunately,
it is difficult to determine the exact point when the whole of the dextrin
has been changed into glucose. When carefully worked the process is,
however, sufficiently accurate for most technical purposes, and yields com-
parative results. The method is largely employed for the determination
of dextrin in the worts made for malt assays. There follows a modifica-
tion of the process adapted to the determination of dextrin in meals and
flours. Having made a solution for the determination of maltose, take
the same quantity of the solution as required for that estimation, viz.,
80 c.c., and add to it 2 c.c. of dilute sulphuric acid (1 part concentrated
acid to 8 of water) , stand the mixture in a water bath, and heat to boiling
for 4 hours. At the end of that time neutralise carefully with caustic
potash solution (KHO), and proceed to estimate glucose by Fehling's
solution precisely as before. The excess of glucose in the second solution
over that produced by the maltose in the first requires to be calculated
back to dextrin. It must be remembered that glucose is produced from
dextrin according to the following equation : —

C12H200IO + 2H20 2C6H1206

Dextrin. Water. Glucose.

Molecular weight = 324. Molecular weight — 360.

Therefore, every 360 parts of glucose thus produced represent 324 parts
of dextrin in the original solution, or 10 of glucose = 9 parts of dextrin,
so that glucose formed from dextrin X 9/10 — dextrin. As already
stated, this method must only be looked on as giving results sufficiently
accurate for technical purposes.

A useful alternative method of estimating dextrin depends on the
fact that it is only very slightly soluble in alcohol of the strength of
ordinary methylated spirits, whereas maltose, erlucose, etc., are fairly solu-
ble under the same conditions. The method is applicable to the soluble
extracts of bread and flour, malt extracts, and similar preparations.
When there are many such estimations to be made, a fairly large quantity
of methylated spirits, say a gallon, should be redistilled (see paragraph
700), tested against purified dextrin, and reserved for this purpose. To

ESTIMATION OF CARBOHYDRATES. 537

purify dextrin, take some of the best light-coloured dextrin of commerce,
and dissolve in water to about a 15 per cent, solution. Pour some of this,
in small quantities at a time, in about a litre of redistilled spirit in a
large flask, shaking vigorously between each addition. Dextrin will be
precipitated, and should be finely divided, if in sticky clots the solution
has been used too strong, and must be diluted. Filter off this precipitate,
wash with alcohol, redissolve in water, and again precipitate with a large
quantity of alcohol as before. Wash and carefully dry; the resultant
purified dextrin should be colourless and tasteless (save for a slight fla-
vour from the spirit). Dissolve 0.1 gram of the dextrin, and make up to
10 c.c. in water ; add this quantity to 125 c.c. of the redistilled spirit, and
shake well : there should be a slight precipitate. Filter and evaporate 50
c.c. to dryness in a weighed dish, and thus determine the amount of dex-
trin dissolved by the particular sample of spirit. Note same in calculated
weight of dextrin held in solution per 270 c.c.

In making a determination, prepare, if possible, a solution of such a
strength that 20 c.c. shall contain approximately 0.2 gram of dextrin.
Add this to 250 c.c. of redistilled spirit in a flask, cork, and shake up :
allow to stand a few hours, then pour off the clear, supernatant liquid on
to a counterpoised filter, disturbing the precipitate as little as possible.
Add 100 c.c. more of redistilled spirit to the precipitate, and shake vig-
orously, then transfer the dextrin to the filter, washing out the paper
with the clear spirit filtrate; dry and weigh against the counterpoise,
which must be washed successively with the first and second spirit fil-
trates. Add on to the weight thus found the 270 c.c. solubility correction.
(The 100 c.c. of spirit used for washing does not redissolve any weighable
quantity of the precipitated dextrin.) At times the dextrin precipitate
sticks somewhat to the flask : in such cases rinse first with a little alcohol,
and then dissolve out with a small quantity of water, and evaporate to
dryness in a weighed dish. Add the quantity thus found to the total.

As in some cases the spirits may precipitate proteins as well as dex-
trin, it is advisable, where special accuracy is required, to make a nitro-
gen determination in the dry precipitate. For this purpose fold up the
filter paper, and Kjeldahlise it together with the precipitate in the usual
manner. Deduct the weight of protein from the total weight of pre-
cipitate.

Occasionally the proteins present will not separate, and produce an
opalescent liquid which filters badly and extremely slowly. In this case
make a fresh estimation, using stronger spirit, say 92-94 per cent., for
precipitation. Let it stand at least 12 hours, or till clear, then wash the
precipitate three times by decantation in the flask, shaking vigorously,
and allowing to subside each time, using for this purpose the weaker
spirit. Collect and weigh as before. In this case make a special test for
the correction with some purified dextrin, operating in the same manner,
and evaporating down known fractions of the lots of spirit used.

It should be added that alcohol precipitates in this manner not only
dextrin, but also other gum-like bodies present, which are frequently
returned in analysis as "indeterminate matters/'

688. Polarimetric Estimations.— In addition to the method already
described of estimating maltose and dextrin by means of Fehling's solu-
tion, there is a second process in which certain optical properties of these
bodies are employed in the determination of dextrin, instead of hydrolys-
ing that substance into glucose by means of dilute acid. This particular
modification is of special value as a part of the process, to be hereafter
described, of the estimation of starch, consequently it requires careful
explanation.

538 THE TECHNOLOGY OF BREAD-MAKING.

As has been already stated, the sugars, in common with several other
bodies, are capable of rotating the plane of polarisation of a ray of light.
They possess this property not only in the solid state, but also when in
solution; further, the amount of rotation is very nearly proportional to
the degree of concentration of the solution.

689. Specific Rotatory Power. — The angular rotation of a ray of
polarised light by a plate of any optically active substance, 1 decimetre
(3.937 inches) in thickness, is termed its "specific rotatory power." In
most substances this has to be obtained by calculation, because of the diffi-
culty of getting transparent plates of a sufficient thickness. A solution of
known strength is prepared, and from the rotatory power of this solution
the specific rotatory power may be calculated. The rotatory power of so-
lutions of the same strength may vary with the temperature, and also
with the solvent employed, hence it is necessary to note the strength of
the solution at the time of the estimation, and also the solvent used. The
apparent or sensible specific rotatory power of a substance is found by
dividing the angular rotation observed in the polarimeter (a) by the
length of the tube in decimetres (I, usually ==2) in which the liquid is
observed, and by the degree of concentration (c), that is the number of
grams in 100 c.c. of the liquid. S being the specific rotatory power, then
the above is represented by the formula —

g== __? == IQOa

" * X nfo l X c

The rotatory power of a substance depends on the nature of the light
used ; as the instrument to be described is one in which the yellow mono-
chromatic light of the sodium flame is employed, all numbers given will
be for light of that description, which is often indicated by the symbol So.

In measuring rotatory powers of sugars it has been found convenient
to take a plate of quartz, 1 millimetre in thickness, as the standard of
comparison. According to the latest and most accurate measurements,
such a plate produces an angular rotation of 21° 44' = 21.73° for the
sodium flame (So). The strength of the cane sugar solution which, in a
tube 2 decimetres in length, shall exercise the same rotary power, is that
equal to 16.350 grams of sugar in each 100 c.c. of the solution.

100X21.73

2 X 16.350
as the specific rotatory power of cane sugar.

All sugars do not rotate the plane of polarisation in the same direc-
tion : thus, some twist it to the right, or in the direction of the hands of
the clock, others twist it towards the left. The terms dextro- and laevo-
rotation are applied to the right-handed and left-handed rotation respec-
tively. Also the symbol -[-is used to represent dextro- and — to repre-
sent laeevo-rotation. The specific rotatory power of substances varies
somewhat with the degree of concentration of the solution. For a solu-
tion of approximately 10 per cent, strength, that of substances of impor-
tance in connection with the chemistry of wheat and flour is appended : —

Specific
Substance. Formula. Rotatory Power.

Cane Sugar C12H22On + 66.5°

Maltose C12H22Oia + 138.3°

Glucose, Dextrose C6H1206 + 52.5°

Fructose, Lsevulose C6H1206 - 98° at 15° C.

Invert Sugar 2C6H12O6 - 22.7° at 15° C.

Dextrin C6H1006 + 200.4°

ESTIMATION OF CARBOHYDRATES.

539

690. The Polarimeter.— In order to measure the amount of rotatory
power possessed by various bodies, an instrument known as a polarimeter
is employed (sometimes spoken of incorrectly as a "polariscope"). There
are various forms of this instrument, but one of the simplest is that
known as the half -shadow polarimeter or "saccharimetre a penombres."
A well-known make of this instrument is illustrated in Fig. 87.

FlG. 87. — Half-Shadow Polarimeter and Vernier.

By means of a specially constructed bunsen lamp, a sodium flame is
produced, and toward this the end, 8, of the polarimeter is directed while
employing the same. When using the polarimeter it is well to work in a
room from which all light other than that of the sodium flame is excluded.
The instrument consists essentially of a tripod support, carrying a hori-
zontal frame, in which is placed the tube filled with the solution under
examination, and having at the one end, P, the polarising prism, and at

the other the analyser, A, together with a
small magnifying arrangement used as an eye-
piece, F. Immediately behind the analyser,
A, is the disc, K, on which is engraved the
scales of the instrument. Following this is
the trough with hinged lid, in which are placed
the tubes containing the liquid under exami-
nation.

691. Polarimeter Tubes. — These are now
usually made of glass and are fitted at the
ends with brass caps. Those most commonly
used are exactly 20 centimetres in length from
end to end inside the caps. The left-hand
illustration, Fig. 88, represents the tube with
the ends screwed on ; the other shows the tube
in section. Each cap contains a glass plate
which fits accurately to the end of the tube;
above the glass plate is a washer of leather ; on
screwing on the cap this washer exerts an
equable pressure on the glass plate, and so
makes a water-tight joint. The mistake must
not be made of placing the washer inside in-
stead of outside the glass plate. When using
the tube, it is first cleaned, then dried, or
rinsed with a few drops of the liquid under
examination; one of the caps is next screwed
on. The tube is then filled with the solution,
any bubbles are allowed to escape, and then

FIG. 88.— Polarimeter Tube.

540

THE TECHNOLOGY OF BREAD-MAKING.

the second glass plate is slidden over the end and screwed tight by means
of the cap. If properly filled, the tube should contain no air, neither
should it leak. If there should be any tendency to leakage, it may be
prevented by very slightly greasing the ends of the tube. It will be
evident that such a tube contains a layer of the liquid exactly 20 centi-
metres in length.

692. Polarimeter Tube, with Thermometer. — Fig. 89 shows a polari-
meter tube of slightly diiferent eonstruction : it is in the first place 22
instead of 20 centimetres long. On the top there is a tubulure, by which
a thermometer is inserted in order to determine the temperature of the
solution at the time the estimation is made. The use of this particular
form of tube will be described hereafter.

FIG. 89. — Polarimeter Tube, with Theimometer.

693. Verification of Zero of Polarimeter. — The first operation to be
performed in starting work with a new polarimeter is to verify the zero
of the graduated scale of the instrument. The commonest and most gen-
erally useful form is a scale graduated into angular degrees, namely, 90°
to the right angle, or 360° to the whole circle. In addition to, or instead
of, the angular scale, some instruments are provided with a sugar scale.
This latter is a scale of 100 degrees, so arranged that when a specified
quantity of cane sugar is taken, the number of degrees indicated by the
polarimeter represents the percentage of pure sugar without any calcula-
tion. For present purposes, the angular scale only need be considered.
On the dial of the instrument being described there is engraved a whole
circle of 360° graduated into half-degrees, the zero being on the right-
hand side, and the degrees reading upward and to the left, right round
to 360. There are two fixed vernier scales, n, n, one on each side of the
dial. Two magnifying glasses, I, I, are provided in order to read the
scales. By means of the milled head, T, the dial may be readily rotated
in either direction, together with the eye-piece and analysing prism. To
make this verification of the zero, commence by placing some fused
sodium chloride in the platinum spoon of the bunsen lamp, then light the
bunsen, and turn the spoon into the flame, so that an intense yellow light

ESTIMATION OF CARBOHYDRATES. 541

is produced. Arrange the axis of the instrument in the direction of the
flame, so that on looking through the eye-piece a brilliant yellow field is
seen. Next fill one of the 20 centimetre tubes with distilled water, and
put it in its proper position in the polarimeter. Place the zero of the
vernier in coincidence with that of the scale, and look carefully through
the instrument in order to see whether both halves of the field are equally
illuminated. Turn the milled head, T, very slightly in either direction ;
one half of the field becomes dark, and the other lighter. Now focus the
eye-piece, F, by drawing it out or pushing it in until the vertical line,
dividing the two halves of the field, is sharply defined. Having focussed
the eye-piece, turn T back again until the two halves of the field are
equally illuminated : note the position of the vernier and see whether it
coincides with the zero of the scale. (For reading the vernier use the
eye-piece, Z, drawing it in or out until the scale is sharply in focus.)
Should the two agree, once more displace T, and again bring it back to
the position in which the two halves of the field are equally bright, and
read the vernier. Observe whether the two readings of the zero are alike.
If the zero of the instrument is found correct, well and good, but if not,
turn T until the zero of the vernier is exactly over that of the scale ; then
slacken the milled heads immediately underneath A, and screw in or out,
until the two halves of the field are of the same depth of tint. Make this
adjustment most carefully; when once made, re-tighten these milled
heads until the tube A is securely fixed in the correct position. The
instrument will then be permanently in adjustment.

The pointer, h, is used for the purpose of regulating the degree of
sensitiveness of the instrument. The nearer the pointer is to zero the
darker is the half-shadow side of the field for the same amount of angular
displacement of the zero of the angular scale, and therefore the more
sensitive is the reading. With absolutely transparent solutions, h may be
fixed at zero, but with solutions that are not quite clear, the pointer must
be moved slightly away from zero so that sufficient light may pass
through. When h is moved, the zero of the dial plate must again be
adjusted by means of the milled heads under A. Usually, when the
instrument is received from the makers, h is arranged in the most con-
venient position for general work, and the zero of the instrument
adjusted accordingly.

694. Method of Reading with Vernier. — To those not accustomed to
the use of the vernier for the purpose of accurately reading graduations
on instruments of exactitude, a few words of explanation of that device
will be acceptable. The vernier is a small scale which slides over the
graduations of the principal scale of the instrument. On the vernier a
length, equal to 29 of the half-degree graduations on the fixed scale, is
divided into 30 equal parts. As a consequence, each division on the
vernier is exactly twenty-nine thirtieths of each on the fixed scale. Bear-
ing this in mind, let us see how the vernier is used in actual work. Sup-
pose that with the polarimeter a sugar solution is placed in the instru-
ment, and the analyser turned until the two halves of the field are illumi-
nated equally. It now becomes necessary to read off the number of
degrees through which the analysing prism has been rotated. On looking
at the scale, we find that the zero of the vernier is between, say 94 and
^94.5 degrees. Look along the vernier scale in the direction of the 95 until
one of the graduations on the vernier exactly coincides with one on the
fixed scale. If this graduation on the vernier is 7 from the zero, then the
accurate reading of the polarimeter is 94° 7' (94 degrees 7 minutes, the
minute being 1/30 of a half-degree, as there are 60 minutes to the

542 THE TECHNOLOGY OF BREAD-MAKING.

degree). In fact, whatever number graduation on the vernier coincides
with one on the other scale, the number of that particular vernier grad-
uation represents the fraction of a half-degree in minutes. This will be
seen to be the case on reflection. A fuller explanation of the vernier may
be found in Ganot's or other work on "Physics."

In Fig. 87, the vernier scale is shown to the right of the illustration.
In that particular instrument the main scale is divided into quarter-
degrees and the vernier scale into 25 parts. Each graduation on the
vernier scale is therefore equal to one twenty-fifth of a quarter-degree, or
0.01°.

695. Polarimetric Estimation of Cane Sugar. — As a matter of prac-
tice the student will do well to make some polarimetric estimations on
pure cane sugar. For this purpose powder finely some clean coffee sugar
crystals, and dry for a short time at 100° C. Make up respectively 10
and 20 per cent, solutions in distilled water, 100 c.c. of each. Fill a two-
decimetre tube with the 10 per cent solution, which must be perfectly
clear and transparent. Prepare the polarimeter for working and intro-
duce the tube. By means of the milled head, rotate the analyser to the
right until the point is attained at which the change from illumination of
the one side of the field to that of the other occurs with great sharpness.
Turn the milled head very slowly, and observe carefully the exact point
at which equal illumination is reached. Read off the number of degrees
by means of the vernier on the right-hand side of the instrument; then
shift the analyser, once more bring it back to the neutral point, and again
read. The two readings should agree to within 2 minutes (2'). If the
sugar be absolutely pure, and the operation performed correctly, the
reading should be precisely 13° 18'. This signifies that the sample under
examination contains exactly 100 per cent, of pure cane sugar. Simi-
larly, if the polarimeter stood at 12° 47', we should state that the sample
contained less than 100 per cent, of pure sugar.

As angular measurements are now frequently expressed in decimals of
a degree instead of in minutes, the following table for the conversion of
one into the other may be of service : —

Minutes — decimals. Minutes — decimals. Minutes — decimals.

1 . . 0.016 11 . . 0.183 21 . . 0.350

2 . . 0.033 12 . . 0.200 22 . . 0.366

3 .. 0.050 13 .. 0.216 23 .. 0,383

4 .. 0.066 14 .. 0.233 24 .. 0.400

5 .. 0.083 15 .. 0.250 25 .. 0.416

6 .. 0.100 16 .. 0.266 26 .. 0.433

7 .. 0.116 17 .. 0.283 27 .. 0.450

8 .. 0.133 18 .. 0.300 28 .. 0.466

9 .. 0.150 19 .. 0.316 29 .. 0.483
10 .. 0.166 20 .. 0.333 30 .. 0.500

The figures 13°18' and 12°47' become 13.30° and 12.783° respectively.
The percentage of pure sugar in the second case can readily be obtained
by calculation : —

12.783 X 100
t—^- : 96.1 per cent.

With the 20 per cent, solution the reading is practically double (sub-
ject to the fact that there is a very slight diminution of specific rotatory
power with increase of concentration of cane sugar). If the sugar be
pure the reading is 26°36' or 26.6°, or with the same degree of impurity
as before supposed, 12°47' becomes 25°34' or 25.566°.

ESTIMATION OF CARBOHYDRATES. 543

696. Polarimetric Behaviour of Inverted Cane Sugar. — It has been
already stated that the operation of treating cane sugar with an acid, and
so causing it to precipitate cuprous oxide from Fehling's solution, is
termed "inverting" the sample. The reason is, that a solution of sugar
thus treated rotates the plane of polarisation to the left instead of to the
right. Take a flask having two marks on the neck, one at 50 and the
other at 55 c.c., fill up to the 50 c.c. mark with the sugar solution, and
then add 5 c.c. of pure fuming hydrochloric acid. Next heat the flask in
a water bath until its contents have acquired a temperature of 68° C. ;
this operation should be so arranged as to occupy about 10 minutes. Cool
the flask by immersion in cold water. Fill the 22 centimetre tube with
this solution, insert the thermometer, note the temperature and read the
amount of rotation, which will be left-handed, with the polarimeter ; that
is to say, the dial must be turned toward the left instead of the right in
order to reach the critical point of equal illumination. That having been
done, the reading must be taken : in the instrument described, the point
on the left hand of the dial, corresponding to zero, is 180 degrees, and the
reckoning is usually taken from that point. Working with the 10 per
cent, sugar solution, and assuming its purity, and that the thermometer
registers 15° C. as the temperature of the solution, then the scale of the
polarimeter read on the left-hand vernier stands at 175°28'. As 180 cor-
responds to zero, this amounts to the minus reading of 4°32'.

180° - 175°28' = = 4°32' = = 4.533°.

In order to distinguish them as left-handed readings, the minus sign
is placed before the reading thus, — 4°32' or — 4.533°. The reason for
having a tube 22 centimetres in length will be evident; the addition of
5 c.c. of acid to 50 c.c. of sugar solution will have diluted the solution to
11/10 of its former volume. When the reading is taken in a 22 centi-
metre tube, that also is 11/10 of the length of the 20 centimetre tube,
consequently a depth of liquid equal to 20 centimetres of the sugar solu-
tion before inversion is looked through. Working in this manner, no cal-
culation is necessary for the dilution resulting from the addition of the
acid. Careful observation has shown that a solution of cane sugar which
before inversion had a right-handed specific rotatory power of + 66.5°,
gives after that operation a rotation of 22.7° to the left, provided the
temperature of the inverted solution is 15° C. Calculated in terms of
specific rotatory power, the plane of polarisation is therefore, by the oper-
ation of inversion, rotated through 89.2°. As has been stated, inversion
produces from the one molecule of cane sugar two molecules of glucose,
one each of dextro-glucose and Ia3vo-glucose. This latter body has a
diminished rotatory power at high temperatures, and hence it becomes
necessary to read the temperature at which the observation is made. At
a temperature of 0° C. the range of inversion is 94.1°, and diminishes
approximately by one angular degree for every three degrees rise in tem-
perature, or 0.33 of an angular degree for each degree rise in tempera-
ture. This rate of diminution gives 89.2° for the temperature of 15° C.
If possible the readings of the inverted sugar solution should be taken at
15° C., or failing that, at as nearly as possible that temperature. The
correction per degree amounts to approximately 1/270 = 0.0037 of the
'total range of inversion. Thus if the reading be taken at 18° C., the
angular range will require to be increased by 3/270 of its total quantity.

A convenient way of expressing rotatory power is in that of
"Rotatory power per gram in 100 c.c., the observations being made in a

544 THE TECHNOLOGY OP BREAD-MAKING.

2 decimetre tube/' The figures thus obtained are one-fiftieth of the
specific rotatory power, and are as follows : —

Rotatory Power per Gram.

Cane Sugar 1.33°

Maltose 2.77°

Glucose, Dextrose . . . . . . . . 1.05°

Fructose, Lasvulose —1.96° at 15° C.

Invert Sugar — 0.45° at 15° C.

Change due to Inversion of Cane Sugar . . 1.78° at 15° C.

Dextrin 4.01°

Thus in the 10 per cent, pure sugar solution, the reading of 13.3°, on
oeing divided by 1.33 gives 10, showing that there are present 10 grams
of sugar in the 100 c.c. Similarly the amount of change as observed is

13.3 + 4.533 = 17.833.

On dividing this by 1.78, the result is again 10, confirming the previ-
ous determination of there being 10 grams of sugar present in the 100 c.c.
In event of the sugar containing 10 per cent, of moisture, the right hand
reading would only amount to 11.97° or 9/10 of 13.3°; similarly, the
reading after inversion and calculation to 15° C. would amount to
-4.08°. The amount of change would then be 11.97 + 4.08 = 16.05.
On dividing -this as before by 1.78, the result is again 9, confirming the
determination by direct reading on the unaltered sugar. If, on the other
hand, some substance, as glucose, were present which is not capable of
inversion by the method adopted, then the left-hand reading would be
less than the theoretical amount for cane sugar. Thus the polarimeter
affords not only a means of observing the percentage of sugar present in
a sample, but also gives valuable indications as to the nature of the
impurity.

In making polarimetric estimations of cane or other sugar or sac-
charine body, 20 grams may be taken and made up to 100 c.c. In the
case of cane sugar, the polarimeter readings may be divided by the fol-

1 ^^ 1 78

lowing factors -^— = 0.266 for direct reading, and ' = 0.356 for
o o

amount of change due to inversion. The result is the percentage of
sugar direct.

697. Polarimetric Determination of Dextrin and Maltose. — Atten-
tion must next be directed to the method of using the polarimeter for
estimating the amount of dextrin in a liquid containing both dextrin and
maltose. Should the liquid contain any coagulable proteins, they should
first be removed by heating a known weight of the liquid for a few min-
utes in the hot-water bath, making up the lost weight with distilled water,
and then filtering. It may happen that the liquid is not sufficiently clear
to be transparent in a layer of so much as 20 centimetres ; it may then be
clarified by treatment with animal charcoal in the following manner: —
Add to the solution, in a flask, about one-fifth of its volume of powdered,
recently ignited, pure animal charcoal.1 Shake up vigorously for a few
minutes, and pass through a dry filter. Return the filtrate to the paper
until it comes through perfectly clear. It is usually preferable, however,
instead of treating with charcoal, to dilute the liquid with water, as char-
coal apparently exercises an absorbent effect on some of the carbohy-
drates. Subject to this reservation, for the polarimetric reading, as con-
centrated a solution as possible should be taken, and the observation made

1 To prepare this, take 1 Ib. of pulverised animal charcoal (bone charcoal)
and boil with 2 quarts of commercial hydrochloric acid, diluted with 1 gallon
of water. Filter through calico, and wash with water till free from acid, dry
and isrnite to redness in a closed crucible. Store in a well-stoppered bottle.

ESTIMATION OF CARBOHYDRATES. 545

in the 20 centimetre tube. After reading with the polarimeter, dilute
down to the right strength, and estimate maltose by Fehling's solution.

Knowing the quantity of maltose present, in order to calculate the
proportion of the polarimetric effect due to dextrin, the amount of rota-
tion due to maltose must be calculated. On multiplying the number of
grams of maltose in 100 c.c. of the solution by 2.78, the result is the
angular rotation due to the maltose. Subtract this number from the
observed angular rotation, and the remainder is the angular rotation due
to dextrin. This angular rotation, on being divided by 4.01, gives the
grams of dextrin in 100 c.c. of the liquid. From these data the per-
centage of dextrin and maltose in the original substance may be cal-
culated.

As an illustration of the polarimetric estimation of dextrin, the fol-
lowing example of the analysis of a sample of wheat germ is given. A 10
per cent, solution of the substance was made with cold water, filtered,
shaken up with animal charcoal, and again filtered until clear. The clear
solution was weighed in a beaker, raised to 100° C. in the water bath,
made up to original weight, and filtered from the coagulated albumin.
The reading with the polarimeter was 2.00° to the right. A maltose esti-
mation was made with 20 c.c. of the solution to 25 c.c. Fehling's solution,
and 50 c.c. of water. The resulting precipitate was in this instance con-
verted by ignition into cupric oxide (CuO) and weighed as such, then—

Wt. of CuO, 0.1515 X 0.7257 = 0.1099 gram of maltose in 20 c.c. of
10 per cent, solution.

0.1099 X 5 = 0.5495 gram of maltose in 100 c.c.

0.5495 X 10 = 5.495 per cent, of maltose in the substance.

Then, 0.5495 X 2-^8 = 1-52 = angular rotation due to maltose.

Total angular rotation, 2 — 1.52 = 0.48 — angular rotation due to
dextrin.

j^ = 0.12 gram of dextrin in 100 c.c.

0.12 X 10 = 1.20 per cent, of dextrin in the substance.
698. Estimation of Starch. — This estimation may be roughly made
by retaining for examination the whole of the washings from the gluten
test for wheat or flour. For this purpose wash the dough in small
quantities of water at a time until the water remains clear, the washings
being poured into a large beaker. Stir the starch and water thoroughly
together, and then strain through a piece of fine silk into a second clean
beaker, in order to recover any fragments of gluten that may possibly
have been in the first instance forced through the silk. Having washed
the whole of the starch through the silk, stand the beaker aside, in order
to allow the starch to subside. Counterpoise a pair of filters and arrange
them in funnels one under the other, so that the lower receives the filtrate
of the upper. Remove the lower funnel and pour the supernatant liquid
from the starch on to the upper filter ; as soon as the filtrate runs clear,
replace the second funnel and continue the filtration, finally rinsing the
whole of the starch on to the filter; wash with distilled water and dry,
first for a few hours at 40° C., and afterwards in the hot-water oven.
The reason for first drying at a low temperature is to prevent the gelatin-
isation of the starch ; this preliminary drying may generally be done on
the top of the hot-water oven. The counterpoise filter may, of course, be
dried direct in the oven, and at the end weighed against the starch and
filter. The process of drying is much accelerated by giving the starch a
final washing with 95 per cent, alcohol so as to remove the water. This

546 THE TECHNOLOGY OF BREAD-MAKING.

treatment gives the weight of starch cells of the wheat or flour. These, it
must be remembered, contain a certain quantity of starch cellulose.

699. Estimation of Soluble Starch by Conversion into Dextrin and
Maltose. — For more refined estimations the method of first converting
the starch into dextrin and maltose, and then determining those bodies, is
preferable. O 'Sullivan gives, in the Journal of the Chemical Society for
the year 1884, a description in detail of his method of making such esti-
mations. The method, is based on first removing dextrin, maltose, and
other soluble bodies from the substance by the use of water and other
solvents, then converting the starch into dextrin and maltose by the
action thereon of malt diastase, and then estimating the dextrin and
maltose by Fehling's solution and the polarimeter. The following special
reagents are necessary : —

700. Alcohol. — This reagent is required absolutely free from water
and also mixed with water in different proportions. "Absolute" or
water-free alcohol may either be purchased or prepared in the following
manner : — Take two quarts of the best methylated spirits, add thereto
about half its weight of recently and thoroughly burnt quicklime, shake
up vigorously two or three times a day for 3 or 4 days. The quicklime
will dehydrate the alcohol, by combining with the water present, to form
slaked lime (calcium hydroxide). The alcohol must next be separated
from the lime by distillation. For this purpose arrange a glass flask in
a large saucepan to be used as a water bath. Fit a cork with leading tube
to the neck of the flask, and connect this up to a condensing worm, pro-
vided with a copious supply of water. Be sure that all joints are per-
fectly air tight. Fill the water bath with water, and make arrangements
for securing the flask, so that, as it becomes lighter by the evaporation of
the spirit, it shall not capsize. Pour off the clear alcohol from the lime
into the flask. Introduce a few small sharp-pointed steel tacks: these
will cause the liquid to boil without bumping. Then connect up the
whole of the apparatus, and raise the bath to the boiling point by means
of a bunsen. Collect the distilled spirit in a dry stoppered bottle. It
must be remembered that alcohol is highly inflammable, and therefore
every care must be taken to prevent an accident through fire. The lime
used for the desiccation of the alcohol will still contain a considerable
quantity of spirit; this may in great part be recovered by pouring the
whole on to stout calico and squeezing as much as possible of the spirit
out.

Dry potassium carbonate is perhaps frequently a more convenient
agent for desiccating alcohol. The carbonate absorbs the water, and
forms a heavy solution on which the alcohol floats. When distilling,
both solutions may be poured into the still together, and distillation in a
water bath continued as long as anything comes over. The residual solu-
tion of potassium carbonate may then be evaporated to dryness in an
ordinary iron saucepan, and used again for the same purpose.

Absolute alcohol has a specific gravity of 0.7937 at 15° C. The per-
centage of water is usually obtained by observing the specific gravity by
means of a hydrometer. This is a glass instrument consisting of a
weighted bulb and stem carrying a scale ; the hydrometer, on being placed
in a liquid, floats higher or lower according to its density. The specific
gravity of water is often reckoned, for convenience, at 1000 ; absolute
alcohol is then said to have a density of 793.7. A hydrometer should be
procured from the instrument makers marked in single degrees from 750
to 1000.

' ESTIMATION OF CARBOHYDRATES. 547

Cool down some of the distilled alcohol to 15° C., and pour out into a
hydrometer jar. (This is a tall glass vessel in which the instrument can
just float.) Introduce the hydrometer, and observe the density of the
liquid ; should this be from 795 to 800, the alcohol may be considered for
practical purposes absolute. Mixtures of alcohol and water of the follow-
ing densities are also required :— 820, 830, 860, 880, and 900 degrees.
These may be prepared by adding water to methylated spirit.

Methylated spirit has itself a density of about 820, and, when redis-
tilled, may be used when that strength is directed. The strength of solu-
tions of other degrees of specific gravity is given below.

Specific Absolute Specific Absolute

Gravity, Alcohol, Gravity, Alcohol,

at 15.5° C. by volume, %. at 15.5° C. by volume, %.

1.0000 0.00 0.8599 -81.44

0.9499 41.37 0.8299 91.20

0.9198 57.06 0.8209 93.77

0.8999 65.85 0.7999 98.82

0.8799 73.97 0.7938 100.00

In order to obtain diluted spirits of the other gravities required, water
may be added in the requisite proportion to methylated spirit. As alco-
hol and water, on being mixed, contract in volume (i.e., 50 c.c. of alcohol
and 50 c.c. of water produce less than 100 c.c. of the mixture), the
amount of water to be added to the methylated spirit to produce each
degree of dilution cannot be calculated with absolute exactness, but still
sufficiently near for present purposes. Knowing that alcohol of sp. gr.
of 820 contains 93.77 of alcohol and 6.23 of water, the quantity necessary
to be added is determined by the following formula : —

A = percentage of absolute alcohol in stronger spirit.
a= „ „ „ weaker

W= „ water „ stronger „

w= „ „ „ weaker

Q = quantity of water to be added to 100 c.c. of the lower
sp. gr. spirit to produce the higher sp. gr. spirit.

Then Q== A X w-— W.

From this formula it is found that to 100 c.c. of 820 spirit the follow-
ing approximate quantities of water must be added to produce the spirits
of correspondingly higher gravities : — sp. gr. 830, 3 c.c. ; 870, 21 c.c. ; 900,
43 c.c.

701. Diastase. — Take 2 or 3 kilograms (5 or 6 Ibs.) of finely ground
pale barley malt, add sufficient water to completely saturate it, and when
saturated to slightly cover it. Allow this mixture to stand for 3 or 4
hours, and then squeeze as much as possible of the solution out by means
of a filter press. Should the liquid not be bright, it must be filtered. To
the clear bright solution, add alcohol of sp. gr. 830 as long as it forms a
precipitate, and until the liquid becomes opalescent or milky. Wash this
precipitate with alcohol of sp. gr. 860-880, and finally with absolute alco-
hol. Press the precipitate between folds of cloth, in order to dry it as
much as possible. Then place the precipitate in a dish, and keep under
the exhausted receiver of an air-pump, together with a vessel containing
concentrated sulphuric acid, until the weight becomes constant. The
kind of air-pump known as a mercury sprengel pump is best fitted for
this purpose. Prepared and dried in this manner, diastase is a white,
easily soluble powder, retaining its activity for a considerable time. Store
the substance in a dry stoppered bottle, and keep in a cool and dry place.

