DAIRY CHEMISTEY

DAIRY CHEMISTRY

BY

HARRY ^ISTYDER, B.S.

PROFESSOR OF AGRICULTURAL CHEMISTRY, UNIVERSITY OF

MINNESOTA, AND CHEMIST OF THE MINNESOTA

EXPERIMENT STATION

THE MACMILLAN COMPANY

LONDON: MACMILLAN & CO., LTD.
1906

All rights reserved

, 1905,

BY THE MACMILLAN COMPANY.

Set up and electrotyped. Published December, 1905.

Nortoooft

J. S. Cashing & Co. — Berwick & Smith Co.
Norwood, Mass., U.S.A.

PREFACE

THIS work is the outgrowth of a course of lec-
tures given by the author for a number of years to
the students of the Agricultural Department of the
University of Minnesota. During recent years
material progress has been made in dairying, and
in writing this book it has been the aim briefly
to incorporate the results of the more important
investigations on the subject. In the prepara-
tion of the work extensive use has been made
of the bulletins and reports of the Agricultural
Experiment Stations of the United States and of
other works on the subject. It is the aim to present
in as concise a form as possible the principal changes
that take place in the handling of milk and in its
manufacture into butter and cheese. While our
present knowledge of some phases of the subject is
incomplete, there are many facts that are known
and have been found very useful as an aid in the
production of dairy products of the highest sanitary
and market value.

It is believed that a knowledge of the general
v

769789

VI PREFACE

principles of dairy chemistry will be found useful
alike to the farmer, to the factoryman, and to the
consumer, and this work has been prepared with
the view of giving information to the layman rather
than to the scientist.

HARRY SNYDER.

COLLEGE OF AGRICULTURE,
UNIVERSITY OF MINNESOTA,
ST. ANTHONY PARK, MINNESOTA,
December 1, 1905.

CONTENTS

CHAPTEE I
THE COMPOSITION OF MILK

PAGE

Complexity of composition ; Milk serum ; Milk solids ; Milk
fats ; Casein ; Albumin ; Milk sugar ; Ash ; Variations
in composition of milk ; Percentage composition, and
total yields ; First or fore milk and strippings ; Milk
serum, Constancy of its composition .... 1

CHAPTER II
MILK TESTING

Importance of milk testing ; Reliability of the Babcock test ;
Sampling milk ; Measuring milk with the pipette ; Mak-
ing the test ; Reading the fat ; Calibration of test bottles ;
Speeding the machine ; Centrifugal action ; The acid ;
Composite sample ; Testing skim milk ; Sampling frozen
milk ; Cleaning glassware ; Water used in milk testing ;
Care of test bottles and apparatus 13

CHAPTER III
MILK FATS

Composition of fats ; Kinds of butter fats ; Palmitin ; Stearin ;
Olein ; Butyrin ; Caproin and Caprylin ; Glycerine and
fatty acid content of fats ; Food value of fats ; Saponifi-
cation of fats ; Iodine absorption of butter fats ; Volatile
fatty acids of butter ; Melting point and physical proper-
ties of butter 29

vii

V1U CONTENTS

CHAPTER IV

THE LACTOMETER AND ITS USE IN DETERMINING MILK

ADULTERATION

PAGE

Quevenne's lactometer ; Specific gravity of milk ; Influence of
temperature ; Other lactometers ; Influence of skimming
and watering ; Calculation of solids in milk ; Joint use
of lactometer and Babcock test 35

CHAPTER V
MILK SUGAR AND LACTIC ACID

Physical properties of milk sugar ; Fermentation of milk
sugar ; Production of lactic acid in the milk ; Determin-
ing the acidity of milk ; Calculating the acidity of milk ;
Alkaline tablets ; Acidity of cream 43

CHAPTER VI
CREAM

Composition of cream ; Testing cream ; Methods of creaming ;
Adulteration of cream ; Ripening of cream ; The use of
pure cultures ; Influence of delay on the creaming of
milk; Creaming of mixed milks; Cream raising by
dilution . 50

CHAPTER VII
THE CHEMISTRY OF BUTTER MAKING

Churning ; Dairy salt ; Buttermilk ; Losses of fat in butter
making ; Composition of butter ; Butter colors ; Over-
runs ; Dividends ; Judging butter 62

CONTENTS IX

CHAPTER VIII
THE SANITARY CONDITION OF MILK

PAGE

Unwholesome milk ; Factors influencing the sanitary condi-
tion of milk ; Condition of the animals as to health ; Care
of the animals ; Care of milk and dairy utensils ; Food
and water which the animals receive ; Colostrum milk ;
Tyrotoxicon; Fibrin in milk; Gases in milk; Keeping
qualities of milk 75

CHAPTER IX
THE CHEMISTRY OF CHEESE MAKING

Cheese making and butter making compared; Proteids in
milk ; Casein ; Albumin ; Rennet ; The rennet test ;
Process of cheddar cheese making; Process of stirred-
curd cheese making; Distribution of milk solids in cheese
making ; Curing of cheese ; The cheese yield of milk ;
Testing cheese by the Babcock milk test ; Composition
of cheese ; Testing whey ; Making out dividends in cheese
factories; Comparative butter and cheese returns from
milk ; Different kinds of cheese 88

CHAPTER X
MILK BY-PRODUCTS

Uses of by-products ; Skim milk — composition, value, and
use ; Whey — composition, value, and use ; Fertilizer
value of milk by-products ; Comparative value of skim
milk compared with milk of other domestic animals . 107

CHAPTER XI
THE ADULTERATION OF DAIRY PRODUCTS

Oleomargarine ; Simple methods for detecting oleomargarine ;
Renovated butter ; Adulteration of cheese ; Adulteration
of milk ; Other methods for testing milk ; Dairy laws . 112

X CONTENTS

CHAPTER XII
MARKET MILK AND CREAM

PAGE

Variable character of market milk ; Changes in composition
of milk during transportation ; Pasteurizing milk and
cream ; Condensed milk ; Milk as human food . .119

CHAPTER XIII

INFLUENCE OF DIFFERENT FOODS UPON THE QUALITY
OF MILK AND DAIRY PRODUCTS

Food and milk secretion ; Feeding fat ; Production of hard
butters ; Production of soft butters ; Effects of individual
foods ; Desirable flavors in milk products ; Influence of
balanced rations ; Milk secretion 125

CHAPTER XIV
THE RATIONAL FEEDING OF DAIRY STOCK

Uses of food ; Nutrients and their functions ; Dry matter ;
Ash ; Organic matter ; Proteids ; Carbohydrates ; Crude
fiber ; Crude fat ; Digestible nutrients ; Caloric value or
heat units of a ration ; Nutritive ratio ; Selection of
foods for rations ; How to calculate a ration ; Compara-
tive cost and value of grains . . . . . .131

APPENDIX

Tables of composition of fodders and feeding stuffs ; Tables
for correction of lactometer readings ; Review questions ;
References 147

INDEX 187

DAIEY CHEMISTRY

DAIRY CHEMISTRY
CHAPTER I

THE COMPOSITION OF MILK

1. Complexity of Composition. — When milk is
separated into its component parts, as water, fat,
casein, albumin, sugar, and ash, the process is called
analysis. While these are the principal compounds
obtained when milk is analyzed, there are a num-
ber of other substances present in smaller amounts
which affect the quality of milk both for manufac-
turing and food purposes. Milk is one of the vital
fluids of the animal body and is necessarily of com-
plex composition.

2. Milk Serum. — Of the various constituents of
milk, the sugar, ash, and albumin are in solution,
and in the fresh milk the casein is practically in a
soluble form. The fat, however, is not in solution,
but is in the form of minute globules suspended in
the solution which contains the sugar, ash, albumin,
and casein and which is known as the milk serum.
The milk serum includes all of the constituents of
the milk except the fat. The term "serum solids"
is applied to those substances of milk which are dis-
solved in the water, — the sugar, ash, albumin, and
casein taken collectively.

B 1

•:&

DAIRY CHEMISTRY

: . ,3, JM&& Solids. 7*7 When milk is evaporated to dry-
• " nes6,* .tli'ei rwg,J;er\ifif . expelled and the milk solids are
obtained. Milk solids are a mechanical mixture of
fat, casein, albumin, milk sugar, and\ash. Normal
milk contains about 13 per cent of solid matter ; some
samples contain as low as 12 and a few as high as
14 per cent. The amount of milk solids varies pro-
portionally with the fat content of the milk, the higher
the per cent of fat the larger the amount of solids.

In the chemical analysis of milk, the solids are
obtained by evaporating a weighed quantity of milk
to dryness in a small dish which has previously been
carefully weighed on a very delicate balance. The
weight of the milk solids is then obtained and the
percentage amounts calculated.

EXAMPLE

Weight of milk + dish
Weight of dish
Weight of milk

Weight of milk -f- solids
Weight of dish
Weight of milk solids

10.51 : 1.345 : : 100 : x.
13.45 x 100

GRAMS

23.360
12.850
10.510

14.195

12.850

1.345

= 12.80 per cent solids.
lu.ol

100 - 12.80 = 87.20 per cent water.
The per cent of water in

FIG. 1.— Determining the solids

in milk. milk is obtained by subtract-

THE COMPOSITION OF MILK 3

ing the per cent of solids from 100, as the loss in
weight during evaporation is the water expelled
as steam. There are rarely more than 88 pounds of
water in 100 pounds of milk ; average milk contains
about 87 per cent, while some of the richest milks
contain 86 per cent or less. The milk solids, unless
obtained in a specially constructed water oven, are
brown in color, due to slight charring of the sugar
and other compounds. The solids of milk are some-
times termed dry matter and sometimes solid matter.
They are composed of fat, casein, sugar, albumin, ash,
and other compounds found in smaller amounts.

4. Milk Fats. — Average milk contains about 3.5
per cent of fat ; some normal samples may contain
3 per cent or less, while others may contain 5 per
cent or more. Fat is the most variable constitu-
ent in milk. Cream contains ordinarily from 18 to
35 per cent of fat, and well-made butter about 85 per
cent. For butter-making purposes the value of the
milk is directly proportional to its fat content. Milk
fat is mainly familiar as the product obtained by
churning cream. Milk fat and commercial butter,
however, are not synonymous terms. By milk fat
is meant the pure dry fat, free from water, salt, or
casein, while butter contains all of these materials
in variable amounts. The determination of the fat
in milk by the Babcock test is discussed in the
second chapter of this work, and the composition
and properties of the fats are considered in other
chapters.

4 DAIRY CHEMISTRY

As previously stated, the fat in milk is not present
in solution, but in suspension in the form of minute
globules. These milk fat globules are about one five-
thousandth of an inch in diameter. A cubic milli-
meter of milk is estimated to contain from 2,000,000
to 4,000,000 fat globules, or a single drop from
100,000,000 to 150,000,000. Under the microscope
the fat globules appear grouped together in small
colonies. The size of the fat globules yaries (1) with
the breed and individuality of the animal, and (2)
according to the length of time the animal has been
in milk. When a cow is fresh, there is a smaller
number of globules, but the globules are larger ;
when the cow is well along in her milking period, the
globules are smaller but more numerous. The milk
from the Channel Island breeds is characterized by
large fat globules, while the milk from the lowland
breeds contains smaller globules. The fat globules
must be massed together and collected when butter
is made. The more completely they are recov-
ered, the greater will be the amount of butter
produced.

The fat globules are simply solid masses of fat.
At one time it was believed that they were sur-
rounded by a membrane, and in churning it was
supposed that the membrane had to be broken before
the globules would mass. Recent chemical investi-
gations have shown that there is no membrane sur-
rounding the fat globules. The fat globules are
lighter than any of the constituents of the milk

PLATE I

JERSEY MILK FAT GLOBULES

PLATE II

HOLSTEIN MILK FAT GLOBULES

THE COMPOSITION OF MILK 5

serum. They retain their form and individuality on
account of surface tension, which is the pressure that
is exerted on the surface of the globules and is equal
on all sides, hence the spherical form of the globules.

5. Casein. — Average milk contains about 3 per
cent of casein, which in fresh milk is practically in a
soluble condition, but in sour milk is precipitated as
curd. The per cent of casein in milk is quite con-
stant, ranging from 2.8 to 3.5 per cent. As a general
rule, normal milk contains less casein than fat. In
a pure state casein is a grayish white powder.
Casein takes a very important part in cheese making
and other dairy operations. Its chemical and physi-
cal properties and the changes which it undergoes
will be considered in other chapters.

6. Albumin. — Average milk contains about one
half of one per cent of albumin, which is nearly iden-
tical with egg albumin, or the " white " of the egg.
Albumin and casein have about the same general
composition, but different properties ; they belong
to the class of bodies called proteids, and are very
complex in composition, differing from fat and sugar
by containing the element nitrogen, which is not
found in the fats and sugars. When fresh milk is
boiled, the coagulum which forms on the surface is
albumin. The amount of albumin in milk is quite
constant and ranges from one half to three quarters
of a per cent.

7. Milk Sugar. — Lactose, or milk sugar, is present
in milk to the extent of about 5 per cent. When

6 DAIRY CHEMISTRY

obtained in the pure state, it resembles in appearance
confectionery sugar, but not in taste. Milk sugar
takes an important part indirectly in butter and
cheese making, as it is the material from which the
acid is formed that sours the milk. The amount of
milk sugar or lactose in milk is quite constant,
ranging from 4.6 to 5.4 per cent. In average milk
it is the constituent which is present in the larg-
est amount of any of the milk solids. The part
which milk sugar takes in butter and cheese mak-
ing will be considered in other chapters of this
work.

8. Ash. — When the milk solids are burned, there
is a small amount of grayish white ash obtained.
The ash content of milk is constant and varies but
little from three quarters of one per cent. Milk ash
is composed of common salt, and phosphates and
chlorids of potassium, calcium, and magnesium, to-
gether with small amounts of other minerals. A
portion of the phosphorus is in combination with the
casein.

When milk is analyzed in the laboratory, the ash
is obtained by completely burning the milk solids at
a low temperature. The small dish containing the
milk solids (see section 3) is placed either over a
specially regulated flame or in a low-temperature
muffle furnace to completely burn the sugar, casein,
albumin, and fat without volatilizing any of the
mineral salts. The dish containing the milk ash
is then weighed and the per cent of ash determined.

THE COMPOSITION OF MILK

Milk taken 10.51 gm.
section 3.

EXAMPLE

See

Dish and milk ash

Dish

Ash

GRAMS

12.928

12.850

0.078

10.51 : .078 : : 100 : x.
.078 x 100

10.51

= .74 per cent ash.

9. Variations in Com-
position of Milk. — Aver-
age milk has about the
following general com-
position : —

FIG. 2. — Determining the ash in
milk.

PEE CENT

RANGE, PEB CENT

Water

87.00

89.6 to 82.4

Fat

3.50

2.5 to 6.0

Casein

3.25

2.5 to 4.0

Albumin ........

050

0.5 to 0.8

Milk Sugar

5.00

4.3 to 6.0

Ash

0.75

0.6 to 0.8

Solids

13.00

10.4 17.6

It is seldom that the extreme limits as given for the
composition of milk are met with ; occasionally an
individual animal may give milk of abnormally high
or low solids and fat, but it is rarely the case that
the milk from an entire herd will contain either the

8

DAIRY CHEMISTRY

maximum or the minimum percentage of milk
solids.

Milk varies in composition with the individuality
of the animal, period of lactation, care, exhaustive-
ness of milking, general condition as to health, and
nature of the food consumed. Individuality, as
breed characteristics, influences the composition of
milk to a greater extent than the other factors
enumerated. The extent to which some of these
factors influence the composition of milk will be
discussed in other chapters of this work.

As an example of the composition of milk from
different breeds, the following table taken from the
New York Experiment Station, and representing
one year's work, is given : —

BREEDS

TOTAL
SOLIDS
PEB CENT

FAT
PER CENT

CASEIN
PER CENT

MILK
SUGAR
PER CENT

ASH
PER CENT

Holstein-Fresian

12.39

3.46

3.39

4.84

0.74

Ayrshire

13.06

3.57

3.43

5.33

0.70

Jersey

15.40

5.61

3.91

5.15

0.74

Am. Holderness

12.63

3.55

3.39

5.01

0.70

Guernsey

14.60

5.12

3.61

5.11

0.75

Devon

13.77

4.15

3.76

5.07

0.76

While these figures do not necessarily hold true for
all herds, or for individual animals of any breed,
they show the average composition of the milk for
an entire season from a number of representative
animals of different breeds. In determining the

THE COMPOSITION OF MILK

value of milk for butter or cheese making purposes,
the yield in pounds as well as the percentage compo-
sition of the milk must be considered, as it frequently
happens that the cows giving the richest milk also
give the smallest yield of milk.

10. Percentage Composition and Total Yields. — In
order to determine the total yield in pounds of each
constituent produced by a cow or by a herd for a
given period, the total weight of milk is multiplied
by the percentage composition. In case it is desired
to compare the yields of milk solids of two cows,
giving respectively a total of 110 and 140 pounds of
milk in three days, an analysis would have to be
made of each milk. Suppose the milks give the
following results upon analysis : —

COMPOSITION OF MILK

Cow No. 1
PER CENT

Cow No. 2
PER CENT

13.14

12.56

Milk fats

4.06

3.26

3.34

3.54

Ash

0.70

0.72

5.04

5.04

TOTAL YIELD OF MILK SOLIDS

Cow No. 1

Milk fats, 110 x .0406 = 4.47
Casein, 110 x. 0334= 3.67
Ash, 110 x. 007 = 0.77

Sugar, 110 x .0504 = 5.54
Total 14.45

Cow No. 2

140 x. 0326= 4.56
140 x. 0354= 4.95
140 x. 0072= 1.01
140 x. 0504= 7.06
17.58

10 DAIRY CHEMISTRY

While the difference in percentage composition of
the milk is .8 of a per cent of fat in favor of cow
No. 1, the total yield of fat for three days is .1 of
a pound in favor of cow No. 2. Cow No. 2, how-
ever, produced a larger amount of milk solids in the
form of fat than cow No. 1. In general it is to
be noted that whenever a cow produces a pound
of butter fat, she also produces about 1.1 of milk
sugar, about a pound of casein and albumin, and
about .15 of a pound of ash. When milk is paid for
on the basis of its fat content for butter making
purposes, the total pounds of fat are obtained by
multiplying the weight of the milk by its per cent
of fat, as 287 pounds of milk testing 3.6 per cent
fat contain (287 x .036) 10.33 pounds of fat. In
dairy operations all comparisons and calculations
are made on the basis of the total fat.

11. First or Fore Milk and Strippings. — As is
well known, the first portion of milk given by any
cow at a milking is poor in fat, while the last
portion, or strippings, is very rich in fat. The
per centage amounts of casein, ash, and sugar, and
other ingredients, however, remain nearly constant.
The difference in fat content between the first or
fore milk and the strippings suggests the impor-
tance of careful and exhaustive milking, and also
thorough mixing of the milk before taking a sample
for analysis. The composition of the first pint and
the last pint of milk from two cows is given as an
illustration.

THE COMPOSITION OF MILK

11

Cow

No. 1

Cow

No. 2

First pint

Last pint

First pint

Last pint

Total solids

per cent

9.42

per cent

19.49

per cent

10.10

per cent
18.47

Fat

0.71

10.84

1.02

9.49

Solids, not fat ....
Ash

8.71
0.68

8.65
0.72

9.08
0.70

8.98
0.74

Casein, albumin . . .

3.44

3.51

3.35

3.65

12. Milk Serum, Constancy of its Composition. —

The solids of the milk serum are fairly constant in
composition. This is well illustrated in the example

Wer Fat Casein /IHKSugtrfl/lmin

FIG. 3. — Average composition of milk.

given of the composition of first or fore milk and
strippings. The solids of the milk serum, also
known as the solids not fat, are never less than 8.25
per cent and rarely more than 9.75 per cent. The

12 DAIRY CHEMISTRY

average is about 9 per cent. The greatest difference
in the composition of various milks is in the fat con-
tent. Any material increase in the total solid mat-
ter of milk is due mainly to an increase of the fat.
The solids not fat are subject to but slight varia-
tions compared with the fluctuations of the fat.

Nearly all of the important fluids of the body, like
the blood, are normally quite constant in chemical
composition. With milk the constancy of composi-
tion is confined mainly to the serum solids, or solids
not fat.

CHAPTER II

MILK TESTING

13. Importance of Milk Testing. — A knowledge
of the fat content of milk is essential in order to
determine (1) any unnecessary waste in the manu-
facture of butter and cheese, (2) the value of indi-
vidual cows, (3) the cost of producing milk, (4) the
value of different fodders and grains for milk-pro-
ducing purposes, and (5) the commercial value of
milk.

A number of simple methods have been proposed
for testing milk ; some of them require a more
extended knowledge of chemical operations than
others. The method which is in most general use
on account of its accuracy, simplicity, and cheapness
is the Babcock centrifugal method.

14. Reliability of the Babcock Test. — This method
has been tested by many chemists, and in all cases
it has been found to give reliable results. There is
a tendency, however, to read the fat percentages too
low. This will be considered more in detail in dis-
cussing that part of the operation. In the case of
skim milk and buttermilk, when the fat is present
to the extent of only two tenths of a per cent or less,
the method may not give absolute results. This

13

14 DAIRY CHEMISTRY

does not impair the usefulness of the test, because
frequently the losses in skim milk and buttermilk
are greater than this, and so far as the whole milk is
concerned the method is perfectly reliable. When
the Babcock test shows only a trace of fat in the
skim milk or buttermilk, the losses are very small.

15. Sampling Milk. — Milk should be thoroughly
mixed before sampling. The milk as it comes from
the cow or when it has been standing is not in a
condition to sample until it has been thoroughly
mixed, either by pouring from one pail to another
or by stirring with a long-handled dipper. Milk
brought to the creamery in cans also requires thor-
ough mixing before sampling. This is best accom-
plished by the use of a long-handled dipper. Before
sampling, the milk should be weighed.

The milk should not be measured into the test
bottles when it is either hot or cold. At a high
temperature the milk is expanded and may contain
an abnormal amount of dissolved air ; while at a low
temperature the milk may be unduly contracted. A
temperature of 70° to 80° is the most suitable for
measuring milk. If the milk has been standing for
some time in the sample bottle, it is necessary to mix
it thoroughly before measuring with tne pipette.
To do this, turn the milk from the sample bottle into
another bottle or dish, pouring it down the side to
prevent the formation of foam. In case the sample
bottle has been standing until the fat has separated
into a layer of cream, the bottle may be placed in a

MILK TESTING

15

bath of warm water, temperature 100°, to liquefy the
fat before mixing. Milk
which shows the pres-
ence of clots of cream or
small particles of butter
formed during the shak-
ing of the sample bottle
is not in condition to
be measured with the
pipette. If the sam-
pling of the milk has not
been carefully done, the
work of testing is of little
value, as the sample
taken fails to represent
the milk tested.

16. Measuring Milk
with the Pipette. — The
apparatus used for meas-
uring the milk is called
a pipette (see Fig. 4). In
order to fill the pipette
put the pointed end into
the milk, apply suction
with the mouth until
the milk rises just above
the point a on the stem ;

, . , , FIG. 4. — Measuring milk with the

then close the end with pipette.

the index finger of the

right hand, holding the pipette in the way shown

16 DAIRY CHEMISTRY

in the cut. The second and third fingers are opposite
the thumb, while the little finger rests against the
stem. When held in this way, the pipette is pre-
vented by the little finger from swaying sidewise ;
while the thumb, with the second and third fingers
on the opposite sides, secures a good hold and leaves
the index finger free to properly control the flow of
milk from the pipette, and thus rapid measurements
can be made. If the pipette is wet, rinse it with a
little of the milk before using it. In passing from one
milk to another, clean the pipette by rinsing it with
the milk that is to be tested. The pipette should be
thoroughly cleaned, first with cold water, then with
hot water at the close of the work. The pipette
holds 17.6 cc. of water, and delivers 18 gm. of
milk. Hold the test bottle in the left hand at an
angle of about 60°. Let the tip of the pipette if
large just touch the inside of the neck of the test
bottle, in order to permit air to pass out of the test
bottle, otherwise the milk will spatter. Allow plenty
of time for the pipette to drain ; remove the last few
drops by blowing.

17. Making the Test. — The test bottle (see Fig.
5) is provided with a neck which has a graduated
scale from 1 to 10. Each larger division is divided
into five smaller divisions, each representing .2 of a
per cent of fat. The test bottle is usually provided
with a copper collar bearing a number. Fill the
acid measure, Fig. 6, up to the 17.6 cc. mark with
sulphuric acid. The action of the sulphuric acid

MILK TESTING

17

will be considered in another paragraph. Pour the
sulphuric acid from the acid measure into the test bot-
tle which contains the milk. The acid and the milk

should be of nearly

the same tempera-

ture, 70° F.
While the acid

is poured in, ro-

tate the test bot-

tle so as to wash

all of the milk

down from the

stem. After the

acid is added, take

the bottle by the

stem and mix

the acid and the

milk by rotating.

The solution be-

comes a dark cof-

fee color, due to

charring
°

FIG. 5 -Milk test
bottle.

FIG. 6. — Acid measure.

the sugar. The
acid first precipitates the casein and then dissolves
it. The acid does not act on the fat.

The fat is separated from the milk serum by cen-
trifugal action. There are a number of different
kinds and sizes of centrifugal machines, but they all
act on the same principle. The test bottles are
placed in the pockets of the centrifugal machine.

18 DAIRY CHEMISTRY

In case there are not enough bottles to fill the
machine, arrange the bottles so there will be an
even number on each side. If this is not done,
the machine is unbalanced, and the bearings will
soon become badly worn. The bottles are to be
whirled five minutes at the rate of 900 revolutions
per minute. Directions for speeding the machine
will be found in another paragraph. The start-
ing and stopping of the machine should be done
gradually.

After whirling five minutes, the test bottles are to
be filled with hot water up to about the eighth mark
on the stem. The air bubbles which are sometimes
caught in the neck should be allowed to escape. The
bottles are then whirled two minutes longer in order
to collect all of the fat in the graduated stem. In
using the machine always put on the cover so as to
prevent any accident.

None of the apparatus used in this test is patented,
and a good homemade centrifugal machine will answer
every purpose. The bottles and other glassware can
be purchased separately.

18. Reading the Fat. — When the test is completed,
the fat in the stem of the test bottle presents the
appearance shown in Fig. 7. Read from the low-
est point b to the highest point a. Each large divi-
sion, as 1 to 2, represents a whole per cent of fat ;
each of the smaller divisions one fifth or two tenths
of a per cent. Suppose the top registers seven large
divisions, and three small, then a = 7.6. If b registers

MILK TESTING

19

two large and three small divisions, b = 2.6. 7.6 —
2.6 = 5.0, the per cent of fat in the milk.

Do not read from other points than a and 6, other-
wise the results will be too low. The bottles are
made to read in
just this way.
The reading
should be done
before the fat
cool sand streaks
down the sides.
In case a num-
ber of readings
are to be made,
the test bottles
should be set in
a pan of hot
water, or hot
water can be
run into the pan
of the machine,
to prevent the
bottles from
cooling. Dividers can be used as indicated in the
figure, but should be spread from 0 to 5.

19. Calibration of Test Bottles. — All test bottles
should be rejected when inaccuracy of the divisions
can be detected with the eye. In the most careful
work they should be calibrated with mercury : 27.18
gm. of clean metallic mercury should just fill the

FIG. 7. — Reading the test.

20 DAIRY CHEMISTRY

space between the 0 and the 10 in the scale. Each
small division is equal to .04 cc., or, as usually made,
about one and one half millimeters. The test bottles
can also be calibrated with water in the following
way: The bottles are filled with pure distilled water
up to the 0 mark, and then from an accurately
graduated burette, graduated to -fa cc., water is
added. It should require 2 cc. of water to fill the
test bottle from the 0 to the 10 mark. For ordinary
work the bottles can all be tested with one sample
of milk, and all bottles rejected that show a greater
difference than one small division. Accurately gradu-
ated test bottles can usually be obtained from supply
houses that deal in chemical apparatus. Inaccu-
rately graduated test bottles are occasionally the
cause of much trouble and dissatisfaction in the
creamery.

20. Speeding the Machine. — A centrifugal of 14
inches' diameter should make about 900 revolutions

FIG. 8. — Centrifugal machine.

per minute. In order to speed the machine count
the number of revolutions that the test bottles make

MILK TESTING 21

for every revolution of the crank wheel. Suppose
the test bottles make 12 revolutions while the crank
makes one. In order that the bottles may make 900
revolutions per minute, the crank must be turned
75 times in a minute (900 -r- 12 = 75). In case the
machine is less than 14 inches in diameter a greater
number of revolutions is necessary.

DIAMETER OF CENTRIFUGAL. INCHES NUMBER OF KEVOLUTIONS PER MINUTE

10 1050

12 975

14 900

16 850

18 800

20 750

21. Centrifugal Action. — As previously stated, the
fats are lighter than the milk serum, and when the
milk is whirled in the test bottles, there is a separation
of milk fats (lighter particles) from the milk serum
(heavier portion). The serum goes to the outside
of the circle of revolution, while the fats mass in the
center, where they are finally collected in the gradu-
ated stem of the test bottle. The sulphuric acid,
which is one and eight tenths heavier than water,
also aids in the separation both by increasing the
specific gravity of the milk serum and by chemical
action upon the albumin and casein. The cream
separator works, on this same principle. In the case
of the separator, provision is made for the escape of
the fat into a tube as it collects at the center. Cen-
trifugal action is well illustrated by whirlpools, where

22 DAIRY CHEMISTRY

all of the foam and light material, as leaves, collect
in the center.

22. The Acid. — Commercial sulphuric acid (sp.
gr. 1.82), about 90 per cent strength, is used.
One pound of acid will make about twenty tests.
When the acid is too strong, the fat presents a
blackened and charred appearance ; if too weak, par-
ticles of undissolved casein appear immediately
below the fat line. When just right, the fat sepa-
rates in a distinct and well-defined layer and looks
like butter. If the acid is too strong, and chars the
fat, use a smaller amount in making the test. In
that case, if the test is not satisfactory, the acid
should be exchanged for a new lot. Do not attempt
to dilute the acid with water. If the acid is too
weak, a larger amount than 17.6 cc. may give satis-
factory results. The strength of the acid can be
determined by using a hydrometer for heavy liquids,
and noting the depth to which the spindle sinks in
the acid. To obtain the best results, the acid should
vary but little from 1.82 specific gravity or 90 per
cent strength.

STRENGTH OF ACID SPECIFIC GRAVITY

88 1.808

89 1.815

90 1.820

91 ; 1.825

92 1.830

93 1.834

94 1.837

95 1.839

MILK TESTING

23

The acid as well as the washings and contents of the
test bottles can be handled only in glass or earthen-
ware.

The acid should never come in contact with tin
or a metallic dish of
any kind. If acid is
spilled on the floor or
desks, wash it up imme-
diately, using plenty
of water. If a large
quantity is spilled, ab-
sorb it with sawdust,
bran, or fine clay. In
case any is spilled on
the clothing, rinse with
water and then apply
ammonia to the spots.
Never throw the acid
waste near a tree or
where a person or ani-
mal is obliged to walk.

A convenient form
of apparatus for meas-
uring the acid where a
large number of tests
are to be made is shown
in Fig. 9. a is the
acid bottle connected

FIG. 9. — Acid measuring apparatus.

with glass tube bb to a pipette. The stopcock /can
be turned so as to allow the acid to run into the test

24 DAIEY CHEMISTRY

bottle g. The automatic pipette is fastened to an
iron stand dd, which rests upon the table. Other
forms of apparatus are also in use. In ordinary
practice a strong glass vessel with a good lip for
pouring is the most satisfactory arrangement for
handling the acid. A white tile is excellent to have
on the table under the acid bottle.

