University of Alberta Librai
0 1620 3416684 1
GLUTEN QUALITY AND THE EFFECT Off DILUTION
OF WHEAT FLOURS WITH STARCH
John William Hopkins
Department of Field Crops
University of Alberta
Edmonton, Alberta
August, 19^0 .
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GLUTEN QUALITY AND THE EFFECT OF DILUTION OF
WHEAT FLOURS WITH STARCH
John William Hopkins
Department of Field Crops
A THESIS
submitted to the University of Alberta in
partial fulfilment of the requirements for
the degree of
MASTER OF SCIENCE
Edmonton, Alberta
August, 1930
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TABLE OF CONTENTS
Page
Introduction . 1
Review . 4
Details of proposed investigation . 7
Exper imental . , . 9
Preliminary experiments . 9
Gluten quality and decrease in loaf volume
per unit decrease in protein content . 14
Starch dilution and diastatic activity, ... 18
Experiments involving the stimulation of
gas production . 22
Discussion of results, and conclusions . 54
Summary., . 57
Acknowledgements . . 58
References . 59
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LIST OF FIGURES.
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Page
1. Loaf volumes obtained with flour diluted
with various starches 11a
2. Decrease in loaf volume with dilution of
selected series of flours 15a
3. Decrease in loaf volume with dilution of
flour from wheat grown after Timothy,
Y/estern Rye Grass, Brome Grass and
Alfalfa 17a
4. Decrease in loaf volume with dilution of
flour from Marquis, Red Bobs No. 222,
Huron and Vermilion wheat. Baked by
ordinary method 23 a
5. Decrease in loaf volume with dilution of
flour from Marquis, Red Bobs No. 222,
Huron and Vermilion wheat. Baked with
the addition of 0.001 per cent potassium
bromate 23b
6. Variation in response to bromate with
dilution of flour from Marquis, Red Bobs
No. 222, Huron and Vermilion wheat 23c
7. Effect of addition of varying amounts of
takadiastase on the diastatic activity of
the four experimental flours 26a
8. Effect of addition of varying amounts of
malt extract (200 deg. Lintner) on the
diastatic activity of the four
experimental flours 26b
9. Loaf volumes obtained by the addition of
varying amounts of maltose + 0.05 per
cent ammonium phosphate to the original
and diluted flour - Marquis 3la
10. Loaf volumes obtained by the addition of
varying amounts of maltose + 0.05 per
cent ammonium phosphate to the original
and diluted flour - Red Bobs No. 222 3lb
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LIST OF FIGURES (Continued).
Page
Figure 11. Loaf volumes obtained by the addition
of varying amounts of maltose + 0.05
per cent ammonium phosphate to the
original and diluted flour - Huron
Figure 12. Loaf volumes obtained by the addition
of varying amounts of maltose -»• 0.05
per cent ammonium phosphate to. the
original and diluted flour - Vermilion
Figure 13. Maximum loaf volumes obtained by the
addition of maltose + 0.05 per cent
ammonium phosphate to the original
and diluted experimental flours,
plotted against protein content
Figure 14. Loaf volume obtained by the bromate
method, minus maximum loaf volume
obtained by the addition of maltose
and ammonium phosphate, plotted
against protein content
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GLUTEN QUALITY AND THE EFFECT OF DILUTION OF
WHEAT FLOURS WITH STARCH.
By John William Hopkins .
INTRODUCTION
Ever since the discovery that the peculiar suitability
of wheat flour for bread-making was the result of the
characteristic protein mixture known as gluten, this
fraction of the flour has been subject to extensive
examination by cereal chemists.
It was early recognized that gluten content must
play an important part in determining the baking " strength”
of any particular flour, but during the first decade of
the present century it became apparent, through the
observations of numerous workers in this field, that
although the best bread-making flours were, in general,
those containing the greatest proportion of gluten, never¬
theless variations in the "quality" or physical condition
of the gluten from different flours often occurred. Gluten
quality was, in many cases, just as important as gluten
quantity. More recent and extended investigations have
only served to strengthen this conclusion; thus Bailey
(1, pp. 258-60) gives an account of baking tests carried
out by different workers, involving in the aggregate
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several hundred samples of flour grouped according to
protein content. The results indicate that when the
averages of a sufficient number of samples are considered,
the order of gluten content is the same as that of loaf
volume, although individual flours were found in each
group which varied in baking quality more or less widely
from the mean of their group. The results also show,
however, that comparisons must be restricted to flours
of the same grade, since equal amounts of protein in
flours of different grade were not in general of equal
value in loaf production; in other words, the quality
of the protein in the lower grades of flour was inferior.