548 THE TECHNOLOGY OF BREAD-MAKING.

702. Method of Performing Analysis. — The analytic operation is
performed in the following manner: — Weigh out accurately 5 grams of
the finely ground meal or flour; introduce this quantity into a wide-
necked flask, with a capacity of 100 to 120 c.c. (a 4 ounce conical flask
will be found most convenient). Add sufficient alcohol of sp. gr. 820 to
just saturate the flour, and then 20 to 25 c.c. of ether. Cork the flask,
and set aside for a few hours, shaking up occasionally. Decant the clear
ethereal solution through a filter, wash the residue three or four times
with fresh quantities of ether, pouring the washings each time on the
filter. To the residue add 80 to 90 c.c. of alcohol of sp. gr. of 900 ; re-cork
the flask, and maintain the mixture at a temperature of 35° to 38° C. for
a few hours, shaking occasionally. When the alcohol solution has become
clear, decant it through the filter used for filtering the ether solution, and
wash the residue a few times with alcohol of the strength and tempera-
ture directed above. Wash the residue in the flask, and any that may
be on the filter, into a beaker capable of holding 500 c.c., and nearly fill
the beaker with water. In about 24 hours the supernatant liquid becomes
clear, when gradually decant through a filter. Wash the residue repeat-
edly with water at 35° to 38° C., and then transfer to 100 c.c. beaker.
Take the filter from the funnel, open out the paper on a glass plate, and
remove every particle by means of a camel-hair brush cut short, and a
fine-spouted wash-bottle. Having thus transferred the whole of the
residue, the beaker should not contain more than 40 to 45 c.c. of liquid.
Boil for a few minutes in the water bath, care being taken to stir well in
order to prevent "balling," or unequal gelatinisation of the starch.
After this, cool down the beaker still in the bath to 62° to 63° C., and
add 0.025 to 0.035 gram of diastase dissolved in a few c.c. of water. In
a few minutes the whole of the starch is dissolved, and a trace of the
liquid gives no discolouration with iodine. Continue the digestion for
about an hour, then raise the bath to the boiling point, and boil for 8 or
10 minutes. Pour the contents on to a filter, and receive the filtrate into
a 100 c.c. measuring flask; carefully wash the residue with small quan-
tities at a time of boiling water. Cool the flask to 15.5° C., and make up
its contents to 100 c.c. with distilled water. Should the washings and
solution exceed 100 c.c., they must be evaporated down to that amount.

Take a polarimetric reading of this solution in the 20 centimetre tube.
Five c.c. of the solution is a convenient quantity to take for the estima-
tion of maltose. This is rather a small quantity to measure accurately;
it may, if wished, be weighed instead, or 25 c.c. may be taken and diluted
down to 100 c.c. with water; 20 c.c. of the diluted solution may then be
taken and added to 25 c.c. of Fehling's solution and 50 c.c. of water.
Proceed as before described with the estimations, and calculate the
quantity of maltose from the weight of precipitated Cu20. Calculate the
relative percentages of dextrin and maltose in the usual manner. Starch
produces its own weight of dextrin and 342/324 = 1.0546 its weight of
maltose. To obtain the weight of starch from the dextrin and maltose it
produces, the weight of the dextrin must be added to that of the maltose
divided by 1.0526, or multiplied by 0.95. These calculations will be ren-
dered clear by the study of the following example taken from 0 'Sulli-
van's paper.

In the analysis of a sample of white wheat, 4.94 grams were taken.
The 100 c.c. solution had an optical activity equivalent to 8.52° for So,
and contained 2.196 grams of maltose.

ESTIMATION OF CARBOHYDRATES. 549

2.196 X 2-78 = 6.10°, angular rotation due to maltose. 8.52° — 6.10° =
2.42°, angular rotation due to dextrin. 2.42/4.008 = 0.605 gram of dex-
trin in 100 c.c.

Maltose, 2.196 = starch, 2.196X0.95 = 2.086
Dextrin, 0.605 == starch, 0.605

Total starch = 2.691

~4~Q4 ~ 54.47 per cent, of starch present.

A duplicate analysis on 6.009 grams differed only by 0.03 per cent.

In the absence of diastase, starch may usually be determined with
sufficient accuracy for technical purposes in the following manner: —
Remove by washing or otherwise all other carbohydrates, and gelatinise
the starch by heating with water. From a known weight of the same
variety of starch prepare a solution of approximately the same strength.
Put 50 c.c. of each in a separate flask, and add 50 c.c. of 10 per cent, sul-
phuric acid. Cork the two flasks, and stand in a hot-water bath until a
drop on being taken out gives no reaction with iodine solution. Then
neutralise by adding solid caustic potash in small fragments, until the
solution gives a faintly alkaline reaction to litmus paper ; and precipitate
from 10 to 25 c.c. of the solution, according to strength, with Fehling's
solution. Knowing by the test with pure starch what weight of Cu20 it
precipitates under these conditions, the quantity of starch in the sub-
stance being tested can be readily calculated.

703. Estimation of Dextrin and Soluble Starch. — It occasionally be-
comes necessary to estimate dextrin in the presence of soluble starch, as,
for instance, in bread soluble extracts. The following method may then
be adopted: — Take 20 c.c. of the soluble extract and add to 250 c.c. of
redistilled spirits ; if the precipitate is very little, take double the quan-
tities; filter and proceed with the estimation precisely as previously
directed for dextrin. Control the results by determining proteins in the
dried and weighed precipitate — the residue is a mixture of dextrin and
starch.

Proceed to estimate the starch in the following manner: — Prepare
first of all the following reagents —

0.5 per cent, solution of wheat starch.
5 per cent, solution of sulphuric acid.
Solution of iodine in potassium iodide of sherry tint.

Take two graduated Nessler glasses, and add to each 0.1 c.c. each of
iodine solution and sulphuric acid; make up to 50 c.c. with distilled
water. To one add 0.5 c.c. of starch solution and stir ; to the other add
the diluted soluble extract from a burette until there is the same depth of
blue tint in each. The solution to be tested is conveniently of approxi-
mately the same strength as the standard starch solution. If this first
test shows it to be too concentrated, dilute, and repeat the estimation.
Having read off the solution necessary to match the 0.5 c.c. of standard
starch, add another 0.5 c.c. to the standard in the Nessler glass, and again
run in the extract solution until the colours are of equal depth of tint.
Take the reading, and add another 0.5 c.c., and repeat the titration. In

550 THE TECHNOLOGY OF BREAD-MAKING.

this way three separate readings are obtained, which should closely agree.
The following are results obtained in an actual analysis : —

Standard Starch Solution. Diluted Bread Extract.

0.5 c.c. 0.30 c.c.

1.0 „ 0.55 „

1.5 „ 0.85 „

3.0 „ 1.50 „

The whole of these come very closely together, and it was assumed
that 1.5 c.c. of the bread extract contained as much starch as 3.0 c.c. of
the standard starch solution.

To ensure success with this method of starch estimation the solutions
must be dilute, and there should be no other colour-producing body than
starch present. The iodine must not be in a large excess, but must give
a pure blue colour with starch : too much produces a dirty greenish blue.
But the iodine must be in excess of the starch present. To ascertain this
by trial, after a titration, add a few drops more starch and the colour
should darken. Both tests must be made up with precisely the same
quantity of each reagent.

Having determined the starch in this manner, deduct the amount
from the total of starch and dextrin precipitated by alcohol ; the differ-
ence is dextrin.

704. Estimation of Cellulose. — The student already knows that
cellulose has the same chemical composition as starch, but that it differs
from that body in being insoluble in boiling water. The cellulose or
woody fibre of grain has been estimated at about 10 per cent, of the
whole : but of this much is soluble in the digestive secretions of animals,
particularly those which ruminate, therefore an estimation of cellulose
simply is not the one most valuable to the chemist whose investigation is
made for the purpose of determining the food value of a substance.
What for this purpose should be ascertained is that percentage of the
grain or flour which is ejected from the alimentary canal in an unaltered
condition. A process is therefore selected which is somewhat similar to
the digestive action which proceeds in the stomach, this action being imi-
tated by alternate treatment with dilute acid and alkali.

705. Special Reagents Necessary. — The first of these is a 5 per cent,
solution of sulphuric acid. In a small beaker weigh out 100 grams of the
concentrated acid, and make up to 2 litres. In the next place prepare a
12 per cent, solution of caustic potash by weighing out 240 grams of the
pure dry sticks, dissolving, and making up to 2 litres with water. It is
important that 20 c.c. of the acid solution should be approximately
neutralised by 10 c.c. of the alkali.

706. Mode of Analysis. — Take 5 grams of the meal or flour, and mix
them thoroughly with 150 c.c. of water in a beaker. Stand this in a hot-
water bath, and raise to a boiling heat in order to effect the gelatinisation
of the starch ; stir frequently with a glass rod ; add 50 c.c. of a 5 per cent,
solution of sulphuric acid, and continue the boiling for an hour, stirring
occasionally, and maintaining the volume at 200 c.c. by adding from time
to time a little water. (The proper volume should be indicated by a mark
made with the diamond on the outside of the beaker.) The acid will by
this time have converted the starch into sugar. To this solution next add
50 c.c. of the solution of caustic potash ; this quantity will neutralise the
free acid, forming potassium sulphate, and will leave an excess of alkali
in the solution approximately equivalent to the amount of acid first used.
Again boil in hot-water bath for an hour, adding water to supply that
lost by evaporation, and occasionally stirring. At the end of this time,

ESTIMATION OF CARBOHYDRATES. 551

dilute with cold water, stir, and allow the residue to subside. Wash by
decantation, using large quantities of tap water (provided it is absolutely
free from sediment), pouring as little as possible of the residue on to the
paper. Stout, well-made quantitative filters of about 8 or 10 inches diam-
eter should be employed. Next transfer the residue to the filter, and
wash once with dilute hydrochloric acid, in order to dissolve any calcium
carbonate that may be precipitated from ordinary water by the potash.
Then wash with distilled water till free from acid, and allow the filter to
drain. While still wet, remove the filter paper from the funnel, carefully
spread it out flat on a sheet of glass, and with a wash bottle and short
camel-hair brush, transfer the whole of the residue to a counterpoised
glass dish ; dry in the hot-water oven and weigh. The dry residue multi-
plied by 20 gives the percentage of indigestible fibre in the sample.

ANALYSIS OF BODIES CONTAINING CARBOHYDRATES.

707. Malt. — It is comparatively rarely that for bakers' purposes an
analysis or assay of malt is required. The principal point is the char-
acter and amount of extract it affords on being mashed ; to this reference
has already been made in Chapter XII., paragraph 396. A miniature
mash of the same proportions may be made in the following manner : —
Finely grind the sample of malt, mix thoroughly, and weigh out 158
grams ; mix with about 900 c.c. of warm water, and place in a water bath
maintained at a temperature of 60° C. Let it remain until a drop taken
out after stirring gives no starch or amylodextrin reaction with iodine.
Then raise to the boiling point, cool, and transfer the whole to a litre
flask; make up to the mark with distilled water; pour out into a larger
flask or beaker, and add another 50 c.c. of water. Thoroughly mix, allow
to settle, and take the density of the supernatant liquid, at a temperature
of 15.5° C., by means of the hydrometer. The quantities taken are
equivalent to 40 gallons of wort from 63 Ibs. of malt : the extra 50 c.c. are
allowed in order to provide for the average amount of "grains" resulting
from this quantity of malt. There are thus 1000 c.c. of wort from 158
grams of malt. The percentage of solid extract yielded by the malt is
readily calculated. Thus, supposing in a test the hydrometer density is
1035, then:—

(1035 — 1000) X10 = 90 9 grams of solid extract in IQQO c.c. of wort.

o.oD

As 158 : 100 : : 90.9 = 57.53 per cent, of solid extract.
The whole of the constants in the above may be reduced by one single
factor, 1.644, and we then have

(1035 — 1000) X 1-644 = 57.54 per cent, of solid extract.
For a detailed description of the method for an exhaustive assay of
malt, the reader is referred to Moritz and Morris' Science of Brewing,
pages 452 et seq.

708. Malt Extracts. — The following determinations should be made
in analysing extracts of malt and similar preparations : — Reducing
sugars, cane sugar, dextrin, proteins, water, phosphoric acid (P205),
other mineral matter, specific rotatory power, and diastatic capacity by
Lintner, or other methods hereinafter described. A 10 per cent, solution
of the substance should first be prepared, which, either with or without
dilution, may be employed for the following estimations.

Reducing Sugars. — Take 2 c.c. of 10 per cent, solution, and precipitate
as usual with Fehling's solution (30 c.c.).

552 THE TECHNOLOGY OF BREAD-MAKING.

Cane Sugar. — This is conveniently determined by O 'Sullivan's
method. Take 20 c.c. of 10 per cent, solution, make up to 100 c.c., raise
to 55° C., and add 0.2 gram of solid brewers' yeast (prepared by drying
the liquid yeast on a towel), or compressed distillers' yeast free from
starch, digest in a constant temperature water bath at 55° C. for 4 hours,
make up loss by evaporation (or conduct the operation in a tightly corked
flask), filter, and determine reducing sugars in 10 c.c. by Fehling's solu-
tion. The difference in weight of Cu20 obtained in this and the preced-
ing determination is Cu2O reduced by the glucose from cane sugar, and
is readily calculated into the percentage of that body.

Dextrin. — Take 20 c.c. of 5 per cent, solution, add to 250 c.c. of spirit,
and proceed as described under Estimation of Dextrin, paragraph 687.
Should the amount of precipitate be very small, recommence the estima-
tion, using the 10 per cent, solution. Determine proteins by Kjeldahl's
process in the dried and weighed precipitate ; deduct from the weight of
precipitate, and calculate as dextrin.

Proteins. -^Determine direct by K jeldahl 's process on 1.0 gram of the
extract.

Water. — Take 5 grams of extract, dry till weight is constant in a
platinum basin ; about 36 hours are necessary at 100° C. When speed is
an object, either a smaller quantity (1.0 gram) may be used, or an oven
at 110° C. employed. Or preferably a vacuum drying oven may be used,
in which case the drying may be conducted at a temperature below
100° C.

Ask. — Ignite the dried residue from 5.0 grams (residuum from water
estimation) until a white ash is obtained. Note, the extract sometimes
swells up enormously as it carbonises ; in such cases allow to cool, and
break down the carbonaceous mass so that it lies easily in the dish. (This
should be done on a sheet of glazed paper.)

Phosphoric Acid. — Dissolve the ash in dilute nitric acid (1 to 3), and
proceed with estimation by molybdate and "magnesia mixture" (see
paragraph 653). The ash, less phosphoric acid, gives "other mineral
matter. ' '

Specific Rotatory Power. — Make up a 20 per cent, solution of the
extract, and take a polarimetric reading precisely as described in para-
graph 697 on Polarimetric Determination of Dextrin and Maltose. Cal-
culate out the specific rotatory power both on the whole and the dried
extract : or, if preferred, the rotatory power per gram of either whole or
dried extract may be calculated. For the whole extract, with a 20 per
cent, solution, this is 1/20 of the total angular rotation. Supposing in
the case of an extract the total solid matter to be 80 per cent., and the
observed rotation 32.4°, then

32 4

—g^r- = 1.62° rotatory power per gram of whole extract ;

<u(J

100 V 1 62

and - - = 2.02° rotatory power per gram of dried extract.

o(J

The specific rotatory power may be obtained by multiplying by 50 in
each case.

Calculation of Results. — The reducing sugar of pure malt extracts,
obtained by concentrating the wort produced by total conversion of the
whole malt, consists principally of maltose. On calculating it as such,
and adding together the results of the whole of the determinations given,
there is usually an excess of about 5, or more, per cent, over 100 : this is
due to some of the reducing sugar being glucose instead of maltose. On

ESTIMATION OF CARBOHYDRATES. 553

the other hand, cold water extracts of malt contain only the pre-existent
sugars of malt, considerable proportions of which are glucose : these, if
worked out as maltose, give far too high a result, while if calculated as
glucose, the result is too low. Again the explanation is that in addition
to glucoses there is maltose also present. It is frequently convenient to
be able to estimate approximately the relative proportions of glucoses and
maltose, and this may be done in the manner to be now described. It
should first, however, be mentioned that doubtless malt extracts contain
certain substances which escape determination in all the estimations
previously given; but these cannot in any case represent a large per-
centage of the whole, and for present purposes may be neglected, the
reservation being made that a small part of the percentage returned as
sugar may consist of indeterminate bodies. Assuming that 100, less the
cane sugar, dextrin, proteins, water, and ash, consists of reducing
sugars, then we have

Total reducing sugar by difference in 1.00 grams extract = S.
Weight of cuprous oxide precipitated by 100 grams extract = W.
„ maltose in 100 grams = m.

glucose „ =g.

„ cuprous oxide precipitated by 1 gram of maltose — 1.238

grams.

„ cuprous oxide precipitated by 1 gram of glucose = 1.983

grams.

Then, m + g = S: (Equation No. 1.)
and 1.238 m-f 1.983 g = W. (Equation No. 2.)
From these the values of m and g may be determined thus :—
Multiplying equation No. 1 by 1.983, and subtracting No. 2 from the
product, we get

1.983 m + 1.983 0 = 1.9838
Less 1.238 m -f 1.983 g = W

0.745 m = 1.983 S — W

1.983 S — W

0745

T W — 1.238 S

In the same way g = — -n -_-r-— -

U.745

or more simply, g = S — m.

The following figures were obtained in the analysis of a sample of
malt extract : —

S — 60.5. W = SQ.

m ^(1.983X60.5)- 80^. ^

0.745

S — m = g, therefore 60.5 — 53.65 = 6.85.

The percentages of maltose and glucose are therefore respectively
53.65 and 6.85.

In pure malt extracts obtained by concentration of the wort of the
entire malt, so mashed as to ensure the hydrolysis of the whole of the
starch, the percentage of glucose should not exceed from 1/7 to 1/8 that
of maltose. With highly diastatic extracts containing also a high per-
centage of proteins, the proportion of glucose is as a rule considerably
greater. On comparing the results thus obtained with the specific
rotatory power of the sample, it will be found that the glucose is almost
entirely of the dextrose or right-handed variety.

The other calculations require no detailed explanation.
709. Diastatic Capacity on Lintner's Scale. — For brewing purposes
diastatic capacity is now almost invariably determined by Lintner's
method, and the result expressed on Lintner's standard, or in "degrees

554 THE TECHNOLOGY OF BREAD-MAKING.

Lintner." That standard is: — "The diastatic capacity of a malt is to
be regarded as 100, when 0.1 c.c. of a 5 per cent, solution reduces 5 c.c.
of Fehling 's solution. ' '

For the determination, "soluble starch" and standard Fehling 's solu-
tion are required. The soluble starch must be prepared according to the
method described in Chapter VI., par. 173. The digestion with acid must
be allowed to proceed fully as long as directed, as, unless the starch is
rendered thoroughly soluble, it naturally gives apparently low diastatic
results. It is well during its preparation to test a small portion at the
end of 7 days by thoroughly washing, and then dissolving in boiling
water : the solution must be absolutely clear and limpid. When about to
make an estimation, take 2.2 grams of the soluble starch and dissolve in
hot water, cool, and make up to 110 c.c. If testing a malt or flour, take
25 grams (of course, finely ground) and digest with 500 c.c. at ordinary
temperatures for 5 hours. Filter until perfectly bright. Arrange ten
test tubes in a stand, and add to each 10 c.c. of the soluble starch solution.
Then to the first, add 0.1 c.c. of the malt or flour filtrate, to the second
0.2 c.c., and so on until the last receives 1.0 c.c. Shake them thoroughly,
and allow the whole to stand for 1 hour in a water bath maintained at the
constant temperature of 70° F. During this time the diastase will have
converted more or less starch, according to its strength. Next add 5 c.c.
of Fehling 's solution to each of the tubes, shake up, and place the whole
series in boiling water for 10 minutes. Allow the precipitate to subside,
and note the condition of the tubes ; in some the blue colour will probably
have entirely disappeared, showing them to be over reduced, while others
will still be more or less blue. Select the two tubes lying together in
which one is slightly over and the other slightly under reduced. The
number of c.c. required to give exact reduction will lie between these, and
should be judged according to which it appears the nearest. Thus, sup-
pose as nearly as possible it is exactly midway between Nos. 5 and 6, then
the quantity of malt solution may be taken as 0.55 ; while if No. 5 is full
yellow, while No. 6 is only very faintly blue, then one would give the
quantity as 0.58 or 0.59, according to how near in one's judgment it
appeared to be to the 0.6. With a little practice one soon gets able to
judge very closely this second decimal. If the result of a test gives 0.5
c.c. as the quantity of malt solution required, then the sample is evidently
only one-fifth of the standard strength of 100, or

01^ 100

S^, — =20° Lintner as diastatic capacity.
U.ou

But there is a certain amount of reducing sugar extracted from malt
by cold water, and this also helps to reduce the Fehling 's solution. The
amount of this is determined in the following manner : — Take 5 c.c. of
Fehling 's solution, 10 c.c. of starch solution, and 10 c.c. of water, and
raise to the boiling point in a small flask. To this add the malt solution
from a burette until the Fehling is exactly reduced ; then determine the
apparent diastatic capacity of this solution. Supposing that 7 c.c. have
been run in in order to reduce the Fehling, then

0 1 V 100

V* =1.43°, correction for reducing sugars extracted from the

malt.

For malts the correction 1.4 may usually be taken as a constant, and
the above results become

20 — 1.4 = 18.6° Lintner.

ESTIMATION OF CARBOHYDRATES. 555

Working with malt extracts, the value of the correction becomes much
higher, and must be determined for each individual sample analysed, and
preferably before the diastase estimation. Take a 5 per cent, solution of
the extract, boil, make up to original volume, filter, and titrate on Feh-
ling and starch as above described. In an actual analysis 1.25 c.c. of the
5 per cent, solution were required ; the correction therefore becomes

- ' /p — = 8.0° correction for reducing sugars present.
1.^5

From this it will be seen that the tenth tube in the diastase determination
is nearly reduced by the sugars present alone. The diastase estimation
should now be made : this in the sample in question amounted to 0.73 c.c. ;
then

1— ^— — = 13.7° apparent diastatic capacity.

U. id

13.7 — 8.0 = 5.7° Lintner, real diastatic capacity.

In malt extracts and other diastatic preparations the diastatic
capacity varies very widely, and either none or all of the series may be
completely reduced. In the former case the diastatic capacity must be
less than 10 mimis the correction. Make another diastase estimation with
a 25 per cent, solution of the extract, and multiply the correction by
5 ; the solution being of 5 times strength, the net figure thus obtained
for real diastatic capacity must be divided by 5 in order to give degrees
Lintner. Should there be no reduction in any of the tubes, the diastatic
capacity must be less than 2 minus the correction, which practically
amounts to its total absence.

On the other hand, the whole of the series may be reduced, showing
that the diastatic capacity is more than 100 minus the correction. In this
case make up a 0.625 per cent, solution, and use it for a diastase estima-
tion ; multiply the result by 8, and take the correction as Vs that with the
5 per cent, solution. The following is the result of an estimation on a
diastase preparation made by the authors : —

Correction for reducing sugars on 5 per cent, solution = 8.2°.

All tubes were reduced.

With 0.625 per cent, solution, reduction effected by 0.42 c.c.

0 1 V' 8

""7c> = 190.5° apparent diastatic capacity.

190.5 —

8.2 ]
— = 1 1.02 = 189.48° Lintner, real diastatic capacity,

The three diastase tests made in this manner give a total range of
from 2° to 800° Lintner, and with each test overlapping the other.

In comparing extracts for bread-making purposes, it is sometimes
advisable to also test on starch paste ; in that case proceed exactly as
with soluble starch, except that ordinary starch is substituted and care-
fully gelatinised without "balling."

710. Diastase Tests on Flours. — These may be made by taking a
given quantity of the extract, mixing with flour and water, and digesting
for a given time at some fixed temperature. The amount of matter dis-
solved and maltose produced may then be determined by direct estima-
tions. Full particulars of such determinations follow.

556 THE TECHNOLOGY OF BREAD-MAKING.

A 0.5 per cent, solution is prepared of the extract. Of this, 100 c.c.
(=0.5 gram extract) is taken, added to 25 grams of flour in a corked
flask, shaken vigorously, and digested for 4 hours in a water bath at
140-150° F. A blank experiment is also made with 100 c.c. water and 25
grams of flour only. The contents of the flasks are filtered, and ' ' soluble
extract" and maltose determined in the clear filtrate.

Baking tests afford the most valuable means of testing diastatic value
of extracts for bakers. These tests should be made as directed in Chapter
XXI., paragraph 644, with the extract added to the water. It is well to
take the uniform quantity of the extract equivalent to 1 Ib. to the sack,
2 grams = 20 c.c. of a 10 per cent, solution (the quantity of water used
for dough-making must, of course, be diminished by the 20 c.c. taken with
the extract). Prepare 100 c.c. of the 10 per cent, solution, place half of
it in a flask, weigh, boil for 5 minutes, and make up to the original weight
with water, and call this No. 2. Prepare duplicate loaves, using the No. 1
or unheated extract solution in the first, and No. 2 or boiled solution in
the second. Make up also a plain loaf, No. 3, with the same flour ; com-
pare carefully the character of the three for volume, colour, pile, moist-
ness, flavour, and any other points of interest to the baker. No. 2 will
have had its diastase killed, and will contain only such maltose and other
bodies as are contained in the extract ; No. 1 will contain in addition all
such substances as have been produced by the diastatic action of the
extract itself.

If wished, determinations may be made of soluble extract and maltose
in each of the loaves. The results may then be returnd as shown in blank
below : —

Soluble Extract. Maltose.

Normal Quantities in Plain Bread, deter-
mined in No. 3 . . . . . .

Quantities added in Extract, 'being differ-
ence between Nos. 2 and 3 . .

Quantities produced by Diastatic Action,

being difference between Nos. 1 and 2

Total

In this way any extract can at once be valued both for added and pro-
duced maltose and other substances.

711. Adulterations of Malt Extract, — Malt extract may be adulter-
ated either with molasses (treacle) or glucose syrups. The former of
these may be detected by the large increase in the quantity of cane sugar
present, as molasses contains from 35 to 48 per cent, of sucrose. It also
usually contains considerable amounts of glucose. The so-called sirupy
" glucoses" contain, when conversion has been arrested at the minimum
point, large quantities of dextrin and maltose, and therefore in that par-
ticular closely resemble malt extracts. Commercial "glucose" is, how-
ever, practically devoid of protein constituents, and in this way is de-
tected when used as an adulterant of malt extract. A polarimetric read-
ing affords a valuable indication as to the purity of malt extracts. The
following table gives the result of a number of such readings calculated
to angular rotation per gram of undried substance in 100 c.c., the
observations being made in a 2 decimetre tube.

ESTIMATION OF CARBOHYDRATES. 557

POLARIMETRIC ESTIMATIONS ON MALT EXTRACT, ETC.

Rotatory Power
No. per Gram.

1. Malt Extract of known purity, tested March, 1893 . . 1.59°

2. Same make of Extract, sample taken April, 1893 . . 1.52°

3. Sample of suspected Malt Extract, very light in colour 1.99°

4. Second sample of suspected Malt Extract . . . . 1.79°

5. Lyle's Golden Syrup, obtained personally by author . . 0.52°

6. No. 1 Syrup, lightest colour } Prn f . . . . 1.05°

7. No. 2 „ intermediate TnuL'tTrers ^ ' ' " °'81

8. No. 3 „ darkest j manutacture fe ^. . . . 0.52°

9. "Glucose" Syrup (White Confectioners') . . 2.30°

10. Mixture made personally by authors —

No. 1, 7.07 grams / -, QQO

No. 6, 4.79 „ } •'

Calculated Rotatory Power from quantities taken . . 1.33°

11. Mixture made personally by authors —

No. 1, 7.07 grams ) -, ^0

"XT f\ r* c\r* /•• •• «• •• •• _L«OtJ

No. 9, 6.26 „ j
Calculated Rotatory Power from quantities taken . . 1.89°

Both the suspected samples had abnormally high rotatory powers, and
were probably adulterated with "glucose" syrup; they agree approxi-
mately with No. 11. For comparison with the rotatory powers of the
pure substances refer to paragraph 695.

CHAPTER XXV.
BREAD ANALYSIS.

712. Principles of Bread Analysis. — Having described the methods
to be employed for the determination of the various constituents of
wheat and flour, a short description must now be given of bread analysis.

Many of the properties by which good bread is distinguished from bad
scarcely come within the range of purely chemical analysis. Among these
are the colour, texture, "piling," odour and flavour of the crumb, and
the colour and thickness of the crust. In the kind of bread known tech-
nically as "crumby" bread, the colour and texture of the joint between
two loaves is to be observed. The analyst, in reporting on bread, should
examine the loaf so far as the above characteristics are concerned, and
include his opinion on the same in his report. In judging each, he may
adopt the plan of employing a series of numbers, say 1 to 10, and using
the lowest number for the worst possible grade, and the highest for the
very best. Or he may use instead the terms V. B., very bad ; B, bad ;
1, indifferent; M, moderate; G, good; V. G., very good; E, excellent. In
either case the same term must, so far as is possible, be applied to the
same grade of quality, whether of texture, colour, or other characteristic.

713. Colour. — The baker's use of this term involves a contradiction;
it is the custom of the trade to speak of a loaf as "having no colour"
when a dark brown, while in the purest white loaf the colour is said to be
"high." This is, of course, exactly opposite to the correct use of these
terms, for white is strictly no colour, while a yellow or brown body is
strongly coloured. It would be a better plan if the respective terms were
"lightly coloured" and "strongly or deeply coloured." Judging colour
by itself alone, the loaf should be a very light yellow or creamy tint,
approaching almost to whiteness. This colour is selected because the
authors are of opinion that, judging bread by the eye alone, the slightest
yellow hue is more agreeable than an absolute snowy whiteness. The
Jatter, perhaps from its frequent association with absence of flavour, is
unpleasant.

It must be remembered that colour, etc., are matters of individual
taste and opinion, and therefore that each individual has his own stand-
ard of comparison. In forming a judgment one naturally most appreci-
ates that in accordance with one's own standard; it does not necessarily
follow that such judgment shall absolutely agree with that of another
person. It is a well-known fact that in different localities the standard of
taste in these matters varies.

For actual measurement of bread colour, the method of testing with
the tintometer should be employed; or baked loaves may be compared
against those similarly prepared from standard samples of flour.

714. Texture. — The texture of a loaf is best observed by cutting it
in two with a very sharp knife. There should be an absence of large
cavities, and also of dry lumps of flour. The honeycombed structure of
the bread should be as even as possible. The bread should not break
away easily in crumbs, but should be somewhat firm. On being gently

BREAD ANALYSIS. 559

pressed with the finger the bread should be elastic, and should spring
back without showing a mark on the pressure being removed.

715. Proof. — Like many other trade terms, this is used in a some-
what different sense in different localities. It usually has reference to the
degree of rise in volume a loaf undergoes before being put in the oven.
In this sense, by a well-proved loaf is understood one that has risen well,
both in the dough stage and after being placed in the oven. It almost
goes without saying that in judging the quality of a loaf the baker likes
it to be as large as possible. Such an opinion is a sound one where size
of the loaf is combined with evenness of texture, and is not the result of
the presence of large cavities in the bread. The opposite of a well-proved
loaf is a heavy one ; hence this matter of the proof of a loaf is of impor-
tance. The loaf which in this particular looks the best is that which is
most digestible and wholesome.

There is another sense in which the term "proof" is applied: thus,
two loaves may have risen equally well, and yet the one be regarded as
being better proved than is the other. The well-proved loaf is, under these
circumstances, viewed as that in which fermentation has proceeded until
the flavour of the bread (the bouquet, if the term may be borrowed) has
developed to the greatest perfection. The well-proved loaf will be sweet
and nutty in flavour, and have all the characteristics of being thoroughly
cooked ; the badly-proved loaf will be lacking in flavour, and have what,
for want of a better expression, may be called a "raw" taste. Un-
doubtedly, this use of the term "proving" refers to a difference which
does exist in the two loaves, a difference which in all probability is due
to the more or less perfect proteolytic action of the yeast on the proteins
during fermentation. The term proof is therefore used in two different
senses, one as a measure of the volume of the loaf, the other as an indica-
1ion of the extent to which the changes accompanying fermentation have
proceeded.

716. Pile. — This is essentially a term referring to the texture of the
crumb of bread, and is doubtless derived from the use of the word "pile"
as indicating the texture of the surface of velvet. In a letter, of which
the following is the substance, Mr. W. A. Thorns explained to one of the
authors the exact sense in which the term is used in Scotland: — "By a
well-piled loaf we do not understand a loaf well risen. Pile is the gloss
of the outside skin, or crumb of close-packed bread, and the more un-
broken the skin, the more silky in feel and glossy in sheen, the higher we
rank the pile. Undoubtedly a well-piled loaf must also be a well-risen loaf.
They have that in common, but a well-risen loaf may be ragged, broken-
skinned and dark, without being over proved ; such a loaf we call coarse,
and say it has a bad or no pile. Proof, in dough or baked bread, refers
to volume or size. These qualities, proof and pile, are due to the same
factor, carbon dioxide, acting on and distending the gluten, and it is the
condition of the gluten at the time in the oven, when the dough is pass-
ing into bread, that determines the pile. The condition, good or bad, of
the gluten in this transition state may be due to the condition of the
flour, the proportion of gluten it contains, or to the action of the yeast
and its by-products on the gluten during the entire fermentation. Un-
healthy yeast will produce an abnormal proportion of acids, and acids
render gluten first friable and then soluble. At the friable stage, bread
may be high, badly shaped, dark and ragged, but deficient in pile."

717. Odour. — This is best judged by pulling a loaf open and burying
the nose deep in the cleft. The bread should have a nutty, sweet smell ;
this denotes the highest degree of excellence so far as this quality is

560 THE TECHNOLOGY OF BREAD-MAKING.

concerned. There may be an absence of smell, or what is perhaps most
forcibly described as a mawkish and damp odour; these belong to the in-
different stage. The bread may smell sour, in which case an unfavourable
opinion is naturally formed. Beyond these are the smells, approaching
to stenches, arising from butyric, ropy, and even putrid fermentation.

718. Flavour. — This of course is one of the most crucial tests to
which bread can be put. It is probably the only one adopted by the vast
majority of the bread-eating public. Fortunately, the judgment based on
flavour is almost invariably a sound one ; a bread which pleases the palate
is usually one that is wholesome. Having made this statement, it may be
well also to indicate one direction in which the palate test is untrust-
worthy; many people are extremely fond of hot rolls for breakfast.
These luxuries are not, however, to be indulged in by every one, for hot
bread is not easily digestible. The reason is a simple one ; the soft nature
of bread, while still warm, causes it to be formed into balls in the mouth,
which are swallowed without the due admixture with saliva.