23. Composite Sample. — In actual creamery prac-
tice the daily testing of each patron's milk, or in the
dairy, the testing of both morning's and evening's
milk from each cow is too expensive. To obviate
this daily testing, a composite or compound sample
is made up by saving a small sample of each milk in
a pint fruit can. At the end of one week or of two
weeks the compound sample is carefully mixed and
tested. Inasmuch as this test represents a propor-
tional part of each lot of milk, it gives the average
amount of fat in the milk for the period. In cream-
eries and factories, where milk is paid for by test,
the composite test when properly carried out gives
good results.

The composite sample should be kept covered so
that the surface of the cream will not become dry
and leathery. The sample should also be kept in a
cool place to prevent fermentation.

Various chemicals are used to keep the milk fresh.
Potassium bichromate has been found to give the
best satisfaction. About one half gram of potassium
bichromate will be sufficient to preserve a pint of
milk. Winton and Ogden state that a .22 pistol

MILS: TESTING 25

shell cut one-half inch long will hold, loosely filled,
approximately one-half gram of bichromate. For
convenience in handling the shell can be soldered to a
piece of stout wire. Put the bichromate in the sam-
ple cans when empty, and no more need be added until
a new composite sample is started. The bichromate
imparts its characteristic yellow color to the milk.

In case corrosive sublimate or any other poisonous
material is used for preserving the composite sample,
it is best to color the milk with aniline so as to pre-
vent accidental poisoning from use of the milk.

Small four or six ounce, wide-mouthed bottles may
be used for holding the composite samples. Bottles
with glass stoppers are the best. Rubber stoppers
may be used, but cork stoppers should never be used.
They are difficult to clean, and they cause the milk to
sour. When the composite sample becomes " lumpy "
and is difficult to sample, a very small (.1 gm.) piece
of caustic potash may be added before mixing the milk.
The potash will dissolve the lumps of curd. A few
drops more than 17.6 cc. of acid should then be used.

When only a small number of tests are to be made,
the following plan may be followed : Save about two
ounces of each milk separately in glass bottles or
cans ; at the next milking add a proportional quan-
tity. A composite sample of the day's milk is thus
obtained, and while still fresh is mixed, and then by
means of a small pipette, 5,9 cc. are measured into a
test bottle twice the size of those ordinarily used, or
test bottles made for 35 cc. of milk. In a similar

26

DAIRY CHEMISTRY

way the milk for six days may thus be measured
directly into the test bottles, and then tested.

24. Testing Skim Milk. — In testing skim milk the
special test bottle devised by Farrington, with the

small neck and the side tube for
the addition of the acid, should
be used (see Fig. 10). Each
division on the neck represents
.05 of a per cent. In using these
bottles, it must be remembered
that the small amount of fat ob-
tained in the neck is not neces-
sarily all of the fat in the skim
milk, because some of it may be
present in such a fine state of divi-
sion that it is not brought up into
the neck. Hence the results are
usually slightly lower than those

U obtained by chemical analysis.

- This, however, does not seriously
impair the test. When the test
shows only a trace of fat, the
FIG. 10.— Skim milk test butter maker can feel satisfied that
. he is doing good work.

25. Sampling Frozen Milk. — When a can of milk
freezes, the ice forms on the outside and there is
usually a central part that does not freeze. The un-
frozen part is richer in fat and solids than the frozen
part. The ice in the center of a can is richer in milk
solids than the ice of the outer portions. When

MILK TESTING 27

frozen or partially frozen, milk is not in a condition
to sample, but should be allowed to thaw and then be
thoroughly mixed.

26. Cleaning Glassware. — In order to secure the
best results, the test bottles and all of the glassware
used in testing milk should be kept clean. The test
bottles should be emptied before the fat becomes
cold and hard. By shaking the test bottle, the sedi-
ment of lime sulphate or gypsum is removed with
the acid mixture. The test bottles can be left to
drain on the drain board placed over the acid waste
jar. A drain board with holes large enough to receive
the neck of the test bottle will be found very useful
in handling a large number of test bottles. The test
bottles should be rinsed while still hot with warm
water and after draining this should be followed by
a second rinsing with hot water. A small brush will
be found useful in keeping the necks of the bottles
clean. Occasionally it will be necessary to give the
test bottles a bath in hot water containing a little
alkali, sal soda, Babbitt's potash, gold dust, or any
similar material dissolved in the water in small
amounts. A small copper tank large enough to re-
ceive a rack containing twelve to twenty-four test
bottles so they may be completely immersed will en-
able the creamery or factory man to keep his test
bottles in a good condition.

27. Water used in Milk Testing. — Hard waters
containing large amounts of lime or alkaline salts
are not suitable for use in milk testing. Rain water

28 DAIRY CHEMISTRY

or other soft water or condensed steam is preferable.
When water containing lime is used, bubbles of gas
are given off, causing foam when the hot water is
added to the test bottles containing the acid. The
presence of foam in the graduated stem of the test
bottle prevents accurate reading of the fat. Some
hard waters are suitable for use provided a few drops
of sulphuric acid are added before heating. If this
is done, of course the water cannot be heated or used
in ordinary metal boilers and receptacles. When a
large number of tests are to be made, a suitable out-
fit should be provided for the addition of hot water
to the test bottles ; a pail suspended three or four
feet above the tester with a rubber tube, a pinch
cock, and a glass tube drawn to a point, will be found
suitable for this purpose.

28. Care of Test Bottles and Apparatus. — The
rims on the necks of test bottles are easily nicked
and broken, and in handling bottles, care should be
exercised to prevent this being done. Some bottles
are provided with ground or roughened places for
labeling or marking with pencil, while others have
numbered copper or metal " collars." In making the
test, the numbers should be carefully checked, and
the proper entries made as to the sample and the fat
content. Many conveniences in the way of home-
made racks and devices for holding the apparatus
will suggest themselves. In milk testing, cleanliness
and accuracy in all the manipulations are the main
essentials for securing correct results.

CHAPTER III

MILK FATS

29. Composition of Fats. — The fat globules of
milk are a mechanical mixture of several separate
fats. All fats are composed of the elements carbon,
hydrogen, and oxygen ; but individual fats differ in
the way in which these elements are combined. In
all the fats, carbon, the principal element found in
coal, is present to the extent of over 75 per cent. The
fats as a class do not contain any nitrogen, differing
in this respect from casein and albumin, which con-
tain about 16 per cent of this element. Each fat has
its own melting point, form of crystals, specific
gravity, and other characteristics, and hence the
physical properties of butter are largely dependent
upon the proportion in which the principal fats are
present. Some of the milk fats are hard, and have a
high melting point, while others are liquid. The
character of butter, as hard or soft, is dependent
largely upon the proportion in which the various
fats, as stearin, palmitin, and olein, are present.

30. Kinds of Butter Fats. — The various fats which
are present in butter are butyrin, caproin, caprylin,
laurin, palmitin, myristin, stearin, and olein. Of

29

30 DAIRY CHEMISTRY

these fats, palmitin, stearin, and myristin make up
about 50 per cent of the composition of butter fat,
olein about 38 per cent, and butyrin, the character-
istic fat of butter, about 6 per cent ; the remaining
6 per cent being made up of laurin, capin, caproin, and
caprylin. For practical purposes, butter fats may be
divided into three classes : (1) hard fats, stearin,
palmitin, and myristin, (2) soft fat, olein, (3) charac-
teristic fat, butyrin.

31. Palmitin is a white, solid fat found in butter,
and also obtained from palm oil. Human fat is rich
in palmitin. When chemically pure, it is tasteless.
Palmitin forms crystals like snowflakes. This fat
has a high melting point, 145.4° F.

32. Stearin is a white, solid fat like palmitin, and
has a high melting point, 157° F. It also crystallizes
in the same way as palmitin. For a long time these
two fats, palmitin and stearin, were thought to be
one fat, to which was given the name margarine.
Among the fats that are particularly rich in stearin
are beef and mutton tallow. These melt at a much
higher point than butter, and are the materials used
in the adulteration of butter, forming a large part of
the product known as oleomargarine, which is a
mechanical mixture of the fats palmitin and stearin
(margarine) with olein. The larger the proportion
of either stearin or palmitin in any fat, the higher
its melting point. When one butter has a higher
melting point than another, it is due to the presence
of a larger amount of palmitin or stearin. These

MILK FATS 31

two fats, with myristin, make up about half of the
weight of the milk fats.

33. Olein is quite different from either palmitin
or stearin. This fat makes up about 40 per cent
of the weight of butter. Under ordinary conditions
olein is a liquid. It solidifies at a temperature
of 40° F. It is liquid at the ordinary temperature
of the cold deep setting of milk, that is, the set-
ting of milk in ice water. Olein has the property
of readily and copiously dissolving palmitin and
stearin. The larger the per cent of olein in a butter
or fat, the softer it is. Sperm oil, cod liver oil, and
many of the vegetable oils are rich in olein.

34. Butyrin melts at a temperature of 77° F.
Milk fats contain from 5 to 7 per cent of buty-
rin. Although it forms such a small proportion of
milk fat, it is the characteristic fat of butter. It is
the butyrin which gives to butter its individuality,
and its presence or absence is the distinguishing
point between butter and oleomargarine. Butyrin,
when decomposed, forms butyric acid. In rancid
and stale butter, the rank odor is due to butyric
acid. Butyrin is not as stable a fat as palmitin,
stearin, or olein.

35. Caproin and Caprylin comprise only a small
part of the fats of milk, and they do not require any
special consideration.

36. Glycerine and Fatty Acid Content of Fats. —
When fats are broken up into simpler products,
glycerine is one of the substances formed ; the other

32 DAIRY CHEMISTRY

, product is a fatty acid with an " ic " ending in place
of the " in " ending of the fat.

By the action of superheated steam. %5iv- -*U

<-/tfyt.O-OH Q44-u-rH

Palmitin yields palmitic acid and glycerine.

e^w^-— Olein yields oleic acid and glycerine.

Qi Stearin yields stearic acid and glycerine. Ni/d

Butyrin yields butyric acid and glycerine. ^ -^ (ftfli) v
Caproin yields caproic acid and glycerine. (3^?(df tj </d^
Caprylin yields caprylic acid and glycerine.g^/3 (njj\ &0

Glycerine is alkaline in its properties, and it is the
glycerol radical which unites with the fatty acids
to form neutral fats. Milk fats are frequently
defined as glyce rides of the fatty acids. They are
neutral bodies. All of the fats are lighter than
water. The mixed butter fats are insoluble in
water ; all are soluble in ether, chloroform, gasoline,
and similar solvents. Butyrin, caproin, and capry-
lin, when exposed to air and light for any length of
time, undergo decided changes in composition, which
finally result in the production of the corresponding
fatty acids which are present in rancid butter.

37. Food Value of Fats. — Fat is a concentrated
form of heat-producing food, because it contains
such a large amount of carbon. In very small seeds,
like flax, the fat is one of the main reserve forms of
food. One pojmd of fat when burned will produce
about two and one fourth times more heat than a
pound of starch. Butter, which contains about 85
per cent of fat, is valuable in a ration for the heat
and energy which it produces.

MILK FATS 33

38. Saponification of Fats. — When certain chemi-
cals, known as alkalies, such as potash and soda, are
heated with fat, they form soap ; the process is
called saponification. When saponification takes
place, part of the alkali unites with the fatty acid
of the fat and forms soap, while the glycerine radical
of the fat unites with the remainder of the alkali
and forms glycerine.

39. Iodine Absorption of Butter Fats. — In common
with other fats, butter fats have the property of
absorbing a definite amount of iodine. The iodine
number of butter, or the percentage of iodine ab-
sorbed by the fats, ranges from 28 to 35, while lard,
tallow, cotton-seed oil, and other commercial fats
and oils generally, have a greater capacity to absorb
iodine and hence have a higher iodine absorption
number. The iodine absorption number is fre-
quently used as an aid in detecting adulterated
samples of butter.

40. Volatile Fatty Acids of Butter. — When butter
fats are saponified and free fatty acids are liberated,
about 8 per cent of the volatile fatty acids are also
liberated and are volatilized in a current of steam.
In the analysis of butter, the amount of volatile
fatty acids obtained from 5 gm. usually requires
from 27 to 28 cc. of a tenth normal solution
of alkali for neutralization ; this is known as the
Reichert-Meissel value of butter, and is extensively
used in detecting adulterated butter. Spurious sam-
ples, as oleomargarine and butterine, have a low

34 DAIRY CHEMISTRY

value, less than 3, because of their not containing
any butyric acid.

41. Melting Point and Physical Properties of
Butter. — Normal butter has a melting point of
about 33° C. Butter with an abnormal melting
point is of poor quality because of an excess of
some fat, as olein, stearin, or palmitin. The specific
gravity of butter fat ranges from .867 to .87 when
taken at a temperature of 100° C. and compared with
water at 15° C., or when compared with water at
100° C., .910 to .915. The specific gravity of other
fats used for adulterating butter is slightly lower
than that of butter. A normal specific gravity is
a definite characteristic of genuine butter. The
specific gravity, melting point, and general physical
properties of butter fat are different from those of
any other fat.

CHAPTER IV

THE LACTOMETER AND ITS USE IN DETERMINING
MILK ADULTERATION

42. Quevenne's Lactometer. — The lactometer is a
piece of apparatus used for determining the specific
gravity of milk. It consists (see Fig. 11) of a bulb
weighted with mercury attached to a glass tube of
cylindrical form provided with a graduated stem,
which enables the operator to determine the depth
to which the instrument sinks in milk. Numbers
registered on the lactometer scale range from 15 to
40. These are called the lactometer degrees. If
the lactometer sinks to a depth of 31 on the scale, it
means that the milk has a specific gravity of 1.031.
In normal milk the lactometer shows a specific gravity
of 1.029 to 1.034. Between each of the numbered
divisions, as 25 to 30, there are five subdivisions,
which enable the operator to read to a .001 on the
specific gravity scale, or less if care is taken in the
observations.

There are other forms of lactometers in use, but
the Quevenne's is generally preferred because of its
greater accuracy. A lactometer should always be
provided with a thermometer in order that the nec-
essary corrections for temperature of the lactometer
readings may be made.

35

36

DAIRY CHEMISTRY

43. The Specific Gravity of Milk. — If a can holds
100 pounds of water, to fill it with milk would require
about 103.2 pounds. This is because
milk has a greater specific gravity than
water. By the specific gravity of a
material is meant the weight of a given
volume compared with the weight of an
equal volume of water under the same
conditions. Milk has a higher specific
f gravity than water because it contains
**• in solution a number of substances, as
sugar, ash, casein, and albumin, which
increase the weight of an equal volume
of milk, causing it to have a higher
specific gravity. The fat of milk, on
the other hand, which is lighter than
water, has a tendency to lower the
specific gravity. As stated in a previ-
ous chapter, the specific gravity of milk
fat is about .91. Since the amount of
sugar, ash, casein, and albumin in differ-
ent samples of milk is fairly constant,
it follows that the specific gravity of
the milk serum is quite constant. Since
the variations in the fat content of
FIG 11 — Que- milk range between 3 and 6 per cent, it
venne's lac- follows^that the variations in the gravity
of milk are due largely to the variations
in the fat content. Since the milk fats vary between
known limits, the specific gravity* of normal milk

THE LACTOMETER AND ITS USE 37

varies between definite limits. The lowest specific
gravity of normal milk is 1.029, while the highest
specific gravity is 1.034. *" The richer a sample of milk
in casein, milk sugar, and ash, the greater its buoyant
power and the higher specific gravity, which results
in the lactometer stem not sinking to so great a depth
as it would if less casein, sugar, and ash were present.
Hence we find skim milk having a greater specific
gravity than normal milk. On the other hand, the
addition of water to milk lowers the specific gravity
below 1.029 almost proportionally with the amount
of water added. Milks very rich in fat have a lower
specific gravity than milks which contain less fat.
This is due to the additional fat in the milk lowering
its specific gravity. A skilled operator can readily
determine whether the increase or decrease in the
specific gravity of milk is due to variation in the
water or the fat content of the milk.

44. Influence of Temperature. — Whenever a lac-
tometer reading is made, the temperature of the milk
should also be recorded, because a variation of 10°
in temperature affects the lactometer reading to the
extent of 1°. When milk is cold, it is contracted in
volume and the lactometer does not sink to as great
a depth as if the milk were warm. This results in
the lactometer recording a high specific gravity.
On the other hand, if the milk is too warm, it is ex-
panded, which has the effect of diluting the milk,
causing the lactometer to sink to a greater depth
and a lower specific gravity to be secured. In mak-

38 DAIRY CHEMISTRY

ing corrections for temperature, the following general
rule can be applied : When the temperature is
greater than 60° F., add .1 of a lactometer degree for
each degree of temperature, and when less than 60° F.,
subtract .1 for each lactometer degree. This gen-
eral rule will apply only for a variation of 15 degrees
either above or below the temperature of 60°. In
case more accurate corrections for variation in tem-
perature are desired, these will be found in the tables
in the appendix.

45. Other Lactometers. — The New York Board of
Health lactometer is graduated into 120°. The 100
mark represents milk with a specific gravity of
1.029; milk with a lower gravity shows a reading
of less than 100 on the lactometer scale, the per-
centage being somewhat proportional to the amount
of water added, a reading of 75 indicating that the
milk is 75 per cent pure, while a reading of more
than 100 indicates that the milk is above legal
standard as to fat content. These readings are, in
general, proportional to the character of the milk
and show whether extensive adulterations, as skim-
ming or watering, have been practiced. But, con-
sidered alone, the lactometer results obtained by
either the Quevenne or the New York Board of
Health lactometer are liable to error, not on account
of any imperfection in the principle or the instru-
ment, but because of the complexity of the composi-
tion of milk. When, for purposes of comparison, it
is desired to change the readings of the New York

THE LACTOMETER AND ITS USE

39

Board of Health lactometer, multiply the readings
by .29. In reading the lactometer, the point to
which it sinks in milk should be carefully noted.
Because of capillary attraction, a meniscus or curved
surface is formed on the surface of the liquid. The
point at which the reading should be made is on a
level with the liquid and not at the top of the miscus.
46. Influence of Skimming and Watering. — Since
milk has a specific gravity varying from 1.029 to 1.034,
it follows, as previously stated, that any addition of
water necessarily lowers the specific gravity, and any
removal of the fats necessarily raises the gravity.

FIG. 12.

•Position of lactometer in normal, skimmed, and watered
milk.

Watered milk often has a specific gravity of 1.035. 1
When skimming alone or watering has been prac-
ticed, it is easily detected by means of the lactom-
eter ; but when milk is both skimmed and watered,
the lactometer results fail to reveal the fact. The

40 DAIRY CHEMISTRY

water lowers the gravity, and the removal of the fat
raises it, so that milk which has been both skimmed
and watered may have the same gravity as normal
milk. This double fraud, however, is easily detected
when the Babcock test is used jointly with the lac-
tometer.

47. Calculation of Solids in Milk. — The proportion
in which the various solids are present in milk
directly influences both the lactometer readings and
the results obtained with the Babcock test. The
solids not fat (casein, albumin, sugar, and ash) in-
crease uniformly at the rate of .25 per cent for each
lactometer degree, and .02 of a per cent for each per
cent of fat. This general relationship between the
fat in milk and the solids not fat has been studied by
a number of investigators, notably Richmond, Fleisch-
mann, and Babcock, who have proposed various for-
mulas for the determination of the solids in milk.
Babcock's formula is as follows : —

Solids

When this formula is applied to a large number of
observations, it will be noted that uthe solids not
fat increase uniformly at the rate of .25 per cent for
each lactometer degree and .02 per cent for each
per cent of fat." This is also practically the basis
of Hehner and Richmond's formula. They found
that the calculated solids were uniformly about .14
of a per cent less than those obtained by chemical

THE LACTOMETER AND ITS USE 41

analysis. Hehner and Richmond have proposed the
following formula : —

Total solids in milk =~ + ^rxl.2 + . 14.
4 -P-

In order to apply the formula, divide the lactometer
number or lactometer degrees by 4. Multiply the per
cent of fat found by test by 1.2. To the sum of the
two results add .14.

EXAMPLE. A milk tests 4 per cent fat and has a spe-
cific gravity of 1.033. Hence the gravity number is 33.
4 x 1.2 = 4.8. 33 -r- 4 = 8.22. 4.8 + 8.22 + .14 = 13.16
per cent solids. This milk contains approximately
13.16 per cent solids.

48. Joint Use of Lactometer and Babcock Test. —
When used jointly, the quality of the milk and the
extent to which any adulteration may have been
practiced can be accurately determined. The fol-
lowing general rules will aid in determining the
quality of milk : A low fat and a high specific gravity !
indicate skimming or removal of fats. A low fat ^
and a low specific gravity indicate the addition of
water. A low fat and a normal specific gravity indi-
dicate that the milk has been both skimmed and
watered. While if there is a normal fat and a nor-
mal gravity, it is safe to conclude that the milk has
been neither skimmed nor watered.

In order to determine the extent to which adultera-
tion may have been practiced, the total solids of the
milk should be calculated by Hehner and Richmond's

42 DAIRY CHEMISTRY

formula. By deducting the percentage of fat, the
solids not fat are obtained ; or the solids not fat
may be determined directly by multiplying the fat
by .2 instead of by 1.2, as given in the formula. The
per cent of solids not fat in milk can also serve as the
basis for determining the extent of adulteration. In
average milk the solids not fat are about 9 per cent.
If the solids not fat are found by calculation to be
7.5, they are 1.5 less than found in normal milk, or
•J$, or 16| per cent, indicating that at least 16J per
cent of water has been added to the milk. The laws
in regard to the solids and fat content of milk vary
in different states. In this state (Minnesota) the
legal standard of milk is 13 for solids and 3^ for fat.
Hence the solids not fat are 9.5. On the basis of
the Minnesota standard, this milk would be f$, or
about 21 per cent, below the legal standard. While
the milk may not have been watered to the full ex-
tent of 21 per cent, it is 21 per cent below the legal
standard for milk.

CHAPTER V

MILK SUGAR AND LACTIC ACID

49. Physical Properties of Milk Sugar. — Milk sugar,
or lactose, is present in milk to the extent of about
5 per cent. When milk sours, the sugar is converted
during the process of fermentation into lactic acid,
and hence the milk sugar takes an important part
indirectly in all dairy operations. Milk sugar is
not as soluble in water as cane sugar. It has about
the same chemical composition as cane sugar, but
differs from it in all of its physical and chemical
properties. In butter and cheese making the main
function of milk sugar is the production of lactic
acid.

50. Fermentation of Milk Sugar. — Under favor-
able conditions milk sugar undergoes lactic acid fer-
mentation. This change is brought about by the
action of minute organisms known as the lactic acid
ferments. The conditions necessary for lactic acid
fermentation are : favorable temperature, 70° to
90° F., and the presence of the ferment body. The
lactic acid ferments gain access to the milk through
the dust particles of the air, from unclean dairy
utensils, and from other sources. The spores or
seeds of the lactic acid organisms readily develop in

43

44 DAIRY CHEMISTRY

milk, and as a result the milk sugar undergoes a
chemical change with the production of lactic acid.
The milk sugar is first split up into two other sugars,
dextrose and galactose, and these sugars are then
changed into lactic acid. One molecule of milk
sugar may produce either two or four molecules of
lactic acid, depending upon the nature of the fermen-
tation change which takes place. In addition to the
lactic acid ferments, there are a great many others
that may gain access to milk, develop there, and cause
various changes to take place. The action of these
ferments will be discussed in another chapter of this
work.

51. Production of Lactic Acid in the Milk. — Fresh
milk, even when first drawn from the cow, gives a
slightly acid reaction, due to the acid character of
the casein and to the composition of the mineral
matter or ash of the milk. In a few hours, if left
exposed to the air, milk readily increases its acid
content until a sour taste is developed. The milk
then contains from .3 to .4 of a per cent of lactic
acid. If the milk contains .4 of a per cent of acid,
it will curdle when boiled. The fermentation usu-
ally continues until .6 to .8 of a per cent of acid is
developed, and then the lactic acid ferments become
inactive. The products of the lactic acid ferments
are destructive to themselves. The amount of acid in
milk is directly proportional to its freshness, and for
many purposes milk with more than .1 of a per cent
of acid is not suitable. The rapidity with which the

MILK SUGAR AND LACTIC ACID 45

fermentation takes place is entirely dependent upon
the temperature and other conditions to which the milk
is subjected.

52. Determining the Acidity of Milk. — The methods
employed in chemical analysis for determining the

FIG. 13. — Apparatus for testing acidity of milk.

per cent of acid present in other materials are also
applicable to milk. The lactic acid that is developed
in the souring of milk belongs to a general class of
bodies — acids — that are capable of uniting with or
being neutralized by substances known as alkalies.
A definite amount of an acid will always require a

46 DAIRY CHEMISTRY

definite and known amount of an alkali for purposes
of combination or neutralization. In determining the
acidity of milk, it is necessary to determine simply
the amount of alkali required to combine with and
neutralize all of the acid present, changing it to the
class of compounds known as salts. For this pur-
pose a standard alkali solution is required. A tenth
normal solution of sodium hydrate is usually em-
ployed for the purpose. The following pieces of
apparatus are required : one 50 cc. burette gradu-
ated to .1 cc. ; a burette holder or support; glass
beakers or earthenware cups ; one 25 or 50 cc. pipette.
Phenolphthalein is used as an indicator. In an acid
solution phenolphthalein is colorless, while in a weak
alkaline solution it gives a pink color and in a
stronger alkaline solution a red color. This indicator
is prepared by dissolving 10 gins, of the powder in
250 cc. of 90 per cent alcohol.

The acidity is determined in the following way :
measure with the pipette 50 cc. of the milk into a
glass beaker or porcelain cup. In case distilled or
soft water is available, an equal amount is added to
the measured milk ; 5 to 7 drops of the indicator
are added, and then the standard alkaii from a
burette a little at a time, until the color of the milk
upon stirring is changed to a faint pink. Before
adding the alkali the height of the liquid in the
burette should be recorded, and at the close of the
operation it should be read again in order to deter-
mine the number of cubic centimeters required to

MILK SUGAR AND LACTIC ACID 47

neutralize the acid in the milk. The amount of
alkali used 'will vary directly with the amount of
acid in the milk, milks of high acidity requiring a
large amount of alkali. The alkali is prepared by
dissolving 4 gm. of pure sodium hydrate or 5.6
gm. of pure potassium hydrate in a liter of distilled
water. This standard alkali should be prepared only
by a chemist. The alkali must be kept in glass-
stoppered bottles protected from the air, and when
used it should not be diluted.

53. Calculating the Acidity of Milk. — Each cubic
centimeter of alkali neutralizes .009 gm. of lactic
acid. In case 50 cc. of milk are used and 20 cc. of
alkali required to produce the pink color, the per
cent of lactic acid in the milk will be found as
follows : —

20 x 100 = .36 per cent.

In case a different quantity than 50 cc. of milk is
used, then substitute the number of cubic centimeters
of the sample tested for the 50 in the formula. The
test can be satisfactorily made with either a 25 or a
20 cc. sample, and if desired a 17.6 cc. pipette can be
used. In case a 20 cc. pipette is used for measur-
ing the milk, then the number of cubic centimeters
of alkali can be multiplied by .045 and the per cent
of acid obtained directly. In making the test, the
operator should cease adding the alkali as soon as a
permanent pink color is obtained. When the alkali

48 DAIRY CHEMISTRY

is first added and the milk is stirred, the color is not
permanent, but after a sufficient amount of alkali is
added, a point is reached when two or three drops
more will produce a permanent color. In making
comparative tests, the operator should always aim to
secure the same degree of color in all the samples
tested. Strong alkali water is not suitable for wash-
ing the milk dishes or for diluting the milk in mak-
ing this test.

54. Alkaline Tablets. — Because of the difficulty in
preparing and securing the tenth normal solution,
Farrington and others have proposed the use of
alkaline tablets. These tablets are so prepared as to
contain a definite quantity of alkali mixed with the
requisite indicator or coloring matter. When used,
the tablets are to be dissolved in pure rain or distilled
water. To prepare the ordinary tablet solution
five are placed in a 100 cc. glass-stoppered cylinder
filled with 97 cc. of water, and when dissolved this
gives an alkali solution of the requisite strength.
In making the test, 17.6 cc. of milk or cream is
measured into a porcelain cup, and the alkali solution
added from the cylinder until the pink color becomes
permanent. The amount of the tablet solution used
is found by reading the amount of solution remain-
ing in the cylinder and subtracting it from the origi-
nal quantity. The number of cubic centimeters of
tablet solution used, divided by 100, gives directly
the percentage of acid in the sample. If 17.6 cc. of
cream requires 40 cc. of tablet solution to produce

MILK SUGAR AND LACTIC ACID 49

the pink color, then the sample of cream contains .4
per cent lactic acid.

55. Acidity of Cream. — Cream that is suitably
ripened for churning should contain about .5 of a
per cent of lactic acid. If the cream contains more
than .6 per cent of acid, it is liable to cause coagula-
tion of the casein and formation of clots in the cream,
and when churned, mottled butter is produced. The
acid test will be found valuable in butter making
as a means of producing a uniform product, which
is accomplished by having the cream each day of the
same degree of ripeness, and churning under uniform
conditions. Any of the methods described for deter-
mining the acidity of cream will be found helpful
in producing a uniform butter product.

CHAPTER VI

CREAM

56. Composition of Cream. — Cream is character-
ized by containing a higher percentage of fat than
milk. Average cream contains from 18 to 25 per
cent of fat ; some samples may contain as low as
8 per cent and others as high as 50 per cent. From
75 to 85 per cent of the solid matter of cream is fat.
The percentage of ash, sugar, casein, and albumin is
slightly less than in milk. The composition of
average cream is about as follows : —

PER CENT

Water 66.41

Solids 33.59

Fat 25.72

Casein and albumin 3.70

Milk sugar 3.54

Ash 0.63

Cream is spoken of as thick, medium, or thin, accord-
ing to its fat content ; thin cream contains from 8
to 15 per cent of fat, and thick cream above 35 per
cent. One hundred pounds of milk will produce
from 15 to 22 pounds of cream, depending upon the
way in which the cream is obtained, and also upon
the composition of the milk. In many states and

50

CEEAM 51

countries the percentage of fat which the cream
should contain is designated by law. In Min-
nesota legal cream should contain 20 per cent
of fat.

In the creaming of milk, the larger globules are
more completely separated, and consequently the
cream contains a higher percentage of large fat
globules than milk, the smaller fat globules being
present in greatest proportion in the skim milk.
There is also a slight mechanical separation of the
milk proteids during the creaming process, resulting
in the casein and albumin being present in a different
proportion in cream than in milk. When inilk is
creamed by gravity process, chemical changes take
place, resulting in the cream containing more acid
than the milk, and the proteids having a different
composition.

57. Testing Cream. — Cream containing from 8 to
15 per cent of fat can be tested by the Babcock test
in the same general way as milk. It will be neces-
sary, however, to divide the 17.6 cc. of cream into
two test bottles and to rinse the pipette with a small
amount of warm water to completely remove all of
the fat, so that each test bottle will contain about
18 cc. of liquid. The amount of fat obtained
in the two bottles is added together, to give the
approximate amount of fat in the cream tested.
For the testing of cream special test bottles have
been devised known as the Bartlett and the Winton
(see Figs. 14 and 15). The Bartlett cream test bottle

52

DAIRY CHEMISTRY

is similar to the Babcock test bottle, except that it is
provided with a bulb in the stem to accommodate
the additional fat from the cream. In using this
bottle, care should be exercised that the right

amount of water is added

^?^\

so as to leave a sufficient
amount of fat both above
and below the bulb for the
purpose of reading. The
Winton test bottle is pro-
vided with a larger gradu-
ated neck than the ordinary
test bottle.

In the testing of cream
greater care is necessary
than in the testing of milk.
When cream is measured
with the pipette, an error
is introduced into the work
because cream has a lower
specific gravity than milk.
IT. 6 cc. of cream testing
25 per cent fat weighs
only about 17.2 gm.
Since the test bottles are

made for 18 gm. of milk, the results are neces-
sarily low when applied to cream. Farrington and
Woll, in " Testing Milk and Its Products," give the
weight of cream delivered by a 17.6 cc. pipette as
follows : —

FIG. 14. — Win-
ton cream test
bottle.