It is, therefore, obvious that some method whereby the
quality of the gluten in any particular flour might be
estimated would be of the greatest value.
"Quality" of course is not an absolute characteristic
of any material, but is a purely relative term denoting
the suitability of the material under consideration for
some particular purpose. For this reason actual baking
tests must always remain the final court of appeal in
the matter of gluten quality. Such tests are, however,
laborious, time-consuming, and require a relatively
large amount of material. More serious objections are
the possible complication of comparisons due to
variations in other factors, especially diastatic
activity, and the difficulty of separating effects
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produced by the quality of the gluten from those the
result of its concentration, since in practice both
quantity and quality usually vary simultaneously. There
has, therefore, been a constant search on the part of
cereal chemists for some comparatively simple determination
which would be an infallible indication of gluten quality:
an ideal which has not yet been attained.
The investigation now to be reported represents an
attempt to modify the usual baking test in such a way as
to render it capable of revealing those differences in
the baking value of different flours which are due to
quality, as opposed to quantity, of gluten. It was
proposed to dilute portions of the flour with starch as
required to bring all flours in a test series to definite
and comparable protein contents, and to bake the original
flours and several such dilutions. There seemed then to
be two possible ways of interpreting the results: (1)
by the falling off in loaf volume per unit decrease in
protein content; (£} by the absolute loaf volume at given
protein contents. The first way being independent of
absolute volume, it seemed at the time justifiable to
neglect diastatic activity. The second way, however,
called for methods of stimulating gas production such as
would ensure all loaves reaching the maximum volume which
the gluten was capable of sustaining.
It was realized that the extra labour involved in the
proposed modifications of the baking test would render
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the method unsuitable for ordinary routine determinations.
This objection, however, would not be an insuperable one
in the case of plant breeders and others to whom the
estimation of gluten quality in a restricted number of
samples is often of great importance, and here, it was
felt, the method, if successful, would be of considerable
service .
REVIEW
The various investigations into the nature and
measurement of gluten quality which have from time to
time been undertaken or proposed fall naturally into
five main groups: chemical, immunological, physico¬
chemical, mechanical, and actual baking.
It is not necessary for our purpose to consider all
*
these aspects of the problem in detail, though had more
satisfactory results been obtained elsewhere the need
for the present investigation might not have arisen.
Suffice it to say that it has not so far been found
possible to differentiate by chemical means between the
corresponding proteins of "strong” and "weak” flours,
(3, 4, 9} or to demonstrate differences in the relative
amounts of gliadin and glutenin, the two main gluten
constituents, in such flours, (15, 16).
Immunological reactions, which have so often proved
valuable in differentiating between proteins, appear to
be capable of yielding even less information in this
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connection them the ordinary chemical methods . Thus Wells
and Osborne (25) found that, using the anaphylaxis
reaction, the gliadins of wheat and rye could not be
distinguished, and also (26) that wheat gliadin and
glutenin actually reacted with each other, though not
so strongly as with themselves.
Physico-chemical studies of dough have led to the
suggestion (13) that gluten from a "weak” flour has a
lower rate of hydration and a much lower maximum
hydration capacity than that from a "strong" flour.
Attempts to utilize the viscosity of flour- in- water
suspensions, which varies with the degree of hydration,
as a measure of gluten quality have not, however, been
successful (5, 11). The bound-water method has also been
applied to the measurement of hydration in flour sus¬
pensions (8), but any differences found were too small to
be used as an index to gluten quality. Negative
correlations have been found (14) between loaf- volume
and the ease with which the gluten proteins are peptised
by certain salt solutions, but the results from a larger
series of samples (12) indicate that the correlation is
not great enough to make ease of peptisation a reliable
index of gluten quality.
Of the various mechanical dough- testers which have
been devised, the Chopin extensimeter (6) is undoubtedly
the most successful. This machine measures the ability
of a dough to extend its area without rupturing. A good
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relationship has been found to hold between the results
thus obtained and the loaf-volume from baking tests.
Unfortunately, however, the apparatus is quite expensive,
and in most laboratories not available.
Coming now to modifications of the baking test
involving the use of starch, we find that Bailey (1)
gives an account of experiments carried out by Jago in
which varying percentages of corn starch were added to a
sample of Canadian patent flour containing 16.1 per cent
of dry crude gluten, and the resulting mixtures baked.