When tasting bread, nothing having a strong flavour should have been
eaten for some little time previously; a small piece of the bread should
be put in the mouth, masticated, and allowed to remain there a short time
before being swallowed. The flavour should be sweet, and of course
there must be an absence of sourness or any marked objectionable taste.
The physical behaviour of the bread in the mouth is also of importance.
The bread should not clog or assume a doughy consistency in the mouth ;
neither, on the other hand, must it be dry or chippy. In addition to tast-
ing the dry bread, a slice spread with butter may be eaten. It need not
be said that in this test the butter must be unexceptionable.

719. Colour and Thickness of the Crust. — The crust should be of a
rich brownish yellow tint ; neither too light on the one hand, nor too dark
on the other. So far as is consistent with adequate baking, the crust
should be as thin as possible.

The act of baking changes the character of several of the constituents
of the flour. Thus, the albumin is coagulated, and thereby rendered in-
soluble. The starch is partly, at least, rendered soluble by the gelatinisa-
tion consequent on heating. The fatty matters of the flour are un-
changed; at times, however, bread is found to contain fat over and
above that normally present in flour. In fancy bread, butter or milk is
sometimes used in the dough ; small quantities of lard are also employed
by some bakers in order to give a special silkiness to the fracture where
two loaves of crumby bread are separated from each other. The ash is
not materially affected in quantity, except in so far as it is increased by
the addition of salt. The water varies considerably. Subjoined are the
results of some analyses collected by Konig and quoted by Blyth. A num-
ber of others by the authors are given in various parts of this work : —

Mean for Mean for
Mini- Maxi- Fine Coarse

mum. mum. Bread. Bread.

Water 26.39 47.90 38.51 41.02

Nitrogenous Substances . . 4.81 8.69 6.82 6.23

Fat 0.10 1.00 0.77 0.22

Sugar 0.82 4.47 2.37 2.13

Carbohydrates (Starch, etc.) . . 38.93 62.98 49.97 48.69

Woody Fibre 0.33 0.90 0.38 0.62

Ash 0.84 1.40 1.18 1.09

720. Quantity of Water in Bread.— The question may fairly be
asked — On what principle is a decision to be made as to whether a bread

BREAD ANALYSIS. 561

contains too much water ? In reply, the loaf having become cool, say 2
hours after being removed from the oven, should on being cut feel just
pleasantly moist, not dry and chippy, nor on the other hand in the
slightest degree sticky or clammy. A second loaf, on being examined in
the same way when 2 days old, should answer to the same tests, and
should not show the slightest signs of sourness or mustiness. Some loaves
of bread containing even 40 per cent, of water would very well pass this
examination; while others which might contain much less water would
nevertheless be damp and sodden, rapidly turning mouldy or sour. Not-
withstanding that the latter contained absolutely the less water, they
would still be condemned as containing more than they ought ; while the
former would be returned as coming within the limit. The quantity of
water permissible in a bread must depend on the nature of the flour used ;
the offence is not in using sufficient water to a strong flour, but in adding
more to a weak flour than it can properly take.

Another question arises — Would it not be well for the public to insist
on being supplied with bread made from such flours as normally require,
for their conversion into bread, a low proportion of water? Again, in
reply, the strongest flours — that is, those which naturally absorb the most
water — are made from the most nutritious, soundest, best matured, and
highest class wheats ; so that the baker who uses a flour with high water-
absorbing capacity, uses also a high priced flour.

721. Standard for Moisture. — By legal enactment the quantity of
moisture present in bread of standard quality may not exceed 31 per cent,
in the district of Columbia, U. S. A. (Foods and their Adulteration,
Wiley.)

As against this, Wiley regards 35 per cent, of moisture as being the
average quantity in typical American high-grade bread (see paragraph
525).

As an example of excessive water, Cameron states that bread supplied
in August, 1896, to the troops at Clonmel, county of Tipperary, Ireland,
contained per 100 parts : —

Water 58.28

Organic Matter 40.57

Ash . . 1.15

100.00
(Analyst, 1896, p. 255.)

722. Analytic Estimations. — In an ordinary analysis of bread, where
the object is not to test for adulteration, the estimations given below may
be made. A thin slice should be cut from the middle of the loaf, the
crust cut off, and then the interior portion crumbled between the fingers ;
the crumbs must be thoroughly mixed, and at once placed in a bottle.

Moisture, Ash, and Phosphoric Acid. — Determine as directed in para-
graph 708 on Malt Extracts.

Proteins. — Determine by Kjeldahl's method on 1 gram of the bread.

Acidity. — Take 10 grams of the bread, grind up in a mortar with a
small quantity of water, transfer to, a flask, and make up to 100 c.c. Allow
to stand for an hour in a boiling-water bath, cool, and titrate with TV/10
soda, using phenolphthalein as an indicator. The acidity may be calcu-
lated as lactic acid.

Fat. — Direct extraction of bread with ether or light petroleum spirit,
however long continued, gives too low results, owing to the fat being en-
closed by the starch and dextrin. The results are lower than those ob-
tained from the flour from which the bread was made. The following

562

THE TECHNOLOGY OF BREAD-MAKING.

method, slightly modified from that suggested by Weibull, gives trust-
worthy results, but it is necessary to work exactly as follows : — 4 gra ms
of new or 3 grams of stale bread or dried bread solids are put into a 70
c.c. beaker, and covered with 15 c.c. of water, after which is added 10
drops of dilute sulphuric acid (25 per cent.). The beaker is then placed
in an ordinary saucepan containing a little water, the lid put on, and the
contents boiled gently for at least 45 minutes, or till the solution gives no
starch reaction with iodine. While still warm, the contents are carefully
neutralised with slight excess of powdered marble or pure precipitated
calcium carbonate. The mixture is then heated over a water bath, or by
standing on the top of the hot-water oven, until concentrated to about 10
o.c., when it is spread on a strip of stout blotting-paper (such as is used
in Adam's milk process, being 22 inches long by 2}^ inches wide), and
any liquid remaining in the beaker is removed by means of a piece of
cotton-wool, which is then put on to the filter paper. The latter resting
on iron gauze, is first dried for 10 minutes at 100° C. The paper is now
rolled into the usual shape, and then dried for 3-4 hours at 100-103°.
After this it is placed in a Soxhlett 's apparatus, and extracted for about
60 times with ether or light petroleum spirit, the extraction occupying in
all about 5 hours. The ether solution is then evaporated, and dried in a
weighed dish in the usual manner.

The following analytic results show very clearly the relation between
the fat as determined by direct extraction, that by Wei bull's method,
and the fat contained in .the meal or flour: —

I. Analysis of fancy loaf containing lard, the fat being determined by
direct extraction.

II. Analysis of same, by one of the authors, the fat being determined
by the method above described.

III. Analysis of same by another analyst, fat determined by similar
method.

IV. Analysis of plain bread, made and analysed by one of the authors.

V. Analysis of fancy loaf containing according to the recipe ^ Ib. of
lard, made and analysed by one of the authors.

VI. Analysis of "all new milk" bread, made and analysed by one of
the authors.

In the first table all the percentages of the various constituents are
calculated for purposes of comparison to the same proportion of water as
was originally found in No. I. analysis.

In the second table is shown the percentage composition of the bread
in the dry state.

TABLE I.

Constituents.

Water

Proteins (Albuminoids), Gluten, etc..
Fat ..

Starch, etc.

Soluble Matter, principally Carbohy-
drates

Mineral Matter ,

40.49
7.55
0.96
38.97

40.49
7.32

1.85

in.
40.49

1.81

IV.

40.49
7.43
0.95

V.
40.49
7.55
2.16

VI.

40.49
8.74
1.84

10.30
1.73

TABLE II.

Proteins (Albuminoids), Gluten, etc. .

Fat

Soluble Matters, principally Carbohy-
drates

Mineral Matter .

12.68
1.60

17.30
2.90

12.16

12.31
3.12

20.44

12.19

1.87

ill.
3.05

20.50
3.15

6.31
1.11

IV.

12.49

1.60

10.62

1.88

15.18
1.37

12.70
3.63

25.52
2.32

8.16
1.28

VI.

14.70
3.10

13.72
2.16

BREAD ANALYSIS.

The mixed meal used in Nos. IV., V. and VI. contained 1.47 per cent,
of fat, equal to 1.69 per cent, in the meal in the dry state. Ordinary
white bread contains on an average in the dried solids : — Fat, 0.7 to 1.14
per cent. ; soluble matter, 5.0 to 8.0 per cent. ; ash or mineral matter,
about 1.5 per cent., of which about 1.0 per cent, is common salt. In the
recipe for the fancy loaf, the addition of the J^ Ib. of lard, if the same is
perfectly pure, raises the calculated percentage of fat on the dried bread
solids by the amount of 2.07 per cent, which agrees almost exactly with
the results of analysis. These figures do not confirm the view sometimes
expressed, that a part of the fat of flour is in bread-making volatilised
in the oven.

Soluble Extract. — Take 25 grams of the bread and 240 c.c. of water,
rub down with a little of the water into a perfectly uniform paste in a
mortar. Transfer to a flask, add the remainder of the water and 1 c.c. of
chloroform. Or, as an alternative method, the bread may be moistened
with a little of the water and then rubbed through a fine sieve. The small
thimble-shaped strainers, sold for attaching to the spout of a tea-pot in
order to strain the tea, answer well for this purpose. The strainer is then
washed with some more of the water and the whole transferred to a flask.
Shake vigorously at intervals during 12 hours, or allow to stand over
night. At the end of the time shake again, and allow to stand for half an
hour for the solids to settle. Filter the supernatant liquid until per-
fectly bright, and evaporate 25 c.c. to dryness for soluble extract. Bread
contains on the average about 40 per cent, of water, and therefore there
are 10 c.c. in 25 grams ; this quantity, together with the 240 c.c. added,
make 250 c.c. The water extract may therefore be viewed as a 10 per
cent, solution of soluble matters. There is probably no generally appli-
cable method which extracts the whole of the soluble matter of the bread,
as a portion is almost certain to remain behind. If, on the other hand,
the bread be subjected to prolonged boiling, some of the constituents
which were not originally soluble are thereby dissolved.

It is not recommended to evaporate the bread to dryness, and make
the determinations of soluble matters in the powdered dry residue, as this
does not at all readily yield up its soluble matter to water.

Maltose. — Usually 10 c.c. of the soluble extract solution may be taken
and precipitated with Fehling's solution in the usual manner. Should the
amount of precipitate be very small, another 10 c.c. should be at once
added.

Soluble Starch and Dextrin. — These may be determined as described
in paragraph 703, Chapter XXIV.

Soluble Proteins. — Take 25 c.c. of the soluble extract solution, evapo-
rate to dryness in a flask, and determine organic nitrogen by Kjeldahl's
process. The difference between total and soluble proteins may be re-
turned as insoluble proteins.

Starch. — This is usually taken as difference, after making all other
determinations; but it may also be determined direct by either of the
various processes given in Chapter XXIV. for estimation of starch.
From the total starch, that estimated in soluble extract solution as soluble
starch must be deducted.

Cellulose. — This may be determined by the method described in
paragraph 704.

CHAPTEE XXVI.
ADULTERATIONS AND ADDITIONS.

723. Standard Works on the Subject. — In giving directions for both
flour and bread analysis, the authors have hitherto confined themselves to
such modes of testing as enable one to determine the quality and charac-
ter of each, apart from any considerations as to the presence or absence
of any foreign bodies. The present chapter contains an outline of the
processes employed in the analysis of flour, bread, and certain other sub-
stances, for the purpose of detecting adulteration. This branch of chem-
istry applied to the arts of milling and baking has received considerable
attention, and several standard works of reference have been written on
the subject; among these may be mentioned those of Allen and Blyth,
both of which represent the most recent and authoritative opinions of
chemists on the problem. For several of the tests to be hereafter de-
scribed the authors are indebted to these works, to which the student is
referred for further and more detailed information.

724. Information Derived from Normal Analysis. — Some of the tests
already mentioned in the description of the normal analysis of flour and
bread serve also as indications as to whether a sample is adulterated.
Thus the moisture, if unduly high, points to the fact that at some stage
of manufacture, water has been added to the wheat, stock, or flour ; water
added for other purposes than normal conditioning or improvement of the
grain or stock must be regarded as objectionable.

The percentage of ash in the flour affords some guide as to whether
the sample has been treated with mineral substances. A flour ash, when
properly burned, should amount to less than 1 per cent. ; greater quanti-
ties than this are probably due to mineral adulteration. Reference has
already been made to certain considerations arising out of the presence
of undue ash for the colour of the flour. See paragraph 648.

725. Impurities and Adulterants of Flour. — The following are some
of the foreign substances that are at times found in the ground form in
flour: seeds of other plants, as corn-cockle and darnel; blighted and
ergotised grains — these are to be viewed rather as impurities than adul-
terants, the latter term being confined to those bodies wilfully added for
purposes of fraud. Among these latter are rye, rice-meal, maize flour,
potato starch, meal from leguminous plants, as peas and beans, and alum
and other mineral bodies. The question of the addition of mineral sub-
stances as "improvers" has been already discussed in Chapter XVII.

The tests for many of these substances are in part microscopical ; the
chapters containing directions for practical microscopic work provide
information and data as to the making of such tests. The following are
the principal chemical tests for the bodies above mentioned : —

726. Darnel.— Treat a little of the flour with alcohol (rectified
spirits of wine, not methylated spirits), digest at 30° C. for an hour,
snaking occasionally. Filter and examine the filtrate. This should be
clear and colourless, or at most should be only of a light yellow colour.
In the event of the flour containing darnel, the alcoholic extract is of a
greenish hue, and has an acrid and nauseous taste.

ADULTERATIONS AND ADDITIONS. 565

Treatment with alcohol and a small quantity of acid is a useful test
for other adulterants. Extract the flour with 70 per cent, alcohol (i. e.,
a mixture of alcohol and water, containing alcohol equivalent to 70 per
cent, of absolute spirit), to which 5 per cent, of hydrochloric acid has
been added. Pure wheat or rye flour yields a colourless extract ; barley
or oats gives a full yellow tint ; pea-flour, orange-yellow ; mildewed wheat,
purple-red, and ergotised wheat, a blood-red colouration.

727. Ergot and Mould. — To test flour for ergot, exhaust 20 grams
with concentrated alcohol in a fat extraction apparatus ; notice the colour,
which in the presence of ergot is more or less red. Mix this solution with
twice its volume of water, and shake up separate portions of this mixture
with ether, amyl-alcohol, benzol, and chloroform. Ergot imparts a red
colour to the whole of these solvents.

Vogel recommends the flour should be stained with aniline violet, and
then examined under the microscope ; should any of the starch granules
have been attacked by ergot or other fungoid growths, they acquire an
intense violet tint; while if they are perfectly sound, they remain com-
paratively colourless.

Ergotised flours evolve the peculiar fish-like odour of trimethylamine
when heated with a solution of potash : the same smell is, however, evolved
by flour otherwise damaged. The test is of service in distinguishing be-
tween sound and unsound flours.

The use of mouldy wheat for the manufacture of flour can be detected
by placing the sample in a tightly stoppered bottle, damping it and plac-
ing it in a bath heated to about 30° C. Any mouldy taint can readily be
observed after thus standing for 2 or 3 hours.

728. Rice in Flour, Gastine. — Gastine recommends for the detection
of rice in wheaten flour its treatment with a colour stain. A trace of the
flour is treated with a solution of 0.05 gram of aniline blue in 100 c.c. of
33 per cent, alcohol. The flour is then dried at about 30° C., and finally
by heating for a few minutes at 110-113° C. The preparation is then
mounted in cedar-wood oil and examined under the microscope. Treated
in this manner the wheat starch granules are almost invisible and very
rarely do they even exhibit a visible hilum. On the contrary the hilums
of the minute rice starch granules show up very distinctly, and usually
in regular clusters, since each fragment of rice is generally built up of a
number of starch granules. When wheat granules are cracked, the fis-
sures show very distinctly as a result of the infiltration of nitrogenous
matter, which readily -takes the stain. Granules of maize and buckwheat
starches behave like rice. (Comptes rend., 1906, 142, 1207.)

729. Maize Meal in Wheaten Flour, Kraemer. — Kraemer states that
flours containing corn-meal give off an odour of roasting corn when
heated in glycerin to boiling for a few minutes. (Jour. Amer. Chem.
Soc., 1899, 662.)

730. Maize Starch in Wheaten Flour, Baumann. — For the detection
of maize starch (corn flour) in wheaten flour, Baumann recommends the
following test : — About 0.1 gram of the flour under examination is mixed
with 10 c.c. of a 1.8 per cent, solution of potash, and the test tube shaken
at intervals during 2 minutes. Four or five drops of 25 per cent, diluted
hydrochloric acid are then added and the tube again shaken. The liquid
must still be slightly alkaline in order to prevent the precipitation of the
dissolved proteins. A drop is taken out and examined under the micro-
scope, when the wheat-starch granules will be found to be completely
ruptured while those of maize are unaltered. As little as from 1 to 2 per
cent, of maize can thus be detected. The test may be employed quantita-
tively by taking mixtures containing known quantities of maize starch,

566 THE TECHNOLOGY OF BREAD-MAKING.

treating them in the same way as the sample under examination, and de-
ciding which matches it when drops of similar size are microscopically
examined. The same method is applicable to the detection of maize in
rye flour. (Zeits. f. Untersuch., Nahr.-u Genussmittel, 1899, 2[1] 27.)

731. Maize in Wheaten Flour, Embrey.— Embrey has not found the
foregoing process to give satisfactory results in his hands, and has there-
fore devised and recommends the following modification: — Mixtures of
pure wheat and maize flours are prepared containing respectively 10, 15,
20, 25 and 30 per cent, of the maize. Weighed quantities (0.2 gram) of
each of these, and of the sample under examination, are placed in test
tubes (15 c.m. X 2 c.m.) which are fitted with paraffined corks. To each
is added, a quantity of 20 c.c. of potassium hydroxide solution (18 grams
per litre), and the tubes shaken uniformly for 3 minutes. Twelve drops
of diluted hydrochloric acid (HC1 of specific gravity 1.16, 50 c.c.; water,
100 c.c.) are" next introduced and the tubes shaken, and then whirled in a
centrifugal machine at 600 revolutions per minute. One c.c. of the clear
liquid is transferred to a Nessler tube and diluted to 50 c.c., after which
1 c.c. of an iodine solution (I, 0.25 gram; KI, 1 gram; water to 250 c.c.)
is added. The tint obtained compared with those of the standard tubes
gives the proportion of maize within about 5 per cent. For a more exact
determination, 10 c.c. of the clear liquid from each tube are boiled for 2
hours with 1 c.c. of dilute sulphuric acid (1:7), then neutralised, diluted
to 50 c.c. and run from a burette into a boiling mixture of Gerrard's solu-
tion, 10 c.c., and Fehling's solution, 2 c.c., until the colour is discharged.
The percentage of maize is obtained from the standard tube of which the
same amount is required to discharge the colour.

Gerrard's Solution is prepared by diluting 10 c.c. of freshly prepared
Fehling's solution with 40 c.c. of water, and adding a solution (about 5
per cent.) of potassium cyanide from a burette, until the blue colour is
only just perceptible. During the addition of the cyanide, the diluted
Fehling's solution is kept boiling and constantly stirred in a porcelain
dish. (Analyst, 1900, 25, 315.)

This process is really an estimation of the soluble starch resulting the
rupture of the granules of wheaten starch by the action of potassium
hydroxide solution. In the first method it is directly estimated as starch
by a colorimetric process with iodine ; and in the second by conversion
into glucose and then volumetrically by a modification of Fehling's solu-
tion. An objection to the method is that variations in the proportion of
wheaten starch in a flour may be due to causes other than the presence of
maize. Thus a very weak flour may contain more starch than a very
strong one, and if the former be also exceptionally dry and the other com-
paratively moist the difference is still further enhanced. Also, if even as
much as 30 per cent, of maize flour is contained in the flour the actual
reduction in wheat starch is only approximately from about 70 to 50 per
cent. On the other hand the amount of maize flour will have been in-
creased from zero to 30 per cent. ; obviously, therefore, a direct estimation
of the maize starch is preferable if practicable. As a modification of
Embrey 's method it is suggested that the solution of clear starch should
be decanted off, the insoluble residue thoroughly shaken up with water,
and again whirled in the centrifugal machine, so as to free it as far as
possible from soluble starch. The residual maize starch may then be dis-
solved by heating with water, and estimated either colorimetrically with
iodine, or by conversion into glucose and estimation by Fehling 's solution
The most important point here is whether or not the sediment is prac-
tically free from soluble wheaten starch.

ADULTERATIONS AND ADDITIONS. 567

In the discussion on the above paper, Bevan mentioned with approval
a qualitative method devised by Wilson, and consisting of mixing the
flour with clove oil, and examining with a *4 or Vs-inch objective, when
the hilum of maize appears as a black dot or star, while wheaten and
other starches are practically invisible.

732. Starch in Yeast. — Bruylants and Druyts recommend the fol-
lowing method of estimating flour or starch in yeast: From 50 to 100
grams of the yeast are to be taken, according to the suspected quantity
of starch, and mixed thoroughly with a dilute solution of iodine in potas-
sium iodide. The mixture is, if necessary, passed through a fine sieve in
order to remove any large sized fragments of impurity. It is then allowed
to settle, when the starch falls first, until the starch is covered by a thin
layer of yeast. The yeasty liquid is poured away and this washing by
decantation continued until only starch remains. A little fresh iodine
must be added from time to time. The sediment is dissolved and con-
verted into glucose by heating with dilute (2 per cent.) hydrochloric acid,
and then estimated in the usual manner. In tests made on yeasts con-
taining known quantities of starch, ranging from 3 to 15 per cent., the
amounts recovered by the method ranged between 96.7 per cent, and 100.8
per cent, of the added starch. (Bull. Assoc. Beige des Chim., 13 [1] 20.)

Instead of dissolving the starch obtained by this process in hydro-
chloric acid, it may be estimated direct by first washing with strong
alcohol and then evaporating and drying in a tared dish. Comparative
experiments should be made on yeasts to which known quantities of
starch have been added.

733. Aniline Blue in Flour, Violette.— Violette states that blue col-
ouring matter is sometimes employed in order to counteract the yellow
tinge of flour. In order to detect such addition a sheet of white filter
paper is floated on the surface of water, and a little of the suspected
flour sprinkled thereon. In the presence of aniline colours, dark specks
soon appear on the paper, which grow in size and form blue spots. (Bull.
Hoc. Chim., 1896, 15, 456.)

734. Mineral Adulterants and Additions. — The presence or absence
of most foreign mineral matters will have been indicated by the per-
centage of ash yielded. Alum is, however, added to flour in quantities
too small to be thus detected. One of the most ready means of separating
mineral substances from flour is by means of what is terniQd the

735. Chloroform Test. — This test depends on the fact that chloro-
form has a density higher than that of the normal constituents of flour,
but lower than that of minerals generally; consequently, on agitating a
mixture of flour and chloroform, and then allowing it to rest, the flour
rises to the surface, and any mineral adulterants sink to the bottom. On
the small scale, for the purpose of a qualitative test, a large dry test-tube
may be about one-third filled with the flour, then chloroform added to
within one inch from the top. The tube must then be corked and vio-
lently shaken, after which it must be allowed to rest for some hours ; the
mineral matter will then be found to have sunk to the bottom. For
quantitative purposes a glass "separator" is requisite. This is a cylin-
drical vessel some 2 inches in diameter, 8 or 10 inches in length, stop-
pered at the top, and furnished with a stopcock at the bottom. Introduce
in this vessel 100 grams of the flour and about 250 c.c. of methylated
chloroform ; treat as directed for the smaller quantity. When the separa-
tion is effected, open the stopcock and allow any sediment, with as little
as possible of the liquid, to run through. Treat this again with a little
more chloroform in a smaller separator, and once more drain the sediment
off through the stop-cock into a watchglass, or small evaporating basin.

568 Tim TECHNOLOGY OF BREAD-MAKING.

Allow the chloroform to evaporate; treat the dry residue with a small
quantity of water, and filter. Any plaster of Paris, calcium phosphate, or
other insoluble mineral matter will remain on the filter, and may be
ignited and weighed. Evaporate the solution to dryness, and examine
the residue carefully with a low power under the microscope for any
crystals of alum.

^ In making this test, flours, which are absolutely free from any added
mineral matter, occasionally give a slight sediment. This was formerly
ascribed to the presence of detritus from the millstones; but this can
scarcely be an adequate explanation, as the authors have obtained such
sediment from pure roller-milled flours.

736. Special Test for Alum. — The most convenient test for alum in
flour consists in adding thereto an alkaline solution of logwood. Take 5
grams of recently cut logwood chips and digest them in a closed bottle
with 100 c.c'. of methylated spirit. Also make a saturated solution of
ammonium carbonate. Mix 10 grams of the flour with 10 c.c. of water,
then add 1 c.c. of the tincture of logwood and 1 c.c. of the ammonium
carbonate solution, and thoroughly mix the whole. With pure flour the
resultant mixture is of a slight pinkish tint. Alum changes the colour
to lavender or full blue. The blue colour should remain on the sample
being heated in the hot-water oven for an hour or two.

737, Mineral Matters in Solution. — Certain mineral matters are at
times added to flour in the state of solution, the solution being sprayed
into the flour or added to a portion of the stock which is then dried,
ground, and mixed in with the flour. If this operation is performed with
sufficent care no particles of the flour are sufficiently weighted by the
adherent mineral matter to sink in chloroform, and so the application of
that test fails to reveal the presence of such added mineral matter. Very
frequently, however, some portion of the flour has absorbed sufficient of
the mineral addition to sink in chloroform. If so, this portion should be
thus separated and the ash in the two portions determined. Any differ-
ence detected is an indication of the addition of some foreign mineral.
The nature of the substance added may be ascertained by further
analysis of the ash.

In cases where it is desired to test particularly for sprayed additions
of mineral salts, it is well to compare the total ash of the flour with that
of a sample of known purity of the same colour and grade, bearing in
mind Snyder 's conclusions on the relation between ash and grade of flour
already given (paragraph 648). In this connection it must be borne in
mind that a bleached flour will contain less ash than a corresponding
unbleached flour. In the next place apply the chloroform test as
described. Should this fail, add to the chloroform and flour in the sep-
arator, absolute alcohol in small quantities at a time, and shake and
allow to settle between each addition. As the mixed liquid approaches
in density to that of flour, a point is reached at which any mineral-
weighted particles of flour may sink and the purer portion float on the
top. In this case separate the two and determine the ash in each sep-
arately. If deemed necessary, make analyses of each portion of ash.
Should the whole of the flour have absorbed the mineral addition with
absolute uniformity, a separation cannot of course be effected by this
method. But in all such methods of introducing foreign mineral matters,
some portion of the flour is almost certain to have absorbed more mineral
matter than others. If the addition is exceedingly small, this mode of
separation is not likely to be effective, and recourse must be had to a
more or less complete analysis of the whole ash. The finding of any sub-
stance in a quantity beyond the extreme amount that may occur as a

ADULTERATIONS AND ADDITIONS. 569

natural constituent of flour is evidence of its presence as an added body.
In the event of the addition of mineral substances to a flour which is
naturally deficient in those substances, and in such quantity as not to
exceed the normal amount which may be present, then even a complete
analysis of the ash may fail to reveal the fact of mineral bodies having
been added. More usually, however, any such additions will not have
the same proportionate composition as normal flour ash, and in this way
Mieir presence will be indicated.

738. Alum in Bread. — Bread is tested for alum by first taking 5 c.c.
of the tincture of logwood, 5 c.c. of the ammonium carbonate solution,
and diluting them down to 100 c.c. This mixture must at once be poured
over about 10 grams of the crumbled bread in an evaporating basin. It
is allowed to stand for 5 minutes, and then the superfluous liquid drained
off. Slightly wash the bread and dry in the hot-water oven. Alum gives
the bread treated in this manner a lavender or dark blue colour, which is
intensified on drying. Pure bread first assumes a light red tint, which
fades into a buff or light brown. After some practice this test gives satis-
factory results, and is so sensitive that as little as 7 grains of alum to the
4 Ib. loaf have been detected. The depth of colour affords a means of
roughly estimating the quantity of alum present. It is essential that the
tincture of logwood be freshly prepared, and that the test be made imme-
diately after mixing the tincture of logwood and ammonium carbonate
solution.

739. Young on Logwood Test for Alum. — In 1886 Young pointed out
{ The Analyst) that under certain circumstances bread which is abso-
lutely free from alum gives the characteristic reaction with logwood. On
investigation it was found that the flour used gave no indication by log-
wood, but that the bread gave a very distinct colouration. The sample
was heavy and sour — subsequent experiments showed that the colouration
was directly due to the acidity. On taking pure breads, which were abso-
lutely negative to the logwood test, and moistening with dilute acetic acid
(1 to 250 of water), and letting stand for one hour, all gave a most
intense blue colour with logwood. So also did pure flour similarly
treated. Young considers this effect to be due to phosphate of alumina
(a body normally-produced from the mineral constituents of flour) being
slightly soluble in dilute acetic acid, and quotes experiments in proof of
this solubility. He further found that such phosphate of alumina exists
in a state of combination with the gluten, and, as a result of careful
washing, was able to procure starch, which, after treatment with acetic
acid and subsequent application of the logwood test, gave no colouration.

In a quantitative experiment some best quality Hungarian flour was
taken, yielding 0.7 per cent, of ash and 8 per cent, of dry gluten. The
gluten was washed out in a muslin bag and dried, 20 grams were taken,
miely powdered, and treated with 250 c.c. of 50 per cent, acetic acid, and
heated in the water bath for 28 hours. The gluten had then dissolved,
leaving a sediment, from which the clear liquid was poured, and the
residue again twice treated in the same manner with the diluted acetic
acid. The three lots of acid extract were evaporated to dryness, and the
residue burned to a perfect ash — this was treated in dilute hydrochloric
acid, and the insoluble residue fused with alkaline carbonates, dissolved
in dilute hydrochloric acid, filtered, and filtrate added to acid solution
of ash. This was again evaporated to dryness, redissolved in small
quantity of hydrochloric acid, filtered, filtrate boiled, and cautiously
added to 25 c.c. of saturated solution of pure sodium hydroxide, also boil-
ing, and kept boiling for a few minutes. The precipitate was dissolved
with hydrochloric acid, and precipitated with saturated solution of

570 THE TECHNOLOGY OF BREAD-MAKING.

sodium phosphate and slight excess of ammonia. After 10 minutes7 boil-
ing, the precipitate of aluminium phosphate was collected, filtered, and
weighed. The 20 grams of gluten yielded 0.0185 gram of aluminium
phosphate, equal to 0.01875 from 250 grams of flour, or 0.0075 per cent.
Alumina was thus shown to be a natural constituent of flour, and asso-
ciated with the gluten. The alumina thus normally present justifies a
deduction being made of from 7 to 8 grains of alum per 4 Ib. loaf from
the amount corresponding to total alumina by analysis.

For further experiments by Young on the solubility of aluminium
phosphate in acetic acid, the reader is referred to The Analyst for April,
1890. He there shows that the presence of ammonium acetate, and also
that of ammonium chloride, prevent the complete precipitation of
aluminium phosphate in the presence of acetic acid.

740. Calcium Sulphate in Bread. — Calcium sulphate is occasionally
found as an added substance in bread. The addition is probably due to
the aeration of the bread by a phosphatic baking powder, in which the
acid phosphate contains calcium sulphate as a natural impurity. As only
traces of sulphates exist ready formed in the cereals, they may be
detected by an examination of the unignited bread. The best plan is to
soak 12.20 grams of the bread for some days in 1200 c.c. of cold distilled
water until mould forms on the surface of the liquid. The solution is
then strained through muslin and the filtrate treated with 20 c.c. of
phenol distilled over a small quantity of lime. The whole is then raised
to the boiling point and filtered through paper; 1000 c.c. of the filtrate
are slightly acidulated with hydrochloric acid and precipitated in the
cold by barium chloride. Every 237 parts of barium sulphate represent
136 parts of calcium sulphate. (Allen's Commercial Organic Analysis.
vol. 1, p. 460.)

741. Mineral Oil for Parting Loaves. — In the case of close-packed
bread it is the custom to smear the contiguous surfaces of loaves with
melted lard or oil for the purpose of preventing their sticking together.
For this purpose a petroleum residue is employed (1896) in Germany,
known as Brotel. Illness has been traced to this practice in Hamburg,
the residue remaining in the loaf and causing digestive disturbances.
(Jour. Soc. Chem. Ind., 368, 1896.)

742. Colouring Matter in Cakes. — In order to determine whether
cakes and other confectionery have been coloured with yolk of egg, or
with other colouring matters, Spaeth recommends that the fat be ex-
tracted and examined. The following are the characteristics of egg-yolk
fat and wheat meal fat respectively : —

Egg Fat. Wheat Fat,

Sp. g. at 100° C. (water at 15° = 1.00) . . . . 0.881 0.9068

Melting point of fatty acids 36° 34°

Saponification number . . . . . . . . 184.43 166.5

Iodine value 68.48 101.5

„ of fatty acids 72.6

Reichert-Meissl value 0.66 2.8

Refractive index at 25° C.' 1.4713 1.4851

„ „ on Zeiss refractometer scale . . 68.5 9.20

When the iodine value exceeds 98, and the phosphoric acid (P2O5) in
the fat is below 0.005 per cent., there cannot be more than traces of egg-
yolk. (Analyst, 233, 1896.)

In this proposed method, no cognisance is taken of the fact that cakes
and similar articles have large quantities of butter and other fats added
to them, the constants of which may vary widely from those of either
egg-yolk or wheat fats.

CHAPTER XXVII.
ROUTINE MILL TESTS.

743. Practical Adaptation of Flour Tests to Mill Routine.— The fore-
going chapters have contained descriptions of the modes of making vari-
ous flour tests and the conclusions to be drawn therefrom. There now
remains for discussion the problem of their adaptation to commercial
milling routine. This may be done in two ways, either by the employ-
ment of a chemist at the mill, or by sending samples by arrangement to
a chemist who undertakes work of this class. In either case some special
training is requisite. A professional knowledge of the science of chem-
istry and the principles of analysis is of course essential ; but in addition
to these a chemist who undertakes the work of commercial flour analysis
should be familiar with the general properties of wheats and of flour.
He should also have had sufficient experience of the physical methods of
testing employed by both miller and baker, and of the carrying out of
baking tests under conditions of scientific accuracy. In cases where it is
decided to carry on such work at the mill, a laboratory must be provided ;
of this some description has been already given in Chapter XX. on
Analytic Apparatus.