FIG. 15.— Bart-
lett cream
test bottle.

CREAM

53

PEK CENT OF FAT IN
CREAM

SPECIFY GRAVITY
(1T.5° C.)

WEIGHT OF CREAM
DKLIVERED, GMS.

10

1.023

17.9

15

1.012

17.7

20

1.008

17.3

25

1.002

17.2

30

0.996

17.0

35

0.980

16.4

40

0.966

16.3

45

0.950

16.2

50

0.947

15.8

In the testing of cream the most satisfactory
results are secured by weighing. This is done by
first weighing the cream test bottle on a balance
provided with a suitable beam for counterpoising,
then adding with a pipette 10 cc. of cream and
weighing the test bottle containing the cream to
determine the weight of the cream delivered. A
little warm water is then added to the test bottle in
order to wash down the cream, and the test is com-
pleted in the usual way. Since the test bottle is
made for 18 gm. of milk, it will be necessary to
multiply the reading found in the test by 1.8. In
case more or less than 10 gm. are taken, the factor
used in multiplying is obtained by dividing the 18
gm. by the weight of the cream used. If a sample
of cream weighing 9.5 gm. gives a reading of 16.2,
the percentage of fat is : —

18

9.5

- = 30.69.

54 DAIRY CHEMISTRY

Prior to the introduction of the Babcock test,
other methods were employed for testing the value
of cream for butter-making purposes. The oil test
churn was one of the methods most extensively used.
In operating the test the number of cubic inches of
the cream sample was determined by measuring the
cream in a cream pail. The cream was thoroughly
mixed by stirring and a measured quantity placed in
a tube which was corked. The tube with others
was then placed in a specially devised churn and the

cream churned into
butter, which was
separated from the
curd by melting and
special manipula-
tion. The amount
of butter obtained
in the tube was
measured by a rule,

and the butter yield of the cream was thus deter-
mined. This method of testing cream, however, has
been entirely superseded by the Babcock test, the
cream now being measured directly into the test
bottles.

In the testing of cream, it is advisable, unless the
operator has developed a high degree of skill, to
make duplicate tests and then take an average.

58. Methods of Creaming. — There are three
methods employed in the creaming of milk, — the
gravity process, cold deep setting, and the cream

CEEAM 55

separator. In the gravity process, the milk is usu-
ally placed in shallow pans and allowed to remain in
a room at a temperature of about 60° for 24 or 36
hours, until the cream is separated by gravity.
When this process of creaming is followed the losses
of fat are usually greater than by any other method.
The losses are especially heavy when the cows are
well advanced in their period of lactation. While it is
possible to do reasonably effectual creaming by the
gravity process, the losses of fat are frequently ex-
cessive, amounting to from 25 to 30 per cent, and
more, of the total fat in the milk, the skim milk
often containing from .6 to 1 per cent of fat.

In the cold deep setting process the milk is set in
deep pails, which are immersed in water of a temper-
ature of 40° to 44° F. At the end of 12 hours
the process of creaming is completed and the skim
milk will usually contain from .2 to .4 of a per cent
fat. For the creaming of milk by the cold deep set-
ting process, it is necessary that the water in which
the milk is immersed be kept at a low temperature.
The creaming commences immediately when the milk
is placed in the water. The milk in the bottom of the
can first becomes poorer in fat, then the middle layer
is affected, and finally the upper layer. The tem-
perature of the water at the time the milk is set is
of greater importance than the temperature of the
milk. A difference of 10° in the temperature of the
milk will not affect the efficiency of the creaming,
but a difference of 5° in the temperature of the

56

DAIRY CHEMISTRY

water will seriously affect the thoroughness of the
process. It is not possible by prolonging the process
to make up in efficiency of creaming for the loss
sustained by the want of a low temperature at the
beginning. There is quite a noticeable difference
in the way in which two milks may respond to
creaming by the cold deep setting process. The
rapidity with which the process takes place when
the conditions are favorable and the effect of less
favorable conditions may be observed from the fol-
lowing table : —

GOOD CONDITIONS
TANK WATER 40°

POOR CONDITIONS
TANK WATER 60°

Per cent

Per cent

Fat in milk

5.00

4.45

Top below 4 inches,

30 minutes

4.60

4.40

Middle,

30 minutes

4.45

4.40

Bottom,

30 minutes

3.40

4.40

Top,

Ihour

4.00

4.30

Middle,

1 hour

3.85

4.30

Bottom,

Ihour

1.30

2.92

Top,

2 hours

3.30

3.90

Middle,

2 hours

2.10

3.90

Bottom,

2 hours

0.75

2.40

Top,

5J hours

1.40

3.00

Middle,

5j hours

1.00

2.90

Bottom,

5£ hours

0.35

2.18

Top,

10 hours

0.40

2.52

Middle,

10 hours

0.30

2.40

Bottom,

10 hours

0.15

1.40

Average fat in

skim milk

0.25

1.40

CREAM 57

When milk is creamed by the separator, the losses
of fat may be reduced to less than .1 of one per cent,
and they are occasionally less than .05 of one per cent.
The principle involved in the creaming of milk by
means of the cream separator is explained in Section
21. There are a great many different kinds of sepa-
rators in use. In determining the efficiency of a
separator, the amount of fat left in the skim milk is the
main factor to consider. In the manufacture of butter,
the losses of fat in the skim milk exceed the losses
in all other ways. This is because the amount of skim
milk is large compared with the amount of butter-
milk, and a loss of .1 of a per cent 'of fat in the
skim milk amounts to a much greater total loss than
.2 of a per cent of fat in the buttermilk. For thor-
ough creaming at least 98 per cent of the total fat in
the milk should be recovered in the cream. In the
creaming of milk by the separator, the dirt, slime,
and foreign matter which milk may contain are
largely removed in the separator slime ; this results
in the production of a better quality of cream for
butter making than that secured by the cold deep
setting process. Cream obtained by the separator
has practically the same composition as that obtained
by other processes. But cream obtained by the grav-
ity and cold deep setting processes is usually in
a more advanced stage of ripeness than separator
cream.

When milk is creamed by the separator, the com-
position of the cream can be regulated by the flow

58 DAIRY CHEMISTRY

of the milk and the adjustment of the cream outlet.
The condition of the milk as to temperature at the
time of separating influences the efficiency of the
creaming. If the milk is too cold, too large an
amount of fat is left in the skim milk. The tem-
perature of the milk at separation should range from
75° to 90° F., depending largely upon the individual-
ity of the milk. It will be necessary to separate
some milks at a higher temperature than others on
account of the fat globules containing a larger pro-
portion of stearin, palmitin, and hard fats. The
temperature should be the lowest that will show the
least loss of fat in the skim milk, so as to avoid any
unnecessary heating of the milk. For data in regard
to trials of different separators and the amount of
fat left in the skim milk, the reader is referred to
the bulletins of the various agricultural experiment
stations, particularly those of the Vermont, New
York, and Wisconsin Stations.

59. Adulteration of Cream. — Cream is adulterated
by the addition of milk, coloring matter, preserva-
tives, and materials to give the cream a higher vis-
cosity. The preservatives used are formalin, boric
acid, and salicylic acid. The coloring matters are
similar to those used for the coloring of butter, just
a sufficient amount being used to give the cream a
yellow tinge suggesting a high fat content. In
order to impart viscosity, the material known as vis-
cogin, consisting of a solution of lime in cane sugar,
is sometimes used. This causes the cream to appear

CEEAM 59

to have a higher fat content by increasing its viscos-
ity. Cream of low fat content is the most frequent
form of fraud practiced.

60. The Ripening of Cream. — Before churning,
cream is usually allowed to undergo the process of
ripening so as to secure more complete churning of
the cream and produce a better quality of butter.
The cream is placed in vats and warmed to a tem-
perature of 60° to 70° F., so as to allow the develop-
ment of the lactic acid ferments. The ripening of
the cream is frequently hastened by the addition of
a small amount of sour milk especially prepared and
known as a" starter." In the ripening of the cream,
it should be the aim to allow the lactic acid ferments
to develop and to prevent as far as possible other
kinds of fermentation from taking place by having
the milk as clean and pure as possible before cream-
ing, so other ferment bodies cannot gain access to
either the milk or the cream, and by the use of a
pure culture or starter. When the cream has
reached the proper degree of acidity, determined by
the lactic acid test (see Sec. 52), it is in condition to
churn. In the handling of cream any change of
temperature should be gradual, as sudden heating
or cooling may seriously affect the quality of the
butter.

61. The Use of Pure Cultures. — In order to secure
the best results, particular care should be given to the
preparation and use of the culture. In the ripening
of cream, the use of a pure culture is equally as im-

60 DAIRY CHEMISTRY

portant as the use of good yeast in bread making.
The milk from a fresh and perfectly healthy cow
should be used in preparing the starter, rather than
the mixed milk of an entire herd. In the prepara-
tion and use of the culture, scrupulous cleanliness
should be practiced. A number of commercial cul-
tures for the ripening of cream have been placed on
the market, as Conn's bacillus No. 41 and Hanson's
lactic ferment. In the use of these, or of home-
made cultures, good results cannot be secured unless
the cream is cared for and manipulated in the
proper way. The best quality of butter cannot be
made from cream that has been contaminated in any
way or contains abnormal ferment bodies.

62. Influence of Delay on the Creaming of Milk. —
When milk is creamed by the centrifugal method,
there is no loss of efficiency in creaming if the milk
is not separated at once, provided the proper tem-
perature is secured when the milk is separated.
When milk is creamed by the cold deep setting pro-
cess, unnecessary delay should be avoided, but undue
haste in placing the milk in the tank water is not
necessary. However, the milk should not be left in
the barn. Experiments at the Maine and Cornell
Experiment Stations have shown that with the
mixed milk of an entire herd there is no appreciable
loss of fat when the placing of the milk in the tank
has been delayed for half or three quarters of an
hour. At the Wisconsin Station experiments showed
that with three lots of cows there was no loss in

CREAM 61

creaming following a delayed setting, but with two
lots a material loss of creaming power resulted.

63. Creaming of Mixed Milks. — In case milk
creams with difficulty on account of the cows being
far advanced in the period of lactation, the creaming
is frequently improved by mixing such milk with
.that of fresh cows. Beneficial effects are usually
obtained by creaming mixed milks. The Babcock
milk test, however, is the only safe guide to follow
in such cases.

64. Cream Raising by Dilution. — When either hot
or cold water is added to milk, the creaming is accel-
erated and a larger volume of cream is obtained.
When the cream is tested, however, it will be found
to contain a low per cent of fat. The addition of
either hot or cold water to milk produces a thin
cream. The total losses of fat from cream obtained
by the dilution process are greater than when the
water is omitted. Experiments have shown that it
is not economical to cream milk by the addition of
either large or small amounts of hot or cold water.
When hot water is used, the cream is often overripe
before it is skimmed, and a smaller amount and a
poorer quality of butter are obtained. Any inter-
ference with the normal process of creaming usually
results in the production of a large volume of poor
cream.

CHAPTER VII

THE CHEMISTRY OF BUTTER MAKING

65. Churning. — When cream is agitated, the fat
globules coalesce, forming granules of butter. Vari-
ous theories have been advanced to explain the
changes which take place during the process of
churning. It is believed, however, that the change
is largely physical in character and that the agitation
of churning is necessary in order to overcome the
resistance offered by the serum of the milk. During
the process of churning, the globules lose their
spherical form and become irregular masses of fat.
These irregular masses more readily coalesce than
spherical bodies. Various forms of churns have
been devised to carry out different theories as to
churning. Some churns have been provided with
paddles and special devices for agitating the cream
and for rupturing the membrane in which the milk
fat globules were supposed to be inclosed. With
change of views in regard to theories of churning,
most of these devices have been discarded, and our
present churns are much simpler in construction and
do not have special devices for agitating the cream,
this being secured largely by the concussion during
the churning process.

The conditions influencing churning are (1) ripe-

THE CHEMISTRY OF BUTTER MAKING 63

ness of cream, (2) temperature of the cream, and
(3) individuality of the cream as affected by period
of lactation, season of tfre year, nature of the fat,
and breed characteristics.

Ripe cream, containing .5 of a per cent of acid,
usually churns more completely than unripe cream.
It is believed that this is due to the acid coagulating
the casein of the cream serum, thereby reducing the
surface tension of the fat globules. The ripeness of
the cream is one of the most important factors in
churning. If creams of different degrees of ripeness
are combined and churned, there is an unevenness in
the butter product due to the mixed cream not churn-
ing evenly, a part producing butter granules be-
fore the rest of the cream has completed the process
of churning. If overripe, a poor quality of butter
is produced, due to the presence of excessive amounts
of fermentation products. It was formerly believed
that an excessive amount of lactic acid caused a loss
of butter fat in churning. It has been found, how-
ever, that lactic acid has no solvent action upon
butter fat. It should be the object to secure the
same degree of acidity for each churning, so as to pro-
duce as even a product as possible. If cream is not
sufficiently ripened, butter of poor keeping quality is
produced, the fermentation changes which take place
in the butter causing it to have undesirable flavors.
One of the objects of the thorough ripening of cream
is to prevent further and undesirable fermentation
processes from taking place later in the butter.

64 DAIRY CHEMISTRY

The temperature at which cream should be churned
varies from 50° to 60° F., depending upon the ripe-
ness of the cream and its general characteristics.
Sweet cream should be churned at a lower tempera-
ture (50° to 55°) than ripened cream (58° to 66°). It
is not possible to assign a definite temperature for
churning so as to secure the best results with all
kinds of cream. The most suitable temperature for
the conditions under which the butter is produced
must be determined by trial. A preliminary churn-
ing can be made at a temperature of 60°, the charac-
ter of the butter noted, and if it is too hard in texture
and fails to churn in a reasonable time, the next
churning can be made at a slightly higher tempera-
ture, 62°. If, however, the butter is soft in texture
and churns in too short a time, the temperature has
been too high. Thick cream should be churned at a
lower temperature than thin cream. The right
temperature for churning also depends largely upon
the character of the fat globules. If the hard fats,
stearin and palmitin, predominate, as is frequently
the case when the cows have been long in milk and
have received an excess of coarse, dry fodders with a
scant amount of grain, the cream will have to be
churned at a high temperature. During churning
there is a rise in temperature of two or three degrees,
due to the agitation of the cream, and when the
churn is first started there is a slight production of
gas which should be allowed to escape.

The completeness and ease with which cream is

THE CHEMISTRY OF BUTTER MAKING 65

churned, or its churnability, is influenced by a num-
ber of factors, as season of the year, food consumed,
period of lactation, and individuality of the animals
producing the milk. When cows have not been salted
regularly, the milk is not normal in composition,
and difficulties in churning frequently arise. The
character of the food consumed influences the com-
position of the butter fats, which in turn affects the
churnability of the cream. The effect of the food
upon the character and composition of the milk will
be discussed in another chapter of this work. When
cows are advanced in their period of lactation, the
globules are smaller in size, the milk is more viscous
in character, and has a different composition from
milk in the first stages oT~TacTation. This affects
the completeness and rapidity with which cream
yields to the churning process. In churning abnor-
mal creams, the conditions must be carefully studied
and the cause of any difficulty determined ; then the
temperature of churning, degree of ripeness, or
other conditions may be changed so as to meet the
requirements of the cream in question. Occasion-
ally abnormal conditions of the cream affecting
churning are due to some form of fermentation
resulting in the production of gas or rendering the
milk proteids more viscous in character, which in
turn affects the churnability of the cream.

The process of churning should be stopped when
the butter globules are granular and about the size
of wheat kernels. If the cream has been properly

66 DAIRY CHEMISTRY

ripened, exhaustive churning has been secured when
the butter is in this condition. Excessive churning
may result in spoiling the grain of the butter and
prevent thorough washing to remove the buttermilk.
The nature and extent of the washing of butter
should be regulated largely by the condition in
which the butter granules are found at the close
of churning. Ordinarily, butter is washed with
water at a temperature of from 45° to 55°, and the
working continued until the washings which drain
from the butter are clear. It is preferable to re-
move the buttermilk as early as possible and then
continue the churning in a not too cold wash water,
rather than to overchurn the cream at first. The
amount of salt necessary to add at the time of work-
ing will depend largely upon the market require-
ments ; usually three quarters to one ounce of salt
per pound of butter will be sufficient. Not all of
the salt added is retained in the butter ; a large
portion of it is removed during the process of work-
ing. From the amount of cream churned and its
richness in fat, the probable butter yield can be
determined ; so the amount of salt required can be
calculated with a good degree of accuracy.

66. Dairy Salt. — For dairy purposes salt of a
high degree of purity is necessary. Many such
salts are found on the market, ranging in purity
from 97 to 99 per cent, the principal impurities
being gypsum and small amounts of other salts.
Salt should be entirely soluble in water, any residue

T11E CHEMISTRY OF BUTTER MAKING 67

being due to impurities. The salt crystals should
be clear and of medium granulation. If the crystals
are too large in size, overworking of the butter may
be necessary in order to incorporate the salt. If the
butter is worked too dry and too much fine salt is
used, the salt will separate and form a crust on the
surface of the butter. A pure salt will not become
very moist when stored in a reasonably dry room,
neither will it form hard cakes which crush with
difficulty. Salts that are not pure may impart an
undesirable taste and flavor to the butter.

67. Buttermilk. — Buttermilk has about the same
general composition as skim milk. It is practically
the skim milk of cream and varies in fat content
with the exhaustiveness of churning. Buttermilk
may contain a high per cent of fat, but ordinarily
it contains .2 of a per cent or less. The composi-
tion of buttermilk is generally about as follows : —

Water 90.50

Fat 0.20

Casein and albumin 3.30

Sugar ........ 5.30

Ash 0.70

If not overdiluted with wash water, buttermilk has
practically the same feeding value as skim milk.

68. Losses of Fat in Butter Making. — When 100
pounds of milk are creamed, about 8Q_pounds of skim
milk and JO jpounds of cream are obtained. If the
milk tests 4 per cent fat, and the cream is care-
fully churned, it will make about 4.6 pounds of

_!22i255S^

68

DAIRY CHEMISTRY

butter. The following table shows how the vari-
ous constituents of 100 pounds of milk are dis-
tributed when the milk is creamed and made into
butter. With poor work, of course, a much smaller
amount of fat is recovered in the butter, and more is
lost in the skim milk and buttermilk.

DISTRIBUTION OF MILK SOLIDS IN BUTTER MAKING

PRODUCTS FROM 100 LB. OF MILK

100 Ib.
of Milk

20 Ib. of
Cream

Skim
Milk

Butter

Butter-
milk

Total solids

13.00
4.00
3.50
4.75
0.75

5.18
3.88
0.50
0.75
0.05

7.82
0.12
3.00
4.00
0.70

4.00
3.83

0.10
0.05

1.18
0.05
0.40
0.70
0.03

Fat . . .

Casein and albumin . .
Sugar and acid ....
Ash

The 4 pounds of solid matter recovered in the
butter, which contains 3.83 pounds of fat, together
with the salt and water present, make about 4.6
pounds of marketable butter.

From 96 to J)^ per cent of the total fat of the milk
is recovered in the butter. About three times more
jatjs lost in the skim milk than in the buttermilk.
Nearly 90 per cent of the casein and albumin and 85
per cent of the milk sugar finds its way into the skim
milk. The buttermilk is composed of the constituents
present in the cream, minus what has been removed
in the butter. About 7 per cent of the ash of the

THE CHEMISTRY OF BUTTER MAKING 69
milk goes into the cream. The buttermilk contains

O

aboutjLQ per cent of the original casein and albumin
and about 15 per cent of the milk sugar.

69. Composition of Butter. — Average butter con-
tains about 10^ per cent of water. Some samples
may contain as low as 8 and others as high as 20
per cent. An excess of water in butter should be
avoided, as it unfavorably influences the keeping
qualities and affects the grain and other desirable
characteristics. An excess of water is due either
to poor methods of butter making or to intentional
incorporation of water to increase weight. If a
butter contains too small an amount of water, as 8
per cent, it fails to have the best physical qualities.
When butter is overchurned and large lumps are
formed, greater amounts of water and buttermilk
are retained in the butter. The water content of
butter is materially affected by the temperature of
churning, washing, and working. Whenever the
churning is done at a high temperature, warm wash
waters are used and the butter is worked but little,
an abnormal amount of water will be present ; while
butter that is churned at a low temperature and
washed with not too cold water will have the mini-
mum water content. If, however, the churning
is continued in not too cold wash water, an addi-
tional but not excessive amount of water can be
incorporated in the butter. Rich creams also have
a tendency to produce butter with the maximum
water content.

70 DAIRY CHEMISTRY

The casein content of butter ranges from one half
to three per cent; average butter usually contains
about one per cent. An excess of casein and albu-
min is usually found in poor butters, causing them to
retain a large amount of water and to readily undergo
fermentation changes. The ash and salt content
ranges from one to three and a half per cent,
average butter containing about two and a quarter
per cent. The amount of fat in butter ranges from
80 to 90 per cent, average butter containing about
85 per cent. The fat varies with the water content,
those butters which contain the most water contain
the least fat, and butters with the highest fat content
contain the least water. There is only a general re-
lationship between the quality of the butter and its
percentage content of water, fat, casein, and ash.
Two butters may have the same percentage of these
ingredients and be widely different in taste, general
physical properties, and commercial value.

70. Butter Colors. — Normal butter has a charac-
teristic yellow color, due to the presence in milk of
a distinctive nitrogenous coloring material called by
Blyth lacto-chrome. The amount of this coloring
matter is influenced by the food consumed and by
the individuality of the animal. Milks or butters
that do not contain this natural color are con-
sidered abnormal, and in order to impart the de-
sired color to the butter, a very small amount of
butter color is used. Most of the butter colors are
made from harmless materials. Occasionally, how-

THE CHEMISTRY OF BUTTER MAKING 71

ever, objectionable coloring substances are used, par-
ticularly those made from the coal-tar dyes. Some of
the butter colors are made from the seed of the Bixa
orellana. The use of harmless butter colors has not
been regarded by courts as adulteration of butter.

71. Overruns. — One pound of butter fat will make
about one and one sixth pounds of butter. During
the process of butter making, the slight loss of fat
in the skim milk and buttermilk is more than com-
pensated for by the added water, casein, and salt
in the butter. The additional butter made from
a pound of butter fat is called the overrun ; that
is, the extent to which the churn overruns the
test. The amount of overrun depends upon the
completeness of skimming, thoroughness of churn-
ing, and the way in which the butter is handled.
In some cases, the overrun amounts to .1 of a
pound per pound of butter fat, and in some cases
to nearly .2 of a pound. The method in most
common use for calculating the butter yield from
the fat content of milk is to increase the weight
of the butter fat by^on^jixjLh.- This factor is the
one most used, and was adopted by the Association
of Agricultural Colleges and Experiment Stations
as the factor for converting butter fat into butter.
A butter maker can readily determine the amount of
overrun by dividing the total number of pounds
of butter produced for a given time by the number
of pounds of fat in the milk delivered to the cream-
ery during that period. In case the overrun amounts

72 DAIRY CHEMISTRY

to only .1, the butter maker can conclude that errors
in the manipulation of the test or excessive losses in
skimming and butter making have occurred. While,
on the other hand, excessive gains in overrun are also
due to errors in manipulation.

72. Dividends. — Since the value of milk for butter-
making purposes is directly proportional to its fat
content, it follows that the amount of fat in the
milk, as determined by the Babcock test, can be
taken as the basis for making out dividends in
creameries. The usual method followed is, first, to
determine the total number of pounds of fat deliv-
ered by each patron ; this is done by multiplying
the total number of pounds of milk by the percentage
of fat as obtained from the composite test. The total
number of pounds of fat delivered to the creamery
by all of the patrons is then determined. The ex-
penses of manufacture, including the sinking fund,
are deducted from the proceeds of the sales. These
expenses depend upon the amount of butter manu-
factured, the amount of money reserved for the
sinking fund, and all other necessary expenses
incurred in the manufacture and sale of the butter.
The cost of manufacture usually varies from 2| to
4 cents per pound for butter. The cost of manu-
facture is deducted from the gross receipts and
then the price per pound of the butter fat is
determined. From the price per pound of the
butter fat (not butter) the dividend of each patron
is calculated.

Tllti CHEMISTRY OF BUTTER MAKING

73

EXAMPLE. Five patrons deliver to the creamery dif-
ferent amounts of milk which, test as follows : —

PATRON

POUNDS MILK

FAT FOUND BY TEST

1

1512

4.0

2

1700

3.6

3

1200

4.8

4

2100

3.4

5

1400

4.5

From this milk 365 pounds of butter are made; the
butter is sold for 21 cents, and 3 cents is deducted for
cost of manufacture and sinking fund. The dividends
are made out in the following way : —

LB. FAT

1512 x. 040= 60.48

1700 x. 036= 61.20

1200 x. 048= 57.60

2100 x. 034= 71.40

1400 x. 045= 63.00

Total

60.48 x. 2094 = $12.66
61.20 x. 2094= 12.82
57.60 x. 2094= 12.06
71.40 x. 2094= 14.95
63.00 x. 2094= 13.19

313,68

365 Ib.
$ 65.70 -r- 313.7

$65.68

$65.70.
$.2094.

73. Judging Butter. — Butter is judged on the basis
of flavor, texture, color, taste, and finish. If butter
is unsound or abnormal in any way, it is apparent
in the general physical properties. In order to
accurately judge butter, a person must cultivate the

74 DAIRY CHEMISTRY

senses of taste and smell so as to detect any objec-
tionable flavors or odors, and the extent to which a
butter may vary from a perfect sample. The scale
of points usually assigned in butter judging are as
follows : —

Flavor 45 Salt 10

Texture 25 Finish 5

Color 15

CHAPTER VIII

THE SANITARY CONDITION OF MILK

74. Unwholesome Milk. — By the sanitary condi-
tion of milk is meant its condition as to wholesome-
ness for either food purposes direct or for manufac-
ture into butter or cheese. Milks that are in the
best sanitary condition are also those most suitable
for butter and cheese making ; milk that is not suit-
able for food should not be used for dairy purposes.
Milks are most frequently unsound because of dis-
eased conditions of the animals or because of the
presence of dirt and filth of various descriptions due
to lack of care of the animals or of the dairy utensils.
The spread of contagious diseases is often due to
unsound milk, where disease germs find lodg-
ment, readily undergo propagation, and are then
disseminated.

75. Factors influencing the Sanitary Condition of
Milk. — The factors which influence the sanitary
condition or wholesomeness of milk are : —

1. Condition of the animals as to health.

2. Care of the animals.

3. Care of the milk and dairy utensils.

4. Food and water which the animals receive.

75

76 DAIET CHEMISTRY

Unsanitary condition of milk may be due to one
or more of these or to other factors, the most fre-
quent causes of contamination being lack of care of
the animals, the milk, and the dairy utensils.

Condition of the Animals as to Health. — A diseased
animal, as one suffering from advanced stages of
tuberculosis or from other disease, does not give
sound or wholesome milk. The variations in the
composition of the milk when cows are suffering
with disease are often slight, scarcely sufficient to
change the percentage composition of the fat, casein,
and albumin. A careful examination of the milk,
however, will usually show the presence of abnormal
bodies, products, of the disease germ many of which
are toxic in character. Milk should be fairly con-
stant in composition from day to day. When the
fat content is found to vary between wide limits, it
is frequently due to a diseased condition of the ani-
mal. Normal health is followed by fairly constant
composition of milk ; limited variations are to be
expected, but not wide ones. Sound health of the
animals is the first requisite in securing a milk sup-
ply of high sanitary condition. In some forms of
disease, the milk will show the presence of an abnor-
mal amount of urea, a white crystalline compound
formed from disintegration of the muscular tissues
of the body which have failed to be excreted and
carried off by the kidneys. In normal milk, this
compound is present to the extent of .001 per cent,
but in diseased milk it is frequently present in much

TEE SANITARY CONDITION OF MILK 77

larger amounts. Other compounds in diseased milk
are albuminous substances known as toxins, which are
products of various disease germs. These toxins are
poisonous in their action and are sometimes more
injurious than the disease germ itself. In the case
of milk from tuberculous animals, a small amount of
toxic material is present. Woll, in his translation of
Grotenfelt's work, " The Principles of Modern Dairy
Practice," says that in the earlier stages of tuber-
culosis the milk often has an abnormal yellowish
tinge.

The condition of the animals as to health is directly
dependent upon the care they receive and the sanitary
surroundings in barns, stables, and fields.

Care of the Animals. — When cows are kept in
crowded and unclean stables with but little fresh air,
sanitary milk cannot be expected. When under such
conditions for any length of time, the animals be-
come unhealthy, and even where they themselves
are not diseased, the milk as soon as drawn absorbs
the unclean atmosphere of the stable, which readily
renders it unsound. Lack of cleanliness in the sta-
bles and in the care of the animals is one of the most
frequent causes of unsound milk. The liquid and
solid excrements of the stable are teeming with
various ferment bodies, the air is rilled with dust
particles which contain ferments and fermentable
substances, and as soon as the milk is drawn it is
contaminated. In order to keep the stables in a
wholesome condition, a liberal amount of bedding

78 DAIRY CHEMISTRY

and absorbents should be used. In localities where
straw cannot be procured, sawdust, shavings, peat,
and other materials are employed. In addition, a
small amount of land plaster, or gypsum, will be
found valuable for the purpose of deodorizing the
stable. Gypsum is used at the rate of about half a
pound per day for each animal and is sprinkled in
the stalls and trenches. Lime in any other form
than the sulphate is not suitable for use in the stable.
Instead of absorbing the odors, quicklime and slaked
lime decompose the refuse materials, causing more
odors to be produced. Lime sulphate, or land plaster,
can usually be procured at about 15.00 per ton, and
is a valuable fertilizer; when added to the manure
it increases its value by preventing unnecessary fer-
mentation and loss of ammonia. Some deodorizing
materials and so-called disinfectants simply mask the
odors of the stable without disinfecting them. Not
only the stables, but often filthy yards and fields, are
direct causes of pollution of milk, and some of the
diseases to which milk is subject are due to contami-
nation from the soil. Where a large amount of
manure is banked against the stable, the air which
diffuses through the walls is contaminated. Un-
drained pasture lands are often a cause of trouble,
and occasionally the output of a creamery or cheese
factory is lessened in value because of such contami-
nation. Numerous cases of this character are on
record. Mr. Willard, a pioneer American cheese-
factory man, found that the production of a poor

THE SANITARY CONDITION OF MILK 79

quality of cheese was due to the milk obtained from
one herd. Whenever the milk from this herd was
omitted, good cheese was produced, and when the
milk was added, a poor quality was obtained. An
examination of the surroundings of the herd which
caused the trouble showed that the cows in passing
to and from the milking shed walked through a
marshy place covered with green pond scum and
other decomposing materials, particles of which ad-
hered to the udders, dried, and then fell into the
milk pails during milking, and fouled the milk. In
the care of animals, the importance of an abundance
of sunlight cannot be overestimated. Many disease
germs are destroyed by the action of strong sunlight.
Strong sunlight and pure air are the best disinfec-
tants, and in many stables there is a great lack of
both. Experiments made with growing animals show
that there is a decided difference in general health
and vigor between those reared in dark and light
stables. When the stable is not properly ventilated,
the carbon dioxid thrown off by the lungs as respira-
tion products unites with the ammonia formed by the
decay of the manure and produces ammonium car-
bonate, which is often deposited in the form of a
white coating upon the stones and beams of the
stable. This shows that the stable is poorly venti-
lated. Ammonium carbonate is an irritating alka-
line compound, and when present in excessive amounts
has a destructive action upon mucous membranes.
It is this material which collects upon carriage tops

80 DAIRY CHEMISTRY

and harnesses stored in poorly ventilated stables. As
is well known, it causes rotting of the leather, and
as could be reasonably assumed has a similar destruc-
tive action upon the mucous membranes. Animals
can stand a low temperature in pure air with less
discomfort than a higher temperature with impure
air. However, good ventilation does not necessarily
mean cold stables. Stables can be so constructed
that the income and outgo of air can be regulated,
rather than leaving the ventilation to faulty con-
struction. Ventilators made of drain tiles are more
sanitary than those made of wood. An old ventilat-
ing flue is often a source of pollution, due to the
moist air causing decay of the wood, which then
furnishes lodgment for disease germs. In order to
secure the best sanitary conditions in a stable, the
walls should be whitewashed at least once a year,
oftener if any contagious disease ha$ occurred.