Each successive addition of starch brought about a
diminution in loaf volume. Bailey had himself carried
out a somewhat similar experiment and noted a steady
decrease in loaf volume and deterioration in texture as
the proportion of starch was increased. Bailey and Le
Yesconte (2) determined the effect of admixture of starch
upon the extensibility of dough, as determined by the
Chopin apparatus. Mixtures containing 0, 10, 20, 30 and
40 per cent of starch exhibited a continuously decreasing
extensibility, indicating that gas-retaining capacity
had been impaired by the added starch. That this was
actually the case was demonstrated by Johnson and Bailey
(17), who added to five portions of a patent flour con¬
taining 10.32 per cent protein, starch sufficient to give
mixtures containing 10, 20, 30, 40 and 50 per cent starch
respectively. Doughs made from these mixtures fell into a
regular sequence as far as gas production and loss of gas
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were concerned, gas retention decreasing with increasing
proportion of starch.
Larmour and Macleod (19), and Larmour (18) have used
a blend of forty per cent soft wheat flour and sixty
per cent of the flour to be tested as a supplement to
the ordinary baking test in order to obtain a measure
of "reserve strength" or blending capacity. This may
afford a satisfactory means of comparing different
flours as such, but makes no provision for estimating
with any degree of exactitude what part of the results
obtained is due to variations in the quantity of
protein, and what to variations in its quality.
DETAILS OF PROPOSED INVESTIGATION
From the foregoing review it will be seen that no
satisfactory chemical or physico-chemical method of
estimating gluten quality has so far been found. The
experiments there referred to involving the use of
starch were all designed to demonstrate the effects of
variation in gluten concentration; but the question
arose as to whether information concerning the quality
of the gluten could not also be obtained in this way.
In particular it was thought that if several flours were
diluted with starch, in such a way as to reduce the
protein content by successive steps, the relation between
decrease in protein content and decrease in loaf volume
might prove to be a linear one. The decrease in loaf
■ ; 3....00 ood oao d ooie -/ oa tJ&enr:'3 0Hoo eiew
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8
volume per unit decrease in protein content might, hov/ever,
vary from flour to flour, the effects of starch dilution
being most marked in those flours whose gluten was "weak"
or of poor quality. When it is considered that the
greater part of the Western Canadian wheat exported to
Europe is used to blend with home-grown or imported
wheat of inferior quality in order to improve the resulting
flour, the practical significance of any test of quality
based on blending or "carrying-power" becomes obvious.
It is, as a matter of fact, known that some British
millers habitually test the quality of Canadian wheat by
mixing flour milled from it with home-grown wheat flour
in proportions ranging from 10 to 90 per cent Canadian
wheat flour, and noting the resulting improvement. As
a quantitative measure this is open to the criticism
that no two home-grown wheat flours would necessarily
yield the same results. The use of a standard starch,
as in the method now proposed would not however be
subject to this criticism, all results thus obtained
being truly comparable. It was proposed, therefore, to
investigate the effects of starch dilution on flour,
and if possible to establish a relation between such
effects and gluten quality, in the hope that a method
for the estimation of the latter might thus be provided.
It is to be noted that the British miller estimates
the quality of Canadian wheat flour by the improvement
it effects when added to his home-grown wheat flour,
b
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9
whereas in the proposed method quality would he estimated
rather by resistance to deterioration on dilution with
starch. There is a fundamental difference in these two
methods, the importance of which will appear more fully
in later discussion.
EXPERIMENTAL
Preliminary Experiments
Preliminary experiments were first carried out to
determine the best type of starch to use as a diluent.
Jago used corn starch. Bailey and Le Vesconte (2) and
Johnson and Bailey (17) do not state what kind they
used. Inasmuch, however, as the starches from different
species of plants often vary considerably in their
physical properties, it was thought that perhaps actual
wheat starch would be the most suitable. A quantity of
a commercial patent flour, found to contain 12.6 per
cent of protein, was obtained, and diluted to a series
of lower protein contents with five different starches.
These were commercial corn starch, starch prepared from
the original flour by the method of Rask and Alsberg (22),
one lot washed with distilled water and one lot with 70
per cent alcohol, and technical and c.p. wheat starches
supplied by Eimer and Amend. The nitrogen content of
these starches was determined, with the following
results, which indicate a satisfactory degree of purity.
, tL ‘
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10
Table 1. Nitrogen content of starches.
Kind of starch
Nitrogen
content
7o
Corn starch
0.09
Starch from flour (by distilled water)
0.06
Starch from flour (by 70$ alcohol)
0.05
E. and A. wheat starch (tech.)
0.05
E. and A. wheat starch (c.p.)
0.06
It was assumed that in the processes incidental to
the preparation of these starches, any protein present
would be denatured; hence no allowance was made for
protein in starches when calculating the amount to be
used in dilutions.