744. Dispatch of Samples and Results. — If the alternative is adopted
of entrusting these duties to an outside chemist, then arrangements must
be made for the collection of the necessary samples and their dispatch.
It should be made the special business of some responsible person to take
the samples at some specified time. This person must be familiar with
che process of sampling, and must take care that the samples are properly
representative of the bulk. The quantities must depend on the nature of
the tests to be' made. Among some of the most frequent of such tests are
those of moisture. For each of these an ounce of the material is sufficient.
Having regard to the ease with which wheat products either absorb 01
.ose moisture, the samples for this purpose must at once be packed in air-
light receptacles. Probably the most convenient form is a glass tube oi
the requisite size, fitted with an india-rubber cork. Special wooden blocks
are made for holding these for postal purposes ; any desired number can
then be packed in the one block and dispatched by post. For an ordinary
analysis, an 8 oz. sample is a suitable quantity, and a convenient package
consists of a small bag made of fine close-textured canvas or similar
material. This in turn should be enclosed in a tin canister with tightly
fitting lid. Wooden boxes should be provided to hold a certain number of
these canisters, for dispatch to the chemist's laboratory. The locks of
Ihese boxes should be provided with two keys to be held respectively bj>
the forwarder and recipient. A systematic course of labelling must bo
adopted. The labels should be affixed to the bags or glass tubes, and not
1 o the covers of canisters or the corks of tubes. The reason is that the
identifying label must not be capable of detachment from the sample
by the act of opening the package. Further, the label should bear the
name and address of the sender. A proper dispatch book must be kept
in which descriptions of samples, identifying marks or numbers, and
dates of dispatch are entered. For baking tests, a larger sample must

571

OF BREAD-MAKING.

be sent, and for this 2 Ibs. is a very convenient quantity. Larger bags
of the same khid of^material as before are on the whole most suitable. It
is notKi]^l§t&;f"nfecessary that they be enclosed in tin canisters, but they
should also be packed in wooden boxes. The sample sent for baking will
also serve for the other^malytical tests, except that for moisture. The
snjjftll flMl^j|fc7^RQ*Vt™^se snoulcl always be packed in the air-tight
tuuefe; ana the larger carrying boxes may be easily fitted with a small
division to hold the tubes. The packed sample cases should so far as
possible be regularly forwarded by a certain mail or train. There are
very few districts in which samples cannot be dispatched in the evening
so as to be in the hands of the chemist early the next morning. He will
of course be perfectly familiar with the routine of treatment on their
reception, the only suggestion to be made being that such results as are
wanted most quickly should be arranged for first. For example, mois-
tures are frequently required with the utmost expedition, and the deter-
minations should therefore be started immediately.

In returning results, they may frequently require to be sent by tele-
graph ; in that case a code should be arranged by which the data could be
sent cheaply and with the least possible risk of mistake. A certain num-
ber of figures can always be sent as a word ; but figures are prone to mis-
takes in transmission, and above all such mistakes are not evident on the
face of them. Code words are not so liable to the same errors, and should
therefore be used in preference. As an example, the following is a con-
venient and simple code for the transmission of moisture results.

9.0 Aback 10.0 Babel 11.0 Cabin 12.0 Dark

9.1 Abbey 10.1 Bank 11.1 Cask 12.1 Date

9.2 Accent 10.2 Beach 11.2 Chart 12.2 Dean

9.3 Adder 10.3 Beef 11.3 Civil 12.3 Dell

9.4 Affix 10.4 Bird 11.4 Clamp 12.4 Dip

9.5 Agate 10.5 Blank 11.5 Clock 12.5 Divan

9.6 Aisle 10.6 Blow 11.6 Code 12.6 Dock

9.7 Alarm 10.7 Boast 11.7 Court 12.7 Dose

9.8 Ambit 10.8 Box 11.8 Crest 12.8 Drag

9.9 Anchor 10.9 Buoy 11.9 Cube 12.9 Duel

13.0 Ear 14.0 Fault 15.0 Gas 16.0 Hack

13.1 Ebb 14.1 Fear 15.1 Gear . 16.1 Hair

13.2 Echo 14.2 Feud 15.2 Gem 16.2 Head

13.3 Eddy 14.3 Field 15.3 Gill 16.3 Help

13.4 Eel * 14.4 Fight 15.4 Give 16.4 Hide

13.5 Effect 14.5 Flock 15.5 Gland 16.5 Hint

13.6 Egg 14.6 Foam 15.6 Good 16.6 Hoax

13.7 Ember 14.7 Fowl 15.7 Gout 16.7 Hole

13.8 End 14.8 Freak 15.8 Grain 16.8 Hulk

13.9 Equip 14.9 Fury 15.9 Gust 16.9 Hurt

All telegraphic results must be confirmed by post, and dispatched so
as to be in the hands of the miller at a regular time.

745. Standard Quality. — It must be borne in mind that high quality
is not a fixed and invariable standard, but depends largely on what are
local requirements. This question most generally arises when systematic
tests are for the first time introduced, and requires its proper answer in
each individual mill before such tests can yield results of much value.
That which is the best flour in the one district is not the best in another,
and therefore the chemist first requires to know the exact kind of flour

ROUTINE MILL TESTS. 573

the miller wishes to make. The miller can usually lay his hands on one
particular parcel, which has the approval of his most skilful and critical
customers, which he would like always to supply, and which he would be
content to take as a standard. If he can also obtain certain samples
which more or less fall short of this standard, and with clearly marked
defects, they will also be of service. The chemist should be supplied with
these samples, and his first object should be to find out where the faulty
examples differ from the standard one. No precise directions can be
given for doing this, since it is here that the skill and judgment of the
expert are brought to bear on the problems of each particular flour. Care
should be exercised in discriminating between differences which are acci-
dental and those which are fundamental. From these data the require-
ments in the standard flour for each particular mill are formulated, and
the effect of any departures from the standard of quality are duly noted.
This is a judgment which cannot be formed immediately; the first opin-
ion must only be looked on as provisional, and must be confirmed or
otherwise by subsequent tests. Still it is remarkable how soon, as a result
of regular testing, the chemist forms an opinion on the quality of the
flour and recognises any deviation. These opinions are usually confirmed
by subsequent baking tests.

746. Uniformity in Quality. — Having formulated standards for each
miller's requirements, the next object is to see that flours of these qual-
ities are being uniformly produced. For this purpose flours are regularly
tested. The first and simplest object of such tests is to serve as a control
on the working of the mill, and to secure the most help from such tests
the miller (i.e., the working miller) should work in unison with the chem-
ist. So far from being antagonistic, their real duties are complementary,
and any real improvement is largely dependent on their mutual co-opera-
tion. The miller will take samples from those parts of the mill which will
afford the most information, and the chemist will duly test same. In par-
ticular if suspicion attaches to the work of any particular machine or
part of the miU, samples of the products of this section will receive spe-
cial attention. In this way tests are made, and the results carefully
recorded. In cases where any marked departure from the usual standard
occurs, attention should be drawn to it, and the flour watched in its
future stages so as to note whether it has been found in any way unsatis-
factory in actual use.

747. Actual Routine Tests Employed. — Of set purpose the selection
of these is left to the judgment of the individual chemist. In previous
pages the nature and objects of the most important tests have been de-
scribed in detail. The following are among those which will probably be
regularly employed.

Moisture. — This test has a very important bearing on the whole ques-
tion of the conditioning of wheat. Samples may be tested of the whole
wheat unmoistened and after the moisture has been added by any means.
The comparison of these shows how much water has actually been added.
Then tests may be made on the whole wheat, the flour, and the bran.
These will show how far and to what extent the moisture has penetrated.
Lack of penetration may be due to a particularly hard bran, or it may be
the result of conditioning not having been carried out sufficiently long
before grinding. Where any system of improving treatment is carried
out as a part of the conditioning process, or by the spraying of either
stock or flour, the moisture tests serve the secondary purpose of determin-
ing the quantities of the improving agents which have actually been
added. Moisture tests, intelligently applied, have therefore most im-
portant uses in the mill.

574 THE TECHNOLOGY OP BREAD-MAKING.

Ash. — As a control on the degree of length of patent, regular ash
determinations are exceedingly valuable when properly made.

Protein Estimations. — The details of them have been given most fully.
The selection must depend on individual judgment. Total proteins,
gluten, and alcohol-soluble proteins will probably be included in most
schemes of protein determinations.

Water-Absorption. — Viscometer tests not only measure an important
property of flours, but also one which serves as a most important check
on uniformity of production.

Colour. — In every well conducted mill, the colour of flour is always
being carefully watched. This is especially necessary where any bleach-
ing process is being employed.

748. Replacement Tests. — Tests for uniformity are not confined to
being a check on the satisfactory working of the mill, but they have a
further most important bearing on the difficult question of replacing in
a mixture one wheat by another. Some useful general information on
this point is given on page 258, but that scarcely more than touches the
fringe of the problem. To start with, the same kind of wheat varies with
its age, and as the crop from a fresh harvest arrives it must be carefully
tested before it can be regarded as the equivalent of that of the preceding
year. When a miller is grinding a mixture of several varieties of wheat,
and one of these runs out, it is imperative that any proposed substitute
shall not seriously alter the character of the flour produced. In making
the change he is limited by the facts that the average price of the wheat
composing his mixture must not exceed a certain amount, and that the
various grades of flour he manufactures must all maintain their specific
qualities ; and so far as possible must be produced in their usual propor-
tions.

In making any tests on the whole wheats, they may be reduced to fine
meal, and the results of gluten or other determinations calculated out on
the assumption of a 70 per cent, yield of straight-run flour. Evidently
this can be nothing more than an assumption, because the flour yield of
wheats varies within wide limits.

Again, for reasons on which the previous subject matter will have
thrown some light, the mixing of various wheats does not always produce
the expected results. A mixture of strong and weak wheats having a
known percentage of gluten, for example, sometimes yields a loaf which
is quite appreciably better or worse than was expected, and there is
always some anxiety as to the result of a new blend until test bakings
have been made on the resultant flour.

749. Milling Tests. — The only true test under these circumstances
is the milling test, in which the various wheats are ground separately and
their resultant flours tested chemically and by baking. They should then
be mixed in the desired proportions and again tested until such a blend is
obtained as satisfies the miller 's desideratum — a maximum of quality at a
minimum of cost. With very small milling plants it is the custom to
make a trial by putting a few sacks of a newly arrived wheat through the
entire mill. But while this is a tedious and expensive experiment with a
small plant, it is practically an impossibility with a large one. The
obvious alternative is to lay down a small milling plant for experimental
purposes. This must not be too large, and yet must be large enough to
make a fairly good commercial sample of flour.

A very convenient plant for making these tests has recently been
introduced, which consists of a machine that in a condensed form is able
to perform all the operations of a gradual reduction roller plant built in

ROUTINE MILL TESTS.

575

one frame, driven by one main belt and taking up a very little space.
This machine is illustrated in Fig. 90, and embodies within itself two
pairs of "Break" or fluted rollers, a sieve between the first and second
pair, a centrifugal dressing machine to dress the flour from the first
break meal and another to deal with the second break stock and tail over
the bran to the sack. There is then left the semolina from the tails of
the first centrifugal and the bran middlings from the "Cut-off" of the
second break centrifugal, to be ground on two pairs of smooth reduction
rollers in sequence, each of which is succeeded by a flour dressing reel.
The whole process is entirely automatic from the incoming wheat to the
marketable products of flour, bran and sharps.

FlG. 90. — Mfdget Testing Mill.

This useful little appliance, which goes by the name of the "Midget,"
and is made by Messrs. Alfred R. Tattersall and Co., 75, Mark Lane,
London, E.G., lends itself admirably to the testing of small parcels of
wheat, as its capacity is to make from 140 to 280 Ibs. of finished flour

FIG. 91.— Wheat Cleaning Machine

576 THE TECHNOLOGY OF BREAD-MAKING.

per hour. , By its means a grist can bo made from two or even one sack of
wheat, and a very passable yield can be obtained. The manufacturers
claim that the Midget Mill produces flour equal in every respect to that
made in the larger mills of the long system. It may therefore be
depended on to yield trustworthy comparative results when used as a
wheat and flour testing mill.

A very useful adjunct to testing mills is a cleaning machine made by
Messrs. Tattersall and shown in Fig. 91. This little machine goes in
very small compass, and has a double sieve to take out large and small
impurities by a powerful aspiration. The floor space it occupies is only
about 15 in. X 40 in.

Working with a plant of this description, any wheat may be taken,
weighed, and milled either with or without conditioning. Its compara-
tive behaviour during milling can be observed, and the total yield of
flour determined. Finally the quality of the flour can be tested against,
and compared with that of, flour milled from the standard mixture on the
same machine.

750. Replacement Calculations. — In making wheat replacements,
the following is a very common occurrence. Given a wheat strong in one
constituent (C), and another wheat weak in the same constituent (C), it
is required to calculate the proportions of each that must be taken to give
a mixture that shall have a desired intermediate percentage of C. Thus
as an example, a wheat has been in use which has 4 per cent, of C. The
only wheats that can be used to replace it are a stronger wheat in that
particular respect, containing 5 per cent, of C, and a weaker one contain-
ing only 2 per cent, of C. In what proportions must they be used to give
a mixture containing 4 per cent, of C ?

Stronger wheat, S, contains 5 per cent, of C.
Weaker „ W „, 2 „ „ C.
Mixture, M, is required to contain 4 per cent, of C.
First calculate the quantity of each that will contain 4 parts of C.
As 5 (of S) is to 4 : : 100 : 80
As 2 (of W) : 4 : : 100 : 200
Therefore, 80 parts of S will contain 4 of C.
200 „ W „ „ 4 of C.
and 100 „ M must „ 4 of C.

Call the quantities that will contain the amount of C in M as just
indicated, QS, QW, and QM.

Then QS (QW — QM) = amount of S to be taken,
and QW (QM — QS) = „ W „

Thus QS (QW — QM) =

80 (200 — 100) = 8000 parts of S to be taken,
and QW (QM — QS) =

200 (100 — 80) = 4000 parts of W to be taken.

Then 8000 parts of S contain 400 of C.

and 4000 W 80 or C.

12,000 „ M „ 480 of C.
and 100 „ M „ 4 of C.

Of the stronger wheat, therefore, 8 parts must be taken, and of the
weaker, 4 parts; or yet more simply in the proportion of 2 to 1.
The following is a somewhat more difficult example : —
S contains 4.3 per cent, of C.
W „ 1.9 „ „ C.

M to contain 2.7 C.

ROUTINE MILL TESTS. 577

As 4.3 : 2.7 : : 100 : 62.8 = QS.
„ 1.9 : 2.7 : : 100 : 142.1 = QW.

Then QS(QW — QM) = 62.8(142.1 — 100) =2643.88 of S.
„ QW(QM — QS) =142.1(100 -62.8) =5286.12 of W.
As S contains 4.3 per cent, of C, 2643.88 of S contain 113.68 of C.
W 1.9 „ „ C, 5286.12 of W „ 100.40 of C.

7930.00 of M „ 214.08 of C.

As 7930 : 100 : : 214.08 : 2.7 = desired percentage of C.
An inspection of the composition of the mixture shows that it contains
as nearly as possible 1 part of the stronger wheat to 2 parts of the weaker
one. In percentages, the result works out thus :

As 7930 : 100 : : 5286.12 : 66.66 per cent, of W.
100 — 66.66 = 33.34 „ „ S.

751. Use of Improvers. — When any system of artificially improving
flours is in operation, the duty of checking and controlling the same will
naturally fall to the chemist whether working in or out of the mill. In
the case of the use of a bleaching plant, the miller will exercise his own
judgment as to the extent of the bleach he requires. The chemist should
compare the reactions of the bleached with the unbleached flour and see
that no essential of the flour undergoes any material alteration.

In event of the employment of any process of saline or other treat-
ment, whether by direct addition, spraying, or otherwise, more exacting
chemical duties are required. The proportions of saline constituents,
sugars, and amylolytic and proteolytic enzymes in what has been called
the mill's standard flour should be carefully estimated. It should also be
ascertained whether any flours which are below standard show any great
deviation in any of the foregoing particulars. Experiments should be
made in order to determine whether the addition of these deficient bodies
improves the quality of the flour, and if so to what extent they should be
added. The object of all these tests is to formulate some definite scheme
for the addition of these agents to the flour of each individual mill.
Some such data having been acquired, the experimental flours of new
wheats should be tested with and without the improving addition, and the
system of adding or not adding any improver carried out on a scientific
basis. It must be borne in mind that the object of all these additions is
simply to remedy the natural deficiencies of some wheats and thus place
them on the level normally attained by other wheats without any addition
whatever. Important responsibilities are thus cast on the chemist, as
non-addition is in some cases as necessary as addition is important in
others.

752. Baking Tests.— Not only the control of the testing mill, but
also that of the mill 's baking tests will probably be within the functions
of the chemist. It will be more especially his duty to see that conditions
of exactitude, both as to quantities and modes of working, are secured.
He will also see that the baking methods used represent as nearly as pos-
sible those under which the flour is baked commercially, and will inspect
the baked loaves and keep a record of their properties. Under certain
circumstances it may be necessary for him to make a more or less com-
plete analysis of the baked bread.

753. Summary of Chemical Functions in Mill. — The preceding para-
graphs contain an outline of suggestions as to the adaptation and organ-
isation of chemical functions to milling routine. They apply equally to
the performance of such work in the mill or in the laboratory of some
outside specialist. The suggestions have not been made too definite,

578 THE TECHNOLOGY OF BREAD-MAKING.

because after all each particular mill's set of problems must be worked
out by the chemist to whom they are entrusted. As to the utility of such
tests, it must be remembered that the chemical aspect of wheat quality
may now be regarded as fairly settled on a scientific basis, and questions
involving chemical investigation must continually arise in practical mill-
ing if the best results are to be obtained with the greatest commercial
success. There is a certain amount of healthy rivalry between what may for
convenience be called " chemical' ' and baking tests on flour. Each has
its own merits, but a frequent criticism is that "baking is after all the
h'nal test of flour." To this no open-minded chemist will demur, but he
will likewise know that his own work also throws most important light
and guidance on milling. And this light and guidance are usually of a
kind which baking tests are absolutely unable to furnish. It is fre-
quently astonishing to note how in regular routine testing of flours the
chemist on observing some departure from the normal is able to predicate
successfully an alteration in the quality of the flour. And the importance
of the knowledge thus furnished lies in the fact that it is not merely the
observation of a result, but is based on the discovery of the cause.

As to the value of chemical work as applied to milling, the following
testimony from the Ogilvie Flour Mills Co., Ltd., who were among the
pioneers in this direction, cannot fail to be of interest : —

"I would say that in the operation of mills of large capacity such
as we control, our experience ha's been that laboratory work is one of
the absolute essentials to successful and economical operation, and
an actual necessity for the maintenance of a uniform product of high
quality. We certainly would not for one moment think of dispensing
with this feature of our business." (Personal Communication,
April, 1908.)

One last suggestion may be respectfully made to those who may decide
to enlist chemical assistance in their milling operations, and that is to
have patience and not expect too much at the commencement. The first
task of any chemist will be to thoroughly familiarise himself with all the
properties of the particular mill's flour, formulate standards on the lines
indicated, accumulate data, and generally study the whole chemical
aspect of the problem before him before he makes or suggests any radical
alterations. This takes time, but the work having once been done, his
recommendations have the merit of being not simply speculative, but
based on a reasonable degree of certainty.

Further, the introduction of the new wheel in the machinery is not
keenly welcomed by those already responsible for its general running. In
certain cases the present mill foremen, testing bakers and others have
keenly resented what they regard as the intrusion of the chemist. It is to
be feared that under such circumstances, even if no active steps are taken
to nullify the recommendations of the chemist, no great amount of
assistance is rendered in the direction of carrying them into effect. Much
will here depend on the tact of the chemist himself, and he can do much
by taking the stand that his functions are not to replace or displace those
who occupied the responsible positions before him, but rather to co-op-
erate with and assist them. It is a truism to say that the miller can make
a good sack of flour, whereas the chemist qua chemist cannot ; but if the
miller and the chemist, by working heartily in unison, can make a better
and cheaper sack of flour than can the former alone, then the milling
chemist has justified his existence. This phase of antagonism and sus-
picion has to be lived down, and the chemist requires at this stage all the
moral support that can be afforded him by his employer.

CHAPTER XXVIII.
CONFECTIONERS' RAW MATERIALS.

754. Flour Confectionery. — Under the general term confectionery
are included articles of such a widely diversified nature, that some sub-
division is necessary. It is a convenient classification to include in one
group those goods of which the cake make be taken as a type, and into
which flour enters as an essential constituent, and call them flour con-
fections. The second group may then include those goods of which sugar
is the basis, and which may be viewed as sugar confections. The present
work attempts to deal principally with the raw materials of the first or
Hour group. Incidentally, some explanation will be afforded of the chem-
ical changes underlying certain confectionery manufacturing processes.

A good deal of the matter of this chapter formed the subject of a
course of Cantor Lectures delivered by one of the authors before the
Society of Arts. The authors' thanks and acknowledgments are due to
the Society for placing at their disposal the report of the lectures, which
appeared in its Journal.

755. Flour. — The composition and properties of flour have already
been dealt with so exhaustively, that but little further reference is nec-
essary at this stage. In bread-making, the baker will naturally prefer a
flour with a high absorbing power, since all else being equal, the cost of
making dough with a larger percentage of water is obviously less. But
with the confectioner, the moistening ingredients are in most cases more
expensive than his flour, and consequently it is to his interest to use a
flour which shall obtain its desired degree of moistness with the minimum
of these more expensive materials. Further, the weaker and softer flours
lend themselves more readily to the manipulation and working necessary,
than do those of stronger nature. It should also be noted that in bread-
making, the flour during the operation of fermentation undergoes consid-
erable softening, while no similar changes occur in the manufacture of
confectionery. For these various reasons, therefore, the confectioner
usually selects a weak and somewhat soft flour containing much starch
and comparatively little gluten, which latter should be of a soft, ductile,
and silky character. For the sake of the colour of the cakes or other
manufactured goods, a flour of a white or delicate creamy tint is pre-
ferred. Among flours used by the confectioner, and answering more or
less to this description, are finest flours from English wheats, Hungarian
flours, and those from the softer white wheats of North America.

MOISTENING INGREDIENTS.

756. Milk. — As a cake moistening ingredient, milk holds a very
prominent place, and requires a somewhat extended reference. There is
probably no substance of which so many analyses have been made, as
milk, and consequently, its composition and variations of composition, are
well known. Milk is used by the confectioner in at least three distinct
forms — new milk, skim or separated milk, and sour separated milk. This
latter is at times supplied mixed with butter-milk, and has special uses,

580 THE TECHNOLOGY OF BREAD-MAKING.

to which reference will again be made. The following table, based on the
authority of Vieth and Richmond, gives the average composition of pure
new milk : —

Fat . . 4.0

Proteins . . . . . . . . . . . . 3.6

Sugar . . . . . . . . . . . . 4.5

Ash 0.7

Total Non-fatty Solids 8.8

Water 87.2

100.0

By the removal of fat the percentage of other solid bodies in milk is
slightly increased, and separated milk has about the following average
composition : —

Fats 0.3

Proteins . . . . . . . . . . . . 3.7

Sugar 4.6

Ash 0.7

Total Non-fatty Solids 9.0

Water 90.7

100.0

The fat of milk, like that of other fats, confers richness on cakes, and
will be dealt with in detail subsequently. The sugar present in milk is a
special variety, to which has been given the name of lactose. Lactose, or
sugar of milk, is represented by the formula, C12H22On, and has there-
fore the same composition as cane sugar and maltose. It is not, however,
identical with either of these bodies. Lactose differs from cane sugar in
that it is far less sweet, and hence is not such a powerful flavouring agent
as sugar of the latter description. The remaining constituent of milk of
importance to the confectioner is the protein matter. This last has, like
the white of egg, no very pronounced taste, but yet its presence confers
on milk a fulness and roundness of flavour (if phraseology may be bor-
rowed from other tasters' vocabularies) which a simple solution of lactose
in water would not possess. In the baked goods, the protein of milk pro-
duces a moistness and mellowness of character, which decidedly differs
from that caused by water only. Summing up, new milk gives richness
through its fat, sweetness through its sugar, and what for lack of a better
term, may be called "mellowness" through its proteins. Separated milk
is practically new milk less' its fat.

757. Milk Standards. — The composition of milk has been indicated
in the analyses already quoted, but these figures are not by any means the
lowest obtainable from undoubtedly pure samples of milk. For purposes
of the Food and Drugs Adulteration Acts, the limits have been adopted
of 3 per cent, of fat, and 8.5 per cent, of non-fatty solids. But for confec-
tioners' purposes, a direct estimate of value is of more importance than
knowing whether or not a particular sample of milk passes the limits of
the public analyst. Thus milks containing respectively 3 and 4 per cent,
of fat, would, so far as the fat is concerned, be passed as free from adul-
teration ; but evidently the former sample has only three-fourths the fat
value of the latter. For some years this subject of the valuation of milks
has engaged the attention of one of the authors, who suggests, and has

CONFECTIONERS' RAW MATERIALS. 581

lor some considerable time employed a standard of valuation worked out
on the following lines : — From an examination of a large number of com-
mercial milks an average conventional standard of quality was first de-
termined, the aim being not to go so low as the Government limit for
adulteration, but to take figures which a buyer might reasonably demand
to be reached in milks supplied to him. These were ultimately taken as
being for

New Milk. Separated Milk.

Total Solids 12.5 9.3

Fat 3.5 0.3

Non-fatty Solids . . . . . . 9.0 9.0

The figure, 9.0, is in reality somewhat too high for the non-fatty solids
of an average new milk, but in order to make the comparison between
new and separated milk as simple as possible, the same figure has been
adopted for each. The difference between 9.0 and the more correct figure,
8.8, does not practically affect the valuations.

At the time when these figures were adopted, the approximate whole-
sale prices of milk were, new lOd. per gallon ; separated, 2l/2d. per gallon.
New milk differs essentially from separated in that it contains an excess
of 3.2 per cent, of fat. According to the wholesale prices this excess of
fat has a market value of 7.5d., and in the same proportion 3.5 per cent,
of fat is worth 8.2d From this the value of conventional standard sam-
ples can be expressed in terms of their constituents : —

New Milk. Separated Milk.

Fat 3.5 = 8.2d. 0.3 = O.ld.

Non-fats 9.0 = l.Sd. 9.0 = 1.8d.

per gallon . . lO.Od. 2.5d.

Obviously other prices can be assigned to new and separated milks
and the values of the constituents similarly calculated.

If the value of standard new milk be called 100, then the value of any

other sample can from the analysis be expressed in terms of percentages
of the standard from the following Table : —

VALUATION OF MILKS.
Fat in Terms of Standard.

Fat Percentage of Fat Percentage of Fat Percentage of
per cent. Standard. per cent. Standard. per cent. Standard.

0.1 = 2.34 1.7 39.83 3.3 77.32

0.2 — 4.69 1.8 42.17 3.4 79.66

0.3 7.03 1.9 44.52 3.5 12.00

0.4 = 9,37 2.0 46.86 3.6 84^34

0.5 = 11.71 2.1 49.20 3.7 = 86.68

0.6 = 14.06 2.2 51.55 3.8 89.02

0.7 = 16.40 2.3 = 53.89 3.9 91.36

0.8 — 18.74 2.4 56.23 4.0 93.70

0.9 = 21.09 2.5 58.57 4.1 = 96.04

1.0 = 23.43 2.6 = 60.92 4.2 98.38

1.1 — 25.77 2.7 = 63.26 4.3 = 100.72

1.2 28.12 2.8 65.62 4.4 3 103.06

1.3 = 30.46 2.9 67.95 4.5 = 105.40

1.4 = 32.80 3.0 70.29 4.6 == 107.74

1.5 = 35.14 3.1 72.63 4.7 = 110.08

1.6 = 37.49 3.2 = 74.98 4.8 = 112.42

582 THE TECHNOLOGY OF BREAD-MAKING.

Non-fatty Solids in Terms of Standard.

Non-Fatty Percentage Non-Fatty Percentage Non-Fatty Percentage

Solids of Solids of Solids of

per cent. Standard. per cent. Standard. per cent. Standard.

4.8 = 9.6 6.4 = 12.8 8.0 = 16.0

4.9 = 9.8 6.5 = 13.0 8.1 = 16.2

5.0 = 10.0 6.6 = 13.2 8.2 = 16.4

5.1 = 10.2 6.7 = 13.4 8.3 = 16.6

5.2 = 10.4 6.8 = 13.6 8.4 = 16.8

5.3 == 10.6 6.9 = 13.8 8.5 = 17.0

5.4 = 10.8 7.0 = 14.0 8.6 = 17.2

5.5 = 11.0 7.1 = 14.2 8.7 = 17.4

5.6 = 11.2 7.2 = 14.4 8.8 = 17.6

5.7 = 11.4 7.3 = 14.6 8.9 = 17.8

5.8 = 11.6 7.4 = 14.8 9.0 = 18.0

5.9 = 11.8 7.5 = 15.0 cfT ~

6.0 = 12.0 7.6 = 15.2 9 2 = 184

6.1 = 12.2 7.7 = 15.4 9.3 = i8.6

6.2 = 12.4 7.8 = 15.6 9.4 = 18.8

6.3 = 12.6 7.9 = 15.8 9.5 = 19.0

In the next Table are given the results of analysis of some typical
examples of milk, their values in terms of standard and per gallon,
assuming standard milk to be worth 10d. per gallon.

Attention is drawn to the fact that milk No. 7, although of highest
value in terms of standard, shows, nevertheless, evidence of having been
watered, and would probably be made the subject of a prosecution if
analysed for the purposes of the Foods and Drugs Acts. The public
analyst is concerned simply with adulteration, while the commercial user
is more vitally interested in the question of actual value.

A gallon of milk weighs approximately about 10.3 Ibs. or 10 Ibs. 5 ozs.,
and if this be bought at 10d., the purchaser gets, if the milk is of stand-
ard value, 0.36 Ibs. = 5.76 ozs. of butter fat, for which he pays S.2d.f or
at the rate of 22.7d. per Ib. ; and 0.93 Ibs. = 14.88 ozs. of mixed protein,
milk-sugar, and ash ; for which he pays 1.8d., or at the rate of 1.9d. per Ib.

A gallon of separated milk of standard value weighs about 10.5 Ibs. or
10 Ibs. 8 ozs., and if this be bought at 2l/2d., the purchaser gets 0.03 Ibs. =
0.48 ozs. of butter fat and 0.945 Ibs. = 15.1 ozs. of mixed protein, milk-
sugar, and ash, making 0.975 Ibs. of total solids, which he buys at the rate
of 2.56d. per Ib.

Taking butter, containing 87 per cent, of butter fat, at Is. per Ib.,
then —

One gallon of separated milk, costing . . . . 2T/2d.
And 0.33 Ibs. of butter, costing

Together costing . . . . . . . . Id.

will yield the equivalent in quantity of the total non-fatty solids and
butter-fat of one gallon of new milk costing lOd.

758. Condensed Milk. — Condensed milks of the unsweetened variety
are at times employed instead of new or separated milks. In ascertaining
the value of these, it is well to dilute them to three times thir original
volume. Then such a milk as No. 9 is, as nearly as possible, of the same
degree of concentration as standard milk. One gallon of such milk, in the
concentrated form, is worth, as against standard milk
9.8 X 3 = 28.4d. per gallon.

CONFECTIONERS' RAW MATERIALS.

583

No.

Description of Milk.

Milk with 26 per cent of added water idg 'not

2 Milk deprived of 40 per cent of its (Fat

Value
in terms
Com- of

position. Stand-
ard.

. 3.2

t 6.6

cream

/Solids not fat

1.8
9.1

3 Old Somerset House limit, below whichfFat

2.5

milks were considered adulterated (Solids not fat 8.5

4 British Government limit

5 Authors' conventional standard

(Fat . . . . 3.0
/Solids not fat 8.5

(Fat .. ..3.5
/Solids not fat 9.0

(Fat
Average composition of pure new niilk|goj|^s 'no^- f'a^

4.0

7 Very rich milk slightly watered

.
High quality sample of skimmed milk

Unsweetened condensed milk diluted
to three times its volume .

(Fat .. ..4.3
/Solids not fat 8.1

(Fat

. . . . 0.4
not fat 9 1

{Fat . . . . 3.5
/Solids not fat 8.2

Unsweetened condensed milk diluted {Fat . . . . 2.0
to three times its volume . . . . / Solids not fat 8.6

74.98
13.20

9.8 88.18

42.17
18.20

10.9 60.37

58.57
17.00

11.0 75.57

70.29
17.00

11.5 87.29

82.00
18.00

93.70
17.60

100.72
16.20

9.37
18.20

82.00
16.40

11.7 98.40

46.86
17.20

Value

per
Gallon.

7.5d.

8.7 d.

12.5 100.00 10.0J.

12.8 111.30 11.1</.

12.4 116.92 11.7 J.

9.5 27.57 2.76J.

9.8J.

10.6 64.06 6.4J.

No. 10 has been deprived, before condensing, of nearly half its fat, and
consequently is only worth

6.4 X 3 = 19.061 per gallon.

Such condensed milks may not only be diluted and used as moistening
agents, but also at times are employed in their concentrated state, as a
more or less complete substitute for butter. These condensed milks have,
or should have, an approximate density of 1.1, and therefore a gallon of
No. 9 will weigh about 11 Ibs., and is worth, on the milk standard, 28Ad.
or 2.58cl per Ib. A gallon of the milk will contain, roughly, 2.70 Ibs. of
non-fatty solids, and 1.15 Ibs. of butter fat. This is the equivalent in
quantity of 2.85 gallons of separated milk, at a cost of 7. Id., and 1.32 Ibs.

584 THE TECHNOLOGY OF BREAD-MAKING.

of butter which at Is. per Ib. costs 15. 8d, or a total of 22. 9d Unless,
therefore, such full value milk as No. 9 is bought at 2.08d. per Ib., its
proteins, milk-sugar and fat, can be more cheaply supplied from sepa-
rated milk and butter.

759. Milk Powders. — By modern processes, milk is now reduced to
the condition of a dry powder, and is an article of sale containing only a
very small percentage of moisture. Full cream, half cream, and separated
milk powders are now on the market. In the absence of moisture, these
bodies have the following approximate composition : —

COMPOSITION OF MILK POWDERS.

Constituents. Full-cream. Half-cream. Separated.

Fat 31.2 17.2 3.2

Proteins 28.1 34.0 39.8

Sugar 35.2 42.3 49.5

Ash 5.5 6.5 7.5

100.0 100.0 100.0

Weight of water required to

convert 1 Ib. of each into liquid

of the same strength as milk. . 7.8 Ibs. 9.3 Ibs. 10.7 Ibs.
One pound of the full-cream powder is equivalent in butter value to
about 5^4 ozs- of butter; in addition to which it contains proteins and
sugar in approximately the same quantities. On mixing the powders
with warm water in the proportions given above, a fluid corresponding to
the original miiK is produced.