Care of Milk and Dairy Utensils. — Milk is often
rendered unsanitary by unnecessary exposure to foul
air, and by handling in unclean pails, pans, and other
dairy utensils. In order to improve the keeping
qualities of milk, it should be cooled by exposure to
clean, pure air. When not cooled at once, fermenta-
tion changes often begin immediately, causing an in-
crease in the bacterial content of the milk. Too
frequently milk is strained in the stable, in which
case it becomes additionally fouled from the stable
air, filled with dust particles carrying innumerable
ferment bodies. The straining should be done out-

PLATE III

DIRT, HAIR, MANURE, ETC., IN CENTRIFUGAL SLIME
FROM MILK

THE SANITARY CONDITION OF MILK 81

side of the stable, preferably in the milk room.
Metal strainers composed of 50 mesh wire gauze
should be reenforced by clean cloth strainers for
the removal of the finer dirt particles. Pressed tin
pails which do not have seams are preferable for
dairy use.

In washing pails, lukewarm water should first be
used. If the water is too hot the albumin of the
milk is coagulated, forming a slime over the surface
of the utensil. Albumin is coagulated at a tem-
perature of about 160° F., and the first wash water
should be below this temperature. The lukewarm
water should be followed by a thorough washing
with hot water and soap, and this in turn by boiling
water, or preferably live steam, so that there will be
thorough sterilizing. The dairy utensils should
then be exposed in a clean place to bright sunlight
for several hours. After being thoroughly cleaned,
the utensils are sometimes contaminated by dust and
dirt particles carried by the wind. Too much care
cannot be bestowed upon the cleaning of the dairy
utensils, particularly the straining cloths. When
milk and cream are delivered at the factory where
live steam is available, the factory man will save
himself much trouble and annoyance by thoroughly
steaming the cans.

Milk rooms are often kept in an unclean condi-
tion, and foul odors are present due to milk
that has been spilled and has putrefied. Particles
of the dried milk containing ferment bodies are

82 DAIRY CHEMISTRY

given off from unclean floors, sinks, and shelves, and
float about in the air of the milk room, and when
fresh milk is exposed to this unclean air it is readily
seeded with the spores of any ferment bodies that
may be present in the dust particles. As an exam-
ple of this, Soxhlet noted that when milk was placed
on a particular shelf in the milk room it soon became
offensive and indicated butric acid fermentation.
An examination of the milk rack showed that at
some time a pan of milk had been spilled on the
shelf above the one causing the trouble. The lower
side of the shelf had not been thoroughly cleaned,
and whenever a fresh pan of milk was placed on the
lower shelf, spores or seeds fell into the milk and
fouled it.

There is great lack of care in the commercial
handling and shipping of milk. It is often unneces-
sarily left exposed at small stations, and the cans are
frequently reshipped without cleaning.

Food and Water which the Animal Receives. — The
nature of the food which the animal receives influ-
ences the sanitary condition of the milk to a some-
what less extent than the other factors enumerated.
Scant or abnormal amounts of food, or foods of
unusual composition, may unfavorably affect the
sanitary condition of the milk. The relation of
the food to the composition and quality of the milk
is discussed in another chapter of this work. Some
foods, as rape, turnips, and rye fodder at the head-
ing-out stage, impart an undesirable taste to milk.

THE SANITARY CONDITION OF MILK 83

This is due to the presence of essential oils and other
noxious compounds which pass directly into the milk
without chemical change. Milk of the highest sani-
tary value is obtained when the animals are properly
fed and the food reasonably conforms to a balanced
ration. Abnormal milk will result from feeding one
material to excess. Whenever cows are fed on a
mixed ration, consisting of two or three grains,
coarse fodders not overripe, and a small amount of
roots or silage, the quality of the milk from a sani-
tary point of view, provided all other conditions are
satisfactory, is all that could be desired.

The purity of the water supply is a very impor-
tant factor in the production of sanitary milk.
Impure drinking water is often the cause of un-
wholesome milk. Surface water collected in stag-
nant pools is unsuitable for animals to drink, for
although it may not produce a diseased condition
of the animals, it will either directly or indirectly
affect the quality of the milk. No animal can do
its best work in milk production if compelled to
drink impure water.

None but pure water should be used for cleansing
milk utensils. Numerous cases of typhoid fever are
recorded which were due to milk pails and cans
being washed in impure water and the typhus bacilli
thus gaining access to the milk.

76. Colostrum Milk. — The milk given by a cow
for the first three or four days after calving is quite
different in color, taste, and appearance from milk in

84: DAIRY CHEMISTRY

its normal condition. Such milk is called colostrum
milk, and has a different chemical composition from
ordinary milk. Colostrum milk is yellow in color
and has a sweetish taste and a characteristic oily
feeling. When boiled it coagulates on account of
the large amount of albumin which is present.
When hot water is poured into colostrum milk, it
curdles. Colostrum milk has a higher specific grav-
ity than normal milk, frequently reaching 1.064.

COMPOSITION OF COLOSTRUM MiLK1

PER CENT

Water ." 71.50

Solids 28.50

Solids contain : —

Fat 6.04

Casein 3.50

Albumin 12.67

Sugar 4.85

Ash 1.35

Undetermined 0.09

28.50

The term " colostrum " is used because of the presence
in such milk of circular bodies larger than the fat
globules, and known as colostrum cells. These co-
lostrum cells are similar in structure to the white
corpuscles in blood, from which it is supposed they
are derived. When examined under the microscope
while the milk is still warm, they show the amoeboid
movement of the white corpuscles.

1 Analysis made by the author.

PLATE IV

COLOSTRUM MiLK.

THE SANITARY CONDITION OF MILK 85

The colostrum cells begin to make their appear-
ance in the milk about a week before the calf is
born. Four or five days after calving the albumin
decreases and the milk gradually reaches its normal
condition. The colostrum acts as a purge upon the
young calf.

The creaming of colostrum milk is very imperfect
on account of the albumin present in such large
quantities. Colostrum milk should never be mixed
with other milk, because it will prevent creaming by
the gravity process and it clogs the separator. Co-
lostrum produces an inferior butter product, and in
cheese making causes trouble as it seriously inter-
feres with the curing and keeping qualities of the
cheese. Colostrum is not as objectionable, for sani-
tary reasons, as it is on account of affecting the
quality of the dairy products.

77. Tyrotoxicon is a poisonous chemical compound
found in stale milk and old cheese. It is produced
by bacteria, and is a ptomaine or poisonous nitrog-
enous body formed from decomposing albuminous
matter. When separated and examined with the
microscope, the tyrotoxicon appears in long, needle-
shaped crystals. When present in milk in small
quantities it produces diarrhoea and symptoms simi-
lar to those of cholera. It proves fatal when in-
jected into the veins of small animals. The
tyrotoxicon is sometimes developed in ice cream
made and handled in unclean ways. Inasmuch as
tyrotoxicon is produced by bacteria which feed upon

86 DAIRY CHEMISTRY

decomposing products, the utmost cleanliness should
be practiced in order to prevent its formation.

78. Fibrin in Milk. — Another nitrogenous com-
pound in milk is fibrin, which is also present in blood
and forms the " clot." The best proof of the presence
of fibrin in milk is the microscopic appearance of the
fat globules. As previously stated, the fat globules
always appear in little groups or colonies. It is sup-
posed that they are held together by bands or meshes
of fibrin which tend to prevent their coming to
the surface in the gravity creaming process. The
fibrin in milk is about the same in amount as the
urea. Fibrin is produced by the action of the fibrin
ferment. The chemical tests for its determination
in milk are unsatisfactory.

79. Gases in Milk. — The gases which are dis-
solved in the milk as it comes from the cow are :
nitrogen, oxygen, and a small amount of carbon
dioxide. Nitrogen and oxygen are found in the
milk in about the same proportion as in pure spring
water. As milk gets older, the oxygen decreases
and the carbon dioxide increases. Carbon dioxide
is the gas which is given off in respired air ; in stale
milk the oxygen has been used up to form carbon
dioxide. At the end of four or five days, 90 per
cent of the gas in milk is carbon dioxide. There is
always more gas in old than in fresh milk. When
the milk becomes saturated with gas, the gas is
given off ; and as it escapes from the surface of cream
or thick milk, it leaves small holes on the surface.

THE SANITARY CONDITION OF MILK 87

In addition to carbon dioxide, other gases of a dif-
ferent character may be present in milk and in
cheese making cause the curd to float : such as
hydrogen, which is given off in butyric acid fermen-
tation, and derivatives of the marsh-gas series of
gases. The gases in milk are a part of the products
formed by bacteria, and impure milk when made
into dairy products may cause trouble, not only
from the gases present, but also from subsequent
action of the bacteria.

80. The Keeping Qualities of Milk are directly
proportional to its germ content. Milks that have
been produced from healthy animals under the most
sanitary surroundings will contain but little dirt
and foreign matter carrying the microorganisms
which produce fermentation changes. Milks which
readily become sour or undergo fermentation are un-
suitable for food purposes, as they indicate previous
contamination in some way. For infant feeding the
wholesomeness or sanitary condition of milk is of
more importance than its fat content.

The microscope is frequently employed to deter-
mine the presence of dirt and foreign materials in
milk. A microscopic examination of the milk supply
of large cities shows that there is much to be desired
in the way of a better quality of milk for general
food purposes. The health of the consumer is jeop-
ardized by continued use of impure milk.

CHAPTER IX

THE CHEMISTRY OF CHEESE MAKING

81. Cheese Making and Butter Making Compared. —
In butter making the object is to secure as much as
possible of the milk fat in the form of butter. In
cheese making the casein as well as the fat must be
recovered. In butter making, fermentation processes
are employed for ripening the cream so as to secure
more exhaustive churning and to produce a better
quality of butter ; in cheese making, also, ferments
are employed for the production of acid to coagulate
the milk and to produce desirable flavors in the
cheese. In cheese making the ferments take a more
extended part than in butter making. The funda-
mental principles of cheese making are best under-
stood by first considering the general properties of
the milk proteids, particularly casein and albumin.

82. Proteids of Milk. — Milk contains r-, number
of proteid or nitrogenous compounds, as casein,
albumin, and derivative products, as albumoses and
peptoses. The nitrogenous compounds or proteids
differ in composition from the sugars and fats by
containing the element nitrogen in addition to the
carbon, hydrogen, and oxygen that are present in the
sugars and fats. The principal proteids of milk,

88

THE CHEMISTRY OF CHEESE MAKING 89

casein and albumin, are alike in general composition,
but differ materially in their physical properties.
The proteids are the compounds to which special
attention is given in human and animal nutrition, for
they impart characteristic value to foods and perform
functional processes which other nutrients are not
capable of doing. The reader is referred to works on
nutrition and the feeding of animals for the func-
tions of protein and its value as a nutrient. The
milk proteids, particularly casein, undergo numerous
changes during cheese making, and the process con-
cerns itself largely with the correct handling of these
compounds.

83. Casein. — In fresh milk the casein is in nearly
a soluble condition and is one of the solids of the
milk serum. With the formation of lactic acid, the
casein is changed from a semi-soluble to an insoluble
condition, and the lactic acid unites with the casein,
forming a new and insoluble compound. When
sufficient acid is developed, the precipitation of the
casein is complete. This is commonly spoken of as
curdling of the milk. The addition of dilute acids
to fresh milk will produce the same result, coagu-
lation, and in cheese making the object of the- fer-
ment action is to produce acid to change the casein
from a soluble to an insoluble condition. Dilute
acids do not coagulate or precipitate the milk
albumin.

84. Albumin. — When milk is allowed to sour and
curdle, it separates into a coagulated mass containing

90 DAIRY CHEMISTRY

the casein and fat, and whey which contains the albu-
min and milk sugar. If the clear whey is heated,
a yellowish white, flakelike substance is formed.
This is coagulated albumin. The albumin in milk
is coagulated at temperatures ranging from 157° to
161° F., but in the ordinary processes of cheese
making the temperatures reached are not suffi-
ciently high for the coagulation of the albumin,
and as a result it remains in the whey. If higher
temperatures were attempted, excessive losses of
fats would occur, the casein would be unfavor-
ably affected, and a poor quality of cheese would
be produced. The chief distinctions between ca-
sein and albumin are that albumin is coagulated
by heat, while casein is not, and casein is coagu-
lated by dilute acids, but the albumin is not pre-
cipitated.

85. Rennet. — In order to control the process of
fermentation and the coagulation of the milk, ren-
net is used. Rennet is an extract prepared from
the mucous membrane or lining of the fourth stomach
of the calf. It contains various ferment bodies, as
lactic and peptic ferments, which are the chief agents
in bringing about the changes necessary for the di-
gestion of milk. When rennet is added to ripened
milk, it produces the same effect as the addition of
dilute acid. A temperature of from 86° to 90° is
favorable for the action of the rennet ferments.
Prior to the addition of the rennet, the milk is
ripened with a starter, as in the ripening of cream.

THE CHEMISTRY OF CHEESE MAKING 91

It would be possible for cheese to be made by allow-
ing the milk to sour by natural processes, but under
such conditions a poor quality of cheese is produced,
for the process of fermentation cannot then be con-
trolled as when a starter is used for ripening the
milk and rennet for coagulating it. The chief
action of rennet in cheese making is to coagulate
the milk. In the ripening of the cheese, the rennet
appears to act secondary to the enzymes or soluble
ferments which are normally present in all milk.

86. The Rennet Test. — The rennet test is employed
in cheese making to determine when the milk is in
the right condition for adding the rennet. The
rennet test is made in the following way : 5 cc.
of rennet extract is diluted and mixed in a flask
with 45 cc. of water, 140 cc. of milk from the
vat is placed in a small cup, 5 cc. of the diluted
rennet solution added and thoroughly stirred, and
the time required for the complete coagulation of
the milk noted. In making the test, a knife is
used to determine when the coagulation is com-
pleted. If more than sixty seconds are required
for coagulation, the milk is not sufficiently ripened
for the addition of the rennet. For ordinary pur-
poses of Cheddar cheese making, the milk is suffi-
ciently ripened when it coagulates in from 45 to 55
seconds. If the milk coagulates in less than 40
seconds, it is overripe and requires different manipu-
lations for cheese-making purposes. The ripeness
of the milk, as shown by the rennet test, materially

92 DAIRY CHEMISTRY

influences the way in which the curd ripens in the
vat ; the rennet test also serves as a guide in subse-
quent manipulations.

87. Process of Cheddar Cheese Making. — In order
to more intelligently discuss the principal changes
that take place in cheese making, the details
of the process of Cheddar cheese making are
here briefly given : When the milk is received at
the factory, it is weighed and its general condition
as to purity noted. A small sample is retained
for testing with the Babcock test, as in creamery
work. Any foul or unsound milk is rejected as
unsuitable for cheese-making purposes. The mixed
milk is then warmed in the vat by means of steam
or otherwise until a temperature of 86° to 88° F. is
reached. The milk is heated gradually, and is
stirred to prevent the separation of the fat. The
starter is added, and when the proper degree of
ripeness is thought to have been reached the rennet
test is applied. If the milk is found to be in suit-
able condition, the rennet is then added at the rate
of 3 to 5 ounces per thousand pounds of milk. If
the milk contains a high percentage of fat, the
maximum amount of rennet is added at the higher
temperature. Ordinarily, however, the quantity of
rennet required and the temperature of the milk
when it is added vary with the season of the year,
the condition or individuality of the milk, and the
kind of cheese desired to produce. These are factors
that must be thoroughly understood by the cheese

THE CHEMISTRY OF CHEESE MAKING

93

maker, and the process of making adapted to exist-
ing conditions. After the rennet has been added and
thoroughly mixed, about twenty minutes are allowed
for complete coagulation of the milk. The time of
coagulation, however, will vary with the conditions
stated. When the curd is in a state where it
readily "breaks" and maintains its form, it is cut
with a curd knife into small cubes. After cutting,
the mass is gently agitated for about five minutes so
as to secure hardening of the curd particles and to
prevent mechanical
losses of fat. This
agitation also pre-
vents the curd from
matting and forming
large masses. The
temperature of the
vat is then raised
gradually at the rate
of two degrees for every five minutes until a tem-
perature of 102° F. is reached. The stirring is
continued at intervals to prevent the curd parti-
cles from matting. The heating of the curd brings
about a number of important changes and results in
contraction of the curd and more complete expulsion
of the whey. The changes brought about by the di-
gestive ferments present in the rennet and the milk
cause a softening of the curd. The ripeness of the
curd in the vat is determined by the hot-iron test.
This test is made in the following way : A piece of

FIG. 17. — Cheese vat.

94 DAIRY CHEMISTRY

cheese is pressed against a hot iron and immediately
withdrawn. The length of the threads adhering to
the iron are proportional to the degree of ripeness
of the curd. If the threads are an eighth of an
inch long, the curd is usually in a sufficiently advanced
stage for the removal of the whey. In case a quick-
curing cheese is desired, threads of greater length
should be shown. After the whey is removed, the
curd is allowed to pack and form large masses in the
bottom of the vat. These masses are cut into blocks
and placed in a pile so as to undergo further diges-
tion changes and develop acid. The curd is ground
when the threads shown by the hot-iron test are a
fourth of an inch or more. The grinding and subse-
quent salting of the curd retard the fermentation
process. Before grinding, the curd is kept at a
temperature of 90° to 95°; after grinding and salt-
ing, the temperature is reduced to about 80° F.
The matting of the curd particles is spoken of
as cheddaring. The ground and salted curd is
placed in molds and pressed in the cheese press.
A gradual and uniform pressure is maintained for
about 24 hours. The cheese is then ready for
the curing room. As in the case of butter making,
exact details for the manipulation of all kinds of
milk cannot be given. The general principles of
cheese making, however, should be thoroughly under-
stood, and then the processes may be varied to meet
different conditions arising in the manufacture of
different kinds of milk into cheese.

THE CHEMISTRY OF CHEESE MAKING 95

In the manufacture of cheese a record should be
kept of the time required for the different opera-
tions. The following points should be noted : —

Condition of milk.

Pounds of milk in vat.

Per cent of fat in milk.

Rennet test for ripeness.

Temperature of milk when set.

Amount of rennet used.

Rate of rennet per 1000 pounds of milk.

Time cut.

Minutes in curdling.

Time heat is applied.

Time required to raise to 102°.

Hot-iron test when dipped.

Time dipped.

Time from cutting to dipping.

Pounds of whey.

Per cent of fat in whey.

Time ground.

Hot-iron test when ground.

Time salted.

Amount of salt in curd.

Rate of salt per 1000 pounds of milk.

Time put to press.

Time pressed.

Weight of green cheese.

Weight of milk per pound of cheese.

Weight of milk per pound of cured cheese.

Remarks.

96 DAIRY CHEMISTRY

88. Process of Stirred Curd Cheese Making. — In
cheddar cheese making, the curd is allowed to mat
in the vat after the whey has been removed. In the
stirred curd process, the curd is not allowed to mat
or cheddar, it is kept stirred and manipulated in
such a way that the whey is drained off and the curd
particles are not allowed to unite. It is then salted,
pressed, and cured. By this process of cheese mak-
ing, a softer and milder-flavored cheese is produced.
This stirred curd process results in the incorporation
of a larger amount of water in the cheese, and the
ripening requires less time than for cheddar cheese.
These two processes, the cheddar and stirred curd,
are often so varied that a sharp dividing line
between the two cannot be made. For firm, long-
keeping export cheese the cheddar process is fol-
lowed, and for a soft, mild, quick-ripening cheese
the stirred curd process is employed.

89. Distribution of Milk Solids in Cheese Mak-
ing. — About one half of the milk solids are recov-
ered in the cheese. The fat is not as completely
recovered as in butter making. The whey usually
contains about 5 per cent of the total fat of the milk.
Of the 12J or 13 pounds of solid matte: in milk,
about S^pounds oFthe casein, 3J pounds of the fat,
and a portion of the ash are recovered in the green
cheese, while the milk sugar, albumin, and a portion
of the ash are lost in the whey. The solid matter
of cheese is mainly composed of fat and casein, and
any increase in the amount of fat in the milk is

THE CHEMISTRY OF CHEESE MAKING 97

followed by a corresponding increase in the fat con-
tent of the cheese. It was formerly believed that
milk of high fat content could not be economically
made into cheese and that only a certain percent-
age of the fat in milk could be recovered in cheese
making. Experiments have shown this idea to have
been incorrect.

90. Curing of Cheese. — New cheese is lacking in
flavor and digestibility. By allowing the cheese to
undergo the ripening or curing process, desirable
flavors are developed, and the casein is changed into
a more soluble and easily digested form. The cheese
was formerly placed in a curing room at a tempera-
ture of 65° to 70°. The curing room was kept at an
even temperature and the moisture content of the air
controlled as far as possible. During recent years,
however, there has been a tendency to cure cheese at
a lower temperature. At one time it was believed
that the rennet used in making cheese was the chief
agent in ripening or curing, and it was held that a
temperature of from 65° to 70° F. was the most suit-
able for the action of the rennet ferments. Investi-
gations by Babcock, Russell, Van Slyke, and others
have shown that the soluble ferments or enzymes,
which are normal products of all normal milk, can
be utilized as the chief factors in the ripening of
cheese, and that it is possible to ripen cheese inde-
pendent of the rennet ferments.

There are two classes of ferments — the organized
or insoluble ferments, and the soluble or chemical

98 DAIRY CHEMISTRY

ferments which are also called enzymes. The in-
soluble or organized ferments are mainly bacterial
bodies of definite form and structure propagated
irom a spore or seed. These organized ferments
develop in milk, meat, or any other suitable mate-
rial if conditions as to temperature and moisture are
favorable. The chemical ferments, or enzymes, are
products of living organisms capable of producing
ferment changes. Chemical ferments cannot be
seen with the microscope ; they are simply chemical
substances capable of inducing fermentation changes
without entering into the composition of the material
or giving up any of their own substance to the re-
acting bodies. Milk contains a tryptic-like ferment
or enzyme, which peptonizes the casein and other
proteids, forming proteoses and other soluble bodies.
In the curing of cheese, it has been found that the
ripening process can be carried on entirely by these
soluble ferments and at a lower temperature than
required by the organized ferments or bacteria. The
process of cheese curing at a low temperature is akin
to the curing of meat in cold storage.

Experiments on a commercial scale h?ve shown
that cheese can be cured at a temperature of less
than 50° F., resulting in the production of a better
quality of cheese, less shrinkage in weight, and less
loss of solid matter than by curing at a high tem-
perature. As a result, the cold curing of cheese has
gradually replaced the old process of high tempera-
ture curing. This is an advantage also in that less

THE CHEMISTRY OF CHEESE MAKING 99

loss occurs from cheese becoming unsound during
the curing process, and larger yields of cured cheese
are obtained from a given amount of milk. In the
cold curing of cheese the fermentation changes are
brought about entirely by the action of the soluble
ferments or enzymes of the milk. It is mainly a
digestion process, the changes taking place being
similar to those which occur in the first stages of
the digestion of the proteids in the stomach. The.
acids produced unite with the casein, forming more
soluble and digestible products. Van Slyke, in his
studies on cheese making, states that lactic acid
forms with casein two compounds, paracasein and
paracasein monolactate, which contains half as much
acid as paracasein.

Since both the insoluble or organized ferments and
the enzymes of milk take an important part in the
manufacture and curing of the product, it is highly
important that the milk be handled in the most
cleanly way possible, so as to reduce the germ con-
tent of the milk and prevent the formation of objec-
tionable flavors and products in the cured cheese.
Attention should be given to the sanitary condition
and surroundings of both the creamery and cheese
factory, as any unsanitary condition may affect the
quality of the product.

91. The Cheese Yield of Milk. — Since the per-
centage of casein to fat varies in different milks, it
follows that the cheese yield of milk is not directly
proportional to its fat content. Milks of the high-

100

DAIRY CHEMISTRY

est percentage of fat are not proportionally richer in
casein than milks of low fat content. When milk
tests 3^ per cent fat, 100 pounds will make about
9.35 pounds of cheese. One pound of milk fat will
make from 2.6 to 2.7 pounds of cured cheese. The
relation of the fat content of milk to its cheese yield,
as found by Babcock at a number of Wisconsin
factories, is as follows : —

No. OF
GROUPS

No. OF
REPORTS

KANGE OF FAT
PEE CENT

AVERAGE
PER CENT
OF FAT

AVERAGE YIELD
OF CHEESE PER
100 LB. MILK

LKS. OF CURED
CHEESE FOR
1 LB. FAT

1

24

Under 3.25

3.126

9.194

2.941

2

90

3.25-3.50

3.382

9.285

2.730

3

134

3.50-3.75

3.600

9.407

2.613

4

43

3.75-4.00

3.839

9.806

2.562

5

46

4.00-4.25

4.090

10.300

2.512

6

20

Over 4.25

4.447

10.707

2.407

groups 347

3.64

9.566

2.628

92. Testing Cheese by the Babcock Milk Test —
The percentage of fat in cheese can be determined
by the Babcock milk test in the following way :
With a sharp knife and in a cool room cut the
cheese into small pieces about the size of wheat
grains. Weigh into a test bottle 5 gm. of this
cheese sample, add about 15 cc. of hot water, and
shake well so as to thoroughly disintegrate the
cheese. When cool, the acid is added and the test
completed in the usual way. The reading of the
test bottle is multiplied by 3.6 to obtain the per cent

THE CHEMISTRY OF CHEESE MAKING 101

of fat in the cheese. This is because the test bottles
are made for 18 gm. of material and only 5 gm.
of cheese were used. A cheese niade -jEriHU; normal
milk should contain at least 3j> per , cent, fa
cheese of good quality shows from 32 -to 80 par*

93. Composition of Cheese. — The percentage of
fat in cheese is directly proportional to the richness
of the milk in fat and the amount of water left in
the cheese. In average cheese the per cent of fat
always exceeds the per cent of casein. This is be-
cause the milk from which the cheese is made con-
tains more fat than casein. Any cheese containing
more casein than fat has been made from skim milk.
The relation of the composition of cheese to the milk
from which it was made may be observed from the
following tables : —

COMPOSITION OF MILK

Water

Fat

Ash •

Casein and
Albumin

Milk
Sugar

1. Average milk . . .
2. 4 per cent milk . . .
3. Milk with cream added

87.52
86.79
85.87

3.50
4.00
6.00

0.80
0.64
0.77

3.22
3.71
3.12

4.80

4.50
4.13

4. Skim milk ....

87.80

2.75

0.80

3.95

4.50

COMPOSITION OF CHEESE

Water

Fat

Casein and
Albumin

1. Average milk . . ....

34.29
31.4
32.43

30.68

33.76
35.3
43.55
27.09

27.47
27.7
20.00
36.00

3. Milk with cream added . . .
4. Skim milk . ....

102 DAIRY CHEMISTRY

94. Testing Whey. — In the making of cheese both
the whey and the drippings from the cheese press

•should •. b& frequently tested for fat, so as to deter-
mine .whether therq has been any unnecessary loss.
].n- testing wheyr the special bottles made for testing
skim milk may be used. It is not necessary to use
17.6 cc. of jicid, because the casein has been removed
from the milk and the acid has less work to do.
Use about 8 cc. of acid.

95. Making out Dividends in Cheese Factories. —
The dividends in cheese factories can be made out
on the basis of the fat content, in the same general
way as described in section 72 for making out divi-
dends in creameries. The fat content of milk is a
more satisfactory and equitable basis for making out
dividends than the gross weight of the milk regard-
less of its composition. As previously stated (section
91), the cheese yield of milk is not always propor-
tional to its fat content. A milk testing 6 per cent
fat will not make twice as much cheese as one con-
taining 3 per cent fat. This is because the casein
does not increase proportionally with the fat. With
average milk, however, testing from 3.4 to 4 per
cent, the amount of cheese that can be made is prac-
tically proportional to the fat content. Inasmuch as
average milk usually tests between these amounts,
the fat test can be safely used as the basis for the
making out of dividends. In the case of exception-
ally rich milk, the quality of the cheese is materially
increased by the additional fat. Experiments have

THE CHEMISTRY OF CHEESE MAKING 103

shown that the value of the cheese is almost directly
proportional to its fat content. While the richer
milks make a smaller quantity of cheese, they make
cheese of higher commercial value, and hence there
is no injustice in paying for milks for cheese-making
purposes on the basis of the fat content. Poor milks
make a slightly larger amount but a poorer quality
of cheese than the richer milks. In making out
dividends, the total number of pounds of fat deliv-
ered by each patron is calculated from the weight
of the milk and its percentage of fat. The cost of
manufacture is deducted from the sales and the price
per pound of the milk fat sold in the form of cheese
determined, and then the amount due each patron is
calculated from the pounds of fat due him and its
value per pound.

96. Comparative Butter and Cheese Returns from
Milk. — In case it is desired to compare the approxi-
mate gross income from the same amount of milk
made either into butter or cheese, the methods for
calculating the butter yields given in section 71 are
used for determining the pounds of butter produced
from a given quantity of milk testing a certain per-
centage of fat. From the data given in section 91,
the estimated number of pounds of cheese produced
from the same quantity of milk can also be calcu-
lated. Comparisons can then be made as to the
gross sales from either the butter or cheese by tak-
ing the average market price of each. If such cal-
culations are made, it will be found that occasionally

104 DAIRY CHEMISTRY

larger proceeds can be obtained from cheese than
from butter, and then again the sales of butter will
be found to give the larger returns. In determining
the net income, the cost of production and the com-
parative value of the by-products must also be con-
sidered. Only general comparisons can be made as
to the probable income from the manufacture of
butter or cheese. As to the relative advantages of
butter or cheese production, much depends upon
location, markets, and general conditions. In the
general average, the production of one will be found
to be about as profitable as the other, and it is not
advisable to make frequent changes.

97. Different Kinds of Cheese. — By varying the
process of cheese making so as to cause the develop-
ment of specific forms of fermentation, different
kinds of cheese, as Neufchatel, Limburger, Swiss,
Edam, Gouda, and Roquefort, are made.

Neufchatel is a soft cheese, made from sweet milk
by adding the rennet at 82° F. After pressing, it is
worked and kneaded, and then put up in packages
and covered with tinfoil.

Limburger is a variety of cheese of characteristic
odor and flavor resulting from special ferment action
daring the curing process.

Stilton cheese is a soft, rich cheese of mild flavor
made from milk to which cream is usually added.
For the curing a long time is required and a fungus
with bluish green threads is developed.

Emmenthaler or Swiss cheese is made by special

THE CHEMISTRY OF CHEESE MAKING 105

manipulation and direct pressing in the curd presses.
The cheese is salted from the outside and certain
forms of fermentation are induced.

Edam is a hard, dry cheese, usually made from par-
tially skimmed milk and cured by a slow process of
fermentation.

Gouda is somewhat similar to Edam, but is softer
in texture.

Roquefort is a soft cheese which owes its char-
acteristics to special forms of ferments added dur-
ing the process of manufacture. When ripened a
characteristic mold will be found permeating the
cheese.

A number of special brands of cheese, put up in
glass and porcelain packages, are made from ordi-
nary cheese by grinding and adding fat, usually in
the form of butter. The sealed package is then
placed in cold storage so as to allow further fer-
mentation changes to take place.

Cottage Cheese. — Cottage cheese can be prepared
in the following way : The milk is first allowed to
sour and is then heated to a temperature of 100° F.,
or the coagulation of the milk can be completed, if
desired, by the addition of hot water, temperature of
175° F., at the rate of about one pint per gallon
of milk. After stirring for two or three minutes,
the coagulated mass is allowed to settle, the whey
is drawn off and the curd collected by straining
through cheese cloth. If the milk is in the right
condition as to acidity, a fine, soft-grained curd is

106 DAIRY CHEMISTRY

secured. Salt is added as desired, and the palata-
bility and food value are increased by the addition
of a small amount of cream when used. Cottage
cheese, when prepared in this way, has a high food
value.

CHAPTER X

MILK BY-PRODUCTS

98. Uses of By-products. — In the manufacture of
butter and cheese the by-products are skim milk,
buttermilk, and whey. These products are used
mainly for animal-feeding purposes and have a high
food value. Also from the by-products a number
of commercial articles are prepared. From whey,
milk sugar is manufactured, and from skim milk,
proteids are precipitated and prepared for commer-
cial uses.

99. Skim Milk — Composition, Value, and Use. — In
the manufacture of butter, about 80 per cent of skim
milk is obtained. The chief ingredients of skim
milk are casein, albumin, ash, and milk sugar. Be-
cause of the removal of the fats in skimming, the
solids not fat are usually present in the skim milk
in slightly larger proportions than in the whole
milk. Skim milk is characterized as a food of high
proteid content and it is valuable in combination
with other foods that are lacking in protein, par-
ticularly for the feeding of young and growing ani-
mals. Average skim milk contains about 9.75 per
cent of solid matter, of which 3.7 pounds are casein
and albumin, and 5.15 pounds are sugar, the remain-

107

108 DAIRY CHEMISTRY

ing .9 of a pound being principally ash and a small
amount of lactic acid and other compounds. The
principal value of skim milk is due to the relatively
large amount of casein and albumin it contains, over
36 per cent of the solid matter being in these forms.
When judiciously used, 5 pounds of skim milk
will produce as much gain in the feeding of young pigs
as one pound of farm grains. Professor Henry, of
the Wisconsin Experiment Station, states that when
corn is worth 28 cents per bushel, skim milk has a
feeding value of 15 cents per hundred pounds. In
order to secure the largest returns from the feeding
of skim milk, it should be fed with grains at the rate
of about 3 pounds of skim milk per 1 pound of grain.
If fed in larger amounts than this, smaller returns
are secured from the skim milk. When the nu-
trients in a pound of grain and 5 pounds of skim
milk are compared, it will be found that 5 pounds
of skim milk contain less total nutrients than the
pound of grain. The unique value of skim milk
lies in the fact that it is rich in protein and when
combined with other feed makes a ration more pala-
table and also increases the digestibility of the feeds
with which it is combined. When judiciously used,
skim milk is valuable not only for the nutrients it
contains, but also because of making the nutrients
of the grains and foods with which it is combined
more digestible and valuable to the body. S am
milk should be fed preferably when sweet. When
partially soured it may cause digestion disorders, due

MILK BY-PRODUCTS 109

to the presence of various ferment bodies. Skim
milk that is fully soured causes less digestion trouble
than when partially soured.

In the handling of skim milk the greatest care
should be exercised to prevent its contamination and
abnormal fermentation from taking place. The
tyrotoxicon organism may develop in skim milk and
cause cholera-like symptoms. The separator slime
should never be added to skim milk, as it contains a
large proportion of the dirt of the milk. Sheuerlen
and Bank state that most of the tubercle bacilli in
milk are separated in the slime of the centrifugal.

The keeping qualities and sanitary condition of
skim milk are improved by pasteurizing or sterilizing
it at the time the milk is separated. If the skim
milk is sterilized, it should be cooled and then pro-
tected from further inoculations. Unless it is prop-
erly cared for, the sterilizing may have but little
effect in improving its value. Too frequently the
factoryman and farmer give but scant attention to
the care of the skim milk. A little foul sour milk is.
left in the skim-milk tank from day to day, and this,
acting as a starter, immediately sours any fresh skim
milk which is added. Some diseases, as hog cholera,
have been spread through lack of care in handling
the skim milk at the creamery.

Separator skim milk differs but little in composi-
tio, from skim milk obtained by the gravity pro-
cess. From the separator skim milk the fat has
been quite thoroughly removed, while that obtained

110 DAIRY CHEMISTRY

by the gravity process contains a larger amount of
fat. Experiments have shown that the additional
fat in the gravity skim milk produces only small
additional gains over separator skim milk, the gains
being of less importance than the commercial value
of the butter fat. Skim milk should not be stored
or handled in rusty iron pails or cans, because the
small amount of acid present has a solvent action
upon metals, and if too much iron zinc or tin is dis-
solved in the milk, it has an injurious effect when fed
to animals. The handling of skim milk, buttermilk,
and whey in unclean ways is frequently the cause
of abnormal fermentation and the contamination of
dairy products.

100. Whey — Composition, Value, and Use. — Whey
differs in composition from skim milk by containing
less solid matter because of the removal of the casein
in cheese making. Average whey contains about 7 per
cent of solid matter, the larger portion of which is
milk sugar, 5.2 per cent. It also contains the albumin
of the milk, which, as previously stated, is not retained
in the cheese. There is less ash in whey than in skim
milk, due to a portion of the mineral matter combining
with the casein and being recovered in the cheese.

While whey contains less solid matter and proteids
than skim milk, it nevertheless has a material feed-
ing value. Experiments have shown that two
pounds of whey are about equal in feeding value to
one pound of skim milk. In general, ten pounds of
whey will produce as much gain in live weight of

MILK BY-PRODUCTS

111

growing animals as one pound of farm grains. In
the handling, care, and use of whey, the same general
statements made in regard to skim milk will apply.

101. Fertilizer Value of Milk By-products. — When
butter is sold from the farm, there is very little fer-
tility lost in the form of the principal plant food ele-
ments,— nitrogen, phosphorus, and potassium. The
butter fats are composed of the three elements, car-
bon, hydrogen, and oxygen. The nitrogen and the
ash or mineral elements are present in the skim milk
and buttermilk, and hence when butter is sold there
is practically no fertility lost. When cheese is sold,
part of the fertility is lost in the form of nitrogen,
which is present in the casein. In dairy farming,
the crop-producing power of the soil is not lessened,
provided the farm manure is judiciously cared for
and used.

102. Comparative Value of Cow's Milk and the
Milk of Other Domestic Animals. — In order to com-
pare the general feeding value of cow's milk and
skim milk with the milk of other domestic animals,
the following table is given : —

WATER

FAT

SUGAR

ASH

CASEIN AND
ALBUMIN

Mare's milk ....
Sow's milk .

88.49

84 00

2.86
4 60

4.75
315

0.55
1 05

3.35
7.25

Sheep's milk ....
Skim, milk

82.25
90 25

5.30
010

4.35
515

1.00

0.80

7.10
3.70

Cow's milk

8700

400

500

075

325

CHAPTER XI

THE ADULTERATION OF DAIRY PRODUCTS

103. Oleomargarine. — Oleomargarine and butterine
are butter substitutes made from animal fats, cotton-
seed oil, and other materials, and resemble butter in
composition and taste. They contain about the same
percentage of water, fat, salt, and nitrogenous matter
as butter, but differ in not containing butyrin and
other characteristic volatile fatty acids present in but-
ter and not in butter substitutes. In the manufac-
ture of oleomargarine, the beef fats are put through
filter presses to remove a portion of the hard fats,
which are used for the manufacture of candles and
soap. The softer fats, with cotton-seed oil, are
placed in churns together with sweet milk, and
churned, salted, and worked like butter. By varying
the proportion of hard and soft fats, different grades
of oleomargarine can be produced, and these are sold
under various trade names. These products are
readily detected upon chemical analysis, as they fail
to yield the requisite amount of volatile fatty acids
(see section 40).

104. Simple Methods for detecting Oleomargarine. —
The boiling or spoon test is made in the following
way: A small piece of the sample is melted in a

112

THE ADULTERATION OF DAIRY PRODUCTS 113

large spoon with gentle heat. The process is has-
tened by stirring. The heat is then increased, the
material is brought to the boiling point and
thoroughly stirred. Oleomargarine and renovated
butter boil with much sputtering and produce no
foam, or very little, while genuine butter in boiling
produces more foam and less noise. The Water-
house test is conducted in the following way: " Into
a small beaker pour 50 cc. of sweet milk. Heat
nearly to boiling and add from 5 to 10 gm. of butter
or oleomargarine. Stir with a glass rod until the
fat is melted. The beaker is then placed in cold
water and the milk stirred until the temperature
falls sufficiently for the fat to congeal. At this
point the fat, if oleomargarine, can easily be collected
into one lump by means of the rod, while if butter
it will granulate and cannot be collected."

105. Renovated Butter. — Low grade and rancid
butters are sometimes subjected to the process known
as renovation. The butter is melted and poured
into cold water, so as to recrystallize the fat and
remove those products which impart the undesirable
flavors and odors. The butter fats are then re-
worked and salted, and the product is ready for the
market. It is often sold as fresh butter. Renovated
butter has poor keeping qualities, and so preserva-
tives, as boric acid, are frequently added to prevent
the fats from becoming rancid. When melted and
recrystallized, the butter fats fail to form crystals
of the same character as the original butter, which

114 DAIRY CHEMISTRY

enables the renovated butter to be easily detected.
Some of the states have laws requiring that butter
treated in this way shall be stamped or labeled
"Renovated Butter."

106. Adulteration of Cheese. — Cheese is adulter-
ated (1) by removing a portion of the fat from the
milk and then manufacturing the skimmed or par-
tially skimmed milk into cheese ; (2) by completely
removing the milk fats and substituting other and
cheaper fats, thus producing so-called " filled cheese."
The foreign fats are incorporated with the skim
milk while in the vats and then the process of
cheese making is completed, with slight modifica-
tions, as outlined in the chapter on Cheese Making.
The addition of foreign fats to the cheese can be
readily detected by chemical analysis, as cotton-seed
oil and other fats have different chemical and physi-
cal properties from butter fats. For the determina-
tion of the per cent of fat in cheese by the Babcock
test, see section 92. Cheese with 28 per cent or
less of fat can be considered as made from partially
skimmed milk, and the lower the per cent of fat in
the cheese, the more extensively has the skimming
been practiced.

107. Adulteration of Milk. — The way in which
the lactometer and Babcock test may be used for
detecting skimming and watering is described in
Chapter IV. In addition to skimming and water-
ing, milk is sometimes adulterated by the addition
of preservatives. The materials employed for the

THE ADULTERATION OF DAIRY PRODUCTS 115

preservation of milk are principally borax, boric acid,
formalin, and salicylic acid. Medical authorities
object to the use of preservatives in dairy prod-
ucts and other foods because they interfere with the
normal process of digestion. Then, too, when milk
is preserved with chemicals, there is a tendency to
practice unclean methods in its handling, and less
care generally is taken of the milk. Abnormal
amounts of preservatives have been found added to
market milk to prevent its becoming sour. The
producer, the wholesale milk dealer, and the retailer
each adding a small amount make in the aggregate
an abnormal and objectionable quantity of preserva-
tives, which may have an unfavorable action upon
the human body. In the creamery and cheese fac-
tory, the addition of formalin and other preservatives
prevents the normal ripening of milk and results in
the production of butter and cheese of poor quality.
Not only from a sanitary but also from a financial
point of view, preservatives are objectionable and
should not be used in the dairy. Various trade
names have been applied to the different preserva-
tives, but they are almost invariably composed of
borax, boric acid, formalin, or salicylic acid.

In addition to the Babcock test, a number of other
methods have been proposed and are occasionally
used for the testing of milk and detecting any adul-
terations. Many of these methods give accurate re-
sults, but they require more skill on the part of the
operator, are more expensive, and require more time

116 DAIRY CHEMISTRY

than the Babcock test, and hence are used but little.
Some of the methods, as the Pioscope and the Lacto-
scope, do not give accurate results.

The Beimling method is quite similar to the Bab-
cock test, a centrifugal being used. The test bottles,
however, are- smaller, and two acids instead of one
are employed. Amyl alcohol is required, and this is
apt to be impure and cause too high results.

The Lactocrite method has been in use in Ger-
many and Denmark for some time. The separation
of the fat is made by means of ac^ic and sulphuric
acids, combined with centrifugal action. In its
workings the Lactocrite is quite like the Babcock
test. The centrifugal used is in form like the Alpha
separator. The method gives reliable results. It is
patented and the apparatus expensive.

With Gerber's butyrometer test, the fat is sepa-
rated by centrifugal action aided by sulphuric acid
and amyl alcohol. This method combines the more
important features of the Babcock and the Beimling
methods. It gives accurate results and is quite
extensively used in Europe.

Short's Method. — In this test an alkali solution is
first added to the milk, which changes the fat into
soap ; the soap is then converted into insoluble fatty
acids by adding sulphuric acid, and the fatty acids
are measured in a graduated tube. The test bottles
are similar to those used in the Babcock test.

In Cochrane's method the fat is separated by the
combined use of sulphuric and acetic acids and

THE ADULTERATION OF DAIRY PRODUCTS 117

ether. The fat is then raised into a graduated tube,
where it is measured. The Cochrane fat bottles are
made with two tubes, one for measuring the fat and
the other for adding the reagents.

In Failyer and Willard's method an acid first is
added to the milk, and then gasoline to collect the
fat. The gasoline is removed by a current of air,
and the fat is collected in the graduated neck of
the test bottle and measured.

The Lactoscope and Feser's Pioscope were quite
extensively used at one time. They are optical
methods and depend upon the opacity of the milk
serum. Both of these methods are totally unreli-
able, the results being very inaccurate.

Most of these short methods are not sufficiently
accurate for scientific work, or as final evidence in
court in case of adulteration.

108. Dairy Laws. — Some states and countries
have passed laws prohibiting the sale of adulterated
dairy products. Congress has also passed a national
law prohibiting the coloring of oleomargarine to
resemble butter. The injury which results from
the sale of oleomargarine and filled cheese is due
more to their being dishonest competitors than to
their unwholesomeness. They are frequently sold
for butter and cheese, and since they are made
to resemble them, it is often difficult for the inex-
perienced person to detect the adulterated article.
As to digestibility and food value, there is not a
great difference between butter and oleomargarine.

118 DAIRY CHEMISTRY

Experiments have shown that butter is slightly more
digestible than oleomargarine. As long as oleomar-
garine is sold under its own name, there is little
objection to its use ; but people naturally prefer
genuine butter and cheese to imitation articles, and
they should be protected in securing them. It is
when oleomargarine is sold as butter that the prin-
cipal injury is done to the butter industry. For
this reason, laws have been passed regulating the
sale of dairy products and prohibiting adulteration.

CHAPTER XII
MARKET MILK AND CREAM

109. Variable Character of Market Milk. —It is

estimated that one third of the milk produced in
this country is used for direct consumption by the
producer or is sold as market milk. The milk
supply of large cities is extremely variable in char-
acter, both in its richness in fat and its wholesome-
ness or sanitary condition. In those states where
dairy laws have been enacted and the laws are
reasonably well enforced, milk of good quality is
secured, but where no legal control is exercised
over the milk supply, it is often of very poor qual-
ity. To meet the requirements of the consumer,
milk should be produced from animals in sound
health, and the milk should be free from dirt, have
good keeping qualities, and contain a reasonable
amount of fat. In order to supply milk of the
best quality, different methods of handling have
been devised, the most satisfactory and cleanly
way being to supply the milk in sterilized sealed
bottles. When milk is conveyed to the consumer
in this form, no opportunity presents itself for
adulteration or for the milk to become contami-
nated by unclean methods of handling or through

119

120

DAIRY CHEMISTRY

exposure in unclean streets. Usually a larger price
is paid for milk prepared in this way. The sanitary
condition or wholesomeness of the milk (see Chap-
ter VIII)- is of more importance than its fat content.
110. Changes in Composition of Milk during Trans-
portation. — When milk is transported in cans and
removed with a long-handled dipper, it changes but
little in composition during transportation, the agita-
tion of the can and the dipping being sufficient to pre-
vent the separation of cream. This question has been
extensively investigated in both this country and
Europe. In England, one of the large dairy firms
supplying milk to the London market had during
the season a number of thousands of samples of
milk taken from the wagons at different points on
the route to prevent the watering of the milk by
the drivers, and it was found that there was but
little change in the solid matter of the milk. Dur-
ing one season over 11,000 samples were analyzed,
with the following results : —

MILK

CREAM

Solid Matter

Solid Matter

12.84

48.3

During d6liv6ry

12.88

At clos6 «

12.92

48.4

At the Cornell University Experiment Station simi-
lar results were obtained, also at the Canadian Experi-

MARKET MILK AND CREAM 121

ment Station at Guelph. The excuse sometimes
offered in court that milk has lost its cream while
being sold is not valid, as all the experimental evi-
dence shows that when milk is dipped from the can
with a long-handled dipper no separation of the fat
takes place. While milk changes in its per cent of
solid matter but little during transportation, it often
becomes sour and foul through unnecessary exposure
and unclean ways of handling.

111. Pasteurizing Milk and Cream. — In order to
prevent milk and cream from readily fermenting, it
is sometimes given the Pasteurizing treatment. This
consists of heating the milk or cream to a tempera-
ture of 159° or 160° F. for a few minutes and then
cooling and protecting it from further inoculations.
This temperature results in rendering inactive the
greater number of ferments in milk, particularly
those of an objectionable nature. The destruction
of the ferment bodies prevents rapid souring of the
milk, especially when the milk is protected from
further contamination. The Pasteurizing of milk
and cream is usually done by machinery, the milk
being agitated so as to secure as even an application
of temperature as possible. The longer the milk is
heated, the more thorough is the Pasteurizing pro-
cess. Not all of the germs or ferments of milk are
rendered inactive by heating to a temperature of
160°. To render inactive the tuberculous bacilli, a
temperature of 180° to 185° is required. When milk
is sterilized, it is heated to a higher degree than

122 DAIRY CHEMISTRY

when it is Pasteurized. At temperatures above 185°,
all of the bacteria are destroyed and the milk is ren-
dered sterile. When milk is sterilized, the albumin
is coagulated; when Pasteurized, the temperature is
not sufficiently high to coagulate it. The Pasteuriz-
ing of milk improves its sanitary condition and often
makes an unsound milk suitable for food purposes.
It is preferable, however, to have a wholesome and
sound milk that is not Pasteurized rather than an
unsound milk that has been given this treatment.
When a milk is Pasteurized, its germ content is
reduced; but the products of the germs, particu-
larly the toxins, are not removed.

The Pasteurizing of cream is often resorted to in
making butter. When the cream has been con-
taminated in any way, Pasteurizing gives good re-
sults. When the milk has been produced under
the most sanitary conditions, Pasteurizing is less
necessary. The preparation and sale of Pasteurized
milk and cream have become prominent features of
the milk industry in a number of cities. For home
use, milk can be Pasteurized in the following way :
glass cans are thoroughly cleansed and then placed
in the oven so as to become sterilized. When par-
tially cooled, they are filled with fresh milk and set
in water at a temperature of about 162°. After being
in the water for from 10 to 15 minutes, with the tem-
perature kept at 160°, the cans are covered, cooled,
and stored at a low temperature. Not all milks are
suitable for food even when Pasteurized. Digestion

MARKET MILK AND CREAM 123

experiments indicate that perfectly sound, normal
milk is more completely digested than either Pas-
teurized or sterilized milk; the difference in diges-
tibility, however, between sound, fresh milk and
Pasteurized milk is small, but in favor of the fresh
milk. Sterilized milk is less digestible than Pas-
teurized.

112. Condensed Milk. — Another method of pre-
serving milk is to remove a portion of the water by
means of condensing in a vacuum pan and then seal-
ing the condensed product while hot. Milk that is
properly condensed can be kept for a long time, and
in some localities it is the main source of milk supply.
Whenever a can of condensed or Pasteurized milk is
opened, the same care is necessary to protect it from
contamination as if it were fresh milk.

113. Milk as Human Food. — There is no food that
has a higher value than pure milk. Too frequently
its nutritive value is impaired by its being impure.
Contaminated milk, like any impure food, should not
be used. Milk should form a part of the dietary, as
it is easily digested, and assists in rendering other
foods more digestible. Experiments have shown
that at average prices milk is not a luxury, but an
economical food. Milk furnishes a large amount of
digestible nutrients, and, in the case of a number of
diseases, it is the only food that should be allowed.
Milks with either the maximum or minimum fat
content are not the best for food purposes, but milk
containing about 4 per cent of fat generally gives

124 DAIRY CHEMISTRY

the most satisfactory results where it forms a large
part of the diet. Milks very poor or very rich in
fat have either too narrow or too wide a nutritive
ratio (see section 133), while normal milk is a well-
balanced food containing proteids, carbohydrates,
and fats in the right proportions for supplying the
needs of the body.

CHAPTER XIII

INFLUENCE OF DIFFERENT FOODS UPON THE QUALITY
OF MILK AND DAIRY PRODUCTS

114. Food and Milk Secretion. — There is a close
relationship between milk secretion and the food
supply. It was formerly believed that the percent-
age amounts of the milk solids could be materially
influenced by the character of the food consumed.
In the numerous experiments that have been made,
a few cases showed the composition of the milk to have
been influenced, but it was not possible in most cases
to materially increase or decrease the percentage of fat
or other constituents of the milk. The total amount
of all of the compounds present, however, can be ma-
terially increased by judicious feeding, and thus,
while it is not possible for the farmer by liberal feed-
ing to increase the per cent of fat in his milk, he
practically accomplishes the same result by increas-
ing the amount of milk.

It was formerly believed that the fat in the food
was the main source of the fat in the milk. A good
cow, however, will produce during a year a much
larger amount of fat in the milk than she consumes
in the food, showing that the fats are in part pro-
duced from other nutrients.

125

126 DAIRY CHEMISTRY

115. Feeding Fat. — The investigations that have
been made show that it is not possible to increase
either the percentage or the total amount of fat in
the milk for any appreciable time by the feeding of
fats or oils. In experiments at Cornell University,
the Iowa Experiment Station, and other institutions
where fats have been fed to cows even at the rate of
two pounds or more per day of tallow, cotton-seed oil,
corn oil, or other fats, the fat content of the milk was
not permanently increased. The quality of the milk
fat and of all the dairy products is, however, appre-
ciably affected by the foods consumed; and while the
fats and other compounds do not pass directly from
the food into the milk unchanged, the character
of the fats and other nutrients materially influences
the quality of the fat globules and the dairy
products.

116. Production of Hard Butters. — When cotton-
seed meal is fed in liberal amounts and is not combined
with other grains, it produces a hard and tallow-
like butter having a melting point of 10° higher
than average butter. Chemical analysis shows that
there is a larger percentage of stearin and palmitin
in such butter. When cotton-seed meal is combined
with other food stuffs and is fed in small amounts,
it exerts but little influence on the butter product.
Cotton-seed meal is a valuable nitrogenous food
when properly combined and fed with other food
materials.

Corn, also, if fed alone and in large amounts, will

FOOD AND QUALITY OF MILK 127

produce an abnormally hard butter, particularly if com-
bined with overripe, coarse dry fodders. This tend-
ency of some food stuffs to produce an abnormal butter
is eliminated when foods are properly combined.

117. Production of Soft Butters. — While cotton- /?
seed meal produces a hard butter, linseed meal, the '
product obtained after removing the oil from

seed, produces a soft butter when fed alone and in
large amounts. Cotton-seed meal and linseed meal
have somewhat the same general composition ; both
are rich in protein and fat, but when fed they have 9*
directly opposite effects upon the character of the
butter.

118. Effects of Individual Foods. — There are a
number of individual food stuffs that have a notice-
able effect upon the quality of the milk and butter.
Gluten meal, a product obtained in the manufacture
of cornstarch, produces a softer butter than corn
meal ; oats, when fed alone and in large amounts,
produce a mediumly firm but rather crumbly butter;
when oats and corn are fed together, the quality of
the butter is much improved. Wheat by-products,
as shorts and bran, produce a mediumly firm butter
of good quality; wheat and barley coarsely ground
also produce normal butter.

There is but little difference in the milk-producing
power of the different farm grains when fed in mixed
rations. Of the coarse fodders, clover hay, corn
silage, and well-cured corn fodder produce the largest
flow and also milk of the best quality for butter and

128 DAIRY CHEMISTRY

cheese making purposes. These coarse fodders, when
prepared under the most favorable conditions, pro-
duce mediumly firm butter in contrast to the hard
and tallow-like butter produced from overripe hay
containing a large amount of fiber and but little pro-
tein. Silage has been found to be of much value in
a ration, as it produces a better quality of butter
than average coarse fodders. It has been objected
to by some because of the silage odor of the milk. It
has been found that this is due largely to lack of
proper ventilation in the stable, as the silage odor
gains access mainly at the time of milking rather than
being transmitted through the milk. When animals
are kept under the most sanitary conditions and
silage forms only a part of the ration, there is no
perceptible odor to the milk and it is of good
quality. As previously stated (section 75), some
food stuffs, as turnips, rape, and onions, affect the
flavor of the milk. This is due to the volatile and
essential oils passing directly from the food into the
milk. There are weeds that are also responsible for
bad-tasting milk, as the wild garlic, which produces a
foul taste.

119. Desirable Flavors in Milk Products. — The
desirable flavors in butter, cheese, and other dairy
products are due to the small amount of chemical
compounds formed by the workings of the bacterial
ferments and the enzymes. As a result of fermen-
tation action, definite chemical compounds, some of
which have pleasant and desirable properties and

FOOD AND QUALITY OF MILK 129

others undesirable ones, are produced. Butyric acid
fermentation is an example of the undesirable kind
and results in the production of butyric acid, which
gives stale butter its characteristic odor. By con-
trolling the processes of fermentation during the
manufacture of dairy products, the undesirable fer-
ments are prevented from gaining access to the milk,
and the desirable ferments are added and given every
opportunity to carry on the normal processes of fer-
mentation. Fresh, normal milk should have a pleas-
ant taste, and when obtained and handled in a cleanly
way, it will contain but few bacterial bodies.

120. Influence of Balanced Rations. — When the
animal body is supplied with the necessary nutrients
for the various functional purposes, the largest
amount and the best quality of milk is secured. It
is only when unusual food stuffs and those deficient
in the requisite nutritive materials are fed that milk
of abnormal character is produced. One of the
objects of combining several grains and coarse fod-
ders to form a balanced ration is to furnish the
nutrients to produce the largest amount and best
quality of milk. Much experimental work has been
done to ascertain the relationship between the vari-
ous food stuffs and milk secretion. It was believed
at one time that certain foods contained special com-
pounds which stimulated milk secretion. It has
been found, however, that there are no special foods
which exert an influence on milk secretion not shared
alike by the common farm grains and well-prepared

130 DAIRY CHEMISTRY

fodders. There are no stock foods that possess prop-
erties for increasing the secretion or flow of milk.
The best results are secured by supplying a variety
of food stuffs containing a liberal amount of nutri-
tive materials. Milk produced under the best sani-
tary conditions from healthy and well-fed animals
has an individuality, and such milk is specially valu-
able for food and for the manufacture of butter
and cheese.

121. Milk Secretion. — The materials of which milk
is composed are abstracted from the blood, and in
order to keep up a good flow of milk suitable food
should be supplied, which may be later elaborated
into milk. Some animals are so constituted that the
food supply is used for the production of fat and
increase in weight rather than for milk production.
Such animals are not profitable for dairy purposes.

There are a number of factors that influence milk
secretion, as regularity of milking and feeding,
manipulation of the udder, exhaustive milking, pro-
tection of the animals from sudden changes in tem-
perature and adverse climatic conditions, and good
sanitary surroundings. These factors all influence
the secretion of milk, because the process is largely
the result of the working of individual cells which
compose the ultimate follicles, and in case the cells
are injured or are not given the best conditions for
doing their work, milk secretion is decreased and the
quality of the product lowered.

CHAPTER XIV
THE RATIONAL FEEDING OF DAIRY STOCK

122. Uses of Food. — Food is used by the animal
body for three purposes : (1) for production of
heat and energy ; (2) for growth and to furnish
materials to renew the worn-out tissues of the body ;
and (3) for the production of animal products, as
milk, meat, and wool. When the animal body has
been supplied with food for heat, energy, and growth,
the excess is then available for the production of
meat and milk. The different nutrients or com-
pounds of which foods are composed serve different
functions in the body, and in the rational feeding of
farm animals it is the object to combine various food
stuffs so that the nutrients will be present in the
right amounts and proportions for the various func-
tions of the body.

123. Nutrients and their Functions. — The com-
pounds of which foods are composed are divided
into two main classes, the nitrogen-containing or
nitrogenous compounds, and those containing no
nitrogen or the non-nitrogenous compounds. The
nitrogenous compounds are spoken of collectively as
the crude protein of food stuffs ; the non-nitroge-
nous compounds are mainly starch, sugar, fat, and

131

132 DAIRY CHEMISTRY

cellulose. The two classes of compounds, nitroge-
nous and non-nitrogenous, serve different functional
purposes in the body. The nitrogenous compounds,
or proteids, are the more expensive and are present
in much smaller amounts than the non-nitrogenous
compounds. Starch, sugar, fiber or cellulose, and
allied bodies, are spoken of collectively as the car-
bohydrates, and in connection with feeding stuffs
only, the three general terms, " crude protein," " car-
bohydrates," and " crude fat " or " ether extract," are
employed. Food stuffs are composed of a great many
other compounds besides these general classes.

124. Dry Matter. — When a substance is dried at
a temperature of 212° F., all of the water is removed,
and what is left is called dry matter. All food stuffs
contain some water. Grains and mill products con-
tain from 10 to 15 per cent of water, dry hay from 12
to 18 per cent, and roots and tubers from 75 to 90
per cent. Some green crops and vegetables contain
as high as 95 per cent of water. The dry matter of
a food is simply a mechanical mixture of the differ-
ent compounds of which the material is composed,
as ash or mineral matter, crude protein, and non-
nitrogenous compounds, including carbohydrates and
crude fats.

125. Ash. — When the dry matter of a food is
burned at the lowest temperature necessary for
complete combustion, the ash or mineral matter is
obtained. In most agricultural plants the ash is less
than 10 per cent of the dry matter, and in the grain

THE RATIONAL FEEDING OF DAIRY STOCK 133

crops it ranges from 2 to 4 per cent. The ash is
composed of lime, potash, phosphates, and other
mineral substances. All of the coarse fodders, grains,
and mill products contain a sufficient amount of
mineral matter for purposes of nutrition, including
phosphates for bone formation and for the production
of milk.

126. The Organic Matter. — That portion of the
dry matter which is burned and converted into vola-
tile products is called the organic matter. It is
obtained by subtracting the per cent of ash from
100, which represents the total amount of- dry
substance.

127. Proteids. — These compounds, which are found
in variable amounts in all food stuffs, are similar in
general composition to the milk proteids described
in section 82. The proteids as a class are character-
ized by containing the element nitrogen in addition
to carbon, hydrogen, and oxygen, which are present
in all the other nutrients of food stuffs. It is the
proteids which serve the special purpose of supplying
the materials for repairing the body waste. Proteids
are the principal materials out of which the muscles
are formed, and they also enter largely into the
composition of all the tissues of the body. All the
vital fluids of the body, as the blood, contain large
amounts of this class of compounds. The proteids
of the body can be formed only from the proteids of
the food; hence the importance of the requisite
supply of this nutrient in the food. An excessive

134 DAIRY CHEMISTRY

amount, however, in a ration is unnecessary. After
the functions of the body are served, the surplus
protein is used for producing heat and energy, and
it quite frequently happens that a ration is unneces-
sarily expensive because of containing an excess of
protein, which is used for the production of heat
where cheaper nutrients, as the carbohydrates, would
serve the same purpose. Neither is a ration that
contains too scant an amount economical, as a full
milk flow cannot be maintained on a scant supply of
protein. The rational feeding of animals is largely
a regulation of the supply in the food of proteids and
carbohydrates for milk production and other pur-
poses. There are a great many different kinds of
proteids in food stuffs. Casein and albumin in milk
are proteids ; egg albumin is also a proteid. The
glutens of wheat and other grains are among the
most common proteids found in food stuffs.