760. Eggs. — Next to milk, eggs are one of the most important moist-
ening agents to the confectioner. The raw white of egg is a viscous glairy
liquid, the yolk being somewhat more fluid in character. In composition,
the white of egg consists of protein matter dissolved in water, while the
yolk contains in addition to protein, fat and colouring matter. The
following table gives respectively the results of analysis of the white,
yolk, and whole interior of the egg : —

White and Yolk
Constituents. White. Yolk. together.

Water 85.7 50.9 73.7

Protein 12.6 16.2 14.8

Fat 0.25 31.75 10.5

Ash . . 0.59 1.09 1.0

The white of egg may be viewed as a solution of one part of albumin
in seven parts of water, while in the whole egg about two-fifths of the
solids consist of fat, and three-fifths of protein matter. The water of the
whole egg amounts roughly to three-quarters of its weight. Or putting it
another way, 1 Ib. of whole eggs contains about 4 ozs. of solids, and 1 Ib.
of white of egg just half that quantity or 2 ozs. When either of these
are used in making a dough with flour, the water part of the egg does the
moistening, and acts in the same way on the constituents of flour as
water alone would do. The white, if used alone, is so nearly tasteless
that it cannot be said to confer any very decided flavour; but, as was
remarked with regard to the protein matter of milk, it imparts the prop-
erty described as that of mellowness to goods in whose manufacture it is
used. The yolk, on the other hand, is very marked in flavour, and just
as eggs themselves are in consequence most pleasant eating, so cakes have
a remarkable richness of flavour caused by the yolks of eggs used in
iheir manufacture.

CONFECTIONERS' RAW MATERIALS. 585

The yellow of the yolk confers its distinctive colour on the cakes and
other goods in which it is employed; as a consequence the full yellow
of a cake has become associated with the idea of its richness. With
cakes made at very low prices, the use of eggs in full proportion becomes
an economic impossibility, and therefore, in the cheaper cakes, an effort is
made to please the eye by adding artificial colouring matter. The nature
and composition of the substances used for this purpose are described in
a subsequent paragraph.

761. Dried Egg Whites. — For certain purposes, in place of the white
of eggs, the confectioner has offered to him such whites as desiccated
albumin. This preparation should consist of the pure white of egg evapo-
rated down to dryness at a temperature well below that of the coagulation
or setting of albumin. Such dried albumin should soften on the addition
of water and form a solution possessing the same properties as fresh white
of egg. The solution should be free from any unpleasant taste or odour
of decomposition. As white of egg contains one-eighth its weight of pure
albumin, it follows that dried egg-albumin should, everything else being
equal, be worth weight for weight eight times as much as fresh white of
egg. In other words, pure egg-albumin at anything below eight times
the cost of white of egg is economically to be preferred to such fresh
whites. The objections to such commercial albumin are first, that it may
be partly coagulated, and second, that it may be unpleasant in odour or
taste either as the result of preparation from unsound eggs, or incipient
putrefaction during its manufacture. Among adulterants, to which dried
egg-whites are subject, are dextrin, sugar, and gelatin. Serum- or blood-
albumin, is less expensive than egg-albumin, and so may possibly be sub-
stituted for it without declaration to the purchaser.

The table on the following page gives the results of analysis of a
number of samples of dried egg-whites, together with that of fresh white
of egg taken for comparison. A 5 per cent, solution of the powdered
albumin in cold water was prepared and filtered through paper. The
total solid matter, and nitrogen by Kjeldahl's method, were determined
on the filtrate. Another portion of the filtrate was acidulated with acetic
acid, and boiled so as to coagulate the albumin, which was in turn filtered
off. The residual soluble matter and nitrogen were then determined in
the second filtrate. In each case the nitrogen multiplied by the factor
6.25 gave a quantity which did not amount to as much as the total matter
present. The difference is therefore returned as non-nitrogenous matter.

The samples 1, 2, and 3 were specimens of commercial dried egg-
whites : A was the white of fresh egg, and AA the results of the same
analysis calculated to what they would have been on the same white
dried to a water-content of 15 per cent., without other change.

The fresh white of egg was diluted to about the same degree of con-
centration as the 5 per cent, solution before analysis. While the fresh
egg-white was perfectly soluble, the dried albumins contained insoluble
matter varying from 5.70 to 10.72 per cent. This is probably albumin
which had been coagulated in drying, as the total nitrogenous matter is
quite up to the normal amount. The insoluble matter and coagulated
albumin together agree very fairly with the coagulated albumin of A A.
The protein matter, which remains uncoagulated under the conditions
of the experiment is practically the same in all samples. The non-coagu-
lated non-nitrogenous matter in the egg-white is more than is usually
given, and cannot be accounted for by assuming the factor used for pro-
teins to be too low. It will be seen that the amount is practically the
same in all the samples. Adulteration with sugar or dextrin would

586 THE TECHNOLOGY OF BREAD-MAKING.

materially increase this figure, while the addition of gelatin would augment
the non-coagulated nitrogenous matter. The whole of these three sam-
ples may be regarded as genuine, but in the act of drying varying
amounts of proteins have been rendered insoluble.

Constituents. 1. 2. 3. A. AA

Water 18.10 15.08 15.08 87.55 15.00

Insoluble Matter 5.70 6.52 10.72 0.00 0.00

Coagulable True Albumin . . . . 52.86 52.27 52.26 8.92 61.90

Associated Non-nitrogenous Matter 4.54 4.53 2.54 0.56 3.93
Non-coagulated Nitrogenous Matter,

as Proteins 7.74 8.15 7.62 1.15 7.98

Non-coagulated Non-nitrogenous

Matter . . 11.06 13.45 11.78 1.62 11.22

762. Moistening Effect of Fat. — Before altogether passing from
moistening action, mention may be made of the moistening effect of
melted fat, as butter or lard. Such moistening is quite different in char-
acter from that of substances whose essential moistening constituent is
water. The latter all affect the gluten of flour, and produce a dough such
as is used in making bread ; the former makes a moist mass, devoid alto-
gether of any tenacity, but, instead of that, distinctly "short." As an
example of the use of butter fat as a moistening agent Scotch shortbread
may be mentioned.

763. Glycerin. — In another sense of the word "moistening," glyc-
erin must be referred to as one of the confectioners' moistening agents.
Glycerin is well known as a colourless, odourless, and viscous liquid, of a
very sweet taste. Its chemical composition and properties are described
in paragraph 105. If exposed to the air, glycerin increases in volume
through absorption of moisture. When used in small quantities in cakes,
the result is that drying is much retarded, and the cake remains moist
and fresh for a considerable time longer than would otherwise be the case.
As glycerin is without injurious effect on the human economy, its use in
this direction may be regarded as perfectly harmless.

AERATING INGREDIENTS.

764. Aerating Agents. — A number of these bodies, such as bicar-
bonate of soda, cream of tartar, tartaric acid, and similar substances have
already been fully described in Chapter XVII., paragraph 512.

765. Aerating Action of Eggs. — It is well known that, under certain
circumstances, eggs are valuable lightening agents, yet they do not give
off any gas whatever within the range of temperature employed by the
confectioner, neither do they cause evolution of gas from any other ingre-
dients he is in the habit of using. In these particulars they differ mark-
edly from the aerating agents before referred to, and their action must
consequently be looked for in some other direction. First of all, eggs,
and especially their whites, have a peculiar glairy consistency. In virtue
of this, if eggs be present in a mixture, any air incorporated with it
prior to baking is retained much more tenaciously. Consequently, when
the goods are placed in the oven, such air expanding with increase of
temperature, increases the volume of the articles by its more perfect re-
tention, as a result of the peculiar viscous and binding nature of the egg-
albumin. Another valuable property of eggs, so far as this effect is con-
cerned, is that of setting or coagulation. Just as in being boiled, the
egg matters become solid during the act of baking : as the temperature of
coagulation is reached they begin to set, and so fix the dough, so to speak,

CONFECTIONERS' RAW MATERIALS. 587

in its expanded state. The lightening function of eggs is therefore
summed up in the statement that they do not of themselves evolve or
cause the evolution of gas, but assist in its retention when developed by
the expansion of air, or obtained from any other gaseous source.

ENRICHING INGREDIENTS.

766. Fats. — The next step to be considered is that of enriching a
cake, an operation which is performed by the addition and incorporation
of fat. Scotch shortbread dough is an instance of dough made with fat
as a moistening agent. The dough itself is short and non-coherent, while
the baked shortbread is extremely rich in flavour and character. As fats
fulfil so important a function, it becomes necessary to inquire into the
properties of the bodies embraced under this general heading of fat.
Reference has already been made in Chapter V. to the composition and
some of the properties of fats, but at this stage a somewhat more extended
description is advisable.

Under this name are included a number of substances, both of animal
and vegetable origin. The fats have various melting temperatures and,
speaking broadly, those which are solid at the ordinary temperature are
called "fats," while those which under this condition are liquid receive
the name of ' * oils. ' ' Pure fats and oils are usually either colourless or of
a faint yellow tinge, while some of vegetable origin possess a green tint,
derived from green vegetable colouring matter. Many fats and oils pos-
sess a distinct smell and taste, agreeable or otherwise, and indicative of
their origin; such characters appertain, however, to minute traces of
associated impurities, rather than to the pure fat and oil itself. Conse-
quently, the act of refining and purifying oils generally tends to deprive
them of special flavour, leaving behind a bland and almost tasteless body.
All ordinary fats and oils possess the property of ' ' greasiness " ; if
dropped in the liquid state on paper or cloth, they produce a grease spot,
and give that well-known "slipperiness" so characteristic of a greased
surface.

Oils and fats are practically insoluble in water, somewhat soluble in
absolute alcohol, or even strong spirit, especially when hot. Ether, chlo-
roform, light petroleum or petroleum spirit, and other somewhat analo-
gous substances dissolve them readily ; so also the various oils and fats are
ieadily soluble in each other, and consequently may easily be mixed in
all proportions. Viewed themselves as solvents, they have practically no
action on most of the substances employed by the confectioner. Thus
the constituents of flour are not dissolved by oil, and this is the reason of
the particular "shortness" of flour mixtures, such as shortbread dough,
into which any fat has largely entered. Oil dissolves some colouring
matter, and also flavourings, so that these amalgamate somewhat readily
with the fatty part of various mixtures.

Fat and oils, if preserved from the atmosphere, remain unchanged for
& considerable time, but on exposure are liable to acquire the property of
rancidity. This is much hastened by the presence of impurities resulting
from imperfect separation from the animal or vegetable source of origin.
Natural fats may be viewed as compounds of the higher fatty acids with
glycerin, or some closely allied body. Among the fatty acids most fre-
quently occurring are those of the stearic series, represented by the gen-
eral formula HCnHgn^Og, and the oleic series represented by HCnH2n 302.
Thus mutton fat is largely composed of stearate of glycerin, which body

588 THE TECHNOLOGY OF BREAD-MAKING.

may be artificially produced by heating together glycerin and stearic acid
thus,

3HC18H3502 + C3H5(HO)3 == C3H5(C18H35O2)3 + 3H2O.

Stearic Acid. Glycerin. Glycerin Stearate. Water.

This body, glycerin stearate, is conveniently called "stearin."

Olive and lard oils consist largely on the other hand of glycerin oleate :
the formula of oleic acid is HC13H330.,, and the oleate is consequently
C3H5(C1gH3302)3. This body has received the name of "olein."

Stearin is a somewhat hard solid, while olein is liquid at ordinary
temperatures ; as may be surmised, therefore, stearin and allied bodies are
more largely found in fats, while oils consist principally of olein and its
congeners.

V67. Melting and Solidifying Points. — The temperatures at which
these changes occur are of considerable importance in the selection of fats
for different purposes ; a fat when once melted remains liquid at a con-
siderably lower temperature than that required for the act of fusion.
Thus mutton fat melts at a temperature ranging between 46.5 and 47.4°
C. ; but when once melted only re-solidifies at a temperature of from 32 to
36° C. In the table following later, the temperatures of solidification are
given. At temperatures varying from 250° C. (482° F.) to 300° C.
!V572° F.), fats are decomposed, yielding various products of a disagree-
able odour.

768. Specific Gravity of Fats. — These bodies are all of them lighter
than water, the specific gravity varying between 875 and 970, water
being taken at 1000. The specific gravity is a valuable means of identify-
ing and distinguishing fats, and consequently has been determined with
considerable care. As the oils are liquid at ordinary temperature, and
the fats solid, it is preferable to select some temperature at which all are
?n the liquid state. That found most generally convenient is the tem-
perature caused by immersion in boiling water, and this in practice regis-
ters at 99° C. The figures given in the subsequent table have been taken
at this temperature; they are somewhat abnormal, as they give the spe-
cific gravity of the fats at 99° C. compared with water at 15.5° C.

769. Chemical Constants of Fats. — There are various data used by
the chemist in recognising different fats," and detecting adulterations.
Among these are the following : —

770. Iodine Value. — This term is applied to a most important deter-
mination now made on fats as the result of investigations by Hubl. If
any fat or oil be dissolved in chloroform, and then an excess of a solution
of iodine and mercury chloride in alcohol added, absorption of the iodine
by the fatty matter proceeds. Using proper precautions, the amount of
iodine so absorbed is capable of very exact measurements, and the figure
thus obtained is that quoted as the "iodine value." Thus, if the iodine
value of a fat is given as 50, this means that under the standard condi-
tions of what is known as Hubl's test, 100 parts of that fat absorb 50
parts of iodine. The iodine value not only throws light on the probable
nature of an oil or fat, but also, in many instances, affords valuable indi-
tions of the purity and quality of the fat in question. Speaking gen-
erally, the more oily a fat, the higher is its iodine value.

771. Reichert-Meissl Value. — Fats have already been referred to as
compounds of fatty acids. Of this group of bodies some are readily
volatile at the temperature of boiling water, while others are non-volatile
under the same conditions. Butter fat is distinguished from almost all
other fats by containing a high proportion of such volatile acids. The
exact determination of the volatile acids in a fat is a work of tediousness

CONFECTIONERS' RAW MATERIALS. 589

and some difficulty. But under standard conditions, a fairly constant
fraction of such volatile acids can be obtained and determined, and this
constitutes a test of considerable importance. A weighed quantity, 5
grams of the fat, is made into a soap, by treatment with excess of potash ;
on adding excess of sulphuric acid, this soap is decomposed, and the
whole of the fatty acid liberated. The solution is altogether diluted with
water to 140 cubic centimetres, and then distilled until 110 cubic centi-
metres of the distilled liquid have been collected. The acidity of this
filtered distillate is then determined by the use of phenolphthalein and
decinormal potash solution. Such acidity is termed the Reichert-Meissl
value. Thus, if 5 grams of butter fat gave a distillate, which took 30
cubic centimetres of decinormal potash to render it neutral, then the
Reichert-Meissl value of such fat would be said to be 30. This figure is
evidently the measure of the quantity of volatile acid which distils over
under certain standard conditions.

772. Butyro-Refractometer Value. — Like other transparent sub-
dances, melted fats have a refractive action on a ray of light passing
obliquely through a layer of them. The amount of such refraction is'
fairly constant for some fats, but varies however with the temperature.
The instrument known as Zeiss' butyro-refractometer is one for rapidly
measuring the amount of such refraction. On looking through the optical
portion of such an instrument, the point of refraction is shown by means
of a scale, and can be read off at once into degrees, which, for example,
may be called 47°. The instrument is also provided with a thermometer,
graduating into arbitrary degrees, and this is also read at the same time
cis the point of refraction of the fat. Suppose that this figure is also 47° ;
then in the case of a butter for which this determination is principally
used, the difference between the two is 0°, and such butter fat is at the
bottom limit of an arbitrary scale of purity. If the reading on the butter
fat is lower than that of the thermometer, then the butter so far as this
test goes is passed as pure : if higher, then the butter is suspicious, and
requires to be further and more systematically tested. The following fig-
ures were obtained during actual examination of various butters : —

Butter reading . . . . 46.4 44.0 50.0 52.5
Thermometer reading . . 47.0 45.9 47.1 47.1

—0.6 -1.9 +2.9 +5.4

Of these tests, the two former were pure butters, the third was a mar-
garine, and the fourth a beef-fat preparation. By means of the arbi-
trarily marked thermometer, the disturbing influence of temperature is
eliminated, as minus results indicate purity of butter fat, and plus results
impurity. Otherwise it becomes necessary to give both the butter read-
ings and the temperature of the fat when it was taken, after which such
readings must be calculated and corrected to a given temperature. Thus
at 25° C. genuine butters have a range of from 49.5 to 54.0°, and marga-
rines of from 58.6 to 66.4°.

773. Tabular Description of Oils and Fats.— In the table on the fol-
lowing page particulars are given of the various fats and oils either
directly used by the confectioner or indirectly as component parts of
various butter substitutes or other confectioners' fats. For these data
and their arrangement the authors are indebted to Allen's Commercial
Organic Analysis, and Lewkowitsch 's Analysis of Oils and Fats.

590

THE TECHNOLOGY OP BREAD-MAKING.

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CONFECTIONERS' RAW MATERIALS. 591

774. Butter. — There can be little doubt that where prime cost is no
object, butter is by far the best and most pleasant fat to be used for the
great majority, if not all, of confectioners' purposes. Substitutes for
butter will succeed or fail according to the degree in which they repro-
duce and possess the characteristics of good butter. Butter is therefore
first described, and other substances which follow are naturally compared
with and tested against butter as a standard.

Butter may be defined as the substance produced by churning the
cream derived from milk. During this process the fat globules coalesce,
and after washing and other treatment, result in the production of butter.

The British sources of butter supply include Ireland, France, Den-
mark, Siberia, Canada, Australia, and New Zealand. The last of these
devotes very special care to its export trade. All butter for export pur-
poses is graded by the State, which in the first place classifies and keeps a
register of all dairies. The Government provides cold storage rooms at
specified ports, in which the butter is deposited while awaiting shipment.
The graders, who are as a rule picked dairy factory managers, examine
each parcel, and give points on the following scale, for creamery butter : —

Points.

Flavour . . . . . . . . . . . . 50

Body, moisture, texture . . . . . . 25

Colour 10

Salting 10

Finish . . 5

100

Butter is placed in the first grade, which secures 88 points and over ;
in the second grade, under 88 points, and over 80 points ; and in the third
grade, with 80 points and under. Of creamery butters examined and
graded in 1899-1900, the following results were obtained : —

First grade . . . . . . . . 92.63 per cent.

Second grade . . . . . . . . 7.10 „

Third grade . . . . 0.27

Another part of the duties of the port graders is to inspect the cold
storage accommodations of ships, and in this way to do all they can to see
that such produce has a good send-off from colonial shores. Its well-being
in this country is attended to by the Produce Commissioner, who sees
that all is well on arrival here, notes critically any defects, and reports
them to New Zealand for remedying in the future. It has been thought
well to thus explain in detail the organised precautions taken to ensure
for this country a supply of the finest possible colonial butter.

775. Composition of Butter. — However well and carefully made, but-
ter contains a good deal else than pure fat; among such other matters
being water, proteins, and milk-sugar — usually classed together in analy-
sis as curd, traces of natural mineral matter, and more or less added salt.
For confectioners' purposes the water is useless. The presence of large
quantities of curd in butters is general evidence of inefficient manufac-
ture, and excess of protein matters by their rapid alteration confers an
unpleasant cheesy taste. Salt is added as a preservative, and also as a
flavouring agent ; but as such is of no service to the confectioner, who, as
a matter of fact, when using a salt butter, will usually wash the salt out

592

THE TECHNOLOGY OF BREAD-MAKING.

as completely as possible as a preliminary to its employment. The user
is thus reduced to the fat, and practically that is the substance in butter
of value : everything else being equal, the greater the proportion of fat
the more valuable is the butter.

A reference to the table already given will show that butter differs
from every other fat quoted in the very high Reichert-Meissl value it pos-
sesses. As already explained, this figure is an indication of the amount
of volatile fatty acids present. These substances give butter those char-
acteristic properties not exhibited by any other fat. Therefore, the de-
termination of Reichert-Meissl value is, in the case of butters, a most
important estimation. In the table below, Composition of Butter and
Margarine, are given the results of analyses of various typical butters
which, except when otherwise stated, have been made by the authors.

Samples Nos. 6 to 12 are fair average samples, and not in any way
picked or choicest butters of their kinds. Looking at the whole series, the
New Zealand butters are characterised by containing the lowest percent-
age of water, and highest of butter fat. The Canadians and Austra-
lians also are very low in water, while next follow the Siberian samples.
The Irish butters are marked by a large percentage, both of water and
salt,

The Reichert-Meissl value of the butters varies from about 26 to over
31 ; the whole of these figures being within the recognised limits of purity.
But evidently a butter with a value of 31 must be richer in volatile acids
than is one with 26, and will be found, if the term may be coined, to be
the more "buttery" butter of the two. In confectioners' valuation of
butter, a high Reichert-Meissl value is of importance since the fullness of
butter flavour indicated will enable such a butter to be mixed with a .con-
siderable proportion of a neutral character fat, such as lard, and yet be
as "buttery" in character as another butter containing normally a low
proportion of volatile fatty acids.

776. Butter Standards. — One of the data given, it will be noticed,
is the value in percentage of "Standard." Taking these butters right
through, it was found that many samples contained 87 per cent., or over,
of butter fat. This figure 87 was accordingly taken as a standard for
butter. In the following table is given, in column two, the value, in

VALUATION OF BUTTERS.

Per-
centage of
Fat.

70
71
72
73
74
75
76
77
78
79
80
81
82

Value in

Quantity contain-
ing same weight

Per-

Terms of

of Fat as 100 Ibs.

centage of

Standard.

of Standard.

Fat.

80.4

124.3

81.6

122.5

82.7

120.8 85

83.9

119.1 86

85.0

117.5

86.2

116.0

87.3

. . 114.4 89

88.5

. . 112.9

89.6

111.5

90.8

. . 110.1

91.9

108.7

93.1

. . 107.4

94.2

. . 106.0

Value in
Terms of
Standard.

95.4
96.5
97.7
98.8
100.0

ioTT

102.3
103.4
104.6
105.7
106.8
108.0
109.2

Quantity contain-
ing same weight
of Fat as 100 Ibs.
of Standard.

104.8
. 103.5

102.3

101.1

. 100.0

97.7
96.6
95.6
94.5
93.5
92.5
91.5

CONFECTIONERS' RAW MATERIALS.
ANALYSIS OF SAMPLES OF BUTTER AND MARGARINE.

No. Mark or Description.

1. English, analysis by Richmond.

2. German, salt ,, ,,

3. Danish, salt „ „

4. Swedish, salt „ „

5. Australian, salt ,, ,,

6. Danish.

7. Normandy, fresh.

8. Normandy, salt.

9. Canadian (I.).

10. Canadian (II.).

11. Australian.

12. New Zealand.

13. Irish, lowest in water of nine samples.

14. Irish, average of nine samples.

15. Irish, highest in water of nine samples.

16. Siberian, lowest in water of ten samples.

17. Siberian, average of ten samples.

18. Siberian, highest in water of ten samples.

19. New season New Zealand, lowest in water of nine samples.

20. New season New Zealand, average of nine samples.

21. New season New Zealand, highest in water of nine samples.

22. Margarine, with admixture of butter.

23. Margarine (II.) ,, ,,

24. Margarine (III.), without butter.

COMPOSITION OF BUTTER AND MARGARINE.

593

Curd

Value in

Reichert- Butyro-

No.

Water.

Salt.

(chiefly

Fat.

Total.

percentage of

Meissl

refractometer

Casein).

"Standard."

Value.

11.6

1.0

0.6

86.8

100.0

89.6

—

12.3

1.3

1.2

85.2

100.0

97.9

—

13.4

1.9

1.3

83.4

100.0

95.8

—

13.8

2.0

1.3

82.9

100.0

95.3

—

12.7

1.6

1.2

84.5

100.0

97.0

—

12.4

1.4

0.6

85.6

100.0

98.3

32.3

—1.9

12.4

0.0

1.7

85.9

100.0

98.7

31.1

—1.2

10.6

1.4

0.8

87.2

100.0

100.2

31.1

—1.0

9.7

1.5

0.6

88.2

100.0

101.3

28.6

—0.05

8.2

1.7

0.3

89.8

100.0

103.3

28.9

+1.1

11.8

3.4

0.4

84.4

100.0

97.0

31.0

—1.2

9.1

2.8

0.5

87.6

100.0

100.6

29.8

—0.2

14.5

4.6

0.9

80.0

100.0

91.9

30.8

—

16.7

6.2

1.1

76.0

100.0

87.3

31.1

—

19.8

7.1

1.0

72.1

100.0

82.8

31.6

—

9.4

1.0

0.8

88.8

100.0

102.0

27.1

—

10.3

1.4

1.1

87.2

100.0

100.2

26.7

—0.5

11.3

1.2

86.3

100.0

99.1

26.9

—

7.2

1.2

0.4

91.2

100.0

104.8

31.9

—0.2

7.6

1.2

0.4

90.8

100.0

104.3

—

8.1

0.9

0.3

90.7

100.0

104.1

30.4

+0.9

13.2

1.7

3.0

82.1

100.0

94.3

5.7

+2.9

7.7

1.7

0.7

89.9

100.0

103.1

4.0

—

6.7

2.3

0.2

90.8

100.0

104.2

0.8

+5.4

terms of the standard, of butters containing various percentages of fat.
Also it is shown in column three how many pounds of the butter are re-
quired to yield the same amount of fat, as do 100 pounds of the standard
butter.

594 THE TECHNOLOGY OF BREAD-MAKING.

Thus supposing that a butter has only 72 per cent, of fat, then every-
thing else being equal, it is only worth 82.7 per cent, of butter of stand-
ard composition. Further, in use 120.8 Ibs. of that butter are required to
go so far in fat as do 100 Ibs. of the standard. Taking on the other hand
a butter with 92 per cent, of fat, such butter is worth 105.7 per cent, of
standard, and in use 94.5 Ibs. only are required to go so far as 100 Ibs. of
the standard.

777. Weak and Strong Butters. — In working butters, there is one
point which may always be noted. Some butters are defined as weak,
while others are strong and waxy. The former, on warming, readily
become oily, while the latter remain tough and wiry. If paste be made
from the former, the paste does not rise well, while the melted fat drains
readily from the hot goods. The tougher butters make lighter paste, and
more fully retained by the articles when baking.

Prior to use in confectionery, butter is usually " creamed"; in this
operation the butter is beaten until of the consistency of cream. The
operation is hastened by slightly warming, although except in very cold
weather such is not absolutely necessary. This act of creaming consists
of breaking down the butter into an emulsion in which both the fat and
the water exist in -minute globules.

778. Rancidity. — A word may here be said as to rancidity in but-
ters ; and on this point some interesting data are given by Lewkowitsch,
of which the following is a summary. When kept under unfavourable
conditions, butter acquires a strong acrid unpleasant flavour, to which
the name of rancidity is given. At the same time, some decomposition of
the fat goes on, and part of the fatty acids is liberated in the free state.
This alone does not, however, produce rancidity, since the addition of
free fatty acid to an oil does not impart a rancid character, although it
gives the oil a sharp taste. It has been surmised that bacteria are re-
sponsible for the production of rancidity, but this has been disproved.
Neither is the presence of moisture necessary, since dried fats are more
liable to this change than those containing a certain amount of moisture.
Rancidity must therefore be considered due to direct oxidation by the
oxygen of the air, this action being intensified by exposure to light. Both
oxygen and light must act simultaneously, in order to produce rancidity,
either of these agents alone being unable to cause any alteration in that
respect. Solid fats, especially those of animal origin, are less liable
turn rancid than liquid fats. With an indication of the causes of ran-
cidity, the means of prevention will suggest themselves to the user of fats.

779. Beef Fat. — This is sometimes found in the well known form of
dripping, but does not by itself reach the confectioner in any great
quantity. When the very fatty portions of the carcase are heated, the
fat melts, and separates from the containing tissues, and in this way a
pure beef fat may be obtained. Like many other animal fats — that of
beef is a mixture of a harder and a softer portion. If the fat be gently
heated, the softer part becomes liquid, while the harder part still retains
its solidity. The fat in this condition may be enclosed in canvas bags,
and subjected to pressure : the more liquid portion passes through and
constitutes a body known in commerce as "oleo, " while the harder part
remains behind, and commercially is termed "beef stearin."

780. Hog Lard. — Lard is obtained from the fat of the pig in much
the same way as beef fat from that of the ox. Lard is a white fat of
somewhat pleasant taste and a soft consistency. Like beef fat, it may be
separated by warmth and pressure into lard stearin and lard oil. The fat
of some portions of the pig is much harder than the others, consequently,

CONFECTIONERS' RAW MATERIALS. 595

some of the fat of the abdomen, if melted down separately, gives a much
harder lard than do other parts, or than would be yielded by the fat of
the whole animal. The harder lards are found to contain a larger pro-
portion of stearin than do those of softer nature. In summer and very
hot weather there is considerable difficulty in cooking with the softer
lards, which become almost liquid. In order to get over this, such lards
may be fortified by the addition of stearin of either lard or beef fat.
Given a soft whole hog lard, there can be little doubt that its cooking
properties are improved by the addition of stearin, while certainly the
wholesomeness is in no way deteriorated. The only point is, that a pur-
chaser who gives the price for the more expensive lard, derived from the
harder parts of the pig, has a right to expect to obtain the same, and not
a soft whole lard, hardened by some foreign fat. Lards are, at the pres-
ent time, almost pure fats ; they melt into a liquid, which is either per-
fectly clear, or only slightly turbid through the presence of a scarcely
weighable quantity of unseparated tissue. The chemist, in analysing
lard, directs his attention principally to the detection of foreign fats or
oils. In doing this, the iodine value is of much assistance to him; the
harder fats, as beef stearin, having a lower value than lard, while most
oils have a much higher value. The difficulty here is that a mixture of
beef stearin and oil may be so arranged as to have the same iodine value
as pure lard. The microscope is called into requisition in order to detect
the addition of stearin, since in samples of lard dissolved in ether, and
then allowed to recrystallise out, the crystals from beef stearin differ in
appearance from those of lard in a state of purity. These crystals are
not only microscopically examined, but also separated and weighed. Un-
fortunately, these tests at times fail to distinguish between added stearin
and natural lards in themselves containing stearin in excessive quantities.
Under such circumstances the decision as to the presence or not of an
adulterant becomes a difficult one.

781. Vegetable Fats and Oils. — These have been already indicated,
though very briefly, in the table given at an earlier stage of this chapter.
But few of these are used alone, the most frequent employment of the oils
being in conjunction with various animal fats. Among the solid vege-
table fats are cacao-butter, which is the natural fat of cocoa or chocolate.

The so-called cocoa-nut oil is, in reality, not a liquid, but a solid, and
is characterised by possessing a somewhat low melting-point, and yet
being a rather hard fat. In its natural state this fat is said to readily
become rancid : the thoroughly purified forms are certainly free from this
very serious defect. In preparing these from the crude cocoa-nut fat, the
fat is melted in a vacuum, and then a current of low pressure steam
forced through. This latter carries off volatile substances of objection-
able or pronounced odour or flavour, and leaves behind a pure and com-
paratively neutral fat. Like the lards, these preparations are pure fats,
and contain no foreign matter. They are distinguished from other fats,
both vegetable and animal (except butter), by possessing a rather high
Reichert-Meissl value.

782. Margarine. — In 1870, the French chemist, Mege-Mouries, first
described a method of making artificial butter on the large scale. Since
then his methods have been considerably developed, and a large industry
has grown up in what were formerly termed artificial butters, butter ine,
oleo-margarine, and now by legal enactment, "margarine." The basis of
the modern methods of preparing this article consists in first rendering
fat of the ox ; this, after melting, is drawn off from solid impurities, and
allowed to cool very slowly. During this process the more solid portion

596 THE TECHNOLOGY OP BREAD-MAKING.

of the fat crystallises out as stearin, and is removed by filtration under
pressure. The liquid portion solidifies into a granular solid of a slightly
yellow colour, to which the name of "oleo" is given. Lard is also pre-
pared in somewhat the same way, and to this the name of "neutral," or
neutral lard, is applied. These two substances constitute the basis of
margarine. The oleo being the harder fat of the two, is taken in larger
quantity for margarine exposed to a warmer climate. The mixed oleo
and neutral are next agitated with milk or cream, or possibly butter
added, and thus the necessary flavour introduced. During the same oper-
ation, an amount of butter colour is incorporated, sufficient to produce a
tint resembling that of butter itself. Different manufacturers use, in
addition to these ingredients, various vegetable oils, in order to soften
the products, and thus render them more adapted to general purposes.
Arachis, cotton-seed, sesame and other oils are thus employed. When
properly made, there can be no doubt as to the wholesomeness and nutri-
tive value of these artificial butters. The conditions of manufacture are
usually hygienic, the materials' being obtained in a fresh state and ster-
ilised before use. The composition of margarine is shown in the last three
analyses quoted in the table of butters before given. The fat value is
generally high, while a clear line of distinction between these substances
and butter is afforded by the low Reichert-Meissl and high butyro-
refractometer values. The former, in the case of No. 24, falls below 1.0,
while in the admixtures of margarine and butter the figures of 4.0 and 5.7
respectively were obtained. At one time mixtures were offered to confec-
tioners stated to contain anything up to 40 per cent, of butter; now, by
law, the proportion of butter permitted to be added to margarine is
restricted to 10 per cent.

783. Other Compound Fats. — Compound lards are yet another form
of mixed fats ; these are sold both under that name and also at times as
pure lards. Their basis is usually beef stearin, or whole beef fat, mixed
with vegetable oil, generally cotton-seed oil. With these more or less lard
may also be incorporated. As lard is generally checked by its iodine
value, these mixtures, if intended as fraudulent lard substitutes, require
to be made so that their iodine value is the same as pure lard.

784, Mineral "Fats." — It is not too much to say that both the
animal and vegetable kingdoms have been thoroughly exploited in order
to find fats for the confectioner. One may go a step further, and say that
the mineral kingdom has also been laid under contribution. There is a
class of bodies known as paraffins, the higher members of which are, when
pure, white, solid, tasteless waxes. Then next, another substance has been
prepared, known sometimes as soft paraffin, and also as vaseline. This
latter, which is also tasteless and odourless, has a soft and semi-buttery
consistency. Its physical nature is very like that of the fats generally,
but it differs in that it is unattacked, even by strong alkalies, and so
cannot be converted into soap. It is therefore matter for little surprise
that vaseline, paraffin, and petroleum products generally, are entirely un-
assimilable by the human digestive system, and consequently absolutely
devoid of nutritive value. WThen a person buys a cake, these mineral
bodies are certainly not of the nature, substance and quality of the article
demanded by such purchaser. While as food these substances are per-
fectly valueless, the authors are not aware of their possessing any posi-
tively harmful qualities. It would seem probable that, according to the
extent to which flour and other bodies were saturated with paraffin, they
would be protected from digestive action within the alimentary tract,
and thus they would be rendered more difficult of digestion and of less
food value.