128. Carbohydrates. — With the exception of fat,
all the non-nitrogenous compounds, as sugar, starch,
and cellulose, taken collectively, are called carbo-
hydrates. By far the largest part of the nutrients
in food stuffs are carbohydrates. Those carbo-
hydrates which are easily rendered soluble, as sugar
and starch, are called the nitrogen-free-extract com-
pounds. Carbohydrates are a complex group of
substances composed of three elements, — carbon,
hydrogen, and oxygen. The chief function of the
carbohydrates is to produce heat and energy, and,
when properly combined with the proteids, they may

THE RATIONAL FEEDING OF DAIRY STOCK 135

serve for the production of fat in the body. The
carbohydrates from different food stuffs vary widely
in character. In the potato, starch is the main carbo-
hydrate ; in beets, it is sugar ; in apples, pectose or
jellylike substances; and in hay and coarse fodders,
pentosans predominate, or bodies that can be con-
verted into sugarlike substances containing five
atoms of carbon in the molecule.

129. CrudeFiber. — The term "crude fiber "is applied
to the cellular tissues of which the framework of
plants is composed. A portion of the fiber is digest-
ible and capable of serving the same functions as the
soluble carbohydrates. Foods with excessive amounts
of fiber are objectionable, but on the other hand some
fiber is desirable in order to give the necessary bulk
to a ration.

130. Crude Fat. — All food stuffs contain some
fatty compounds. In farm grains from 2 to 5 per
cent of ether extract or crude fat is present ; in coarse
fodders from 1J to 2.25 per cent; while in some of
the specially prepared mill products, as oil meal, 10
per cent or more of fat may be present. The fat
in food stuffs is extracted with ether, and hence the
term "ether extract " is used. In addition to the fats,
ether extract contains small amounts of other sub-
stances, as chlorophyll and resin. Hence the ether
extract is not pure fat. From grains and mill prod-
ucts, however, the ether extract is nearly pure fat,
while in that from coarse fodders there is only from
50 to 75 per cent of pure fat. Fats are character-

136 DAIRY CHEMISTRY

ized by containing a larger amount of carbon than
either starch or sugar, and hence, when burned or
digested in the body, they produce a larger amount
of heat and energy. A pound of fat will produce
2.25 times as much heat as a pound of starch.

131. Digestible Nutrients. — Only a portion of the
compounds of which foods are composed is digested,
absorbed by the body, and used for some functional
purpose. In average food stuffs from 15 to 45 per
cent of the nutrients are indigestible and unavailable
to the body. That portion of a compound which
is digested and utilized is called a digestible
nutrient. Foods contain digestible protein, digest-
ible fats, and digestible carbohydrates. The total
nutrients are only in part digestible. The digestible
nutrients of a food stuff are determined by means of
digestion experiments, in which the income and outgo
of the nutrients of the food, including the amount
which fails to digest, are accurately determined. As
a result of numerous digestion experiments, the
digestion coefficients or the percentage of the nu-
trients that are digested are determined. The diges-
tion coefficients are used for the construction of
tables of digestible nutrients in foods. In using
these tables in rational feeding, it is only the digest-
ible nutrients that are to be considered, as the in-
digestible portion of the food furnishes no material
for functional purposes.

132. Caloric Value or Heat Units of a Ration. -
When food is digested, heat is produced and the

THE RATIONAL FEEDING OF DAIRY STOCK 137

amount of heat is directly proportional to the per-
centage of fat, carbohydrates, and proteids present.
A balanced ration produces about 32,000 calories, or
heat units. A calory is the unit of heat, or the
amount of heat required to raise 1 kg. of water 1°
on the centigrade scale, or one pound of water about
4° on the Fahrenheit scale. A pound of digestible
fat produces 4225 calories, and a pound of digest-
ible carbohydrates or protein produces 1860 calories.

133. Nutritive Ratio. — The term "nutritive ratio "
is used to express the ratio which exists between the
digestible protein and the digestible carbohydrates.
A nutritive ratio of 1 to 6.5 means that there is one
part of digestible protein to 6.5 parts of digestible,
non-nitrogenous compounds. A wide ration means
a large proportional amount of carbohydrates to
protein, while a narrow ration means a compara-
tively small amount of digestible carbohydrates to
protein. In calculating the nutritive ratio, the crude
fat or ether extract is multiplied by 2.25, because
the fats are 2.25 times more concentrated than the
carbohydrates.

134. Selection of Foods for Rations. — In the feed-
ing of dairy animals the selection of the food mate-
rials is of equal importance with the amount of
nutrients they contain, because, as stated in a pre-
ceding chapter, the amount and quality of the milk
and products are dependent largely upon the charac-
ter of the foods consumed. To give the best results,
a ration should contain grains, mill products, coarse

138 DAIRY CHEMISTRY

fodders, and roots blended in such a way as to meet
all the requirements of the body. A ration should
have the requisite bulk, be palatable, and contain a va-
riety of food materials with sufficient digestible nutri-
ents. The coarse fodders most satisfactory for dairy
feeding are clover hay, alfalfa, corn fodder, corn si-
lage, oat hay, and the best grades of timothy, upland,
and prairie hay. Common farm grains, as barley,
oats, and corn are equally as valuable for milk pro-
duction as the common mill products, — bran and
shorts. Farm grains, however, are not quite as valu-
able pound for pound as the more concentrated mill
products, such as oil meal and cotton-seed meal.
The quantity of food an animal receives should
vary with the amount of milk produced. When an
animal is giving a full flow of milk, the maximum
amount of food should be supplied. A standard
ration or one for a cow giving 25 to 30 pounds of
milk should contain from 1.7 to 2 pounds of digest-
ible protein and about 14 pounds of digestible carbo-
hydrates per day. Such a ration will produce about
32,000 calories or heat units. A ration that is well
suited for dairy purposes will return fro^n 10 to 12
per cent of the dry matter of the food in the milk.
About one quarter of the protein in the food of a
milk cow is used for maintenance purposes, about
one half for the production of the milk, and about
one quarter is voided as indigestible. It is not pos-
sible to formulate definite standards in the feeding
of dairy stock that are alike applicable to all animals

THE RATIONAL FEEDING OF DAIRY STOCK 139

and all conditions. The quantity of food that can
be consumed to the best advantage must be deter-
mined experimentally by the feeder and should be
varied as occasion demands in order to give the best
results. Ordinarily a ration of from 7 to 10 pounds
of farm grains and mill feeds, with 18 to 25 pounds
of mixed coarse fodders, will supply approximately
the requisite amount of nutrients for the production
of milk. There is but little difference in the milk-
producing value of the different farm grains when
fed in mixed rations. For economical production,
as much of the digestible protein as possible should
be supplied in the coarse fodders, so as to reduce the
quantity of grains that are required for feeding
purposes.

135. How to calculate a Ration. — The foods that
are to be combined to form the ration should be
selected on the basis of cost and composition. In
case corn fodder, clover hay, oats, corn, and mangels
are raised on the farm, these foods can be combined
to form a balanced ration either with or without any
commercial foods. In case it is desired to make a
ration of these foods with bran, the general state-
ments given in paragraph 134 as to quantities of
food should be noted. About 20 pounds of coarse
fodder, 10 to 12 pounds of grains, and 10 pounds of
mangels will form the roughage of a reasonably well-
balanced ration for a cow giving from 25 to 30
pounds of milk per day. The digestible nutrients
in 100 pounds of the foods combined are first noted.

140

DAIRY CHEMISTRY

As given in the table in the Appendix, they contain
the following amounts of digestible nutrients : —

DlGEBTIBL

E NUTRIENTS IN 1C
FOOD MATERIALS

0 LB. OF

Protein

Carbohydrates

Fats

2.5

34.6

1.2

6.8

35.8

1.7

Oats

9.2

47.3

4.2

7.9

66.7

4.3

Bran •••••••*

12.9

40.1

3.4

1.1

5.4

0.1

Since the figures represent the amounts of digestible
protein, carbohydrates, and fats in 100 pounds of the
foods, the amount of digestible nutrients in 1 pound
is obtained by moving the decimal point two places
to the left. A trial ration is first made with 10
pounds each of corn fodder, clover hay, and mangels,
and 7 pounds of oats, 3 of corn, and 2 of bran. The
pounds of digestible protein, carbohydrates, and fats
in 10 pounds of the corn fodder, clover hay, and man-
gels are obtained by moving the decimal point one
place to the left. The pounds of digestible protein
in the 7 pounds of oats are obtained by multiply-
ing .092 by 7, and the pounds of digestible carbo-
hydrates by multiplying .473 by 7, and the fat by
multiplying .042 by 7. In like manner, the digest-
ible nutrients in the 3 pounds of corn and the

THE RATIONAL FEEDING OF DAIRY STOCK 141

2 pounds of bran are obtained by multiplying the per
cent of each digestible nutrient by the weight of the
material used. The pounds of digestible protein, car-
bohydrates, and fat in the several foods are as follows :

TOTAL DIGESTIBLE NUTRIENTS

Protein

Carbohydrates

Crude Fats

Corn fodder,

10 Ib. . . .

0.25

3.50

0.12

Clover hay,

10 Ib. . . .

0.68

3.58

0.17

Mangels,

10 Ib. . . .

0.01

0.05

—

Oats,

7 Ib. . . .

0.65

3.31

0.29

Corn,

3 Ib. . . .

0.24

1.99

0.12

Bran,

2 Ib. . . .

0.25

0.80

0.06

Total .

2.08

13.23

0.76

.76 x 2.25 = 1.71 ;

2.08

= 7 nutritive ratio.

Heat units: (13.23 + 2.08) x 1860 = 28,476.6

.76 x 4225 = 3,211.0

Total 31,687.6

This ration contains 2.08 pounds of digestible pro-
tein, 13.23 pounds of digestible carbohydrates, and
.76 pound of digestible fats. The nutritive ratio
is 1 to 7, and the ration yields a total of 31,687.6
calories. Compared with the requirements of a
standard ration for a cow giving 25 to 30 pounds
of milk, it will be found that these amounts con-
form sufficiently to the standard to warrant this
ration being used. It is to be noted that the pro-

142 DAIRY CHEMISTRY

tein is largely supplied by the clover hay and oats,
and the carbohydrates in nearly equal amounts by
the corn fodder, clover hay, and oats. Corn and
bran are used in smaller quantities, but add appre-
ciable amounts of digestible nutrients to the ration.
While the mangels do not supply a large amount of
nutrients, they are very valuable in the ration in
other ways. They impart palatability and promote
secretion of the gastric and digestive fluids. In
case a smaller amount of milk is produced, the quan-
tity of grain should be reduced. If more than 30
pounds of milk are given, the grain part of the ration
should be proportionally increased. The ration con-
tains a sufficient variety of food materials, and the
foods are combined in such a way as to produce a
good quality of milk. It is not necessary that a
ration should conform absolutely with the tables.
A variation of .1 to .2 of a pound of protein in a
ration, provided there is a corresponding increase
in the other nutrients, will not seriously affect the
milk-producing power of the ration.

The figures given in the Appendix represent the
average composition of feeding stuffs, as iound by
a number of experiment stations. Individual sam-
ples of coarse fodders may vary appreciably from the
average that is given. For example, it is possible for
corn fodder to contain as low as 1.5 pounds of digest-
ible protein per 100, or as high as 3.5 pounds. When
the coarse fodders are raised on rich soil and prepared
under the best conditions and cut when not overripe,

THE RATIONAL FEEDING OF DAIRY STOCK 143

they will contain the maximum amount of nutritive
materials, and such fodders can be used in appreci-
ably less amounts than fodders grown under less
favorable conditions and which contain more fiber
and less digestible protein and carbohydrates. Be-
cause of differences in the quality of the same class
of fodders, it is possible for two farmers to feed the
same kinds of feeding stuffs and grains and yet
secure widely different return in milk yields.

While it is not necessary to conform too closely to
the standards in the feeding of dairy stock, a wide
variation is not desirable, as milk cannot be produced
economically when the stock is not fed on reasonably
well-balanced rations, and the quality of the product
is often abnormal. Numerous experiments have been
made to determine the rations that are most suitable
for milk production. It has been found that a com-
paratively narrow ration of 1 to 5.5 will produce a
larger flow of milk than a wider ration of 1 to 8.
But if the narrow ration is fed in large amounts, the
milk is not produced as economically as when the
wider ration is fed. Maximum returns are secured
when a ration is fed which has a nutritive ratio of
from 1 to 6.5 or 7.5. It frequently happens in the
feeding of dairy stock that heavy grain rations are
not economical because the excess of protein is not
used for vital purposes, but serves a purpose which
would be as well served by the use of the cheaper
carbohydrates. In the case of young stock it is ad-
vantageous to feed a liberal ration, as this will have

144 DAIRY CHEMISTRY

a tendency to encourage a larger flow of milk dur-
ing later periods of lactation.

In the feeding of dairy stock, sudden changes in
the ration should be avoided. In case it is necessary
to make a change in the coarse fodder or grains, it
should be done gradually. A good feeder can tell
from the appearance of the stock and the avidity
with which the ration is consumed whether the
grains and coarse fodders are being fed to advan-
tage. In many of the feeding trials that have been
made, the experimental periods have been too short
to give reliable results.

136. Comparative Cost and Value of Grains. — The
market and feeding value of grains often vary between
wide extremes, and it is frequently found that a given
sum of money, if invested in one food, will procure a
larger amount of digestible nutrients than if invested
in other foods. In general, it can be said that there
is but little difference in the milk-producing value
of grains when fed in a mixed ration, and hence the
price per pound can be taken as the deciding factor
as to what shall constitute the main part of the ration.
In case it is desired to compare the amount of nutri-
ents that can be procured for a given sum of money,
it can be done in the following way : Determine the
number of pounds of food material that can be pur-
chased for $ 1.00, and then calculate the number of
pounds of digestible nutrients in this quantity of food.
For example, if oats are 30 cents per bushel, a dollar
will purchase 107 pounds. Since 100 pounds of

THE RATIONAL FEEDING OF DAIRY STOCK 145

oats contain 9.2 pounds of digestible protein, 4.2
pounds of fat and 47.3 pounds of digestible carbo-
hydrates, 107 pounds will be found to contain 9.84
pounds of protein, 4.5 pounds of fat, and 50.6 pounds
of carbohydrates. In case it is desired to compare the
nutrients in oats at 30 cents per bushel with the nu-
trients in corn at 50 cents per bushel, the same pro-
cess of calculation is carried on. One dollar will
purchase 112 pounds of corn, and since 100 pounds
contain protein, fat, and carbohydrates in the pro-
portion given in section 135, 112 pounds will con-
tain 8.85 pounds of protein, 4.83 pounds of fat, and
74.7 pounds of carbohydrates. The 107 pounds of
oats contain about a pound more digestible protein
than the 112 pounds of corn, but on the other hand
the corn contains about 24 pounds more digestible
carbohydrates. For ordinary purposes of feeding, a
larger return will be secured from 24 pounds of car-
bohydrates than from 1 pound of protein. If, how-
ever, the ration contains a scant amount of protein,
then 'preference should be given to the protein. But
at the price stated, corn could be used more econom-
ically than the oats. In determining the compara-
tive value of two grains, preference should always be
given to the protein ; but in case the difference in the
amount of digestible protein that can be purchased
for $1.00 is not large, while the difference in digest-
ible carbohydrates is quite large, then the food that
contains the smaller amount of protein, but larger
amount of carbohydrates, would be the cheaper food.

146 DAIRY CHEMISTRY

In the combination of foods to form balanced
rations there are a numbep of factors that should
receive consideration. The foods should be in the
best mechanical condition. In the case of some
grains, coarse grinding should be practiced. Seeds
with hard seed coats, as wheat and barley, should
be coarsely ground, particularly if the animals are
giving large amounts of milk. If the animals are
giving a smaller quantity of milk, grinding is not
so necessary, as more energy can then be profitably
expended in the mastication of the food. In order
to meet with success in feeding, practical experience
in the handling of stock is necessary. Too frequently
the foods are portioned out by volume rather than by
weight, and the feeder has but little knowledge as to
the weight of the food he is feeding. Since the weight
per bushel of grains varies so widely, volume or meas-
ure is a very unsafe basis for portioning out food.
For example, a quart of corn will weigh much more
than a quart of oats, although a pound of oats will
contain more digestible protein than a pound of corn.
It makes a great difference in the amount of digest-
ible nutrients which the animals receive when the
foods are portioned out by volume instead of by
weight.

In the feeding of dairy stock, the sanitary con-
ditions discussed in Chapter VIII must be taken into
consideration, because the best returns cannot be se-
cured from foods when the animals are not cared for
under the most sanitary conditions.

APPENDIX

DIGESTIBLE NUTRIENTS IN FODDERS

NAME OF FEED

DBY

MATTER

IN

100 LB.

DIGESTIBLE NUTRIENTS
IN 100 LB.

PROTEIN

CARBOHY-
DRATES

ETHER
EXTRACT

Corn (all analyses) ....
Dent corn

89.1
89.4
88.7
91.2
89.3
84.9
90.9
91.8
89.6
88.9
89.5
88.1
88.5
87.7
88.2
87.9
88.4
88.4
88.4
90.7
89.1
89.8
24.3
91.8
89.0
92.3

7.9
7.8
8.0
8.8
0.4
4.4
7.4
25.8
9.0
7.5
10.2
12.2
12.9
12.3
12.2
12.8
"9.8
9.9
11.5
11.9
8.7
18.6
3.9
15.7
9.2
12.5

66.7
66.7
62.2
63.7
52.5
60.0
59.8
43.3
61.2
55.2
69.2
39.2
40.1
37.1
50.0
53.0
51.0
67.6
50.3
45.1
65.6
37.1
9.3
36.3
47.3
46.9

4.3
4.3
4.3
7.0
0.3
2.9
4.6
11.0
6.2
6.8
1.7
2.7
3.4
2.6
3.8
3.4
2.2
1.1
2.0
1.6
1.6
1.7
1.4
5.1
4.2
2.8

Flint corn

Sweet corn

Corn and cob meal ....

Gluten meal

Germ meal

Wheat

Wheat bran

Wheat bran (spring wheat)
Wheat bran (winter wheat)
Wheat shorts

Wheat middlings ....
Wheat screenings ....
Rve .

Rye bran

Rye shorts

Malt sprouts
Brewer's grains (wet) . . .
Brewer's grains (dried) . .
Oats

Oat feed or shorts ....

147

148

DAIRY CHEMISTRY

DIGESTIBLE NUTRIENTS IN FODDERS— Continued

NAME OF FEED

DRY

MATTER

IN

100 LB.

DIGESTIBLE NUTRIENTS
IN 100 LB.

PROTEIN

CARBOHY-
DRATES

ETHER
EXTRACT

Oat hulls

90,6

87.4
89.5
90.8
90.8
89.9
91.8

20.7

57.8
59.5

20.0
34.9

38.4
37.8
16.0

86.8
91.1

78.8
92.3
87.1
83.4
91.1

90.4
90.8

1.3

7.7
7.4
20.6
29.3
28.2
37.2

1.0
2.5
1.7

2.5
3.0
1.2
2.6
1.8

2.8
4.8
4.8
4.5
5.9
7.9
4.3

0.4
1.2

40.1
49.2
30.4
17.1
32.7
40.1
16.9

11.6
34.6
32.4

10.2
19.8
19.1
18.9
7.1

43.4
46.9
C7.3
51.7
40.9
40.1
46.4

36.3
38.6

0.6
1.8
1.9
29.0
7.0
2.8
12.2

0.4
1.2
0,7

0.5
0.8
0.6
1.0
0.2

1.4
1.4
2.0
1.3
1.2
1.5
1.5

0.4

0.8

Buckwheat

Buckwheat bran

Flaxseed

Linseed meal (old process) .
Linseed meal (new process)
Cotton-seed meal ....

Coarse Fodders
Fodder corn (green) . . .
Fodder corn (field cured)
Corn stover (field cured) . .
Fresh Grass
Pasture grasses (mixed) . .
Kentucky blue grass . . .
Timothy, different stages .
Oat fodder

Peas and oats . . . . . .

Hay
Timothy

Redtop ....

Kentucky blue grass . . .
Hungarian grass ....
Mixed grasses

Ho wen (mixed)

Oat hay

Straw
Wheat

Oat

APPENDIX

149

DIGESTIBLE NUTRIENTS IN FODDERS — Concluded

NAME OP FEED

DRY

MATTER

IN

100 LB.

DIGESTIBLE NUTRIENTS
IN 100 LB.

PROTEIN

CARBOHY-
DRATES

ETHER
EXTRACT

Fresh Legumes
Red clover, different stages .
Alsike, bloom . . . . .

29.2
25.2
19.1

84.7
78.8
90.3
91.6
89.3

20.9

21.1
13.5
9.1
11.4
11.4

9.1
10.2
12.8
9.6
9.4
9.9
6.6

2.9

2.7
2.4

6.8
5.7
8.4
11.0
16.8

0.9

0.9
1.1
1.1

1.0

0.8

1.0
0.6
3.6
3.1
2.9
3.9
0.8

14.8
13.1
13.9

35.8
32.0
42.5
39.6
38.6

11.3

16.3
10.2
5.4

8.1
7.8

5.8
7.3
4.9
4.7
5.2
4.0
4.7

0.7
0.6

0.5

1.7
1.9
1.5
1.2
1.1

0.7

0.1
0.1
0.1
0.2
0.2

0.3

3.7
0.8
0.3
1.1
0.3

Crimson clover ....

Legumes
Red clover, medium . . .
Red clover, mammoth . .

Alfalfa

Silage

Roots and Tubers
Potato

Sugar beet

Mangel beet

Carrot

Miscellaneous
Pumpkin (field)

Cow's milk

Skim milk (gravity) . . .
Skim milk (centrifugal) . .
Buttermilk

Whey

150

DAIRY CHEMISTRY

W H
H <<

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o o

IM c^cceo rococo co co co cc

r-l r-l i-i rH r-t rH 1M Cq C1 M M

XiOOOOCOCOQOQOt-t-b-t-

'

rJH rH rH •* CO CO CO CO 03 <N

Tl5 K5 >C ^5 t- 00 Ci O »-5 7-i TO
(N C-4 C^ C<l C"1 !M N CO CO CO CO

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aaxa

-K010V1

s

?5 (M <N CO CO 1C' CO CO CO CO CO

•^ t- 1- 1- co co oo cn cr. G-. ~.

APPENDIX 151

REVIEW QUESTIONS

CHAPTER I
^

1. What are the milk solids, and how are they obtained?
2. Of what compounds are the milk solids composed ? 3. Give
the approximate percentage amounts in which these compounds
are present/ 4. What is milk serum? 5. To what extent does
the solid matter in milk vary ? ; 6. How much water does aver-
age milk contain? 7. What are the fat globules of milk?
8. Why are they globular in form? 9. To what extent do
the globules in milk vary in size and number ? 10. Are the fat
globules surrounded by a membrane ? 11. What breeds pro-*
duce milk containing the largest fat globules? 12. What is
casein ? 13. In what dairy operations does it take the most
important part ? 14. What is albumin, and how can it be ob-
tained from milk? 15. What is milk sugar ? 16. How does
it resemble and how does it differ from ordinary sugar?
17. What is the ash of milk? 18. Of what is it composed?
19. How is the ash of milk obtained? 20. To what extent do
different milks vary in composition? 21. What is the most
variable ingredient in milk? 22. Why should the quantity of
milk be considered jointly with its percentage composition?
23. How can the total yield of fat and other compounds of
milk be determined? 24. How does the first or fore milk
differ from the strippings? 25. What are the solids not
fat ? 26. To what extent do they vary in different milks ?

CHAPTER II

27. What is the object of testing milks? 28. What method
is most generally used in milk testing? 29. What can you say
of the reliability of this method ? 30. How should a sample
of milk be taken from a can or pail? 31. What treatment
should milk in the sample bottle receive before measuring with
the pipette? 32. Why is careful sampling of the milk neces-

152 DAIRY CHEMISTRY

sary? 33. What is the pipette? 34. How is milk meas-
ured with the pipette ? 35. How much milk does the pipette
deliver? 36. What is the test bottle? 37. How is the
scale made to read ? 38. How would you measure acid and
pour it into the test bottle? 39. After adding the acid, what
is the next step in the test? 40. How is the test completed?
41. How is the fat read? 42. What precautions should be
taken in reading the fat? 43. What causes some tests to
show particles of casein below the fat in the test bottle ? 44.
Why are some tests black or charred ? 45. How would you
determine whether a test bottle is correctly graduated or not?
46. Why is it necessary to have accurately graduated test bot-
tles ? 47. What causes the separation of the fat in the test ?
. In the handling of the acid what precautions are to be
observed? 49. How can the machine be speeded? 50. Why
should the number of revolutions per minute vary with the
diameter of the machine? H>1. What is a composite sample?
52. What material is used for its preservation ? 53. How
long should the composite sample be kept? 54. What is a
convenient way for handling and measuring the preservative ?
55. What kind of bottles should be used for the composite
sample? 56. How is skim milk tested? 57. How is the fat
content in skim milk read? 58. What effect does partial
freezing have upon the composition of milk? 59. How
should the glassware used in making the test be cleaned?

60. What kind of water should be used in making the test?

61. Why are some waters objectionable ? 62. What are some
of the necessary precautions to take in milk testing?

CHAPTER III

63. Of what are the fat globules of milk composed? 64.
What are the three elements of which fats are composed?

65. Name the different fats of which butter is composed.

66. To what extent are these fats present? 67. Name the
three classes into which these fats may be divided. 68. Give

APPENDIX 153

the characteristics of the principal fats of butter. 69. Why
does butter differ in composition from all other fats ? 70. What
is meant by the glycerine and fatty acid content of fats?
71. What is meant by saponification of fats ? 72. What are
the volatile fatty acids of butter? 73. Why do butters pro-
duced from different creams vary in hardness and other physi-
cal properties ?

CHAPTER IV

74. What is the lactometer and for what is it used ? 75.
What are the lactometer degrees? 76. How is the specific
gravity of milk determined? 77. Why does milk have a
higher specific gravity than water? 78. What influence
does the removal of the fat have upon the specific gravity of
milk? 79. What influence does the addition of water have
upon the specific gravity of milk? 80. To what extent do
changes of temperature influence the lactometer readings?
81. How is skimming or watering of milk detected? 82. How
can the Babcock test and the lactometer be used jointly in
milk testing? 83. How are the milk solids calculated from
the fat content and the specific gravity ? 84. How would you
determine the extent to which milks have been either watered
or skimmed ?

CHAPTER V

85. Give the physical properties of milk sugar. 86. What
changes does milk sugar undergo when milk sours ? 87. What
is produced? 88. Name the conditions necessary for fermen-
tation of milk. 89. What causes the fermentation to take
place? 90. To what extent may lactic acid form in milk?
91. What causes milk to sour and curdle? 92. How can the
amount of lactic acid in milk be determined? 93. Describe
the test employed for obtaining the acidity of rnilk. 94. How
is the amount of acid in the milk calculated? 95. Of what
value is this test in butter making ? 96. What per cent of
acidity should well-ripened cream show ?

154 DAIRY CHEMISTRY

CHAPTER VI

97. What is cream ? 98. To what extent does it vary in
fat content? 99. Give the three ways in which milks are
creamed. 100. How is cream tested? 101. Why is it more
accurate to weigh instead of measure the cream used in test-
ing? 102. What is creaming by gravity? 103. To what
extent do losses of butter fat occur in gravity creaming?

104. How is milk creamed by the cold deep-setting process?

105. What are the essential conditions for efficient creaming
by this process? 106. To what extent do losses of fat occur
when milks are creamed by the separator? 107. How can
the composition of separator cream be regulated ? 108. What
should be the temperature of milk when separated ? 109. Why
should different milks be separated at different temperatures ?
110. In what ways is cream adulterated? 111. Explain the
ripening process of cream. 112. What is the object of the
ripening of cream ? 113. Explain the workings of the culture
or starter. 114. What influence does delay have in the grav-
ity creaming of milk? 115. Is there any advantage in grav-
ity creaming of mixed milk? 116. What is cream raising by
dilution? 117. Is it a desirable process ? 118. Why?

CHAPTER VII

119. What is churning? 120. What changes take place in the
form of the fat globules during churning? 121. What are
the conditions necessary for exhaustive churning ? 122. Does
the ripeness of the cream affect churning? 123. Does the fat
content of cream affect churning ? 124. Why should unripened
mixed creams first be ripened before churning? 125. Why
should the temperature of churning vary with different creams ?
126. How would you determine the best temperature for churn-
ing ? 127. What are some of the factors influencing the churn-
ability of cream? 128. At what stage should churning be
stopped? 129. To what extent should the butter be washed

APPENDIX 155

and worked ? 130. How can the water content of butter be
influenced by working? 131. What are the characteristics of
a good dairy salt ? 132. What is buttermilk, and how does
it compare in composition with skim milk? 133. What be-
comes of the casein in butter making ? 134. Of the milk sugar?
135. Of the albumin ? 136. To what extent do butters vary
in water content ? 137. How much fat does average butter
contain? 138. How much casein ? 139. Of what are butter
colors composed ? 140. Why does one hundred pounds of fat
make more than one hundred pounds of butter? 141. How
is the butter yield estimated from the fat content of milk?
142. How would you make out a dividend in a creamery on the
basis of the weight of the milks and their fat content ?

CHAPTER VIII

143. Define sanitary condition of milk. 144. Name the fac-
tors which influence the sanitary condition of milk. 145. Why
is milk from diseased animals unsanitary ? 146. To what extent
do diseases affect the composition of the milk ? 147. How does
the care of the animals influence the sanitary condition of the
milk ? 148. Why should the utmost cleanliness be practiced
in the handling of milk? 149. What are the most frequent
causes of contaminated milk? 150. Why should milk not be
left in stables? 151. What causes the difference in the bac-
terial content of milk? 152. Why should stables be well
ventilated? 153. How do unclean dairy utensils foul milk?
154. How should pails and cans be washed ? 155. What effect
does the storing of milk in unclean milk rooms have upon its
wholesomeness? 156. In what ways does the water supply
influence the quality of the milk? 157. What is colostrum
milk, and how does it differ in composition from other milk?
158. What is tyrotoxicon? 159. How is it produced in
milk? 160. What is fibrin? 161. What gases are present
in milk? 162. To what is the color of milk due ? 163. How
would you pick out milks of the highest sanitary value?

156 DAIRY CHEMISTRY

164. How may milks be the cause of the spread of contagious
diseases?

CHAPTER IX

165. What milk solids are recovered in cheese making?
166. What are the proteids of milk? 167. How do the proteids
differ in composition from the fats ? 168. In what condition is
the casein in milk ? 169. What causes coagulation of the casein ?

170. Is milk albumin recovered in ordinary cheese making?

171. What is rennet? 172. How is it obtained? 173. For
what is it used? 174. What action does it have upon milk?
175. What is the rennet test and how is it made ? 176. What
is the object of this test ? 177. Describe briefly the process of
cheddar cheese making. 178. Why is it called the cheddar
process? 179. How does it differ from the stirred curd pro-
cess? 180. To what is the curing of cheese due? 181. What
are the enzymes ? 182. What part do they take in cheese ripen-
ing? 183. What is the cold curing process ? 184. What is
gained by this process of curing cheese ? 185. What relation-
ship exists between the fat content and the cheese yield of
milk ? 186. How can the fat content of cheese be determined ?
187. How much fat should cheese contain? 188. How much
casein? 189. How are dividends made out in a cheese factory
on the basis of the fat content ? 190. Is this an equitable basis
for making out dividends ? 191. How may the approximate
cheese and butter yield of milks be determined? 192. What
are some of the kinds of cheese occasionally manufactured?
193. How is a long-keeping export cheese made ? 194. How
is a quick-ripening or home-market cheese made ? 195. What
is the hot-iron test, and how is it used in cheese making?
196. How do the losses of fat in cheese making compare
with the losses in butter making? 197. Can rich milks be
made into cheese economically? 198. How does the fat
content of milk affect the quality of cheese? 199. When
milk curdles, what becomes of part of the lactic acid that is
formed ?