CONFECTIONERS' RAW MATERIALS. 597

SWEETENING INGREDIENTS.

785. Sugars. — The principal sweetening agents of the confectioner
belong to a group of substances known as sugars, of which bodies an ex-
tended description has already been given in Chapter VI. The following
are the most important of the various substances, containing one or more
of the sugars, that are of service in confectionery.

786. Honey. — Among bodies which are naturally sweet, perhaps that
best known is honey. Since this substance is collected and stored by bees,
man, in even a most primitive state, was familiar with honey, and valued
it because of its sweetness. It would seem that honey was once the staple
sweetening agent of many peoples, being used for that purpose in this
country, and also as a source of those beverages which require a sugar as
their basis. Although collected by the bee, honey is naturally a vegetable
product, and is obtained from flowers. Honey not only possesses sweet-
ness, but also distinct and various flavours, due to certain odoriferous and
flavouring matters present in the flowers from which it is derived. This
natural form of sugar is still used by the confectioner, and is one of the
principal ingredients in the sweet basis of nougat.

In composition, according to Allen, honey is a concentrated solution
of glucose (dextrose) and fructose (laevulose) in water. At times there is
also present a small quantity of sucrose. In addition, honey contains
email quantities of wax, pollen, mineral matter, and traces of flavouring
Hiid bitter substances, and formic acid. The following are the results of
analysis of a number of samples of honey by various observers : —

Glucose (Dextrose) 22.2 to 44.7 per cent,

Fructose (Laevulose) . . . . 32.1 „ 46.9

Total Glucose and Fructose . . 61.4 „ 82.5

Wax, Pollen, and Insoluble Matters trace „ 2.1 ,,

Ash 0.02,, 0.49 „

Water expelled at 100° C. . . 12.4 „ 24.9

Undetermined Matters . . . . 1.3 „ 10.8 „
In the great majority of samples, the total glucose and fructose range
from 70 to 80 per cent., the water from 17 to 20, and the ash from 0.10 to
0.25 per cent. Among adulterants of honey are found srlucose syrup
(confectioner's glucose), cane sugar, invert sugar, and molasses (golden
syrup). Dextrin is not found in genuine Jioney.

787. Cane Sugar, Sucrose. — The earlier names given to the sugars
were derived from the source of each particular sugar ; but it is now well
Known that one and the same variety of sugar may be obtained from a
iiumber of substances. When, therefore, a sugar is named cane sugar, the
name indicates not necessarily that the sugar in question is derived from
the sugar-cane, but that it is sugar of precisely the same kind as that
originally derived from that source. Cane sugar occurs not only in the
juice of the sugar-cane, but also in certain roots, especially that of the
beet, and in the sap of some trees, of which maple sugar is a familiar
example. Various seeds, such as the almond, barley, and also fruits
contain cane sugar. The process of manufacture Consists first in express-
ing the juice whether of the cane or the beet, heatmg to boiling point, and
then getting rid of various impurities by the addition of lime. To get
rid of the colour, the solution of sugar is filtered through animal char-
coal, after which the syrup is evaporated in steam-heated pans and
finally in vacuo. Crops of crystals of sugar are thus obtained, leaving
behind a residuum of syrup known as molasses.

The types of sugar used by the confectioner, such as sugar crystals;
castor sugar, and pulverised sugar, are almost chemically pure. Moist

598 THE TECHNOLOGY OF BREAD-MAKING.

sugar, or " pieces," contains water in varying quantities up to about 8
per cent. Various commercial sugars have the following percentage com-
position : —

COMPOSITION OF VARIOUS SUGARS.

Raw Cane Raw Beet Refined Sugar,

Constituents. Sugar. Sugar. Cane or Beet.

Sucrose . . .. 87 to 99 89 to 96 91.1 to 99.9

Glucose and Fructose . . 2 „ 9 trace „ 0.3 none „ trace

Ash 0.2 „ 2.3 1.6 „ 2.6 trace „ 0.15

Water .. .. . . 0.4 „ 6.8 2.0 „ 4.3 trace „ 0.25

Organic Matter not Sugar 0.3 „ 9.7 0.4 „ 4.0 none

So long as sugars are imperfectly refined, and not absolutely freed
from the residual syrup, beet sugar is inferior in quality to that of the
cane. But by modern processes, the sugar is obtained in what is essen-
tially a chemically pure state ; and in this condition sucrose, whether
derived from the cane or the beet, is identical in character, and samples
obtained from the two sources are undistinguishable from each other.

Refined sugars are now almost invariably * ' blued ' ' in order to correct
any slight yellowish tint. Minute traces of ultramarine, or other blue, are
added for this purpose. Such an addition is usually regarded as harmless.

788. Molasses, Treacle, or Golden Syrup. — The residual juice of the
sugar cane, before referred to, forms when concentrated a pleasant smell-
ing and tasting syrup ; therefore the molasses from cane sugar is agree-
able to the taste. The concentrated beet juice contains, however, sub-
stances which are not pleasant in odour or taste, and therefore beet sugar
molasses is not acceptable for food purposes. Here are given analyses
of golden syrup and treacle, Nos. 1 and 2, by one of the authors, and 3
and 4 by Wallace.

COMPOSITION OF GOLDEN SYRUP AND TREACLE.

Golden Golden

Constituents. Syrun. Trpnc'fi. Syvin. Treac'e.

Cane Sugar 34.40 32.55 39.6 32.5

Glucose and Fructose . . . . 46.35 42.85 33.0 37.2

Water 18.50 15.20 22.7 23.4

Mineral Matter J n 7^ q dn f 2'5 3-5

Other Organic Matter . . J \ 2.8 3.5

100.00 100.00 100.6 100.1

789. Inversion of Cane Sugar. — The chemical changes involved in
the inversion of cane sugar were explained in Chapter VIII., paragraph
276. As there stated, they result in the formation from one molecule of
sucrose of a molecule each of glucose (dextrose) and fructose (laevulose).
The following deals with the bearing of cane sugar inversion on certain
processes of the confectioner. It may be of interest to mention that dex-
trose is found largely in the juice of grapes. When dried into raisins,
these on becoming old develop gritty masses in their interior. These
little lumps are aggregates of small crystals of dextrose, which at times is
called grape sugar. The laevulose, so-called from its left-handed rotation,
is now frequently termed fructose or fruit sugar, and crystallises only
with great difficulty ; hence its presence acts as a preventative of crystal-
lisation. If a saturated cold solution of cane sugar be divided into two
equal parts, and the one inverted by treatment with hydrochloric acid,
the two may be placed away together for purposes of observation. Even

CONFECTIONERS' RAW MATERIALS. 599

though the unaltered sucrose have water added to it in the same volume
as hydrochloric acid was added to the other moiety, yet as time proceeds
the cane sugar crystallises rapidly. In such solutions thus made and set
aside by the authors, the cane sugar had at the end of some three weeks
become almost solid, while not a single crystal had developed in the solu-
tion of invert sugar. Not only is invert sugar itself singularly free from
a tendency to crystallise, but its presence tends also to prevent crystallisa-
tion of cane sugar present in the same solution. Striking illustrations of
this occur in the boiling of jams, where a solution of sugar is heated with
fruit containing organic acids. In a sample of raspberry jam made in
the authors' laboratory from cane sugar and fruit only, it was found,
after keeping, that some 50 per cent, of the sugar had undergone inver-
sion. As already mentioned, cane sugar, on heating, is changed into an
amorphous variety ; and hence the * ' glassy ' ' type of sugar in such sweets
as barley sugar. Still in these there is the tendency to crystallise, and
such sweets would become opaque on being kept. To prevent this, acid is
added during the boiling, and by the inversion of part at least of the
sugar completely prevents, or very considerably retards, the process of
crystallisation. Whenever sugar is inverted by acid during a process of
sugar working, or invert sugar is introduced in a mixture, then the gen-
eral effect is to retard or prevent crystallisation. Although invert sugar
or glucose is thus almost continually being formed from many sugar-
working processes, yet it is rarely if ever added or employed as a pre-
viously prepared product by the confectioner.

790. Comparative Sweetness of Cane and Invert Sugar. — When un-
ripe fruit is used in the manufacture of pies and puddings, they are too
sour to eat without the addition of sugar. Sugar may be added, and
cooked with the fruit, or else subsequently at the moment of eating.
Various opinions have been expressed as to the respective advantages of
these two methods. When added previous to cooking, more or less of the
&ugar is inverted by the acids present, and the degree of sweetening action
of the added sugar must evidently depend on the comparative sweetness
of cane sugar, and the invert sugar produced therefrom. In order to
throw light on this point, one of the authors made an experiment, in
which a solution of cane sugar was divided into two equal parts, and the
one moiety carefully inverted and neutralised, after which both were
made up to the same volume. On being compared for taste by half-a-
dozen persons, the general verdict was that, for initial taste, the cane
sugar was, if anything, the sweeter. On the other hand, the sweetness
of the invert sugar was much more persistent and lasting on the palate.
Owing to this latter property, the invert sugar was, in its total effect,
considered the sweeter of the two. In the next place, an attempt was
made to decide which had the greater "covering power" for acids, and
for this purpose each solution was acidulated with an equal quantity of
dilute sulphuric acid, and again tasted. The acid flavour is very rapid in
its effect on the palate ; and consequently, the cane sugar which seemed
to act on the palate with almost equal speed, mingled its sweetness with
the taste of the acid, and so produced a homogeneous flavour. When the
invert sugar was tried, the first sensation was one of overwhelming sour-
ness, followed by the gradually accumulating sweetness of the slower but
more lasting taste of sugar after inversion. The more preferable method
of sweetening the fruit of pies and puddings would therefore seem to be
that of adding the sugar subsequent to the cooking. But if the full
advantage of the sugar thus added is to be derived, the sugar should be
in a finely divided state, and allowed to dissolve in the juice of the fruit

600 THE TECHNOLOGY OF BREAD-MAKING.

before being eaten. It is probable that the apparently greater sweetness
of previously added sugar may be due to its having been thoroughly dis-
solved, as against the addition of large crystals of sugar after cooking,
and their deglutition without solution. The question discussed throws an
interesting side-light on problems of flavour generally. Much may be due
to the selection of flavours which, when realised by the palate at the sam >
time, shall conjointly produce a favourable impression ; or if appreciated
in succession, shall give a sequence of effects which is in itself pleasant.
That the distinction is a real one, is evinced by the frequent discrimina-
tion of flavours into "taste" and "after-taste."

791. Sugar Boiling. — If the temperature of sugar be maintained for
some time just a little above the melting point, the sugar is changed
without loss of weight into a mixture of dextrose, and a substance called
laevulosan, thus :—

C12H2Ai = C6H1206 + C6H1005..

Sucrose. Dextrose. Lasvulosan.

Further application of heat causes water to be given off, with the
probable conversion of the dextrose into glucosan, thus : —
C6H1206 06H1005 + H20.

Dextrose. Glucosan. Water.

At a yet higher temperature further decomposition ensues, both lasvu-
losan and glucosan being converted into caramelan, C12H18O0, thus : —
2C6H1005 C12H1809 + H20.

Glucosan and Caramelan. Water.

Laevulosan.

Caramelan when pure is colourless, has a slightly bitter taste, and is
highly deliquescent.

Further elevation of temperature to from 374° F. (190° C.) to 410°
F. (210° C.) results in the formation of so-called caramel, which is a mix-
ture of dark-brown, bodies, more or less soluble in water and alcohol.

This statement of the chemical changes occurring when sugar is sub-
jected to the action of heat will serve as a prelude to a description of
what is called "sugar-boiling" by the confectioner. This process is
usually conducted in deep round copper pans, the size of which will nat-
urally depend on the extent of the contemplated operations. These pans
may. be heated either by gas or direct fire heat. It is well to have an
ample margin of sufficiency of heat, since rapid heating to a given point
will produce results which differ from slowly raising the temperature to
the same degree. The confectioner places in his pan say 7 Ibs. of white
cube sugar or crystallised sugar, and one quart of water. This is set on
the fire and the contents raised to the boiling point : directly this occurs,
rhe liquid is carefully stirred with a spatula, so as to dissolve any lumps
of sugar which may happen to remain. At this stage the mixture is a
solution of sugar in very hot water. On continuing the boiling a little
longer, the temperature of the solution rises, and if taken by a thermome-
ter, will be found to be at from 215 to 220° F. Each particular stage of
temperature corresponds to a certain degree of sugar boiling, to which a
technical name is given. Thus at the temperature of 215 to 220°, the
degree of smooth is reached. The workman identifies these degrees by
physical tests which he applies to the sugar. Thus he dips a clay pipe
stem into the liquid, and draws it between the finger and thumb ; at the
smooth degree the sugar feels oily, and hence the name of the degree.
Proceeding still further with the heating, a temperature of 230 to 235° is
reached, and now the sugar is at the thread degree. During this time
water has been driven off from the sugar, and now on cooling, the solu-
tion is sufficiently viscous to draw into threads, if a little is pulled out

CONFECTIONERS' RAW MATERIALS. 601

between the finger and thumb. With further heating, a temperature of
240 to 245° is reached, and the sugar is in the blow or feather degree.
At this stage the liquid has become so viscous that the steam generated
in boiling blows the mass into huge bubbles, and in fact, may easily boil
over the pan. If a little of the sugar be tossed in the air, it will exhibit a
feathered appearance. At 250 to 255°, we reach the ball or pearl de-
gree, and a little of the sugar taken on a pipe stem or glass rod and
dipped into water acquires a consistency about equal to that of putty. We
now proceed to carry our heating operation a considerable distance fur-
ther, and when the thermometer registers from 310° to 316°, the sugar
is at the crack degree. If now cooled in water, the sugar rapidly hardens
and becomes brittle. Very little further heating causes an incipient cara-
mjelising, and the confectioner's caramel degree is reached.

During these stages the water originally added is being driven off ;
while toward the last the sugar is undergoing those successive steps of
degradation towards caramelan, by "shedding" or losing molecule after
molecule of water. It will be noticed that throughout, the sugar still
retains the chemical composition of a carbohydrate.

792. Cutting the Grain. — At this stage an explanation must be given
of what the confectioner terms "cutting the grain" of sugar. When
heated above 250° F. the sugar will, if allowed to cool, crystallise into a
hard granular mass. The sugar, in fact, re-solidifies from fusion and
crystallises in so doing. To "cut" or destroy this graining tendency, the
confectioner employs some acid substance, that most frequently used
being cream of tartar, which is the acid tartrate of potash (hydrogen
potassium tartrate). Instead of this, tartaric, citric, or acetic acids may
be employed. The cutting agent may be added to the sugar when first
mixed with water, and the whole heated together. Sugar thus treated,
instead of graining, remains pliable while hot, and transparent when cold.
The sugar has in fact lost its crystalline nature, and has become an
amorphous or vitreous substance. From what has been previously ex-
plained, it will at once be seen that cutting the grain consists of inverting
more or less of the sugar by means of an acid body.

793. Fondant Sugar. — This preparation is used both in flour and
sugar confectionery. Sugar, water, and cream of tartar are first boiled
to the feather degree. Then, in hand-working, the syrup is stirred until
it becomes creamy through the production of minute crystals. On the
large scale the same effect is obtained by pouring the requisitely boiled
syrup into a vessel in which, during cooling, it is violently agitated by
paddles or stirrers; crystallisation goes on, and the creamy mass of fine
crystals, suspended in syrup, pours out from the lower end of the vessel.
The crystalline portion of the fondant is simpty unaltered cane sugar
crystals, the softer and non-crystalline portion consists of invert sugar.

794. Starch-Sugar, "Glucose." — By processes already explained
(paragraph 528) malt is converted into the preparation known as malt
extract. Starch forms a much cheaper source of malt sugar or maltose,
and may be changed into a mixture of maltose and dextrin by the action
of diastase, or more conveniently by hydrolysis by dilute acid. But while
diastase is incapable of carrying hydrolysis further than maltose, acids
produce by further conversion more or less glucose. Starch sugar finds

* many uses, and consequently its production is an important branch of
manufacture. Maize starch is that most commonly employed. The
starch, water, and a small quantity of sulphuric acid, are heated together
in large wooden vats by the introduction of steam. This operation is con-
tinued until a small portion of the liquid ceases to give the starch reaction

602 THE TECHNOLOGY OF BREAD-MAKING.

with iodine. Chalk (calcium carbonate) is next added in slight excess, so
as to neutralise the acid. The calcium sulphate is allowed to settle, and
the upper liquid decolourised by filtration through animal charcoal, and
concentrated by evaporation until the solution, when cold, has a specific
gravity of about 1.3 to 1.4. Starch sugar thus obtained is a colourless,
odourless, and transparent syrup, possessing a pleasant, sweet taste.

795. Analysis of "Glucose." — The following are analyses of malt
extracts, for purposes of comparison, and commercial starch sugars : —

ANALYSES OF MALT EXTRACT AND "GLUCOSE."

Malt Malt Starch Starch

Extract. Extract. Sugar. Sugar.

Constituents. No. I. No. II. No. I. No. II.

Water 22.23 26.30 18.24 15.20

Mineral Matter 1.10 1.60 0.26 0.18

Proteins 3.01 5.40

Dextrin 12.90 7.65 16.00 16.20

Sucrose 3.59 4.07

Maltose 54.84 47.01 55.50 59.00

Dextrose and L^vulose (Glucose) . . 2.33 7.97 10.00 9.42

100.00 100.00 100.00 100.00

The starch sugar, being made from the purified starch only, contains
none of the ready-formed sugars of the grain, nor any proteins, such as
are found in malt extract. The mineral matter consists of a trace of cal-
cium sulphate held in solution in the syrup. The essential constituents of
starch sugar are dextrin and maltose, which in the figures given in the
first analysis, together form about 87 per cent, of the total solid matters
present. The remainder is composed almost entirely of dextrin. Starch
sugar has a remarkably high right-handed rotatory power on polarised
light, the figure for the first sample quoted being 2.75° per gram of
solids in 100 cubic centimetres of the solution when measured in a two-
decimetre tube.

It will be seen, therefore, that starch sugar has about double the right-
handed rotary power of cane sugar, which high figure absolutely differen-
tiates it from invert sugar or glucose, with its left-handed rotary power.
In the analysis quoted the high rotary power indicates that the proportion
of glucose present (if any) must consist practically entirely of dextrose,
or the right-handed variety of glucose.

In the preceding analyses of starch sugar, the dextrin was determined
by direct precipitation. Subsequent investigations showed that in this
body there were present considerable quantities of malto-dextrin (see
paragraph 192). This needs a revision of the figures giving the results
of analysis, which then become : —

Water 15.20

Mineral Matter . . 0.18

Dextrin 5.02

,,-,/, A. (Dextrin 7.32J

Malto-dextrm |Maltose 3<86| 11.18

Maltose 68.42

Dextrose nil

100.00

CONFECTIONERS' RAW MATERIALS. 603

If the conclusion based on the analysis of this sample be correct, the
substance known as starch sugar may be viewed as essentially a mixture
of dextrin, malto-dextrin, and maltose.

With the well-marked composition of starch sugar it is to be regretted
that the name used both popularly and commercially is a misnomer.
Starch sugar is commonly called starch "glucose," whereas evidently a
far better name is either starch sugar or, if preferred, "starch maltose."

Of the constituents of starch sugar it may be said that maltose,
although a crystalline sugar, crystallises much less readily than does
cane sugar. Dextrin, or as it is sometimes called, British gum, is a
tasteless gummy body, which does not crystallise itself, and exercises an
inhibitory action on the crystallisation of other sugars. Its use is, there-
fore, as a preventative of crystallisation ; and in some goods starch sugar
is employed, in order to prevent cane sugar crystallising, on much the
same lines as a portion of the cane sugar is inverted by the addition of
cream of tartar or other similar acid during sugar boiling. In addition
to this, dextrin also seems to exercise a specific moisture-retaining effect,
and the use of starch sugar is therefore indicated in those goods which
are desired to retain a moist character.

FLAVOURING INGREDIENTS.

796. Fruit. — Fruit of various kinds is a most important flavouring
agent in flour confectionery. Passing mention only need be made of the
employment of fresh fruits in season ; thus, gooseberries, currants, rasp-
berries, cherries, plums, and apples, in their respective turns, are used
in the manufacture of pies, tarts, and puddings. In chemical composi-
tion, most of the fruits consist largely of water, in next highest propor-
tion containing carbohydrates, and lastly small quantities of other bodies,
as set out in the following table, quoted from Hutchison's Food and
Dietetics : —

Per cent.

Water 85 to 90

Carbohydrates . . . . . . . . . . 5.5 to 10.5

Cellulose 2.5

Protein 0.5

Fat 0.5

Mineral Matters . . . . . . . . 0.5

The carbohydrates consist mostly of sugar, the principal one being
laivulose, or fruit sugar, besides which there are varying amounts of cane
sugar and dextrose. In addition to sugar, many fruits yield gum-like
bodies, to which, as a group, the name of "pectin" has been given. In
unripe fruits there is present an insoluble body known as pectose, which,
by the action of a natural ferment, is converted into pectin. Pectin exists
ready formed in ripe fruits, and also very largely in Irish moss. Pectin
is soluble in water, and is devoid of any marked flavour and odour.
Treatment with a small quantity of acid causes its solution to gelatinise.
Like most other gelatinising substances, the power of this setting or
"jellying" is seriously diminished, or even destroyed by long continued •
boiling of its solution. A solution of apple juice, on being concentrated,
exhibits this jelly-like consistency in a very marked form, and apple jelly
may be regarded as a pectin jelly sweetened by the addition of cane
sugar.

Fruits contain notable quantities of various organic acids, among
which are tartaric, citric, and malic acids. Cellulose is also present in

604 THE TECHNOLOGY OF BREAD-MAKING.

more or less amount. In the act of ripening, the sugar of fruit increases
in quantity, while the free acids diminish ; at the same time, the cellulose
also more or less disappears.

The characteristic flavour of different fruits is dependent on traces of
various ethereal and allied bodies. Some of them have been identified
and isolated, but many are present in such small quantities as to render
their effectual examination impossible. When dealing with fruit essences
reference will be made to some of these bodies.

797. Dried Fruits. — Certain kinds of fruit are more especially used
in either the dried or otherwise prepared form. Most prominent among
these is the ordinary dried currant of the grocer and confectioner. The
currant is not a fruit of the same type as our fresh currant of this coun-
try, but is a small stoneless grape, which when dried in the sun consti-
tutes the currant of commerce. The smaller raisin, known as a sultana,
is also a dried grape of larger size than the currant. Both these owe their
sweetness to crystallisable grape sugar or dextrose. Cherries are also
prepared for somewhat similar use, by being stoned and then soaked in
a concentrated solution of cane sugar. The following is the result of
analysis of a good sample of currants, washed and dried, and sold as '
the best quality. The fruit was carefully hand-picked so as to ensure the
pbsence of stones or grit before analysis.

Per cent.

Water 23.24

Carbohydrates, principally Sugars . . . . 71.82

Cellulose 1.19

Proteins 1.67

Fat ... 0.10

Mineral Matters . 1.98

100.00

Energy in Calories 302.24

798. Peel. — A portion only of the fruits of the orange and lemon
type is commonly used in confectionery, that portion being the peel. The
peel of the orange, lemon, and citron are preserved by treatment with
sugar syrup, then drained, and cut into slices. Peel largely owes its
characteristic flavour to the essential oils found in that portion of the
fruit, and to which reference will subsequently be made.

799. Preserved Fruits. — One obstacle to the regular use of fruit by
the confectioner is that fresh fruit is in season for only a limited time of
the year. To get over this difficulty, recourse is had to various methods
of preservation. The simplest in principle is that of preserving the fruit
itself without the addition of any other body. This object is effected by
filling clean bottles with the whole fruit, and adding water to the neck.
The bottles are then stood in tanks containing water at such a height as
to submerge the whole of the bottle except the neck. The water is slowly
heated until the boiling-point is reached. The bottles are then securely
corked and capsuled, and if the operation be successfully performed, the
contents are preserved indefinitely. To understand the principles
involved in the preservation of fruit, it must be remembered that putre-
faction and decomposition are due to the action of certain microscopic
living organisms present on the surface of the fruit, and also pervading
the atmosphere. If the life of these organisms be destroyed, then no
putrefactive changes can occur in the fruit. The heat of boiling water is
in this case found to be sufficient for the purpose. This preservation,

CONFECTIONERS' RAW MATERIALS. 605

without sugar, results in maintaining the fruit in a condition approxi-
mating more closely to that of natural fruit than when foreign preserva-
tive agents are added.

800. Jam. — More usually, fruit is preserved in the form of jam,
since the cooking, and also the addition of sugar, are, for many purposes,
of advantage rather than otherwise. Jam may be defined as a " cooked
confection of fruit to which has been added cane sugar or other whole-
some sweetening and preservative agent or agents." The public demand
that jam shall be palatable and also pleasing to the eye ; further, that it
shall be absolutely wholesome in character and contain nothing in the
slightest degree deleterious. If it fulfil the whole of these conditions, it
is difficult to see where the interest of the consumer is in any way
furthered by limiting the range of constituents of jam any more than
is done in the case of any other confection.

The busy time of the jam-maker is in the fruit season. Fruit, sugar,
and if necessary a little water, are added together in a steam-jacketed
copper pan fitted with a mechanical stirrer. High pressure steam is
admitted to the jacket, the fruit and sugar thus boiled being continually
stirred the whole of the time. The boiling having proceeded sufficiently
far, the jam is poured out of the copper into a suitable vessel, and then
conveyed away to the filling-room, where it is placed in jars or other
convenient receptacles. In practice, it is found an advantage to make
only a portion of the fruit into jam during the actual fruit season. Large
quantities of fruit are simply converted into pulp by appropriate pulping
machines, then boiled sufficiently to thoroughly sterilise and thus preserve
the pulp. Such pulp is stored until required, when it is transferred to
the boiling coppers, the requisite quantities of sugar added, and the jam
boiled and prepared in the same manner as with fresh fruit.

The chemistry of jam-boiling follows lines already indicated in other
manufacturing operations which have been described. Various kinds of
jam must differ according to the character of the fruit, the differences
largely depending on the degree of acidity of the fruit in question. Dur-
ing the act of boiling, such acid inverts more or less of the cane sugar
added. As was fully explained during the treatment of sugar-boiling,
invert sugar exercises an inhibitory action on the crystallisation of the
cane sugar also present. Therefore, the inversion of cane sugar by the
acid of the fruit prevents subsequent crystallisation of the jam. The less
acid the fruit contains the less is the amount of such inversion. With
very ripe and comparatively non-acid fruits the requisite amount of
inversion may be obtained by prolonging the boiling, since the effect of a
small quantity of acid acting for a longer time is much the same as that
of a large quantity for a shorter time. But too prolonged boiling intro-
duces another difficulty — the pectin in the jam, like other analogous sub-
stances, has its setting or "jellying" properties diminished or destroyed
by too prolonged boiling, and therefore it is not always feasible or advis-
able to push inversion by a too prolonged boiling. In the case of sugar-
boiling, an alternative method to the use of acid for "cutting the grain"
was described, in which the prevention of granulation was due to the
addition of starch sugar (or starch maltose). The jam manufacturer
finds the same agent of service for the same purpose, and accordingly
with some kinds of fruit, and under certain conditions, a portion of the
sugar used consists of that from starch. The maltose crystallises less
readily than does cane sugar, and in this way lessens the tendency to
crystallisation, But the dextrin also present in starch sugar is probably

606 THE TECHNOLOGY OF BREAD-MAKING.

a yet more effective preventative, and exercises a very powerful retarding
influence on the crystallisation of the jam. In those kinds of jam pre-
pared from acid fruits, no addition of starch sugar is necessary. When
\ery acid-free fruits are employed, the addition of starch-sugar is an
advantage, and in no way lessens the palatability or wholesomeness of the
jam. Recently some preparations of marmalade have been put on the
market, in which the slices of fruit float in a thick, transparent, sirupy
jelly. These forms appeal very strongly to the eye and also to the palate ;
In their manufacture starch sugar is almost a necessity.

In jam-making, the boiling itself is a very efficient agent of preserva-
tion ; but the sugar also acts as- a preservative agent, since although dilute
sugar solutions ferment readily, yet sugar in this concentrated form is a
powerful antiseptic body.

Among things to be condemned without reserve in the manufacture of
jam is the use of unsound or decomposed fruit, and also that of low grade
and impure sugars, whether of the sucrose or maltose variety. These
lower the quality of the jams, and render them decidedly unwholesome.
Well-made jam does not require the addition of formalin, salicylic acid,
or other similar preservatives. The addition of artificial colouring matter
is also unnecessary, although with modern harmless colours, no actual
injury results from their employment.

Jam for confectioners' purposes requires to be made of such a con-
sistency that it will readily stand the heat of cooking in tarts, etc., with-
out becoming so liquid as to run out. This point is a very important one,
mid hence specially stiff jams are manufactured for use in confectionery.
The purchaser of jam is warned against jams containing one particular
adulterant, agar-agar, or Japanese isinglass. The essential constituent of
this substance is gelose, a compound consisting of carbon 42.77, hydrogen
5.77, and oxygen 51.45 per cent. Gelose has remarkable gelatinising
power, and one part in 500 of water will set to a jelly. The addition of
this substance to jams enables them to carry an excessive quantity of
water and yet to be of firm consistency. But such jams become exceed-
ingly fluid on the application of heat, and run out of any goods in which
they are used in the act of baking.

801. Nuts. — Nuts are characterised by the high proportion of oil or
fat which they contain ; this amounts to from 50 to 60 per cent, of the
whole nut, the remainder consisting of protein, carbohydrate in small
quantities, and cellulose. The oil of nuts is likely to become rancid on
keeping ; for this reason walnuts and other nuts are liable to acquire an
unpleasant taste if exposed to the air. Almonds are supplied not only
as the whole kernel of the nut, but also in a ground condition. In this
latter form there is opportunity of considerable sophistication. Buyers
of ground almonds should be on their guard against removal of oil,
and addition of starch, sugar, or other foreign matters. The cocoa-nut is
also largely used for confectioners' purpose. The nut, after removal
from the shell, has the outer skin pared off; the flesh of the nut is then
shredded and carefully dried. Again the purchaser should satisfy him-
self that no oil has been removed.

802. Essential Oils. — In the case of a very large number of sub-
stances, their special and peculiar flavouring qualities are due to the pres-
ence of small quantities of substances possessing the particular taste and
smell in a marked degree. These flavouring matters have, in many cases,
been isolated and obtained in a state of purity. In a large number of
instances their physical properties are those of a volatile oil; that is to

CONFECTIONERS' RAW MATERIALS. 607

say, they are liquid, more or less oily in their nature, evolve a distinct
and often powerful odour at ordinary temperatures, and boil or distil at
a much lower temperature than the common or fixed oils.

803. Oil of Peppermint. — This substance is prepared from the plant
known as peppermint. The herb is cut and soaked in water in the boiler
part of the well-known still; heat is applied and as the water boils, its
steam carries along with it the vapour of the essential oil of peppermint.
The steam is condensed, and the resultant water is found to be charged
with the odour and taste of peppermint in a much more concentrated
form than in the plant itself. In this way was made the old-fashioned
housewife Ts ' ' peppermint water. ' ' But with this operation of distillation
properly conducted on large quantities of peppermint, the distilled pep-
permint water is found to contain an oil which rises to the surface, and
may then be separated. On these principles are prepared commercial oil
of peppermint, and the manufacture of this oil may be taken as a type
cf that of many other essential oils.

In composition this oil consists largely of the substance termed men-
thol, which is a crystallisable solid, melting at 42° C., and an alcohol in
chemical composition. This body in its free state is a well-known article,
and is simply obtained by freezing the oil, when menthol separates in the
solid form, and is purified from the still liquid adherent oil by pressure,
or drying in a centrifugal machine. This de-mentholised oil is either sold
as such, or used as an adulterant of the oil itself. Another form of
adulteration is the addition of either wood turpentine or other bodies of
the terpene group.

804. Analysis of Essential Oils. — Substances commanding such a
high price as essential oils offer peculiar and special temptations to the
adulterator, hence their composition should be checked by analysis. The
following is an outline of the principles involved in such examination :—

I. Essential oils have a fairly definite specific gravity varying for the
one oil with well-defined limits.

II. Many oils exercise a rotary power on polarised light; conse-
quently, like the sugars, essential oils are examined by the polarimeter.
It is usual to express the results in degrees of dextro- or laevo-rotation
when measured in a decimetre tube.

III. The boiling point of essential oils is fairly constant for the same
oil, and so the temperature of the boiling point is also determined.

IV. The oil may contain some special compound on which its value
largely depends. If this compound can be readily estimated with
accuracy, such determination is an important guide in the commercial
valuation and determination of purity of the oil.

Applying these principles to oil of peppermint, the following are the
requirements of this oil :—

I; Specific Gravity, 0.900 to 0.920 at 15.5° 'C.

II. Optical Rotation, Laevo-rotary, — 20 to — 30°.

III. Boiling Point. The oil should not boil below 200° C., but should
distil almost completely between 200° and 215° C.

IV. The menthol in the oil may be determined approximately by cool-
ing the oil by means of a freezing mixture, and then introducing a small
crystal of menthol. If the oil has been de-mentholised it remains more or
less liquid, but if pure, it forms a crystallised mass through separation of
solid menthol. This test is preferably replaced by an estimation of men-
thol by purely chemical methods.

805. Essential Oil of Lemon. — This oil is of vast importance to the
confectioner, and is well known as a light yellow liquid of extremely

608 THE TECHNOLOGY OF BREAD-MAKING.

fragrant odour. Unlike peppermint oil, that of lemon is not usually
obtained by a process of distillation. The essential oil resides in small
cells immediately below the outer surface of the lemon, and these are
burst on bending the peel. For many cookery purposes, the flavouring
matter is obtained by grating. off the outer layer of the skin, which grating
is then known as the ''zest" of the lemon. The process of manufacture
is conducted on similar principles. The interior of the lemon is first
removed, leaving its rind in two cups; these are turned inside out, and
the ejected essence wiped off the originally outer surface by a sponge.
This operation is continued until the sponge is saturated, when the oil is
squeezed out into a vessel, and the collecting operation continued.

In composition, oil of lemon consists principally of a terpene, having
an analogous composition to that of wood-turpentine, and to which the
names of lemon-terpene and limonene have been given. This body differs
from turpentine in that it possesses a higher boiling point and a higher
rotary power than the latter. As a flavouring agent the terpene of lemon
oil is comparatively of little value, the essential flavouring matter being
an, aldehyde, C10H160, known generally as citral. Oil of lemon contains
citral in quantities varying from 4 to 7 per cent. For some purposes the
presence of the lemon terpene is considered an objection, and, therefore,
there are at present put on the market so-called terpeneless oils of lemon
in which all or part of the terpene has been removed, and the citral with
other flavouring ingredients alone remains. Such oils are prepared by a
process of distillation in vacua-, the terpenes, having a lower boiling
point, first distil over and leave behind the citral residue.

Like the other oils, there are certain requirements which that of lemon
are expected to fulfil ; of these the following is a summary : —

I. Specific Gravity. 0.857 to 0.860.

I. Optical Rotation. Not below -f- 59°.

III. Boiling Point. Not below 170°.

IV. On being subjected to fractional distillation, the first 10 per cent,
distilled over will exhibit a less optical rotation than that of the original
oil, but such difference should not exceed two degrees. This last limit is
that laid down by the British Pharmacopoeia, but the amount of such dif-
ferences varies considerably in different years. A fairer figure for gen-
eral use is 3.0°, and this is the limit adopted by Parry. Thus recently
examined oil of undoubted purity gave the following figures : —

Optical rotation for whole oil . . . . . . -j- 62.5°

Optical rotation of first 10 per cent, of distillate . . -f- 57.4°

Difference 5.1°

Oils of lemon are frequently sold with the results of a direct estima-
tion of citral given; but, for several reasons, this is no very true guide
to value. In the first place, the results obtained by the rougher methods
of estimating citral may be far from accurate, and an investigation of the
methods of sophistication indicate other and more cogent reasons for dis-
trusting citral estimations as an indication of actual value.

806. Adulteration of Oil of Lemon. — In earlier days, the principal
adulterant of oil of lemon was turpentine, and even now samples are at
times met with containing some 40 or 50 per cent, of this body. The limi-
tations previously given will readily serve to detect adulteration with oil
of turpentine, since this body has an optical rotation of from — 40° to
+20° according to source, and a boiling point of about 157°. Any large
admixture of turpentine will lower the optical rotation of oil of lemon,
but this can be to some extent masked by the addition of cheap oil of

CONFECTIONERS' RAW MATERIALS. 609

orange, which has a rotation of from -j-92 to 98°. By boiling and frac-
tionally distilling, the presence of turpentine is clearly revealed. First,
it lowers the boiling point ; and, secondly, the first fraction of distillate
will have a much lower optical rotation, since the terpenes of either oil
of lemon or oil of orange agree very nearly with the original oils in rotary
power. It is for this reason that the limit of 3° has been laid down,
although, as first stated, this is not sufficiently elastic to include all pure
oils. But when a difference of as much as 12 or even 15 degrees occurs,
as was the case in some samples examined, which had been recently sold
by well-known firms, then evidently the buyer is being subjected to a
fraud of a very marked kind. But the use of oil of turpentine is now
largely superseded by adulteration of a much more insidious description.
In the manufacture of terpeneless oil of lemon, lemon terpenes are
largely produced as a waste product. As such terpenes constitute some
93-95 per cent, of pure oil of lemon, it will be seen that their addition
cannot, very largely, alter the chemical constitution of the oil, except by
lessening the proportion of the (approximately 5-6 per cent, fraction of)
citral and allied constituents. Neither the boiling point nor the optical
rotation of the oil is thus affected ; and further, the first 10 per cent, of
distillate will also agree with the standard tests. There remains the
direct estimation of citral, but unfortunately, from the present point of
view, oil of lemon is not the only source of citral. Verbena, or as some-
times called ''lemon plant," and also lemon grass, yields oils which con-
tain about 80 per cent, of citral, and consequently lemon grass oil forms
a comparatively very cheap source of citral. A mixture of say 94 parts
of lemon terpene with 6 of lemon grass oil, will answer not only to the
B.P. (British Pharmacopoeia) limitations before quoted, but also to a
direct citral estimation. Therefore, the simultaneous addition of lemon
grass oil as well as lemon terpenes to oil of lemon evades both the B.P.
tests, and also a direct citral determination. But although such a mix-
ture may answer to the tests mentioned, it is in no way a true or efficient
practical substitute for pure oil of lemon. Oil of lemon contains other
odoriferous constituents than citral, which latter are not furnished by
lemon grass oil ; and this oil contains odorous and flavouring matters
which are foreign to oil of lemon. The presence of lemon grass oil is
revealed by the odour of verbena possessed by the oil, and this can fairly
readily be detected by the expert. A considerable assistance in applying
the "nose test" to lemon oil is to have it distilled in vacuo to 10 per cent,
of the original volume, and then smell the concentrated citral, etc.,
residue either in its normal condition or after dilution with pure concen-
trated alcohol. In the absence of the terpenes the nose can often better
judge the character, origin, and quality of the essential flavouring bodies
present. When making an analysis of oil of lemon it is no very difficult
matter for the chemist to return this concentrated residue of distillation
to his client, and allow him to exercise his own judgment on its odorous
qualities. Nobody can feel more strongly than chemists the urgent neces-
sity for buying oil of lemon only on analysis; but failing this very
obvious precaution, the buyer may generally take it for granted, that
given a range of oils supplied by one and the same dealer, he will get as
good (if not the best) value for his money by selecting oils of the top
quality, as by taking those of lower price. If he has a preference for
diluted oils, the most economic method of gratifying it is by buying pure
oil, and lemon terpene, and mixing them at his own discretion.

807. Essential Oil of Orange. — This oil like that of lemon is pre-
pared from the rind of the fruit. In commerce there are two varieties,

610 THE TECHNOLOGY OF BREAD-MAKING.

the oils of sweet and bitter orange. Pure orange oil has a specific gravity
of 0.848 to 0.856. The optical rotation of these oils is very high, usually
falling between -f-94° and +98°. The oil commences to boil at 173° to
174°. As with the oil of lemon adulteration is practised by the addition
of waste terpenes of oils of orange and lemon.

808. Orange Flower Water. — An odoriferous and flavouring agent
is also contained in the flowers of the orange, and is extracted by adding
water to the petals of the flower and then distilling. The resultant dis-
tillate contains an essential oil known as oil of neroli. When the distil-
late is sufficiently concentrated this oil floats on the surface and is sep-
arated. The watery portion owes its flavour and odour to the fact that
it holds a trace of the essential oil in solution, and is termed orange flower
water.

809. Essential Oil of Almonds. — Almonds riot only contain a true
and non-volatile oil, but also a substance called amygdalin, which by tak-
ing up water, is converted into, dextrose, essential oil of almonds, and
hydrocyanic acid. The essential oil is obtained by a process of distilla-
tion, and is then freed by appropriate processes from the hydrocyanic
acid. Such volatile oil of almonds is essentially benzaldehyde, C7H60,
and has a pungent characteristic odour. This oil is employed to fortify
almond confectionery, a less proportion of almonds being used, and a
larger portion of sugar or other sweet bodies employed. In ground
almonds, as supplied ready-made to the confectioner, this type of adulter-
ation should be carefully watched for. It is only within certain limits
that this employment of essential oil is advisable, since its too generous
use gives a strong over-powering flavour, markedly different from the
delicate taste of the almond itself. Pure natural oil of almonds, freed
from hydrocyanic (prussic) acid, used to be worth from 25s. to 30s. per lb.,
while inferior oils and fraudulent and poisonous substitutes ranged at the
same time in price from 20s. to as low as Qd. per lb.

Benzaldehyde is manufactured on the large scale, and is found on the
market as * * artificial oil of almonds. ' ' This substance is used as a cheap
perfuming agent, but its odour is not sufficiently delicate to permit of its
being used in the highest class of perfumery, to say nothing of confec-
tionery.

Oil of Mirbane is sometimes employed as an adulterant of oil of
almonds, and chemically consists of nitrobenzene, C6H5NO2, mixed with
various impurities. It has a coarse almond-like odour, and is poisonous
when taken internally. Comparatively recently a fatal case of poisoning
occurred through oil of mirbane being mistaken for oil of almonds.

810. Other Essential Oils. — These must be passed over with but the
slightest reference. The various spices, allspice or pimento, cinnamon,
cloves, etc., all yield essential oils, and these are in many ways of use to
the confectioner. Among the spice oils the most important are that of
allspice or pimento, and oil of cloves. These are somewhat similar in
character, and both contain a phenol known as eugenol. In oil of cloves
the eugenol amounts to as much as from 85 to 90 per cent. The oil should
have a specific gravity of 1.048 to 1.065, and a slight left-handed optical
rotation, never more than — 1.5° and usually under — 1.0°. In pimento
oil the specific gravity should not fall below 1.040, and the optical rota-
tion is usually about — 2°, and should never exceed — 4°.

These oils already dealt with may be taken as types, and for particu-
lars of others, systematic treatises, such as Parry's Essential Oils, must
be consulted.

CONFECTIONERS' RAW MATERIALS. 611

811. Essences. — There is a more or less subtle distinction between
essential oils and essences. Thus, essence of lemon is not necessarily the
same as essential oil of lemon. Many essences are solutions of essential
oils and other flavouring ingredients in alcohol. An illustration of these
is offered by the well-known essence of mixed spice of the confectioner,
and used largely in the manufacture of "Hot-cross Bun." The real
favouring matter of such essence is a mixture of essential oils of different
kinds of spice; but many samples also. contain alcohol in large quantities
running up in some cases to as much as 80 per cent, (and in extreme
instances 90 per cent.) of the total essence. Samples such as these are
now, however, of great rarity. With the increased duty on spirits, the
oils themselves are frequently but little dearer than the alcohol. Such
essences now frequently consist of a mixture of the essential oils with
lemon or orange terpenes. As diluting agents these bodies are quite as
suitable as alcohol.

Essential oils and essences require constant supervision, and all users
of any but the very smallest quantities, will find their frequent analysis
to amply repay them.

812. Fruit Essences. — The composition of fruits has been already
discussed, but as their flavouring matters are prepared in a more or less
concentrated form, they require some attention under this section of our
subject. There is a small class of fruits of which the flavouring matter
has been identified as largely composed of one or more definite chemical
compounds. Thus as already explained, the essential oil of bitter almond
consists of, and is identical with, benzaldehyde. The following are other
instances of chemical compounds which are the source of the flavour of
fruits : —

Fruit. Flavouring Compounds.

Jargonelle Pear . . . . . . Amyl acetate.

Quince . . . . . . . . Ethyl pelargonate.

Pine-apple . . . . . . . . Ethyl butyrate.

By this is meant, not merely for example, that the flavour of the
jargonelle pear is simulated by acetate of amyl, but that that substance
is the actual flavouring body of the pear itself. For these and possibly
one or two other bodies, the essential flavouring ingredients are thus
obtained in a pure form from outside sources ; and what is sold as essence
of jargonelle pear is largely, if not entirely, amyl acetate in a more or
less concentrated condition.

Another group of essences consists of those of an artificial nature,
built up from a number of essential oils and other flavouring ingredients,
according to each particular manufacturer's recipe. Some of these are
pleasant in flavour, and others the reverse ; but whether pleasant or
unpleasant, most of them bear but a very distant resemblance to the fruit
they are supposed to imitate.

Manufacturing chemists have devoted considerable attention to the
problem of conserving the natural essences of fruits in a concentrated
and permanent form, and these efforts have met with considerable suc-
cess. It would be impossible to attempt here any description of the man-
ufacturing processes; but it may be said that the raw material is fresh
ripe fruit. If one takes the most luscious fruit imaginable, its water,
cellulose, proteins, fat, and mineral matter do not materially, if at all,
contribute to the flavour. The pectin-like bodies are also flavourless,
while the sugars, although sweet, are not distinctively flavouring. As
these constitute the main proportions of the fruit, it is evident that a
considerable concentration of the flavouring portion is conceivable, and,

612 THE TECHNOLOGY OP BREAD-MAKING.

as a matter of fact, the solid portion of the fruit can be removed as an
almost tasteless mass. It remains to drive off as much of the water as
practicable, so as to obtain a strong solution of those constituents to
which belong the characteristic taste. This being done, the fluid is
sterilised so as to preserve it from decomposition, and, as a result, there
is the purely natural essences of the fruits.

813. Vanilla and Vanillin.— Turning to yet another distinctly dif-
ferent type of flavouring matters, there may be taken as an example the
well-known vanilla flavour. This flavour is familiar as a result of its
presence in chocolate, ices, and other confections. The actual source is
the pod or fruit of the vanilla plant. Close inspection of these pods
shows them to be covered with a white efflorescence ; this consists of the
essential principle of vanilla, which has exuded and crystallised. To this
body the name of vanillin has been given. Vanillin constitutes about 2
per cent, of the pod, and like many other flavouring and odoriferous sub-
stances is an aldehyde in composition. To obtain the flavour of vanilla
in the most thorough and efficient manner there is probably no simpler
method than to powder the pods themselves with sugar as a diluent, say
1 part of vanilla to 9 parts of sugar. The objection to this is that in
light-coloured cakes and ices the appearance of what look not unlike
particles of snuff scattered throughout the substance is unsightly. To
obviate this, a tincture or essence of vanilla may be prepared by macerat-
ing the vanilla in alcohol and filtering off from the insoluble matter. The
soltuion thus obtained yields all the flavouring bodies of the pods without
the presence of the objectionable solid portion.

814. Synthetic Vanillin. — Vanillin is one of those substances which
have been artificially prepared, the process usually adopted being that of
subjecting eugenol, the essential constituent of oil of cloves, to a process
of oxidation. When thus prepared and thoroughly purified, vanillin con-
sists of a white crystalline matter of an intense vanilla odour. It is
important that the vanillin should be thoroughly freed from the oil of
doves from which manufactured, or else the substance is liable to have
itself a distinct odour and taste of cloves. When first put on the market
vanillin commanded a very high price, and in 1876 was quoted at £160
per lb., while in 1898 the price had fallen to £2 12s. for the same
weight. Vanillin is liable to adulteration with various harmless but
valueless substances, the presence or absence of which can be determined
by analysis. The manufacturers point out that a mixture of 2^ per
cent, of vanillin in sugar is equivalent in strength to the vanilla pod
itself. As the equivalent of the confectioner's " vanilla sugar," they
recommend that 2^ per cent, vanillin sugar should be taken in the same
quantity as would be taken of actual vanilla. Vanillin forms a very use-
iul substitute for vanilla, and from its greater cheapness is somewhat
extensively used. It is doubtful, however, whether for the most delicate
flavouring purposes it can be considered a complete substitute for true
vanilla. While undoubtedly vanillin is the chief and predominant
flavouring ingredient of vanilla, yet it is probable that there are traces of
other flavouring matters present, and the flavour of the pod is therefore
that of vanillin, plus such additional flavours as are given by these other
bodies, which are absent in artificial or synthetic vanillin.

Reverting a moment to the essence of vanilla, while the best is pre-
pared from fresh pods, inferior qualities consist of tinctures made from
the almost exhausted residue, which are subsequently fortified by the
addition of artificial vanillin.

CONFECTIONERS' ft AW MATERIALS. 613

815. Confectioner's Perfumes.— :Not only are flavouring matters em-'
ployed by the confectioner, but he also finds a use for bodies which are
ordinarily regarded as scents or perfumes only. Among these the otto of
roses, and musk, find a place in the store rooms of the larger manufactur-
ing confectioners. They, like the essences, are bodies whose chemistry
possesses an intense interest, but in common with many other topics must
perforce be excluded from the present review of confectioners ' materials.

816. Colouring Matters. — The confectioner uses colouring matters
for two distinct purposes. The one is to give a richer colour to confec-
tions which are Comparatively colourless; the second is the use of colour
for purely decorative purposes.

817. Egg Colours. — Cakes which are made with few or no eggs lack
the rich yellow tint produced by eggs unsparingly used. To compensate
for this, artificial egg colouring matter is frequently employed. For this
purpose vegetable yellows may be employed; and in fact, in the west of
England the saffron bun is a well-known and popular institution. Not
only is saffron here used as a colouring matter, but also as a flavouring
agent, for such saffron buns have a distinct taste of their own, which is
entirely lost if the saffron be omitted. Other vegetable colours are also
used ; but the greater number of egg yellows and egg colourings offered to
the confectioner belong to the group known popularly as aniline colours.
Some time ago the authors examined a large number of so-called egg-
yellow colourings, including practically every make of importance on the
market; and among other things investigated their tinctorial power
weight for weight, and price for price. In tinctorial power, as against
unit weight, the most intense colour was about 180 times as strong as the
weakest. In the matter of cost for the same amount of colour, some sam-
ples were just 30 times as expensive as others. On being tested for
arsenic, the great majority of these colours were absolutely pure; some
one or two, however, gave a sufficient arsenic reaction to make their use
inadvisable. When it is remembered that these colours are offered at
prices of from Is. to 10s. 6d. per lb., it will be seen that accurate scientific
valuation becomes a matter of importance.

818. Decorative Colours. — The most familiar example of the use of
colours for decorative purposes is that of the tinted sugars employed for
covering the tops of birthday and similar cakes. The colours used are
soluble and are blended with the mixture of sugar and white of eggs while
in the pasty state. Such colours should not be altered by traces of acid,
since acetic acid in small quantity is generally used in making up icing
sugar. Preferably, they should also be unaffected by weak alkalies as
sodium carbonate. The principles which underlie the blending of colours
for artistic effect lies outside the scope of the present work.

819. Harmless and Injurious Colours. — Certain colouring matters
are generally recognised as harmless, while others must be regarded as
doubtful, and some as decidedly injurious.

Harmless Colours. — Among the first or harmless group are, with some
few exceptions, all organic colours obtained from the vegetable and
animal kingdoms. To these are usually added the various aniline colours
so long as they are pure and contain no arsenic. The examples most fre-
quently found among confectioners' colours are: —

Red. — Cochineal, carmine, the juice of beet and red berries.

Yellow. — Saffron, safflower, turmeric, 'marigold.

Blue. — Indigo, litmus, saffron blue.

Green. — Spinach juice.

Brown, various shades of. — Caramel (burnt sugar).

Also various aniline colours.

614 THE TECHNOLOGY OF BREAD-MAKING.

Doubtful and Injurious Colours.-— A few of these, such as picric acid
and gamboge, are of organic derivation. They are mostly, however, of
mineral origin, and may contain mercury, lead, copper, arsenic, chro-
mium, and zinc. The following are specific examples : —

Yellows. — Barium chromate, and compounds of lead, arsenic, and
antimony.

Greens. — Compounds of arsenic, and copper.

Blue. — Prussian blue.

820. Legal Enactments as to Colours. — In various countries laws
have been passed defining exactly such colours as may and may not be
used. Thus as early as February, 1891, the Official Municipal Bulletin
of the city of Paris contained the following regulations : —

Paris Ordinance, 1890. — "Ordinance concerning the colouration of
alimentary substances.

Article 1. — The employment of the colours herein after designated is
forbidden for the colouration of all substances entering into articles of
food.

MINERAL COLOURS.

Composed of copper. — Blue dust (cendres bleues), mountain blue.

Composed of lead.— Massicot, Minium or red lead, litharge. Carbon-
ate of lead (white lead). Oxy chloride of lead (Cassel's yellow, Turner's
yellow, Paris yellow). Antimoniate of lead (Naples yellow). Sulphate
of lead. Chromates of lead (chrome yellow, Cologne yellow).

Chromate of barium. — Ultramarine yellow.

Composed of arsenic. — Arsenite of copper, Scheele's green, Schwein-
furt green.

Sulphide of mercury. — Vermilion.

ORGANIC COLOURS.

Gamboge. — Aconit Napel.

Colouring matters derived from coal-tar, such as fuchsine, Lyons blue,
methylene blue; phthaleins and their derivations; cosin, erythrosin.

Colouring matters containing among their constituents nitrous gases,
such as naphthol yellow, Victoria yellow.

Colouring matters prepared by the aid of diazo compounds, such as
tropeolins, xylidin reds.

Article 2. — It is permitted to use for the colouration of sweets and
other food substances the following coal-tar colours, because of their
restricted employment, and the very small quantity of the colouring sub-
stances which these products contain : —

Red colours:

Eosin.

Erythrosin (methyl and ethyl derivations of eosin).

Bengal red, ploxine (iodine and bromine derivations of fluorescin).

Bordeaux reds, ponceau.

Acid fuchsin (without arsenic and prepared by Coupier's process).

Yellow colours:

Acid yellow, etc.

Blue colours:

Lyons blue, light blue, Coupier's blue (derived from triphenyl rosani-
line or from diphenylamine).

Green colours:

Mixtures of the above blues and yellows.

Malachite green.

CONFECTIONERS' RAW MATERIALS. 615

Violet colour:

Paris violet or methylaniline violet."

American Regulations, 1907. — Pood Inspection Decision 76 of the
United States Department of Agriculture makes the following regula-
tions for the employment of colouring matters in articles of food : —

' * The use in food for any purpose of any mineral dye or any coal-tar
dye, except those coal-tar dyes hereinafter listed, will be grounds for
prosecution. Pending further investigations now under way and the
announcement thereof, the coal-tar dyes hereinafter named, made spe-
cifically for use in foods, and which bear a guarantee from the manufac-
turer that they are free from subsidiary products and represent the
actual substance the name of which they bear, may be used in foods. In
every case a certificate that the dye in question has been tested by com-
petent experts and found to be free from harmful constituents must be
filed with the Secretary of Agriculture and approved by him.

The following coal-tar dyes which may be used in this manner are
given numbers, the numbers preceding the names referring to the number
of the dye in question as listed in A. G. Green's edition of the Schultz-
Julius Systematic Survey of the Organic Colouring Matters, published in
1904.

The list is as follows : —

Red shades:

107. Amaranth.

56. Ponceau 3 R.
517. Erythrosin.

Orange shade:
85. Orange I.

Yellow shade:

4. Naphthol yellow S.

Green shade:

435. Light green S. F., yellowish.

Blue shade:

692. Indigo disulphoacid.

Each of these colours shall be free from any colouring matter other
than the one specified and shall not contain any contamination due to
imperfect or incomplete manufacture. ' '

THE END.

Absolute temperature

- Weight of hydrogen
Absorption of heat
Acetic acid .

— fermentation
Acetone

Achroo-dextrins .
Acid, Acetic. .

— , Butyric

— calcium phosphate .
— , Carbonic .

— , Formic

— , Hydrochloric .

— , — , Use of, in breadmaking .

— , Hydrofluoric .

— , Lactic .....

— , Margaric ....

— , Nitric ....

— , Nitrous ....

— , Oleic ....

— , Palmitic. ....

— , Phosphoric

— , — , Determination of

— potassium phosphate
sulphate

— , Silicic ....
— , Stearic ....
— , Succinic ....
— , Sulphuric
— , — , Normal
— , Sulphurous
— , Tartaric ....
Acidimetry and alkalimetry
Acidity of bread

meals or flours .

Acids, bases and salts

— , Basicity of ...

— , Fatty ....

— of nitrogen

— of bread ....
— , Organic ....
Adulterations and additions
Aerating agents . 35(
Aeration of bread, other than by

yeast

— process

Age, Effect of, on flours
.Albumins . . .
— , Egg

— of wheat .
Albuminates

INDEX.

PAGE PAGE

Albuminoids . . .92, 97,

100

Albumoses

Alcohol, Absolute . . 45,

546

— of various strengths

547

— , Absolute, Preparation of

546

— , Detection of .

189

— Ethyl

— in bread, Proof of presence of

355

— , Methyl

Alcohols

— , Propyl, butyl, and amyl

357

Alcoholic fermentation, and yeast

149

, Substances inimical to

166

, — produced by

150

— , — susceptible of

149

? •

360

viewed as a chemical change

149

Aldehydes . . .

Aldoses . .

Aleurone cells . . 240,

244

— grains . .

251

Alkalies . .

Alkalimetry

514

Alkaline earths

Alkaloids . .

504

Allspice, Essential oil of .

610

358

Almonds, Essential oil of .

610

358

Alum

358

Alum, copper sulphate, and lime,

Use of

353

Alum baking powders

359

— , Special test for . . 568,

569

515

American and Canadian methods

317

— high-grade bread, Composition

50,

356

376

514

— wheats, Composition of

254

340

Amides .....

298,

516

Amines .....

Amino acids and amides .

Ammonia .....

Ammonias, Compound

Ammonium carbonate

356

340

- salts

Amyl acetate . . . 48,

611

564

— alcohol . . .

359,

586

Amylans .....

Amylo-dextrin ....

355

Amyloins

361

Amylopsin .....

135

495

Amyloplasts ....

249

Analyser

95,

584

Analyses of English and foreign

103

wheats

527

^ .

Analysis of bread . . 376,

558

617

618

INDEX

Analytic apparatus

— balance

, Adjustment of .

— weights .
Apparatus, Measuring

PAGE

463
463
466
466
470

Appert's method of preservation

from putrefaction . . 187

Argon ...... 12

Ascospores .... 166, 176

Ash of flour, Snyder on . . 503

— of wheat 69

wheats and flours, Deter-
mination of . . . . 503

Asparagine 54

Aspergillus glaucus . . .191

Atmosphere ..... 34

Atomic or combining weights . 13

, List of ... 12

- theory . . . . . 14'

Atomicity or quantivalence . 17

Atoms and molecules . . 14
Attemperating and measuring

tank 426

Attenuation of worts . . . 235
Auto-dividing, proving, and

moulding plant . . . 443

Automatic bakery . . 409, 461

— machine bakeries . . . 409

— ovens 458

— prover 442

— temperature regulator . . 218
Avogadro's law . . . 15

Bacilli 182

Bacillus subtilis . . . .182
Bacteria . . . . 181, 182
— , Diastatic action of . . 184
— , Growth forms of . . ' . 181
Bacterial and putrefactive fer-
mentations . . . 181, 186

— Fermentation, Action of oxy-

gen on 186

Bacteriological purity, Compara-
tive, of flours . . . 390
'Bacterium lactis .... 187

— termo 182

Bakehouse building, Require-
ments in .... 397

— , Constancy of temperature in 399

— design .... 396, 402

— for two peel ovens . . 401

— machinery . . . . 412
, when it pays . . . 409

— over shop .... 405
— , Requirements for . . . 397

, Compactness of . . 398

— , Single drawplate oven . 404

— , Single peel oven . . . 401

Bakehouse, Site for . . . 396

— , Ventilation of ... 398

PAGE

— , Wholesale bread and cake 409, 411
— , Working requirements of . 398
Baker and Hulton on strength

of flour 279

toxins in flour . 215

Baker and Hulton's researches . 216
Bakers' home-made yeast . 231

Bakeries, Large . . . .411
Bakery registers . . . 462

Baking 324

— , Effect of, on bacterial life . 343
— , Time necessary for . . 325
Baking powders .... 359

— tests . . . 268, 496, 577

, Alternative scheme of . 500

, American .... 496

, Authors' method of making 497

Balance, Analytical . . . 463
Barley, Germination of . . 252

— meal, Unsuitability of, for
bread-making . . . 362

Barm, Compound . . . 238
— , Parisian .... 236

— , Virgin 238

Barms, Scotch flour . . . 236

— , , Meikle's formulae . 237

— , , Montgomerie's formulae 236

Base, Definition of . . 17

Basicity of acids .... 18
Beard of wheat .... 246
Bearing supports . . . 415
Bearings . . . • . 415

Beef fat 594

Belt fasteners . . . .417

Belting 417

Benzaldehyde .... 610
Bermaline bread, Analysis of . 377
Biuret reaction of proteins . 94
Bleaching of flour . . . 299

- powder, chloride of lime . 31
Blending and sifting plant, Gen-
eral arrangement of . . 423

— of flour .... 363, 422

- of wheat 363

Blood or serum albumin . . 95
Bottcher's moist chamber . . 169

Boyle's law 8

Brake horse-power . . . 418
Bran 244

— cellulose 247

Bread, Aerated . . . .355
— , Alcohol in . , . . 355

— , Alum in 569

— , American, Analysis of . . 376

— analysis .... 558, 561

— and cake factory . . . 409
— , Attractiveness and palatabil-

ity of 391

— , Calcium sulphate in . ; 570

— colour .... 352, 558
— , Complementary foods to . 392
— , Composition of ... 376
— , Cooling of . . . 326

— crumbliness .... 352

INDEX

619

Bread crust, Colour of
— , Daren

— , Dark line in cottages
— , Faults in

PAGE

560

377
352
351

— , Flavour of .... 560
— , Gluten 362

— Holes in 351

— , Hovis . . . . .377

— improvers ..... 377
— , Leavened .... 355

- Mineral, Nutritive value . 387
— , Mineral oil in ... 570
— , Musty and mouldy . . 193
— , Nutritive value of . . 382

- odour ..... 559
— , Palatability of ... 391
— , Pile of .... 268, 559

— , Proof of 559

— , Protruding crusts of . . 352
— , Quantity of water in . . 560

— , , Standard for . 561

— , Red spots in . . . .192
— , Relative nutritive values of

different varieties of . . 387
— , Ropiness in . . . 345

— Rye 362

— , Souring of .... 330
— , Texture of . . . .558
— , Turog . . . . .377
— , Typical American high grade 376

— , Vienna 354

— , Water in .... 560
— , Whole meal .... 360
Bread-making .... 308
— , American methods . . 317
— .Canadian methods . . 317

— methods, Present, Callard on 314
— , Objects of .... 309
— , Special methods of . . 354
— , Scotch practice . . . 316
— , U.S.A. practice . . .316
— , Use of alum in ... 353
— , Various stages of . . . 310
Breads, Commercial analysis of 376
Brewers' yeast .... 223
Promine, iodine, and fluorine . 38
Brown and Morris on molecular

weights of carbohydrates . 75
Brown, Heron, and Morris on

starch conversion . . 129

Brown on influence of oxygen

on fermentation . . . 161
"Brownian" movement . . 182
Buchner on influence of oxygen

on yeast . . . .165
Bunt or stinking rust . . . 195
Burette, Water-absorption . 482

Burettes and floats . . .470

Butter 591

— , Composition of . . 591, 593
— , Grading of . . . .591
— , Rancidity of . . . .594

— standards 592

Butter-making, Selection of

ferments for .
Butters, Weak and strong
Butyl alcohol

Butyric acid ....
— fermentation

PAGE

188

594

189

Cakes, Colouring matter in . 570

Calcium and its compounds . 39

- acid phosphate . . . 357
Calculations of quantities . . 21

Calorie 382

Camera lucida .... 62
Cane and invert sugar, Compara-
tive sweetness of . . . 599

— sugar .... 85, 597
— , Action of malt extract on 129

, Estimation of . 532, 533, 542

— , Hydrolysis of . . 138, 143

, Inversion of ... 598

Caramel ... 86, 600, 613

Carbohydrates .... 74

— , Classification of . . 74

— , Constitution of ... 76

— , Definition of . . . . 74

— , Estimation of ... 531

Carbon . . . . . . 31

— , Compounds of, with hydrogen 33

— dioxide ..... 32

— monoxide .... 32
Carbonate of soda . . . 356

Carbonates 33

Carbonic acid .... 33

Catalysis 121

Cellulose 76, 88

— , Composition of ...