APPENDIX 157

CHAPTER X

200. What are the by-products of milk? 201. What are
the principal compounds in skim milk? 202. To what does
skim milk owe its feeding value ? 203. How does skim
milk compare in feeding value with corn and other grains?
204. What is the best proportion to feed skim milk with
grain? 205. Why should separator slime be kept out of
skim milk? 206. What is the difference between separator
skim milk and skim milk obtained by the gravity process?

207. How does whey differ in composition from skim milk?

208. Plow does whey compare in feeding value with skim milk
and grains? 209. What fertilizer value do the milk by-
products possess? 210. Why is there but little loss of fertil-
ity from the farm in dairying? 211. Why should skim milk,
buttermilk, and whey be handled in the most cleanly way?

CHAPTER XI

212. What is oleomargarine ? 213. Butterine? 214. How
are these materials made? 215. To what extent do they
resemble butter? 216. How do they differ from butter?
217. What simple methods can be employed for detecting
oleomargarine? 218. What is renovated butter and how is
it made? 219. How does it differ from other butter?
220. In what ways may cheese be adulterated ? 221. In
addition to skimming and watering in what other ways may
milks be adulterated? 222. Why do medical authorities
object to the use of preservatives in milk? 223. What other
methods are sometimes used in testing milks? 224. Which
of these methods are unreliable ? 225. Why are dairy laws
enacted ? 226. What is gained by in spection of dairy products ?

CHAPTER XII

227. Why are market milks so variable in character?
228. To what extent does milk or cream vary in composition

158 DAIRY CHEMISTRY

during transportation? 229. What is Pasteurized milk?
230. How is milk Pasteurized? 231. What is sterilized milk,
and how does it differ from Pasteurized milk? 232. Could
cream used for butter-making purposes be Pasteurized to
advantage? 233. How could milk be Pasteurized on a small
scale for home use ? 234. What is condensed milk ?

CHAPTER XIII

235. What relationship exists between milk secretion and
food supply? 236. To what extent can the per cent of fat in
milk be increased by the food ? 237. What is the result of the
tests where fats were fed in large amounts to dairy cows?
238. How does feed affect the total yield of milk ? 239. Is
the fat in milk formed from other nutrients than the fat in the
food? 240. What effect on the quality of butter does cotton-
seed meal have when fed to cows in large amounts? 241. What
influence does corn alone and in large amounts have upon the
quality of the butter ? 242. When corn or cotton-seed meal are
combined with other grains, what is the effect on the quality of
the butter ? 243. When cows are fed large amounts of linseed
meal, what quality of butter is produced ? 244. What effect
does gluten meal have upon the quality of the butter ?

245. When oats are fed, what kind of butter is produced?

246. What effect do the wheat by-products have upon the
butter ? 247. To what extent do farm grains differ in milk-
producing power in mixed rations? 248. What coarse fodders
produce the best quality of milk? 249. What effect do over-
ripe and fibrous fodders have upon the quality of the milk and
butter? 250. Does silage exert a favorable influence upon
the character of the butter? 251. To what is silage odor in
milk largely due? 252. How do turnips, rape, and onions
affect the flavor of milk? 253. To what are the desirable
flavors in milk due? 254. What causes the undesirable
flavors? 255. Why does a balanced ration produce dairy
products of the best quality? 256. Under what conditions

APPENDIX 159

are abnormal milks and dairy products produced ? 257. Are
there any foods that exert a marked ability to cause an increase
in milk secretion ? 258. How do so-called stock foods affect
milk yield? 259. Under what conditions of feeding are the
best returns in milk yield and quality of product secured?
260. Why is liberal feeding necessary to produce prolonged
milk secretion? 261. To what extent do individual animals
differ in their ability to utilize foods for milk production ?
262. What factors influence milk secretion ? 263. To what
extent can the secretion of milk be influenced ?

CHAPTER XIV

264. What uses are made of the food by the body ? 265. Do
all the nutrients of the food serve the same purpose ? 266. What
is a nutrient? 267. Into what two classes of nutrients are
the compounds of foods divided? 268. What is the differ-
ence in composition between these two classes of nutrients?
269. Which class of nutrients is found in smaller amounts
in food stuffs? 270. Which class is the more expensive?
271. Give an example of each class. 272. What is the crude
protein? 273. What are the carbohydrates? 274. What
is dry matter? 275. How is it obtained? 276. To what
extent does the water content of foods vary? 277. Define
ash or mineral matter. 278. To what extent is ash present
in grains? 279. What compounds are present in plant
ash ? 280. What is organic matter, and how is it obtained ?
281. What functions do the proteids of food serve? 282.
Why should foods contain a fairly, liberal supply of proteids ?
283. What is the result when the food contains too scant an
amount of proteids? 284. Why are abnormal amounts of
proteids in foods objectionable? 285. What is the object
of the rational feeding of animals? 286. What functions
do the carbohydrates of foods serve ? 287. Do carbohydrates
found in different food materials have the same general com-
position? 288. What are some of the carbohydrates found

160 DAIRY CHEMISTRY

in food stuffs? 289. What is crude fiber, and how is it ob-
tained? 290. To which of the two large classes of compounds
found in food stuffs does crude fiber belong? 291. What is
crude fat, and why is it sometimes called ether extract?
292. How does fat as a nutrient compare with starch in
heat-producing power ? 293. What are digestible nutri-
ents? 294. How are they obtained? 295. What is the
caloric value of a ration? 296. What is the nutritive ratio?
297. What is a wide ration? 298. What is a narrow ra-
tion? 299. On what basis should the foods for the dairy
be selected? 300. How do farm grains compare in milk-
producing power with average mill products other than oil-
seed products ? 301. Name the coarse fodders most suitable
for dairy feeding. 302. How should the amount of grain
which an animal receives be regulated? 303. How much
coarse fodder should a cow receive? 304. How much grain
should a cow yielding twenty-eight pounds of milk receive?
305. Give the amount of nutrients which should be present
in the ration of a dairy cow. 306. How is a ration for a
dairy animal calculated? 307. How would you determine
whether a ration conformed sufficiently to a standard ration ?
308. How would you determine when it is desirable to use
one grain in a ration in large amounts in preference to an-
other? 309. How would you calculate the amount of digesti-
ble nutrients which can be purchased for $1.00 when grains are
at different prices? 310. In selecting grains, to what nutrient
should the preference be given? 311. In case there is only
a small difference in the amount of this nutrient which can be
purchased for $1.00, then what nutrient should be taken as the
basis? 312. Why is it possible for two farmers to feed the
same kinds of grains and coarse fodders and yet secure entirely
different returns in milk yields? 313. In order to secure the
best returns in milk yields from the food consumed, why should
the animals be cared for under the most sanitary conditions?
314. Why should grains be weighed when fed? 315. To what
extent do grains and mill products vary in bulk and weight?

APPENDIX 161

REFERENCES

THE references given in the following pages are not intended
to represent a complete bibliography of the subject. The stu-
dent is advised to consult some of the bulletins and articles
referred to so as to obtain more information upon many of the
topics that are only briefly discussed in this work. It has not
been possible to give the references and authorities for each
statement that has been made in this book, or in those cases
where different and conflicting views are held, to enter into
discussion of questions. The literature of dairying is very
extensive, and there are a number of works that treat of
special topics, as : Testing Milk and its Products, by Woll and
Farrington ; Dairy Chemistry, by Richmond ; Dairy Bacteriol-
ogy, by Russell; Milk and its Products, by Wing; Feeds and
Feeding, by Henry ; and Feeding of Farm Animals, by Jordan.
These should be frequently consulted in studying the subject.
The student should early acquire the habit of consulting dif-
ferent works, as many topics are presented more clearly in one
than in another.

REFERENCES TO CHAPTER I

1. The Composition of Milk. Konig : Chemie der Mensch-
lichen Nahrungs- und Genussmittal.

2. The Composition of Cow's Milk. Blyth : Food Analysis.

3. The Physical Composition of Milk. Duclaux : Le Lait,
Etudes Chemiques et Microbiologiques.

4. The Composition of Milk. Wisconsin Experiment Sta-
tion, Bulletin No. 19.

5. The Constitution of Milk. Wisconsin Experiment Station,
Bulletin No. 18.

6. The Composition of Milk and its Products. Richmond :
Analyst, August, 1894.

7. The Composition of Milk as affected by Change of Milkers

162 DAIRY CHEMISTRY

and Change of Quarters. Wisconsin Experiment Station Re-
port, 1889.

8. Variations in the Fat Content of Milk. Weilandt : Milch
Zeitung, 24 (1895).

9. The Average Composition of Milk. Vieth : Analyst, 18,
192, 193.

10. Historical Article regarding Milk. Blyth : Food Analysis.

11. The Composition of Milk from Different Breeds. Michi-
gan Experiment Station, Bulletin No. 68.

12. The Composition of Milk from Different Breeds. New
York State Station Report, 1891.

13. The Composition of Milk. Maine Experiment Station
Reports, 1890, 1893.

14. Variations in Milk during the Period of Lactation. Ver-
mont Experiment Station, Sixth Annual Report.

15. Composition of Milk. Wisconsin Experiment Station
Report, 1889 ; also Bulletins Nos. 15 and 16 ; also Fifth Annual
Report.

16. Composition of Milk. New Jersey Experiment Station,
Bulletins Nos. 61, 65, 68, 77.

17. Composition of Milk. Massachusetts State Station Re-
ports, 1888, 1889, 1890, 1891, 1892.

18. The Number and Size of Fat Globules in Milk. Wis-
consin Experiment Station Report, 1890.

19. The Fat Globules of Milk. Maine Experiment Station,
Annual Report, 1890.

20. Conditions influencing the Number and Size of the Fat
Globules. Milch Zeitung, 24 (1895).

21. On the Variation in the Number and Size of Fat Glob-
ules. Pennsylvania Experiment Station Report, 1895.

22. The Size of Fat Globules in Milk. Vermont Experiment
Station, Fourth Annual Report.

23. Size of Fat Globules in the First and Last Half of Milk-
ing. Indiana Experiment Station, Bulletin No. 24.

24. The Size of Fat Globules in Milk of Cows of Different
Breeds. New York State Experiment Station Reports, 1891, 1592.

APPENDIX 163

25. Composition of First Milk and Strippings. Connecticut
State Experiment Station Report, 1886.

26. Fore Milk and Strippings. Blyth : Food Analysis.

27. Relation of Fat and Casein in Milk. Vermont Experi-
ment Station, Fourth Annual Report.

28. Liquid Condition of the Fat. Soxhlet : Landwirtschaft-
lischen Versuchs-Stationen, 1876.

29. No Membrane about Milk Fat Globules. Martiny : Die
Milch.

30. Artificial Emulsions representing Milk. Duclaux : An-
nales de 1'Institut Nat. agronomique, 1882.

31. The Membrane of the Milk Fat Globule. Jurstenburg :
Die Milch drusen die Kuh.

32. The Membrane of the Fat Globule. Bechamp : Comptes
Rendus, 1888.

33. Composition of the Ash of Milk. Maine Experiment
Station Report, 1890.

34. Milk Ash Analysis. New Hampshire Experiment Sta-
tion Report, 1888.

35. Average Composition of Milk Ash. Kb'nig : Chemise he
der menschlichen Nahrungs- und Genussmittel. Band II.

36. The Phosphates of Milk. Duclaux: Annals Pasteur
Institute, 1893.

37. Calcium Phosphate and the Casein. Soldner : Die Land-
wirtschaftlichen Versuchs-Stationen, 1888, 35.

38. Yield of Front and Rear Udder of Cow. Wis. Rept., 1898.

39. The Milk Yield of Quarters on Same Side of Udder.

40. The Composition of Frozen Milk. Wisconsin Station,
Twentieth Annual Report.

41. The Fat Globules of Cows' Milk. Wisconsin Station,
Twentieth Annual Report.

42. On the Average Composition of Milk of Pure-bred Cows of
Different Breeds. Wisconsin Station, Twentieth Annual Report.

43. On the Average Composition of Milk of Pure-bred Cows
of Different Breeds. Wisconsin Station, Eighteenth Annual
Report.

164 DAIRY CHEMISTRY

44. Variations in Milk and Milk Production. Illinois Ex-
periment Station, Bulletin No. 51.

REFERENCES TO CHAPTER II

1. The Babcock Test. A New Method for the Estimation
of Fat in Milk, especially adapted to Creameries and Cheese
Factories. Wisconsin Experiment Station, Bulletin No. 24 ;
also Annual Report, 1890.

2. Babcock Test. Notes on its Use and the Lactometer.
Wisconsin Experiment Station, Bulletin No. 31.

3. Application of Dr. Babcock's Centrifugal Method to the
Analysis of Milk, Skim-milk, etc. Cornell University Experi-
ment Station, Bulletin No. 29.

4. New Points in Manipulation of the Babcock Test. Illi-
nois Experiment Station, Bulletin No. 27.

5. The Babcock Test. Association of Official Agricultural
Chemists' Report, 1890.

6. The Babcock Method of finding the Amount of Butter-fat
in Milk. Connecticut State Experiment Station, Bulletin No.
106 ; also Reports, 1891, 1894.

7. Directions for using the Babcock Milk Test. Pennsyl-
vania Experiment Station, Bulletin No. 33, Report, 1895.

8. The Babcock Method of Milk Analysis. F. T. Shutt:
Analyst, 17, 200 ; Chemical News, 64, 4.

9. Accuracy of the Babcock Milk Test. Cornell University
Experiment Station, Bulletin No. 25.

10. Accuracy of the Babcock Milk Test. Illinois Experi-
ment Station, Bulletin No. 14.

11. Comparative Trials of the Babcock Milk Test. Hein-
rich : Molkerei Zeitung, 1893, No. 4.

12. The Babcock Test. Wiley : Agricultural Analysis, Vol. III.

13. Marking Test-bottles. Illinois Agricultural Experiment
Station, Bulletin No. 18.

14. Milk Sampling. Delaware Experiment Station, Bulletin
No. 31.

APPENDIX 165

15. The Testing of Milk. North Carolina Experiment Sta-
tion, Bulletin No. 113.

16. Composite Milk Samples. Patrick : Journal of Analyti-
cal and Applied Chemistry, 5, 8.

17. The Composite Test. Wisconsin Experiment Station,
Bulletin No. 36.

18. Composite Sampling of Milk. Iowa Experiment Station,
Bulletins Nos. 9, 14, and 22.

19. Composite Method of Milk Sampling. Illinois Experi-
ment Station, Bulletins Nos. 16 and 18.

20. Method of Sampling Milk for Analysis. Pennsylvania
Experiment Station, Annual Report, 1892.

21. Preservatives for Milk Samples. Iowa Experiment Sta-
tion, Bulletin No. 11.

22. Milk Sampler. Wiley : Agricultural Analysis, Vol. III.

23. The Trowbridge Method of Calibrating Babcock Test-
bottles. Wisconsin Experiment Station, Eighteenth Annual
Report.

24. Methods and Apparatus for testing Milk and Milk
Products. Wisconsin Experiment Station, Twentieth Annual
Report.

25. Examination of Babcock Apparatus. Connecticut Ex-
periment Station, Report 1901, Part IV.

26. Testing Dairy Products by the Babcock Test. Maine
Experiment Station, Report of 1897.

27. The Babcock Test. New Hampshire Experiment Sta-
tion, Bulletin No. 114.

28. Inspection of Babcock Milk Test-bottles. New York
Experiment Station, Bulletin No. 178.

REFERENCES TO CHAPTER IV

1. Table for Corrections of the Temperature in Lactometry
(Centigrade Scale). Konig: Untersuchungen in landwirt-
schaftlich und gewerblich Wichtiger Stoffe.

166 DAIRY CHEMISTRY

2. A Simple Formula for calculating the Solids not Fat.
Babcock : Wisconsin Experiment Station, Bulletin No. 34.

3. The Adulteration of Milk. Blyth : Foods ; Composition
and Analysis.

4. Comparison of Results by the Use of the Formulas of
Hehner and Richmond, Fleischmann, and Babcock, with the
Gravimetric Method. Report of the Eighteenth Annual Conven-
tion of the Association of Official Agricultural Chemists, 1894.

5. Effect upon the Specific Gravity of Milk by allowing the
Milk to stand after Milking. Richmond : Report of Eighteenth
Annual Convention of Association of Official Agricultural
Chemists, 1894.

6. Lactodensimeter. Quevenne-Miiller : Grandeau, Analyse
des Materies Agricoles.

7. The Adulteration of Milk. Various articles in the current
numbers of the Analyst.

8. Legal Cases relating to the Adulteration of Milk. Various
and numerous articles in the current numbers of the Milch
Zeitung.

REFERENCES TO CHAPTER V

1. Influence of Sugar on the Nature of the Fermentation
occurring in Milk and Cheese. Wisconsin Experiment Station,
Eighteenth Annual Report.

2. Galactase, the Inherent Digestive Enzyme of Milk. Wis-
consin Experiment Station, Twentieth Annual Report.

3. Milk Fermentations. United States Department of Agri-
culture, Farmers' Bulletins Nos. 9 and 29, also cuirent numbers.

4. Dairy Bacteriology. United States Department of Agri-
culture, Office of Experiment Stations, Bulletin No. 25.

5. The Number of Bacteria in Milk. (Storrs) Connecticut
Experiment Station, Seventh Annual Report.

6. Bacteria in their Relation to the Dairy. Lugger : Minne-
sota Experiment Station, Annual Report, 1893.

7. Ripening of Cream and Milk Fermentations. Article in
Handbook of Experiment Station Work.

APPENDIX 167

8. The Action of Different Classes of Bacteria on Milk.
Adametz: Monatsschrifte fur Thierheilkunde, 1890.

9. Bacteria in the Dairy. Conn : (Storrs) Connecticut Ex-
periment Station, Third, Fourth, Fifth, Sixth, Seventh, and
Eighth Annual Reports.

10. Milk Sugar. Remsen: Organic Chemistry.

11. An Acid Test of Cream. Illinois Experiment Station,
Bulletin No. 32.

12. The Alkaline Tablet Test of Acidity in Milk or Cream.
Wisconsin Experiment Station, Bulletin No. 52.

13. Lactic Acid Ferments. Pasteur: Studies on Fermen-
tation.

14. Outlines of Dairy Bacteriology. Russell.

15. Le Lait, Etudes Chemiques et Microbiologiques. Du-
claux.

16. Determining the Acid in Milk. Hopkins and Powers :
Report of the Association of Official Agricultural Chemists,
1895.

REFERENCES TO CHAPTER VI

1. Ripening Cream with Pure Cultures. Conn : (Storrs)
Connecticut Experiment Station, Fifth, Sixth, and Seventh
Annual Reports.

2. Ripening of Cream with Artificial Cultures. Adametz:
Landwirtschaftlichen Versuchs-Stationen, 1892.

3. Artificial Butter Cultures. Storch : Milch Zeitung, 1890.

4. Artificial Butter Cultures. Weigmann : Milch Zeitung,
1890.

5. Experiments with Cream : Ripening, Flavor, Aroma, Acid.
Conn : (Storrs) Connecticut Experiment Station, Bulletin
No. 16.

6. Experiments in the Ripening of Cream by Means of Pure
Cultures. F. Fries and H. P. Lunde : reported in Experiment
Station Record, 7, No. 3.

7. Abnormal Ripening of Cream due to Faulty Character of
Milk. L. Adametz : Milch Zeitung, 1893, No. 18.

168 DAIRY CHEMISTRY

8. Cream Ripening with Pure Cultures. Milch Zeitung.
Experiment Station Record, 7, No. 1.

9. The Composition of Cream. Massachusetts Experiment
Station Reports, 1889, 1890, 1892, 1893.

10. On the Raising of Cream on the Milk Route. Berg-
mann : Milch Zeitung, 1893.

11. Effects of Transportation upon the Fat Content of Milk.
Klein : Chemisches Centralblatt, 89, 397.

12. Variations in Fat Content in Milk served from Cans to
Customers. Legal Case. Analyst, 17, 189.

13. Variations in Fat of Milk served to Customers in Dip-
ping from Cans. Cornell University Experiment Station,
Bulletin No. 20.

14. Variations in the Fat of Milk served to Customers
from Milk Cans. Ontario Agricultural. College, Bulletin
No. 16.

15. Effects of Delay in Creaming Milk. Maine Experiment
Station Report, 1890.

16. Effects of Delayed Setting. Wisconsin Experiment Sta-
tion, Bulletin No. 29.

17. Delay in Setting. See Creaming Article in Handbook
of Experiment Station Work.

18. Effects of Delay in Creaming Milk. Cornell University
Experiment Station, Bulletin No. 29.

19. Cream Raising by Dilution. Cornell University Experi-
ment Station, Bulletins Nos. 20 and 29.

20. Cream Raising by Dilution. Illinois Experiment Station,
Bulletins Nos. 12 and 18.

21. Cream Raising by Dilution. Vermont Experiment Sta-
tion, Fourth and Fifth Annual Reports.

22. Cream Raising by Dilution. Indiana Experiment Sta-
tion, Bulletin No. 44.

23. Cream Raising by Dilution. Article, Creaming of Milk,
in Handbook of Experiment Station Work.

24. Testing Cream and Milk. Maine Experiment Station,
Bulletin No. 4.

APPENDIX 169

25. Testing Cream by the Babcock Test. Connecticut Ex-
periment Station (New Haven), Eighteenth Annual Report.

26. The Babcock Test as a Basis for Payment in Cream-
gathering Creameries. Connecticut Experiment Station (New
Haven), Bulletin No. 119.

27. The Composition of Cream. Konig : Chemie der Mensch-
lichen und Genussmittel, Band II.

28. Test of Cream Separators. Cornell University Experi-
ment Station, Bulletins Nos. 66 and 105.

29. Test of Cream Separators. Pennsylvania Experiment
Station, Bulletins Nos. 20 and 21, Annual Report, 1895.

30. Report on Separators, Gravity, Creaming, etc. Iowa
Experiment Station, Bulletin No. 25.

31. Tests of Dairy Implements. North Carolina Experi-
ment Station, Bulletin No. 114.

32. Hand Power Cream Separators. Delaware Experiment
Station, Bulletin No. 27, Fifth Annual Report.

33. Cream Raising by the Cold Deep-setting Process. Min-
nesota Experiment Station, Bulletin No. 19.

34. Creaming of Milk. Article in Handbook of Experiment
Station Work.

35. Creaming Experiments. Babcock: Wisconsin Experi-
ment Station, Bulletin No. 29.

36. The Ripening of Cream. Conn : (Storrs) Connecticut
Experiment Station, Report, 1900.

37. Commercial Butter Cultures. Pennsylvania Experiment
Station, Bulletin No. 44.

38. Variations in Cream and Milk Tests. South Dakota
Experiment Station, Bulletin No. 73.

39. Cream Testing. Iowa Experiment Station, Bulletin No. 52.

40. A Modified Cream Test Bottle. Wisconsin Experiment
Station, Nineteenth Annual Report.

REFERENCES TO CHAPTER VII

1. Loss of Fat in Butter-making. Iowa Experiment Station,
Bulletin No. 11.

170 DAIRY CHEMISTRY

2. Loss of Fat in Butter-making, with increase in Lactation
Period. New York State Experiment Station Report, 1891.

3. Butter Production from Milk at Different Periods of
Lactation. Maine Experiment Station Report, 1889.

4. Loss of Fat in Butter-making. Article on Butter-making
in Handbook of Experiment Station Work.

5. Composition of the Slime from the Centrifugal Bowl.
Fleischrnann : Lehrbuch der Milch wirtschaft.

6. Butter- making. Fleischmann : Lehrbuch der Milchwirt-
schaft.

7. Churning and Butter-making. Gurler: American Dai-
rying.

8. Churning. Article in Handbook of Experiment Station
Work.

9. Churning Experiments. Iowa Experiment Station, Bul-
letin No. 22.

10. On the Churning Process and the Formation of Butter.
A. Jscher Kasserd : Milch Zeitung, No. 23, 1894.

11. The Churning Temperature of Sweet and Sour Cream.
New York State Experiment Station Report, 1889.

12. Tests of Box and Barrel Churns. Vermont Experiment
Station, Bulletin No. 27.

13. The Acidity of the Cream and the Yield of Butter. Illi-
nois Experiment Station, Bulletin No. 9.

14. Churning the Cream from Cows at Different Periods in
Lactation. Haecker : Hoard's Dairyman, 1894.

15. Butter-making. Powrian : La laitiere : Art de traiter
le lait, de fabrique le beurre et les principaux from ages.

16. The Composition of Butter. Minnesota Experiment
Station, Bulletin No. 19.

17. Composition of Butter. Wisconsin Experiment Station,
Annual Report, 1889.

18. Composition of Butter. Massachusetts State Station,
Annual Report, 1889.

19. Composition of Butter. Pennsylvania Experiment Sta-
tion, Annual Report, 1893.

APPENDIX 171

20. The Composition of Butter. Connecticut State Station,
Annual Report, 1892.

21. Composition of Sweet Cream Butter. West Virginia
Experiment Station, Annual Report, 1890.

22. Composition of Sweet and Sour Cream Butter. Iowa
Experiment Station, Bulletin No. 18.

23. The Composition of Butter from Different Countries.
Konig : See reference No. 6.

24. Abnormal Amounts of Water in Butter — Legal Cases.
Current numbers of the Analyst.

25. The Yellow Coloring Matter of Milk. Blyth: Foods,
their Composition and Analysis.

26. The Proteids of Butter in Relation to Mottled Butter.
New York Experiment Station (Geneva), Bulletin No. 263.

27. Heated Milk for Butter-making. Pennsylvania Experi-
ment Station, Bulletin No. 45.

28. Paying for Separator Cream at the Creamery. Vermont
Experiment Station, Bulletin No. 100.

29. Salt in Butter. Iowa Experiment Station, Bulletin
No. 80.

30. Moisture Content of Butter and Methods of controlling
it. Iowa Experiment Station, Bulletin No. 76.

31. Keeping Qualities of Butter. Iowa Experiment Station,
Bulletin No. 71.

32. Influence of Certain Conditions in Churning on the
Amount of Water in Butter. Iowa Experiment Station, Bul-
letin No. 52.

33. Effect of Salt and the Size of Butter Granules on the
Water Content of Butter. Wisconsin Experiment Station,
Twentieth Annual Report.

34. Salt Crystals on the Surface of Butter. Wisconsin Ex-
periment Station, Twentieth Annual Report.

35. Score of Butter, as affected by the Size of Package.
Wisconsin Experiment Station, Twentieth Annual Report.

36. Composition of Dairy Salt. Wisconsin Experiment
Station, Twentieth Annual Report.

172 DAIRY CHEMISTRY

37. Calculating Dividends for Milk and for Cream at the
Same Factory. Wisconsin Experiment Station, Seventeenth
Annual Report.

REFERENCES TO CHAPTER VIII

1. The Behavior of Anthrax Bacilli in Milk. O. Caro:
Chemisches Centralblatt, 1894, 1, 164.

2. Behavior of Cholera Germs in Milk. Heim : Milch
Zeitung, 21, 1892.

3. Vitality of Tuberculosis Bacilli. Forster and Mann :
Milch Zeitung, 22, 1894.

4. Tuberculosis and Public Health, etc., Law. New York
Experiment Station, Bulletin No. 65.

5. Typhoid Fever disseminated through the Milk Supply.
Russell: Science, November 15, 1895.

6. Diseases conveyed by Milk. B. Lee : Agriculture of Penn-
sylvania, 1894.

7. Milk as a Source of an Epidemic of Typhoid Fever.
Schmidt : Milch Zeitung, 23, 1894.

8. Danger from consuming the Milk of Sick Cows. F. Baum :
Archiv wissech und praktische Thierheilkunde, 18, Heft 384.

9. On Ptomaines in Milk. V. Maleiichini : Zeitschrift
Nahrungsmittel Untersuchen und Hygiene.

10. The Care of Milk for Cheese Factories and Creameries.
Ontario Agricultural College, Bulletin No. 44.

11. Cleanliness in Handling Milk. North Dakota Experi-
ment Station, Bulletin No. 21.

12. Poisonous Milk and Milk Panics. Wanklyn : Milk Analy-
sis.

13. Milk Inspection affecting Death Rate of Children.
Milch Zeitung, 9, 24, and 349.

14. Citric Acid as a Normal Constituent of Cow's Milk.
Henkel : Die Landwirtschaftlichen Versuchs-Stationen, 39.

15. Citric Acid in Milk. Abstract. Sixth Annual Conven-
tion (1889), Association of Official Agricultural Chemists,

APPENDIX 173

16. The Composition, Creaming, and Churning of Colostrum.
Vermont Experiment Station, Fifth Annual Report.

17. Composition of Colostrum Milk. Kruger : Molkerei
Zeitung, 1892.

18. The Chemical Composition of Cow's Colostrum. Blyth :
Foods, their Composition and Analysis.

19. Nature of the Colostrum Cells. Heidenhain : Handbuch
der Physiologie.

20. Tyrotoxicon. Vaughan : Michigan State Board of
Health Report, 1886.

21. The Chemistry of Tyrotoxicon, and its Action on Lower
Animals. Vaughan: Analyst, 13, 141.

22. Fibrin in Milk. Proceedings of the Society for the Pro,
motion of Agricultural Science, 1888.

23. Fibrin in Milk, and its Effects upon Creaming. Wiscon-
sin Experiment Station, Bulletin No. 18.

24. Gases in Milk. Kirchner: Handbuch der Milchwirt-
schaft.

25. Gases in Milk. Blyth : Foods, their Composition and
Analysis.

26. Gas-producing Organism. Baumann : Molkerei Zeitung,
7, 1893.

27. Blue Milk, Red Milk, Brownish Red Milk, Bitter-milk.
Lugger : Minnesota Experiment Station, Annual Report, 1893.

28. Creaming and Aerating Milk. Cornell University Ex-
periment Station, Bulletin No. 39.

29. Aeration of Milk. Vermont Experiment Station, Sixth
Annual Report.

30. Aeration of Milk for Butter Production. Indiana Ex-
periment Station, Bulletin No. 44.

31. "Soapy" Milk, and the Sources of Bacteria in Milk.
Weigmann and Zirn : Milch Zeitung, 23, 1893.

32. The Care and Handling of Milk. Michigan Experiment
Station, Bulletin No. 221.

33. Aeration of Milk. Michigan Experiment Station,
Special Bulletin No. 16.

174 DAIRY CHEMISTRY

34. Ropiness in Milk. Michigan Experiment Station,
Bulletin No. 140.

35. Economical Methods for improving the Keeping Quali-
ties of Milk. Maryland Experiment Station, Bulletin No. 88.

36. Classification of Dairy Bacteria. (Storrs) Connecticut
Experiment Station Report, 1899.

37. The Comparative Growth of Different Species of Bacte-
ria in Normal Milk. (Storrs) Connecticut Experiment Station
Report, 1901.

38. Efficiency of a Covered Pail in excluding Filth and Bac-
teria from Milk. (Storrs) Connecticut Experiment Station
Report, 1901.

39. Dairy Conditions and Suggestions for their Improve-
ment. Illinois Experiment Station, Bulletin No. 84.

40. Methods of controlling Contamination of Milk during
Milking. Nebraska Experiment Station, Bulletin No. 87.

41. Ropiness in Milk and Cream. New York (Cornell) Ex-
periment Station, Bulletins Nos. 165 and 195.

42. Investigations concerning the Germicidal Action in Cow's
Milk. New York (Cornell) Experiment Station, Bulletin No. 197.