— , Estimation of ... 550

— , Existence of in wheat . . 77

— of bran 247

— of endosperm . . . 248

— of wheat 77

Centinormal solutions . . 516

Cerealin or aleurone . . 240, 244

cells .... 245

Cereals, Composition of . . 254
— , Diseases of . . . .194

Chaffing machine . . . 461

Chains, Annealing of . . . 422

Chemical calculations . . 19

— combination by volume . . 16
weight .... 12

— composition of flour . . 291
wheat .... 254

— equations .... 13

— functions in mill . . . 577

- laboratory .... 463
Chemistry, Definition of . . 10

Chimneys 397

Chloride of lime, bleaching pow-
der . 31

620

INDEX

PAGE

Chlorides 31

Chlorine 30

Chloroform ..... 48

— test on flour .... 567
Chlorophyll .... 249

Cilium 182

Cinnamon, Essential oil of . 610

Cloves, Essential oil of . . 610
Coagulated proteins . . .96, 99

Code for telegrams . . . 572

Coke combustion, Nature of . 458

Collagen 100

Colloids . . . . .25

Colour investigations . . 491

— of bread 489

- of flour . . .291, 299, 489
Colouring matter in cakes . 570

- matters 613

Colours, Harmless and injurious 613

— , Legal enactments as to . 614

Combination ovens . . . 452

Combining or atomic weights . 13

— , List of . . . 12

— proportion .... 13
Combustion, Heat of . . . 382

— of coke, Nature of . . . 458
Commercial breads, Analysis of 376

- testing and chemical analysis

of wheats and flours . 269, 463
"Comp." or bakers' "patent"

yeast 231

Comparison between brewers'

and distillers' yeasts . . 213

Composition of ash of wheat . 69

— of organic bodies ... 42

— of roller milling products . 291
Compound ammonias ... 53

— radicals . . . . . 17
Compounds of carbon with

hydrogen .... 33
— , Definition of . . . . 11
Compressed yeasts, Character-
istics of 230

, Manufacture of . . 226

Conduction of heat ... 9
Confectioners' aerating ingre-
dients .... 356, 586

— enriching ingredients . . 587

— flavouring ingredients . . 603

— flour ... . . . 579

— moistening ingredients . . 579

— raw materials .... 579

— sweetening ingredients . . 597
Conidia . . . . .191
Constituents of wheat . . 68
Constitutional formulae . . 13
Construction of wheat grain . 68
Constructive metabolism of

plants 248

Convection of heat ... 8

Cooling of bread . . . 326
Copper sulphate, Employment

of, in bread-making . . 353

Cottage loaves, Dark line in . 352

PAGE
Counterpoised and weighed

filters 508

Coverplate oven .... 457
Cream of tartar . . . . 356
- substitutes . . . 358
Crumbliness .... 352

Crusts, Protruding . . . 352
Crystalloids and colloids . . 25
Cupric oxide reducing power . 83, 85

Currants 604

Cuticle of wheat grain, bran . 244

Cystine 93

Cytase 123, 124

Damping wheats . . . 293

Daren bread .... 377

Darnel 564

Dauglish's process of aerating

bread ..... 361
Decinormal solutions . . . 516
Deficiency diets . . . 387, 395
Derived albumins ... 95
Designs, Typical, for bakeries . 401
Detection of alcohol ... 45
Deutero-albumose ... 96

Dextrin 83, 90

- and maltose, Polarimetric

estimation of ... 544

— and soluble starch, Estima-

tion of .... 549

— , Chemical character of . . 84
— , Estimation of ... 536

— , Hydrolysis of . . . 139
— , Molecular constitution of . 131
Dextrose or dextro-glucose . 86

Dialysis 24

Diastase ..... 125
— , Action of, on starch . . 128
— , Nature of .... 128

— ot raw grain .... 135
— , Preparation of ... 547

— test on flours .... 555
— , Translocation . . . 250
Diastatic action or diastasis . 127

of bacteria . . . .184

, Conditions and substances

inimical to . . 135, 143

, Effect of heat on . .134

, Effect of time and concen-
tration on .... 134
/Further experiments on . 372

— capacity, Measurement of 127, 553
Dictionary of wheat, Voller . 260
Diffusion, Gaseous ... 22
Digestibility . . . 383, 385

— of bread 382

Disease ferments . . . 190

Diseases of cereals . . . 194
Distillers' yeast . . .172, 226

INDEX

621

PAGE

Dough 311

- dividers ..... 435

- mixing and kneading ma-

chines. . . . . 427

— proving ..... 435

— trucks 434

Doughing machinery . . . 427
Doughs, Off-hand . . .311

Drawplate ovens . . . 449

Drives, Belt .... 417

Duclaux's method of estimating

fatty acids, Discussion of . 332

Durum wheat, Norton . . 256

Egg albumin ... 95

— colours ..... 613

— whites, Dried .... 585
Eggs ..... • • .584
— , Aerating action of . . 586
Electric motors .... 413
Element, Definition of . . 11
Elements and compounds, De-
scription of . . . . 28

— , List of 11

Empirical formula ... 20

Endocarp ..... 244

Endosperm .... 244, 299
— , Cellulose of . . . .248

English weights and measures . 27

Enzymes and diastatic action . 121

— or soluble ferments . . 122

— Chemical properties of . . 124
Classification of ... 124
Composition of . .123
List of . . . . .123

Proteolytic of resting and

germinating seeds . . 138

Epicarp 244

Epidermis of wheat grain . 244

Episperm 244

Epithelium ..... 252

Equations, Chemical ... 13

Erdmann's float .... 470

Ergot 195, 565

Erythro-dextrins ... 84
Essences . . . . .611

— , Fruit 611

Essential oil of allspice . . 610

almonds . . . 610

cinnamon . . . 610

cloves .... 610

lemon .... 607

neroli .... 610

orange .... 609

— peppermint . . . 607

Essential oils . . . 606, 610

, Analysis of ... 607

Esters or ethereal salts . . 47

Ethane 44

Ethereal salts .... 47

Ether, Light-bearing ... 65

Ethers . 47

PAGE
Ethyl 42

— alcohol 44

— butyrate 48

Etiolin 249

Expansion and contraction of

gases 7

— by heat 7

Extractive matters of cereals . 88
Eye-piece 58, 60

— micrometer oO

Fat, Beef . . . . .594

— , Determination of . . 508

— , Moistening effect of . . 586

— Soluble A . . . .394

Fats 49, 587

— , Butyro-refractometer value

of 589

— , Chemical constants of . . 588

— , Compound .... 596

— , Iodine value of ... 588
— , Melting and solidifying

points of .... 588

-, Mineral 596

— , Properties of . . . . 590

— , Reichert-Meissl value of . 588

— , Specific gravity of . . . 588
— , Vegetable . . . .595
Fatty acids, or acids of acetic

series ..... 48

— matters of wheat ... 70
Faults in bread .... 351
Fehling's solution . . . 531
Ferment .... 310, 318

— and dough .... 312

— , Potato 310

— , sponge, and dough . . 314

Ferments 187

Fermentation .... 144

— , Acetic 189

— , Action of, on gluten . . 203

— , Aerating system . . . 229
— , Alcoholic (see also under

alcoholic fermentation) 149, 180

— , Butyric . . . . . 189
— , Changes in flour, resulting

from 365

— , Comparison of brewers' and

distillers' yeast . . . 213

— , Conditions affecting speed of 326

— , Course of . . . . 329

— , Definition of . . . . 147

— , Earlier views on . . . 144
— , Effect of addition of various

substances on ... 201

— , — - salt on . . . . 323

— , temperature on 210, 211, 329

— , Experimental basis of, Mod-
ern theory of ... 148
— , experiments, Authors' . . 280
— , History of views of . . 144
— , Influence of oxygen on . 161
I — , Lactic 187

622

INDEX

Fermentation, Liebig's view of

— , Loss during .

— -, Modern theory of .

— of filtered flour infusion

— of flour, Effect of salt on
— , Origin of term

PAGE
145
324
148
206
210
144

— , Panary, Review of . 318, 320
— , Pasteur's view of . . . 145
— , Physiological significance of 215
— , Putrefactive . . . .186
— , Quick versus slow . . . 327
— , Spontaneous .... 190
— , Substances inimical to . . 166
— , Summary of course of . . 329
— , Technical researches on . 197
— , Theory of leaven . . . 355
— , Toxic effect of flour on . 214
— , Varieties of . . . .149
— , Vienna system . . . 228

— , Viscous 190

— , Zymase theory of . . . 147
Fermentative properties of vari-
ous substances —

Albumin 201

Filtered flour infusion . . 206

Flour 203

Pepsin 201

Potato and potato infusion . 210
Separate constituents of flour 203

Sugar 201

Wort 203

Yeast mixture .... 203

Fibrin 96

Filter ash, Weight of . . . 507
Filters, Counterpoised and

weighed . . . .508

Flagellum 182

Flasks, Alkalinity of . . . 332
— , Measuring .... 471
— , Pasteur's . . . .167
Flexible moulder . . .439
Float for burette . . . 470

Flour, Alum in . . .568

— , Aniline blue in ... 567

— barm, sponge and dough . 315

— bleaching . . . .299

, Action at law . . . 306

— , Gas-retaining Power of . 284

, Griess-Ilosvay test . . 307

, Snyder .... 299

, U.S. Board of Food

decision .... 306

- blending .... 363, 422
- machinery .... 425
— , Changes in, resulting from

fermentation .... 365

— Chloroform test on . . 567
Colour of . .291, 299, 489
Composition of ... 291
Darnel in .... 564
Effect of age on . 304, 495, 529

germ on ... 295

size of starch grains on,

Armstrong .... 277

PAGE

— , sugar on ... 272

— , Ergot in . . . . .565

- for confectioners . . . 579
— , Fourteen years old, Tests on 529

- hoisting . ... 420
— , Impurities and adulterants

of 564

— , inferior, Fermentation of . 203
— Infusion, Fermentation of . 203
— , Maize in . . . . . 565
— , Mineral adulterants and ad-
ditions to .... 568
— , Mould in .... 565
— , Physical properties of . . 267
— , Preservation of, by cold . 299

- Properties . . . .291

— , Rice in 565

— , Self-raising .... 359

— sifting machinery . . . 425
— , Specific heat of ... 5
— , Standards of quality for . 572
— , Strength of . . . 267, 279

— , , Definition of . . 267

— , - — , Present-day conclu-
sions . . . .279

— , , Relation to gas-retain-
ing power .... 284
— , Sugar in . . . . . 283

— Sugar, effect of on . . 2/2

- testing 472

Methods, Foreign . . 496

— , Toxic effect of, on fermenta-
tion 214

— , Uniformity in quality of . 573

- used in Scotland . . . 317
— , Water-absorbing powrer

of 291, 482

Flours, Acidity of . . 298, 516

— , Baking characteristics of . 298

— , Fatty matters of . . . 298

— , old, Analysis of . . . 529

— , Seasonal variations in . . 298

— , typical, Characters of . . 296

— Unsound, working with . 353
Fluorine ..... 38

Fondant sugar .... 601

Food, amount required . . 383

Force ...... 2

Foreign wheats, Composition of 256

Formaldehyde, formalin . . 51

Formic acid 48

Formula from percentage com-
position, Calculation of . 19

Formulae 12, 13

— , Constitutional ... 13
— , Empirical .... 20

Fructose or laevulose . . 86
Fruit . . . . . .603

"Fruit" (potatoes) . . .318
Fruits, Dried .... 604

— , Preserved . . . .604

Fungi 174, 191

Fusel, or Fousel, oil . . 47

INDEX.

623

PAGE

Gases, Expansion and contrac-
tion of 7

— , Relation of pressure and vol-
ume of .

Gaseous diffusion ... 22
— solution . . . . ; 23
Gearing and power transmis-
sion 414

Gelatin 100

Gelatinisation of starch . . 80, 89
Gelose ...... 606

Germ, Composition of . . 294
— , Effect of, on flour . . . 295
— , Structure of . . 243, 256
Germination of wheat and bar-
ley 252

Girdle cells . . 247

Glazing 325

Gliadin .... 99, 105

— determinations . . . 270

Estimation of ... 522

by starch . . .524

— on flour . . . 523

on wet gluten . . 524

one protein only . . . 270

- ratio, Relation to strength of

flour 287

— , Variations in composition of 270
Globulins 95, 97

- of wheat 104

Globuloses 96

Glucose, or grape sugar . . 86
— , Analysis of .... 602
— , Commercial . . . 86, 602
— , Confectioners', Composition

of 602

— , Estimation of . 534, 552, 602
Glutamine . . . . . 54

Glutelins 97, 98

Gluten .... 107, 120, 290
— , Action of fermentation on . 203

— bread 362

— cells . . . . . .240

— , Composition of, Norton . 271
— , Conditions affecting quantity

and physical character of . 288

— determination .... 479

, Value of . . . .290

— , Distribution of, in wheat . 298
— , Effect of salts on . . . 290

- extraction . . . 479

— from wheat-meal . . 481
— , Fermentation of ... 203
— , Formation of . . . .114
— , Mechanical disintegration of 286
— , Relation between, and pro-
teins 284

- testing . . 479

— tests on commercial flours . 526

— on special flours and

wheats 527

— , "True," Estimation of . . 521

Glutenin

Glycerin

Glycoproteins

Golden syrup

Grain life, Physiology of

Gram

PAGE

98, 109
47, 586
. 97, 99
. 598
. 248
27

Hsematimeter .... 63

Haemoglobins 97, 99

Hander-up ....

Handing-up .... 441

Hangers ..... 415

Hansen on analysis of yeasts . 176

yeast culture . . . 168

Heat ....

— , Absorption of ... 10

— , Conduction of ...

— , Convection of ...

— , Elements of .

— , Expansion by ...

— measurements ... 2
— , Mechanical equivalent of . 10

— of combustion . . . 382
— , Quantity of .

— , Radiation of .

— , Solid and flash . . . 325

— , Sources of .... 6

— , Specific

— , Transmission of

Hemi-peptones .... 96

Hetero-albumose ... 96

Hexoses 51, 86

High yeast 170

Higher fatty acids, and salts of 49

Hilum

Histones 97

Hoisting of flour . . . 420

Holes in bread .... 351

Homologues, Definition of . 50

Honey 597

Hordein 99

Hot water oven .... 476

Hovis bread and meal . . 377
Humidity of air, Effect of, on

flour 478

Hydr-acids 16

Hydrazones or phenylhydra-

zones ..... 55
Hydrides of organic radicals,

paraffins .... 43

Hydrochloric acid ... 30

— , Use of, in bread-making . 360

Hydrofluoric acid ... 38

Hydrogen 28

— , Absolute weight of . . 15

— peroxide or hydroxyl . . 30
— , Sulphuretted .... 37
Hydrolysis . . . 121, 139, 143
— , Details of ... . 138, 141
Hydrolytic agents . . .121
Hydrometer .... 236
Hydroxides or hydrates . . 16
Hyphae 191

624

INDEX.

Iceland spar

Improvers, Bread

— , Control of

Indicators

Insoluble proteins of wheat

Invert sugar

Invertase

— , Intestinal

Iodine ....

— reaction with starch

lodoform

PAGE

. 377

. 577

. 514

109, 114

86, 543

. 136

. 137

Isolation of yeast and other

organisms .... 166

Isomerism 50

Jam . . . . . 605

Jockey pulleys .... 418

Katabolism 248

Ketones 51

Ketoses 51

Kjeldahl's methods for estima-
tion of proteins . . . 518
Kneading machinery . . . 427
— machines with revolving

blades 428

rotating pans . . 430

Laboratory ..... 463

Lactic acid 50

, Volatility of ... 331

— ferments, Hansen on isola-

tion of 188

— fermentation .... 187
Lactose or milk sugar . . 86
Lasvulose or Isevo-glucose . . 86

Lard 594

Leaven 355

— fermentation, Theory of . 355
Leavened bread .... 355

Lecithin 389

Lecithoproteins . . . .97,

Legumelin ..... 9

Legumin 98

Lemon, Essential oil of . . 607

— , Oil of, Adulteration of . . 608

Leucine 54

Leucosin 98, 99

Light, Polarisation of . 65

Lignose, lignified cellulose . * 77

Lime, Use of, in bread-making . 354
Lintner on measurement of

diastatic capacity . 125, 553

Lintner's scale .... 553

Liquids, Solution of . . . 23
Litmus . . . . • . .514

Litre 26

Loaf, Shape of, Wood . . 274

Loss during fermentation . . 324
Low grade flours, Working

with . 353

Lubricating
Lucombe

PAGE

415, 419
421

Machine bakery .... 412

Machine-moulding, Quality of . 441

Machinery 400

— , Maintenance of ... 419

Magnesia mixture . . . 505

Magnification in diameters . 61

Maize, Composition of . . 254

Malt, Analysis of ... 551

— , Aqueous extract of . . 129

— bread, Analysis of . . . 376

— , Composition of ... 139

— , Mashing of .... 143
— , Mashing of, together with

unmalted grain . . . 141
— , Saccharification of, during

mashing .... 140

- extract .... 129, 379
— , Action of, on bruised

starch 130

— , — — , — cane sugar . . 129

, — , — , — starch paste . 131

, — — , — ungelatinised

starch 129

, Analyses of ... 381

— breads 376

— , Cold water . . .380

, Diastatic action of . . 372

, Spent 380

, Types of . . . .379

f Whole .... 380

- extracts, Adulterations of . 556
— , Analysis of ... 551

, Diastatic capacity of . 555

, Highly diastatic . . 375

— , Yield of 235

Maltase . . . '. .137

Malting system, Ordinary . . 227

, Pneumatic .... 227

Malto-dextrin ... 88, 139

— , Hydrolysis of ... 139
Maltose . . . , . 84, 90
— , Estimation of, by Fehling's

solution ... 85, 535

— , Hydrolysis of ... 139

— , Molecular constitution of . 131
— , Polarimetric determination

of . . . . . .544

Maltose, Reducing power of . 85

Mannjte or Mannitol ... 47
Manufacture of compressed

yeasts 226

- starch 80

Margaric acid .... 49

Margarine ..... 595

Martin on wheat proteins . . 101
Mashing malt together with un-
malted grain . . .141

Matter

— , Indestructibility of . . 11

INDEX.

625

Measures of weight and volume
— and weights, English
Mechanical equivalent of heat .

Metabolism

Metalloids or non-metals .

Metals

Metamerism .

Metaproteins .

Methyl

— alcohol

PAGE

25
27
10

248
12

12, 39
51
97
42
44

515
51
46
25
25

192
60
61
57
59

— orange ....
Methylamine

Methylated spirits of wine
Metre ....
Metric system
Micrococcus prodigiosus
Micrometer ....
Micromillimetre, or m k.m.
Microscope, Description of
— , How to use
Microscopic character of

starches ....

— counting ..... 63

— examination of starches . 88

- yeast . 154, 180, 224, 236

— objects, Measurements of . 60

- sketching and tracing . . 62
Midget testing mill . . . 575
Mildew of wheat . . . .194

Milk 579

— , Condensed .... 582

— powders 584

— standards .... 580

— sugar 86

Milks, Valuation of ... 581

Milling tests . . . 571, 574

Millon's reaction of proteins . 94
Mineral constituents of wheat . 68, 72

- matters, Determination of . 503
— , Nutritive value of . . 387

Mirbane, Oil of . . . . 610

Mixing and kneading machinery 427

Mixture, Definition of . . 11

Mk.m. ..... 61

Modern baking machinery and

appliances .... 412

Moisture, Estimation of . . 474

— of flour, Effect of humidity

on 478

— of wheat 474

— telegraphic code . . . 572

Molasses 598

Molecular constitution of carbo-
hydrates .... 75

- starch, dextrin, and

maltose 131

Molecules 14

Molybdic solution . . . 504

Motive power in bakeries . . 412

Motors, Electric .... 413

-Mould in flour .... 565

Moulding 437

— machines .... 437
Moulds . 181

Moulds and fungoid growths
Mucor mucedo
Musty and mouldy bread .
Mycelium ....

Mycoderrna aceti .

ccrevisiae

— vim .

Myosin, Vegetable

PAGE
191
191
193
174
189
174
174
101

Neroli, Essential oil of . . 610

Nicol's prism .... 66

Nitrates 37

Nitric acid 36

— oxide ...... 35

Nitrobenzene .... 610

Nitrogen ..... 33

— , Oxides and acids of . 35

— peroxide ..... 36

— trioxide 36

Nitrogenous organic com-
pounds

Nitrous acid and nitrites . . 36

Normal sodium hydroxide . . 516

carbonate .... 514

Normal solutions . . . 514

— sulphuric acid .... 515

— temperature and pressure

N. T. P. 8

Nucleoproteins .... 97, 99

Nutrition and food . . . 382

Nutritive ratio .... 384

— value, Mineral . . . 387

— values of different varieties

of bread . . . 382, 385

Nuts ... 606

Oats, Composition of . . 254
Objective ..... 58
Off-hand doughs . . . .311
Oil of almonds . . . .610
lemon .... 607

mirbane .... 610

— orange .... 609
peppermint . . . 607

wheat 71

Oils, Essential .... 606

— Vegetable .... 587

Oleic acid 49

Oleo 596

Orange, Essential oil of . . 609

— flower water . . . .610
Organic acids .... 48

— chemistry, Definition of . 41

— compounds .... 41

, Classification of . .42

, Composition of . . . 42

— , Nitrogenous ... 53

— radicals . . . . . 42
Hydrides of, Paraffins . 43

626

INDEX.

PAGE

Organised structures ... 41

Oryzenin 98

Osazones or phenylosazones . 56
Osborne and Voorhees on wheat

proteins .... 101

Osmose and dialysis ... 24

Oven chimney .... 397

— firing 458

— fittings 457

— furnaces, Arrangement of . 457

— heating, Perkins' principle . 448
— , Hot-water .... 476

— light 457

— pyrometers 3

— types 449

Ovens ...... 447

— Arrangements for . . . 400
Automatic .... 458
Combination .... 452
Coverplate .... 457
Drawplate .... 449
Electric ..... 448

Field 454

Hot air . . . . . 448

Hotel 455

Internally heated . . . 447

Mechanically heated . . 448

Portable .... 453, 454

— drawplate . 453

Ship ..... 455

Split drawplate . . . 450

Steam-pipe .... 448

Vacuum 476

Vienna 455

Oxides of nitrogen ... 35

Oxydase. .... 353

Oxygen 28

Oxy-acids 16

Ozone 28

Palmitic acid . . . . 49
Panary fermentation, or panifi-

cation, Review of . . 318, 320
Papain . . . . . .100

Paraffins, Hydrides of organic

radicals 43

Parenchymatous cellulose . . 77
Parisian barm .... 236
Pasteur on effect of oxygen on

yeast 160

Pasteur's flasks . . . 167

— fluid 201

Patent yeast . . . .233

Pectin 603

Pediococcus cerevlsiae . . .190

Peel 604

Peel ovens 453

Pekar's colour test for flour 291, 491
Penicillium glaucum . . . 191

Pentosan 53

Pentose . . . ... 53

Peppermint, Essential oil of . 607

PAGE
Pepsin and trypsin . . . 137

Peptase 137

Peptides 97

Peptones . . . .96. 97, 100
Percentage composition from

formula, Calculation of . 19
Perfumes, Confectioners' . . 613
Peroxide of hydrogen . . 30

— of nitrogen .... 35
Phenolphthalein .... 515
Phenylhydrazine .... 55
Phenylhydrazone or hydra-
zones ..... 55

Phenylosazones or osazones . 56
Phosphate powders . . . 359
Phosphates, Nutritive value of 389

Phosphoproteins .... 97, 99
Phosphoric acid .... 39

, Determination of . . 504

Phosphorus, phosphoric acid

and phosphates ... 39
Physical structure of wheat

grain 240

Physiology of grain life . . 248
Pile of Bread . . . 268, 559

Pipettes 471

Plans, Typical, for bakeries . 402
Pneumatic maltings . . . 227
Polarimeter, The . . 67, 539

Polarimetric estimations . . 537
Polarisation of light ... 65

Polariser 67

Polymerism .... 50
Polypeptides . . . .93
Potash, Determination of 504, 507
Potassium and its compounds . 40
Potato ferment . . . .310
Potatoes, Action of, on fermen-
tation 210

Potatoes, Composition of . . 318
Power transmission . . .414
Precipitates, Washing and igni-
tion of 506

Prolamins 97, 98

Proof spirit ..... 45
Propyl alcohol .... 46
Propylamine . . . 51

Protamines 97

Proteans . . . . .97, 99

Proteins 92

— , Amount of various, contained

in wheat . . . .112
— , Animal 95

— Character of . . . . 92
— , Classification of ... 95, 97
— , Composition of . . 92
— , Decomposition of . . . 119
— , Estimation of ... 518
— , Estimations of, in commer-
cial flours .... 526

— , , in special flours and

wheats ..... 527

— , List of 97

— , Nomenclature of . . . 92

INDEX.

627

PAGE

Proteins of wheat . 100, 112, 118

— , albumins . . . 103
— , Distribution of . . 119

, Earlier researches on . 101

— , globulin . . .102

— , Osborne and Voor-
hees on . . . . . 101

, soluble in water . . 102

— , Summary . . . 117
— of oat kernel . . . .118
— , Precipitation of . . 94
— , Reactions of . . . 93, 120
— , Salting out of (precipita-
tion) 95, 98

— , Separation of . . . .95, 98

— , Simple 97

— , Soluble, Estimation of

102, 120, 522

— , Solubility of . . . . 93
— , Summary of properties and

composition of ... 117
— , True, Estimation of . . 521
— , Vegetable .... 97
Proteolytic enzyme of seeds . 138
Proteoses . . .96, 97, 100, 104

— of wheat 104

Proto-albumose .... 96
Protoplasm ..... 248
Prover, Automatic . . . 442

— , Final 447

Proving 441

Ptyalin and amylopsin . . 135
Puccinia Granimis . . . 194

Pulleys 416

— , Jockey 418

Putrefaction . 119

— , Conditions inimical to . . 186
— , Products of . . . .187
Putrefactive fermentation . . 186
— , Action of oxygen on . 186
Pyrometers ..... 3

Quantities, Calculation of . . 21
Quantity of heat . .
Quantivalence or atomicity . 17

Radiation of heat . . . 9

Radicals, Compound . . . 17

— , Organic .... 42

Radium . v . . . 12

Raffinose 88

Rancidity 587

Raoult on molecular weights . 75
Raw grain diastases . . .135

Red spots in bread . . . 192

Reducing power of maltose . 85

Registers for bakeries . . 462

Remedies for sour bread . . 344

Replacement tests . . . 574

Rice, Composition of . . . 254

PAGE

Ring lubrication .... 415
Ripening of wheat grain, Teller 258
Ritthausen on wheat proteins . 101
Rochelle salts ... 50, 357
Roller bearings .... 415
— milling products, Composi-
tion of 291

, Richardson's analyses

of 291

Ropes, Wire .... 422
Ropiness in beer and bread . 190
- bread, Watkins . . .345
Rotary mixers .... 427
Rotatory power, Specific . . 538
Rousing, Action of, on yeast . 161
Routine mill tests . . . 571
Rye bread . . . . .362
— , Composition of ... 254

Saccharification . . . .121

— of malt during mashing . 140
Saccharoniyccs ccrcvisiac . .170
, Life history of . . . 155

— , Classification of . . 16°

- ellipsoidcus . . . 169, 173

- minor .... 169, 173
— mycoderma or mycodcrma vini 174

— pastorianus . . . 169, 173

Sack hoist 421

Salt, Definition of ... 17
— , Common, Action of, in bread-
making ..... 308

— , — , — — , on fermentation . 210

— , Use of 323

Samples, Collection and dispatch

of . . . . . .571

Sanitary aspects of baking ma-
chinery .... 412

Schizowycctcs . . . . 181

— , Spore formation of . . 184

Scotch flour barms . . . 236

- methods of bread-making . 316
Scutellum ..... 252
Section cutting and mounting . 243
Self-raising flour .... 359

Setters 445

Shafting 414

— , Power absorbed by . . 418

Shaking apparatus . . . 525

"Sheen" 495

Sifting machine for flour . . 425

Silicic acid ..... 38

Silicon, silica, and the silicates . 38

Simple proteins .... 97

Smut 194

Soaps and Fats .... 49

Sodium bicarbonate . . . 356

Sodium chloride .... 308

— compounds .... 40
Solid and flash heats . . . 325
Solids, Solution of ... 24
Soluble ferments . . 122

628

INDEX.

PAGE

Soluble proteins of wheat . . 102

— extract 512

— starch 81

— , Estimation of . . 546, 549

Solution ..... 22

— , Gaseous 23

— of liquids ..... 23

— of solids ..... 24

Sour bread 330

, Researches on . . 331

-, Remedies for . . . 344

, Separation and identifica-
tion of acids of ... 331

, Summary of views on . 343

Souring of bread, Ammonia

produced during . . . 341
, Effect of high tem-
peratures on . . . . 341
Sourness, Relation of, to acidity 339
Soxhlett's extraction apparatus 509
Specific gravity .... 27
of worts and attenuation . 235

— heat

— rotatory power . . . 538
Spirits of wine, alcohol . . 44

, Methylated ... 46

Sponging and doughing . . 321

Sponge 310

— and dough . . . 313, 321

, Management of . . 323

Sponge-making machines . 433

Spontaneous fermentation . . 190

Sporangia 191

Spores .184

Stability of flour . . . .322

, tests . . . .322

Starch . . . . . . 77

— , Action of caustic alkalies and

zinc chloride on . . . 82
— , Action of diastase on . . 128
— , Action of iodine on . . 82
— , bruised, Action of malt ex-
tract on .... 130

— cellulose 77

— ,. Estimation of ... 545

— , Fermentation of . . 203
— , Gelatinisation of . . . 80, 89

— , — , Temperature of . . 81

- grains, Effect of size of, on

flour, Armstrong . . . 277

— , Hydrolysis of . . 138, 141

— in yeast 567

— , Molecular constitution of . 131

— , Occurrence of ... 77

- of wheat . . . .77, 78, 79
Starch paste, Action of malt ex-
tract on 131

— , Preparation and manufac-
ture of 80

Properties of, in solution . 82

Saccharification of . . 121

Solubility of . . . . 80

Soluble 81

— , Estimation of . . , 549

PAGE

— solution, Properties of . . 82
, Reactions of ... 82, 90

— sugar, glucose . . . 601
— , ungelatinised, Action of malt

extract on .... 129
Starches, Microscopic character

of various .... 79

— , — examination of . . . 88

Steam oven ..... 448

Stearic acid 49

Storage of flour .... 422

Strength of flour . 267, 272, 274

, Conditions requisite

for 269

, Present-day conclu-
sions 279

— _ yeast 197

Substitution, or compound, am-
monias .....

Succinic acid .... 50

Sucrose, cane sugar . . 85, 597

Sugar boiling .... 600
— , cane, inverted, Polarimetric

behaviour of . • . . 543

— , Cutting the grain of . . 601
— , Fondant . . . . .601

— , Polarimetric estimation of . 542

Sugars 597

— , Commercial, Composition of 598
— , Estimation of, by Fehling's

solution ..... 531

— , — — , by polarimeter . . 542

Sulphates 38

Sulphites ..... 37

Sulphur 37

— dioxide 37

Sulphuretted hydrogen . . 37

Sulphuric acid and sulphates . 38

Sulphurous acid and sulphites . 37

Symbols and formulae . . 12

Tannin, Effect of, on bacteria . 189

Tartar, Cream of • . . . 356

Tartaric acid ... 50, 356

Tartaric powders . . . 359

Telegraphic codes . . . 572
Temperature ....
— , Absolute zero of .

— , Automatic regulator . . 218

— , Effect of, on fermentation . 211

Testa 244

Test mills 474

Testing with viscometer . . 486

Thermometer . . . , . 3

Thermometric scales . . . 3

Tintometer 489

Total proteins, Estimation of . 518

Tourmaline ..... 66

Toxalbumins . . . 214

Transmission of heat ... 8

Treacle 598

INDEX.

629

PAGE

Trimethylamine .... 51

True gluten, Estimation of . 521

Trypsin ..... 137

Tuberin 98

Tnrog bread .... 377

Tyrosine ..... 54

Unsound, or very low grade

flours, Working with . . 353

Ustilago scgetum .... 194

Vacuum oven
Vanilla and vanillin .
Vanillin, Synthetic
Veda bread, Analysis of
Vegetable albumin
— myosin

Vernier, Description of
Vibrio subtilis
Vienna bread

. 476
. 612
. 612
. 376
97

98, 101
541

. 184
. 354

- ovens ..... 455
Viennara kneading machine . 430
Virgin barm .... 238

Viscometer ..... 484
— , Mode of testing with . . 486
Viscous fermentation . . . 190

Vitamines 393

Vitellin .95,98

"Volatile," ammonium car-
bonate 356

Voller on wheats . . . 258
Voller's dictionary of wheat . 260
Volume, Laws of chemical com-
bination by .... 16
— , Measures of . . . . 25

Walsh and Waldo on effect of

baking on bacterial life . 344

Wash-bottle .... 506

Water 29, 308

— bath 513

— , Corrosive action of . . 427

— , Estimation of ... 474

— for washing wheat . . . 293

— free from carbon dioxide . 516

— heating 459

- — , Measuring and attemperating

or tempering . . . 426

— of wheat 474

— , Softening of . . . . 309

— , Soluble B .... 395

— , Solvent power of . . . 29
.Water-absorbing power of

flour .... 291, 482

Water-absorption burette . . 482

Watkins on ropy bread . . 345

Weighed niters . 508

Weighing of bread

— , Operation of .

Weight, Measures of .

Weights, Analytic

— and measures, English

PAGE

. 437

. 468
25

. 466
27
Weyl and Bischoff on wheat

proteins .... 101

Wheat ash, Composition of . 69

- blending 363

— , Chemical changes during

ripening of . . . . 258

— , Chemical composition of . 254
— , Cleaning machine for test-
ing ...... 575

— , Commercial assay of . . 269
— , composition, Effect of shade

on 266

— , Constituents of . .68, 72, 254

— , Damping of . . . . 293

— , Distribution of gluten in . 298

— , Durum, Norton . . . 256

— , Fatty matters of . . . 70

— , Foreign matters in . . 473
— , frosted, Shutt . . .266

— , Germination of ... 252

— grain, Construction of . 68, 240

— , Crease of . . . . 242

— , Functions of ... 240

— Grinding of samples . . 473
— , Insoluble proteins of, gluten

107, 120, 290

— , Mineral constituents of . 68

— mixtures, Voller . . . 258

— oil, de Negri, Frankforter,

and Harding ... 71

— , Organic constituents of . 70

— products, Nutritive ratio of . 384

— replacement calculations . 576

- tests 574

- section cutting . . . 243

— testing ..... 472
— , — Commercial, Snyder . 269

- washing, Water for . . 293
— , Water-soluble phosphates

of, Wood .... 278

— , Weight per bushel . . 472
— , — of 100 grains . . .472
Wheats, Composition of, Fleu-

rent 256

— , Damping of . . . .293

— , Replacing mixtures of . . 258

White bread, analysis of . . 377

Whole meal bread . . . 360

, Analysis of . . . 377

Wild yeasts 178

Wire ropes ..... 422
Wood on strength of flour . 272
Worts, Preparation of . . 227
— , Specific gravity of, and at-
tenuation 235

Xanthoproteic reaction of pro-
teins 94

630

INDEX.

PAGE

Yeast . . ' . . . .149
— , Admixture of starch with . 567

— and other organisms, Isola-

tion of . . . . . 166

— as an organism . . . 152
— , Ascospores of . 165, 166, 176
— , Bakers' home-made . . 231
— , Behaviour of free oxygen

to 160

— , Botanic position of . . 153
— , Bottom-fermentation species 179
— , Brewers' . . . 214, 223

— brewing, Suggestions on . 234
— , Budding of . . . .154

— cells, Nature of ... 154
— , Chemical composition of . 151
— , — reactions of ... 154
— , compressed, Characteristics

of 230

— , — , Manufacture of . . 226

— counting ..... 63
— , cultivated, Varieties of . 179

— culture and isolation . . 166
— , Distillers' . . . .172
— , — , Manufacture of . . 226
— , Effect of rousing on . . 161
— , Endogenous division of . 165

— growth, Influence of tempera-

ture on . . . . .157
— , High . . . . .170
— , — and low, Convertibility

of 170

— , — — , Distinctions be-
tween 170

— , Insufficiency of either sugar
or nitrogenous matter only
for nutriment of . . . 159
— , Isolation of . . . . 166
— , Keeping properties of . . 222
— , Life History of . .155

— , Low or sedimentary . . 170
— , Mai-nutrition of . . . 165
— , Manufacture of . 226

PAGE

Yeast, Manufacture of bakers'
"patent" or home - made
malt and hop . . . 231
home-made malt and hop . 231

— , brewers' . . . 223

— , compressed . . . 226

— , — - Scotch flour barm . 236
— , Methods of isolation of, and

other organisms . . . 166
— , Microscopic study of

180, 224, 236
— , Mineral matters necessary

for growth of ... 159
- mixture .... 201, 221
— , Multiplication of, by en-
dogenous division . . 165
— , Nature of cells of . . .154
— , Necessity of saccharine

matter for . . . .157
— , Nitrogenous nutriment of . 158
— , "Patent" .... 231

— , — , Formula for . . . 233
— , — .Suggestions on . . 234

— , Purification of . . 166, 188
— , Sporular reproduction of . 165
— , Starch in .... 567
— , Strength of . . . .197
— , Technical researches on . 197
nutriment of . . . .157
— , Technical researches on . 197
— testing .... 197, 229
- Apparatus . . . 197, 218
— , Top-fermentation species of 179
" — , varietv and quantity used 154, 32?
Yeasts, Classification of . . 169
— , Detection of wild . . .178
— , Hansen on analysis of . . 176
Young on alum .... 569

Zein ....

Zero, Absolute

Zooglcea

Zymase

— theory of fermentation

99
7

182
138
147

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Full text of "The technology of bread-making, including the chemistry and analytical and practical testing of wheat flour, and other materials employed in bread-making and confectionery"

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