43. The Care and Handling of Milk. New York (Cornell)
Experiment Station, Bulletin No. 203.

44. Stagnant Water Germs in Milk. Oregon Experiment
Station, Bulletin No. 71.

45. Investigations of Methods of Milking. Wisconsin Ex-
periment Station, Twentieth Annual Report.

46. Thermal Death Point of Tubercle Bacilli under Com-
mercial Conditions. Wisconsin Experiment Station, Seven-
teenth Annual Report.

47. Outbreak of Anthrax Fever traceable to Tannery Refuse.
Wisconsin Experiment Station, Seventeenth Annual Report.

48. The Effect of Different Stable Temperatures upon the
Milk Yield of Dairy Cows. Wisconsin Experiment Station,
Twenty-first Annual Report.

49. Infectiousness of Milk from Tubercular Cows. Wiscon-
sin Experiment Station, Twenty-first Annual Report.

APPENDIX 175

50. Effect of Short Periods of Exposure to Heat on Tubercle
Bacilli in Milk. Wisconsin Experiment Station, Twenty-first
Annual Report.

REFERENCES TO CHAPTER IX

1. The Content of Pepton in Milk. Schmidt and Miilheim :
Reported in Konig, Chemie der Menschlichen Nahrungs- und
Genussmittel, Band II.

2. The Proteids of Milk. Halliburton: Journal of Physi-
ology, 2, 459.

3. The Chemistry of Casein and the Theory of the Curdling
Action of Rennet. G. Courant : Abstract in Experiment Sta-
tion Record, 5.

4. Three Forms of the Casein in Milk. Struve : Journal fur
practische Chemie, 1884.

5. The Action of Rennet on Milk. Hammarsten : Popular
Form given in Milk, its Nature and Composition by Aikman.

6. The Curdling of Milk by Ferments which render the Milk
Alkaline. Warrington : Journal of the Chemical Society
(England), 1888.

7. A Study of the Coagulating Power of Commercial Ren-
nets. Patrick : Abstract in Experiment Station Record, 5, 100.

8. The Isolation of Rennet from Bacteria Cultures. Conn :
(Storrs) Connecticut Experiment Station, Fifth Annual Report.

9. The Nature of Rennet. Russell : Outlines of Dairy Bacte-
riology.

10. Beitrage zur Erfarschung der Easerif ange. Baumann :
Die Landwirtschaftlichen Versuchs-Stationen, 42, et seq.

11. Cheese-making, Directions for. Iowa Experiment Sta-
tion, Bulletins Nos. 19 and 21.

12. Cheese Factory Notes. Wisconsin Experiment Station,
Annual Report, 1892.

13. Cheese-making. Article relating to Recent Work on
Dairying. Allen : Experiment Station Record, 5. Nos. 10 and
11.

14. Cheddar Cheese-making. Decker.

176 DAIEY CHEMISTRY

15. A, B, C in Cheese-making. Monrad.

16. Cheese-making in Switzerland. Monrad.

17. The Manufacture and Production of Cheese. Alvord:
United States Department of Agriculture, Year Book, 1895.

18. The Manufacture of Some Fancy Brands of Cheese.
Luschinger : Report Sixteenth Annual Convention of the Min-
nesota Dairy Association.

19. The Changes during the Ripening of Cheese. Iowa Ex-
periment Station, Bulletin No. 24.

20. Salt and its Preventing the Swelling of Cheese. Yon
Freudenreich : Abstract in Experiment Station Record, Vol. V,
p. 921.

21. The Forms of the Nitrogen Compounds in Cheese.
Stutzer: Reported in Wiley's Agricultural Analysis, Vol. III.

22. Manufacture of Sweet Curd Cheese. Haecker : Minne-
sota Experiment Station, Bulletin No. 35.

23. Experiments in Cheese-making. Minnesota Experiment
Station, Bulletin No. 19.

24. Cheese-making, Distribution of Ingredients, and Losses
of Fat. Handbook of Experiment Station Work.

25. Losses in Cheese-making. Vermont Experiment Station,
Fifth Annual Report.

26. Experiments in Cheese-making. Ontario Agricultural
College Report, 1894.

27. Losses of Milk Solids in Cheese-making, and the Addi-
tion of Crea'm to the Milk. Minnesota Experiment Station,
Bulletin No. 19.

28. Determining the Amount of Fat in Cheese by the Bab-
cock Test. Wisconsin Experiment Station, Bulletin No. 36.

29. Composition of Different Kinds of Cheese made in Dif-
ferent Countries. Kbnig: Chemie der Menschlichen Nah-
rungs- und Genussmittel, Band II.

30. The Composition of English Cream Cheese. (Cream
added to the Milk.) P. Vieth : Milch Zeitung, 1887, 120.

31. The Composition of Milk, Cheese, and Whey, in Relation
to One Another. Ontario Agricultural College Report, 1894.

APPENDIX 177

32. The Composition of Cheese made from Cream. Hassall :
Foods, Adulterations and the Methods for their Detection.

33. The Composition of Cheese. Connecticut State Experi-
ment Station Report, 1892.

34. Ripen ing of Cheese. Adametz : Berlin. Landwirtschaffr-
licher Jahrbiicher, 1889.

35. The Abnormal Ripening of Cheese. Adametz: Milch
Zeitung, Nos. 21 and 22, 1892 and 1893.

36. An Aromatic Bacillus in Cheese. Iowa Experiment Sta-
tion, Bulletin No. 21.

37. Influence of Cold Curing on the Quality of Cheddar
Cheese (Second Paper). Wisconsin Experiment Station, Nine-
teenth Annual Report.

38. Influence of Temperatures approximating 60° F. on the
Development of Flavor in Cold-cured Cheese. Wisconsin Ex-
periment Station, Nineteenth Annual Report.

39. Investigations relating to the Manufacture, Curing, and
Handling of Cheese. See Wisconsin Experiment Station, Sev-
enteenth, Eighteenth, Nineteenth, Twentieth, and Twenty -first
Annual Reports.

40. Investigations relating to the Manufacture, Curing, and
Handling of Cheese. See New York State Agricultural Ex-
periment Station, Bulletins Nos. 37, 43, 45, 46, 56, 65, 68, 110,
184, 203, 207, 214, 215, 219, 231, 233, 234, 236, 237, 245, and 261.

REFERENCES TO CHAPTER X *

1. The Composition of the Milk of the Mare, Ewe, Goat,
Sow, etc. Konig: Chemie der Menschlichen Nahrungs-und
Genussmittel, Band II.

2. Composition of Mule's Milk. Aubert and Colby : Journal
of Analytical and Applied Chemistry, 7, No. 6.

3. Analyses of Skim-milks. Wisconsin Experiment Station,
Annual Report for 1889.

4. The Composition of Whey. New York State Experiment
Station, Bulletins Nos. 37, 43, 45, 46, 47.

178 DAIRY CHEMISTRY

5. The Composition of Buttermilk. Maine Experiment Sta-
tion, Annual Report for 1890.

6. The Composition of Skim-milk and Whey. C. B. Cochran :
Journal of the American Chemical Society, 15, No. 6.

7. The Feeding Value of Skim-milk. Massachusetts State
Experiment Station, Annual Reports for 1884, 1885, 1886, 1887,
1888, 1889, etc.

8. The Effects of Skim-milk in a Ration for Pigs. Maine
Experiment Station, Annual Report for 1889.

9. The Feeding Value of Skim-milk. Vermont Experiment
Station, Bulletin No. 18.

10. The Effects of Skim-milk in a Ration for Pigs. New
Hampshire Experiment Station, Bulletin No. 11.

11. The Comparative Feeding Value of Skim-milk and But-
termilk. Wisconsin Experiment Station, Annual Report for
1886.

12. The Comparative Feeding Value of Buttermilk and Skim-
milk. Massachusetts State Experiment Station, Annual Re-
ports for 1884, 1885.

13. The Comparative Value of Sweet and Sour Skim-milk.
Vermont Experiment Station, Annual Report for 1891.

14. The Feeding Value of Whey. Wisconsin Experiment
Station, Bulletin No. 27.

15. The Average Composition of Skim-milk, Buttermilk,
and Whey. Konig : Chemie der Menschlichen Nahrungs- und
Genussmittel, Band II.

16. Influence of Temperature on Skim-milk Tests. Wiscon-
sin Experiment Station, Seventeenth Annual Report.

REFERENCES TO CHAPTER XI

1. A New Milk Test (Beimling's). Vermont Experiment
Station, Bulletin No. 24.

2. Determining the Fat in Milk. Leffmann and Beam : Ana-
lyst, 18, 193.

3. Acid Butyrometer. Gerber : Chemiker Zeitung, 16, 839.

APPENDIX 179

4. The Lactocrite. United States Department of Agricul-
ture, Division of Chemistry, Bulletin No. 13.

5. The Lactocrite. Biedermann's Centralblatt, 17, 627.

6. A New Method for detecting the Fat in Milk. Short:
Wisconsin Experiment Station, Bulletin No. 16.

7. The Determining of Fat in Milk by Short's Method.
Journal of Analytical Chemistry, 2, Part 4.

8. Cochran's Method for determining the Fat in Milk.
Journal of Analytical Chemistry, 3, Part 4.

9. A Description of Cochran's Method for determining the
Fat in Milk. Cornell University Experiment Station, Bulletin
No. 17.

10. Methods of manufacturing Butter Substitutes ; Whole-
someness of Artificial Butter; The Adulteration of Butter,
including References and Methods of Analysis. Wiley : United
States Department of Agriculture, Division of Chemistry:
Foods and Food Adulterants, Part First, Dairy Products.

11. Extent and Character of Food Adulterations. Wedder-
burn: United States Department of Agriculture, Division of
Chemistry, Bulletins Nos. 25 and 32.

12. The Analysis and Adulteration of Foods. Part III.
James Bell.

13. The Adulteration of Butter and Cheese. Blyth : Foods.
Their Composition and Analysis.

14. Influence of Preservatives upon the Food Value of Milk.
Maryland Experiment Station, Bulletin No. 86.

15. State and Municipal Milk Legislation. Delaware Ex-
periment Station, Bulletin No. 43.

16. Butter, its Composition, Artificial Imitation, and Adul-
terants. North Carolina Experiment Station, Bulletin No. 166.

17. Process Butter. A Dairy Fraud. Utah Experiment
Station, Bulletin No. 79.

18. Inspection of Milk Tests and Feeding Stuffs. Vermont
Experiment Station, Bulletin No. 68.

19. Official Tests of Dairy Cows, 1903-4. Wisconsin Experi-
ment Station, Twenty-first Annual Report.

180 DAIRY CHEMISTRY

20. Reports of the following State Dairy and Food Commis-
sioners : Minnesota, Michigan, Illinois, North Dakota, Connec-
ticut, Kentucky, and other states.

21. Dairy and Milk Inspection. Alabama Experiment Sta-
tion, Bulletin No. 97.

REFERENCES TO CHAPTER XII

1. The Action of Heat on Milk. Richmond: Analyst, June,
1893.

2. The Sterilization of Milk on a Large Scale. Hesse : Zeit-
schrift fur Hygiene, 1890, 85.

3. The Chemical and Physical Changes attendant upon the
Sterilization of Milk. Leeds : Journal of the American Chem-
ical Society, 13, No. 1. ,

4. Methods of Milk Preservation. Weigmann.

5. The Pasteurization of Skim-milk. Lunde : Abstract in
Experiment Station Record, 4, 383.

6. Methods of Sterilizing and Pasteurizing Milk. Review of
Kinds of Apparatus Used. Allen : Article in Recent Work
on Dairying. Experiment Station Record, 5, 1051.

7. Pasteurization and Milk Preservation, with a Chapter on
Selling Milk. Monrad.

8. Preservation of Milk. Blyth : Foods.

9. Experiments in preserving Milk Samples. Newman n :
Milch Zeitung, 22, 93.

10. Preservatives and their Importance in Dairying. Kruger :
Molkerei Zeitung, 1892, No. 34.

11. The Composition of, and Objections to the Use of, Preserv-
atives in Milk. Current numbers of the Analyst, 1890-91, etc.

12. Compilation of Analyses of Condensed Milks. Konig:
Chemie der Menschlichen Nahrungs- und Genussmittel, Band II.

13. Variations in the Composition of Milk during Delivery.
Vieth : Analyst, 1891 and 1892.

14. Standard Milk. New Hampshire Experiment Station,
Bulletin No. 103.

APPENDIX 181

15. The Value of a Pound of Milk Solids in Milk Poor and
Rich in Fat Content. (Storrs) Connecticut Report, 1904.

16. The Comparative Digestibility of Raw, Pasteurized, and
Cooked Milk. Maryland Experiment Station, Bulletin No. 77.

17. Standard Milk and Cream. Illinois Experiment Station,
Bulletin No. 74.

18. City Milk Supply. Illinois Experiment Station, Bulle-
tin No. 92.

19. Domestic Pasteurizing Methods and the Care of Milk in
the Home. New Jersey Experiment Station, Bulletin No.
152.

20. The Efficiency of a Continuous Pasteurizer at Different
Temperatures.

21. Pasteurization of Skim Milk. Wisconsin Experiment
Station, Twentieth Annual Report.

22. Pasteurization as applied to Butter-making. Wisconsin
Experiment Station, Twentieth Annual Report.

23. Preservation of Milk for Direct Use by Pasteurization.
Wisconsin Experiment Station, Twentieth Annual Report.

24. On the Increased Resistance of Bacteria in Milk Pasteur-
ized in Contact with the Air. Wisconsin Experiment Station,
Eighteenth Annual Report.

25. Estimation of Fat in Sweetened Condensed Milk by the
Babcock Test. Wisconsin Experiment Station, Seventeenth
Annual Report.

26. Effect of Pasteurization and Sterilization on the Viscos-
ity and Fat Globules of Milk and Cream. Wisconsin Experi-
ment Station, Twentieth Annual Report.

27. Restoration of the Consistency of Pasteurized Milk and
Cream. Wisconsin Experiment Station, Twentieth Annual
Report.

REFERENCES TO CHAPTER XIII

1. The Composition of Butter-fat as affected by Food. New
Hampshire Experiment Station, Bulletins Nos. 16 and 18.

2. Effect of Food upon the Quality of Butter. Article on

182 DAIRY CHEMISTRY

Butter-making in Handbook of Experiment Station Work.
United States Department of Agriculture.

3. Effect of Cotton-seed Meal on the Composition of Butter.
Texas Experiment Station, Bulletins Nos. 11 and 14.

4. Effect of Cotton-seed Meal on Butter. Alabama (College)
Experiment Station, Bulletin No. 25.

5. Injurious Effects of Certain Plants on Milk and its Prod-
ucts. Milch Zeitung, 1892, 46.

6. The Effect of Peanut Cake and Cotton-seed Cake on the
Fat Content of Milk. Backaus : Journal fur Landwirtschaft,
41,4.

7. Effects of Different Kinds of Food upon Butter. A.
Mayer: Die Landwirtschaftlichen Versuchs-Stationen, 41.

8. Influence of Food upon the Qualities of Butter Fat.
Frear : Agricultural Science, 1833, 7.

9. Transmission of Nitrates to Milk. Richmond : Analyst,
1893, 279.

10. On the Effect of feeding Fat to Cows. Wing : Cornell
University Experiment Station, Bulletin No. 92.

11. Recovery of the Food Ingredients in the Milk. New
York State Experiment Station Report, 1891.

12. Effects of Rye Pasture on the Taste of Milk. Breeder's
Gazette, 26, 203, 220, 239.

13. Transmission of Substances from Food to Milk. Froh-
ner: Zeitschrift fur Fleisch und Milch Hygiene, 10, 1.

14. Influence of the Quality of Food upon the Economy of
Milk and Butter Production. Pennsylvania Experiment Sta-
tion, Annual Report for 1895.

15. Quality of Butter as influenced by Food. Pennsylvania
Experiment Station, Bulletin No. 17.

16. Influence of Roots and Silage on the Composition of
Milk. Pennsylvania Experiment Station Report, 1890.

17. The Quality of Butter as affected by Food. Maine Ex-
periment Station Report, 1891.

18. Simple Methods of determining Milk Fat (Short's and
Cochran's). Pennsylvania Experiment Station, Bulletin No. 12.

APPENDIX 183

19. Failyer and Willard's Method for determining the Fat
in Milk. Journal of Analytical Chemistry, 3, Part 3.

20. Parsons' Method for determining the Fat in Milk.
Journal of Analytical Chemistry, 3, Part 3.

21. The Oil Test for Cream. Wis. Ex. Sta-., Bui. 12.

22. Patrick's Method of testing Milk. Iowa Experiment
Station, Bulletins Nos. 8 and 11.

23. Milk Tests, Comparison of Simple Methods. Illinois
Experiment Station, Bulletins Nos. 10 and 14.

24. Comparison of Various Methods for testing Milk. West
Virginia Experiment Station, Third Annual Report.

25. Milk Tests. Handbook of Experiment Station Work,
United States Department of Agriculture.

26. Feser's Lactoscope. Die Lands. Vers.-Stat., 27, 2, 135.

27. The Lactoscope. Biedermann's Centralblatt, 9, 302.

28. Effects of Feed upon the Quality of Milk. Iowa Experi-
ment Station, Bulletins Nos. 13, 14, 16, 17.

29. A Study of Milk Secretion. (Storrs) Connecticut Ex-
periment Station Report, 1904.

30. The Effect of Silage on the Acidity of Milk. (Storrs)
Connecticut Experiment Station Report, 1904.

31. Weedy Flavors in Butter. California Experiment Sta-
tion, Annual Report, 1903.

32. Studies in Milk Secretion. New York (Cornell) Experi-
ment Station, Bulletins Nos. 152 and 169.

33. The Relation of Food to Milk Fat. New York (CorneU)
Experiment Station, Bulletin No. 173.

34. Methods of Milking. New York (Cornell) Experiment
Station, Bulletin No. 213.

35. Record of an Attempt to increase the Fat in Milk by
Means of Liberal Feeding. New York (Cornell) Experiment
Station, Bulletin No. 222.

36. The Source of Milk Fat. New York State Experiment
Station, Bulletin No. 132.

37. Flavors in Milk and its Products. New York State
Experiment Station, Bulletin No. 183.

184 DAIEY CHEMISTRY

38. Fat in Milk from Starch in Food. New York State Ex-
periment Station, Bulletin No. 197.

39. The Immediate Effect on Milk Production of Changes in
the Ration. New York State Experiment Station, Bulletin
No. 210.

40. The Effect of Food on Economic Dairy Production.
Texas Experiment Station, Bulletin No. 47.

41. A Study of Butter Increasers. Iowa Experiment Station,
Bulletin No. 52.

EEFERENCES TO CHAPTER XIV

[NOTE. — The literature on this subject is so extensive that only a
few typical references are given. For references to special topics, as
the characteristic value of any food for milk production, the student is
referred to the card catalogue index issued by the United States De-
partment of Agriculture, Office of Experiment Stations. In calculat-
ing rations, it is best to use the figures given for the average composi-
tion of American feeding stuffs, except in those cases where extended
special investigations have been made of the fodders of a state by an
Experiment Station.]

1. Manual of Cattle Feeding. Armsby.

2. Landwirtschaftliche Fiitterungslehre. Ernil Wolff.

3. Feeding Farm Animals. Allen : Office of Experiment
Stations, United States Department of Agriculture, Farmer's
Bulletin No. 22.

4. A Compilation of Analyses of American Feeding Stuffs.
Jenkins and Winton: Office of Experiment Stations, United
States Department of Agriculture, Bulletin No. 38.

5. One Hundred American Rations for Dairy Cows. Woll :
Wisconsin Experiment Station, Bulletin No. 38.

6. Investigation in Milk Production ; Feeding Dairy Cows.
Minnesota Experiment Station, Bulletins Nos. 71 and 79.

7. Feeding Experiments with Dairy Cows. Alabama Ex-
periment Station, Bulletin No. 114.

8. Feed and Care of the Dairy Cow. Kansas Experiment
Station, Bulletin No. 81,

APPENDIX 185

9. Ration Tests for Dairy Cows ; the Best Week in a Cow's
Lactation Period. Nebraska Experiment Station, Bulletin
No. 76.

10. Discussion of the Amount of Protein required in the
Ration for Dairy Cows. (Storrs) Connecticut Experiment
Station Report, 1904.

11. A Study of Rations fed to Milch Cows in Connecticut.
(Storrs) Connecticut Experiment Station Report, 1900.

12. A Study of Rations fed to Milch Cows. (Storrs) Con-
necticut Experiment Station Report, 1901.

13. Economic Feeding of Milch Cows. (Hatch) Massachu-
setts Experiment Station, Bulletin No. 39.

14. Rations for Milch Cows. Rhode Island Experiment
Station, Bulletin No. 77.

15. Individuality of Cows. Rhode Island Experiment Sta-
tion, Bulletin No. 80.

16. Feeding Dairy Cows. Michigan Experiment Station,
Bulletin No. 149.

INDEX

Abnormal creams, churning of, 65.

Absorption of odors by milk, 78.

Acid, adding of, to milk, 16;
butyric, 31; disposal of, waste,
23; handling of, 23; lactic,
production of, 44; measure, 17;
strong, 22 ; weak, 22.

Acidity, calculation of, in milk,
47; of cream, 49; of milk, 47.

Acids, fatty, 31 ; volatile fatty, 33.

Adulteration of butter, 112; of
cream, 58 ; of milk, 41.

Aerating milk, 86.

Albumin, 5, 89; coagulation of , 5.

Alkali, standard, 47.

Alkaline tablets, 48.

Apparatus, care of, 28.

Ash, 6.

Ash of foods, 132.

Babcock's formula, 40.

Babcock test, 13-28 ; reliability of,

13.

Balanced rations, influence of, 129.
Bartlett test bottle, 51.
Boric acid in milk, 113.
Butter, adulterations of, 112 ; color,

70 ; composition of, 69 ; fats, 29 ;

hard, 29; judging, 73; melting

point, 34; renovated, 113; soft,

29; working of , 66.
Buttermilk, composition of, 67.
Butters, hard, production of, 126 ;

soft, production of, 127.
Butyric acid, 31.
Butyrin, 31.
By-products of milk, 107.

Calculation of acidity in milk, 47;
of rations, 139.

Calibration of test bottles, 19.

Caloric value of foods, 136.

Carbohydrates, of foods, 134.

Care of dairy utensils, 80 ; of milk
rooms, 81; of test bottles and
apparatus, 28.

Casein, 5, 89.

Centrifugal action, 21.

Centrifuge, 17 ; action of, 21 ; speed-
ing of, 20.

Cheddar cheese, 92.

Cheese, composition of, 101 ; differ-
ent kinds of, 104; filled, 114;
making, 88-106; quick-ripening,
97 ; slow-curing, 97 ; skim milk,
114; testing of, 100; yield of
milk, 99.

Churning, 62; abnormal creams,
65; exhaustive, 65; and grain
of butter, 65; influence of food
on, 64; influence of ripeness of
cream on, 63 ; influence of season
on, 64; influence of temperature
on, 64 ; thick and thin cream, 64.

Cleaning glassware, 27.

Coarse fodders, influence of, in ra-
tions, 127.

Cochrane, method of, 117. -

Cold curing of cheese, 98.

Cold deep setting, 55.

Color of milk, 70.

Colostrum milk, 83.

Composite sample, 24.

Composition of butter, 69 ; of but-
termilk, 67; of fats, 29; of
fodders, 148-149; of grains, 147;
of milk, 1-12; of milk, individ-
ual cows, 8, 9.

Condensed milk, 123.

Corn, influence of, on butter, 126.

187

188

INDEX

Cost and value of foods, 144.

Cottage cheese, 105.

Cotton-seed meal, influence of, on
butter, 126.

Cream, 49-61 ; acidity of, 49 ; adul-
teration of, 59 ; amount of, from
milk, 50; composition of, 50;
heating of, 59; raising by dilu-
tion, 61 ; ripening of, 59 ; separa-
tors, 54 ; test bottle, 51 ; testing,
51; thick, 50; thin, 50; viscosity,
58 ; weighing of, for testing, 53.

Creaming, gravity process, 54 ; in-
fluence of delay, 60 ; methods of,
54 ; milk, temperature of, 58 ; of
mixed milks, 61.

Crude fat, 135.

Crude fiber, 135.

Cultures, 59.

Curd, grinding of, 94.

Curd knife, 93.

Curing of cheese, 97.

Dairy laws, 117.

Dairy salt, 66.

Dairy utensils, care of, 80.

Delay in creaming, 60.

Detection of the skimming of milk,

39; of the watering of milk,

69.

Determination of lactic acid, 45.
Digestible nutrients of foods, 138.
Dilution, cream raising by, 61.
Disease and foul air, 79.
Dividends, 72.
Dry matter, 132.

Edam cheese, 105.

Enzymes and cheese ripening, 97.

Exhaustive churning, 65.

Fat, feeding of, in ration, 126 ; glob-
ules, 4 ; size of globules, 4 ; losses
of, in skim milk, 57 ; losses of, in
butter making, 67; reading of,
in test, 18.

Fats, composition of, 29; food
value, 32; melting point, 34;
milk, 3; present in butter, 29;
properties of, 29-34; saponifica-
tion of, 33; specific gravity, 34.

Fatty acids, 31.

Feeding of dairy stock, 144 ; skim
milk, 107 ; value of whey, 100.

Fermentation of milk sugar, 43.

Ferments, lactic acid, 43.

Fibrin, 86.

Filled cheese, 114.

First milk, 10.

Flavors imparted by foods, 128.

Fodders, coarse, influence of, in
rations, 127.

Food value of milk, 123.

Foods, caloric value of, 136; car-
bohydrates, 134; crude fat of,
135; crude fiber of , 135 ; influence
of, on butter, 127, 128 ; selection
of, for ration, 137; uses of, by
body, 131.

Fore milk, 10.

Formalin in milk, 115.

Formula, Babcock's, 40; Hehner
& Richmond's, 41.

Foul air and disease, 79.

Frozen milk, sampling of, 26.

Gases in milk, 86.

Gerber's Butyrometer, 116.

Germ content of milk, 77.

Glassware, cleaning of, 27.

Globules, fat, 4.

Gluten meal, influence of, on

butter, 127.
Glycerine, 31.
Gouda cheese, 105.
Grain of butter, influenced by

churning, 65.
Gravity creaming, 54.

Hard butters, production of, 126.

Heating of cream, 59.

Hehner & Richmond's formula, 41.

INDEX

189

Illegal milk, 41.

Indicator, 46.

Influence of foods on quality of

butter, 127, 128 ; of water on milk

supply, 83.
Iodine absorption, 33.

Judging butter, 73.

Lactic acid, determination of, 45;
ferments, 43 ; production of, 44.
Lactocrite, 116.
Lactometer, its use, 35-42.
Lactose, 5.
Laws, Dairy, 117.
Limburger cheese, 104.
Loss of fat in skim milk, 57.
Losses of fat in butter making, 67.

Maintenance ration, 131.

Mare's milk, 111.

Market milk, 119-130.

Measuring acid, 16 ; milk, 15.

Melting point of fats, 34.

Method of cheese making, 93-94.

Methods of creaming, 54.

Milk, absorption of odors by, 78;
acidity of, 47; ash, 6; as hu-
man food, 123 ; by-products, 107 ;
changes during transportation,
120; cheese, yield of, 99; color
of, 70; complexity of composi-
tion, 1; composition of, 1-10;
composition of, individual cows,
8-9; condensed, 123; contami-
nated by soil, 78; fats, 3; from
diseased animals, 76; gases
in, 86; germ content, 77; il-
legal, 41 ; influence of storage
in stables on, 77; mixing of
samples, 14; pails, washing of,
80; pasteurizing of, 121; pipette,
15 ; proteids, 88 ; rooms, care of,
81 ; sanitary condition of, 75-87 ;
secretion, 125; serum,!; solids,
2 ; solids, calculation of, 40 ; spe-

cific gravity, 36; sterilized, 121;
sugar, 7; sugar, fermentation
of, 43; supply, influence of tu-
berculosis, 76; testing, 13-28;
testing, importance of, 13; water
in, 2; yields, 9; urea in, 76.

Nutrients, 131.
Nutritive ratio, 137.

Oats, influence of, on butter, 127.
Oleomargarine, 112 ; tests for, 112.
Organic matter of foods, 133.
Overruns, 71.

Palmitin, 31.
Pasteurizing milk, 121.
Pipette, milk, 15.
Potassium bichromate, 24.
Preservatives in milk, 113.
Proteids of foods, 133 ; of milk, 88.

Quick ripening of cheese, 97.

Ratio, nutritive, 137.
Ration, calculation of, 139.
Rational feeding, 131-146.
References, 161-185.
Rennet, 90 ; test, 91.
Renovated butter, 113.
Review questions, 151-160.
Ripening of cream, 59.
Roots, value of, in ration, 142.
Roquefort cheese, 105.

Salt, dairy, 66.

Samples, mixing of milk, 14.

Sampling frozen milk, 26; milk,

14.

Sanitary condition of milk, 75-87.
Saponification of fats, 33.
Secretion of milk, 125.
Selection of foods for ration, 137.
Separators, efficiency of, 57.
Separator slime, 57.
Serum, milk, 1.

190

INDEX

Serum solids, 11.

Sheep's milk, 111.

Short, method of, 116.

Silage, influence of, on butter, 128.

Skim-milk cheese, 114 ; feeding of,
107.

Skimming, detection of, 39.

Skim milk, testing of, 26.

Slow-curing cheese, 97.

Soft butters, production of, 127.

Soil contamination of milk, 78.

Solids, milk, 2; in milk, calcula-
tion of, 40 ; not fat, 11.

Sow's milk, 111.

Specific gravity of fats, 34; of
milk, 36 ; of skim milk, 37.

Stables, sanitary condition of, 77 ;
storing milk in, 77; ventilation
of, 79.

Standard alkali, 47; ration, 138.

Stearin, 31.

Sterilizing milk, 121.

Stilton cheese, 104.

Strippings, 10.

Sugar, 7.

Sulphuric acid, 22.

Sweet and sour cream, churning of,
64.

Swiss cheese, 104.

Tables of composition of foods,
147-149 ; for correcting lactome-
ter readings, 150.

Tablets, alkaline, 48.

Temperature of creaming milk, 58;
of churning, 64; influence of, on
lactometer, 37.

Test, rennet, 91.

Test bottles, 17; calibration of,

19; care of, 28; for cream, 51;

for skim milk, 26 ; whirling of,

18.
Testing cheese, 100; cream, 51;

milk, 12-28; importance of

milk, 13 ; skim milk, 26 ; whey,

102.

Tests for oleomargarine, 112.
Thick and thin cream, churning of,

64.
Transportation of milk, changes

during, 120.

Tuberculosis and milk supply, 76.
Tyrotoxicon, 85.

Urea in milk, 76.

Use of pipette, 15.

Uses of food by body, 131.

Value and cost of foods, 144.
Ventilation of stables, 79.
Viscosity of cream, 58.
Volatile fatty acids, 33.

Water, addition of, to test bottles,
18; in butter, 69; influence of,
on milk supply, 83; hi milk, 2.

Watering of milk, detection of,
39.

Weighing cream for testing, 52.

Wheat by-products, influence of,
on butter, 127.

Whey, testing of, 102; value for
feeding, 100.

Whirling test bottles, 18.

Winton test bottle, 51.

Working butter, 66.

Yields, milk, 9.

The Chemistry of Plant and Animal Life

By HARRY SNYDER

Professor of Agricultural Chemistry, University of Minnesota

Cloth i2mo $1.25 net

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the composition of plant and animal bodies, the chemistry of
the plant and of its food and growth, the chemistry of human
foods and animal nutrition, the digestibility and value of foods,
and the laws governing their economic use. A few topics of
an industrial nature, but closely related to plant and animal life,
are also included.

" It has been the aim throughout to present the topics in such
a way that they would be easily understood, and to develop the
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