Sufficient starch was added to portions of the flour
to reduce the protein to 12.0, 11.0, 10.0 and 9.0 (dry
basis) , series of this nature being prepared using each
of the five starches. The mixtures obtained, together
with the original flour, were then baked according to the
following formula (all bakings being performed in duplicate).
Flour . 100 grams (at 13.5$ moisture)
Yeast . 3 "
Salt . . . 1 "
Sugar . 2.5 "
Water . sufficient
The resulting loaf volumes are shown in Table 2
.
. . . ' : -
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OG. G
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60. 0
c ,
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[LcdooiB Go? \rtf } uon " : gob oooocrB
, o . ooox ' . : - . . . x, , ;
. . ' : -■ . G . :•
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:ii.oGooo \,T- . rj, qp. o tjx -t 3 .^s.O Be ac x G.ao.e go oq arid'
10 z exco- a:.;v. oonswoXlB ext ooh30 ; boxx/G eneb ed bljow
. oG xna/cxxri oil/ ooixoIxiQ l^e nerlx aelooe : ,, gI nxoioiq
. B<, ... • '0. i : • 0 •' 0 '*•• G j
o . .1 -1 to 2/uj lx -ioq o'j Goo.dg sbw noT^a a.icaicxtOi/c
> * - . ,
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lel../o' fo/.'l ox ?• • \ .Tool/ lo /xt/'.- '>1/ .::U\~w
...
..• * :1 ; a ■. ‘.to 001 > , . » , . , . o. o .0
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11
Table 2. Loaf volumes obtained with flour diluted with
various starches.
Protein
Loaf volume
content
Corn
starch
Starch
from
flour
(dist.
water)
Starch
from
flour
(70%
ale . )
E. and A.
wheat
starch
( tech. )
E. and A.
wheat
starch
(c.p.)
cc .
cc .
cc .
cc .
cc .
12.6
498
498
498
498
498
12.0
475
458
458
460
456
11.0
433
444
432
425
422
10.0
427
406
410
376
395
9.0
380
382
369
342
371
These results have also been plotted (Figure 1} .
In the case of some of the starches the points thus
obtained are rather irregularly distributed, but in each
instance a straight line could be fitted to them. It
will be seen that the rate of decrease of loaf volume
with dilution is not the same for the different diluents.
The technical wheat starch supplied by Eimer and Amend
gave the line of steepest slope and also showed the
least scattering of points. It was, therefore, decided
to use this in all future experiments.
Determinations of the resistance of certain of these
starches to diastatic action was made by the method of
Malloch (El) . Similar determinations were also performed
in the case of the flour and the dilutions of it made with
Eimer and Amend tedhnical wheat starch.
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Figure 1. Loaf volumes obtained with f}.our diluted
with various starches.
- 12 -
Table 3 . Starch resistance of flour, starches and
starch dilutions.
Material
Starch
resistance
Starch from flour (washed by distilled water)
40
Starch from flour (washed by 70 per cent
alcohol)
39
Wheat starch, E. and A. (tech.)
151
Flour, 12.6 per cent protein
38
Flour, 12.0 per cent protein (diluted with
E. and A. wheat starch (tech.)
34
Flour, 11.0 per cent protein (diluted with
E. and A. wheat starch (tech.)
33
Flour, 10.0 per cent protein (diluted with
E. and A. wheat starch (tech.)
37
Flour, 9.0 per cent protein (diluted with
E. and A. wheat starch (tech.)
38
The figures for starch resistance represent one
thousand times the reciprocal of the number of milligrams
of maltose produced by 10 grams of dry material when
digested for one hour at 27° C. with 0.03 grains of taka-
diastase. It will be noted the starch prepared by washing
out from the flour had the same resistance, within the
limits of error of the method, as had the original flour.
The Eimer and Amend wheat starch had a much higher
resistance, but the resistance of the mixtures in which
it was used as a diluent did not differ significantly
from that of the original flour. This seeming anomaly
as do*t
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- 13 -
may be explained by assuming that, since only a small
proportion of the total starch available is converted
into sugar, there was present, even in the highest
dilutions, an excess of the more easily hydrolyzed
flour starch over the total amount capable of being
converted into sugar by the enzyme. This flour starch
might then be supposed to be attacked by the enzyme in
preference to the more resistant starch used as a
diluent .
The diastatic activity of these mixtures was also
determined, using Malloch1 s (20) modification of
Rumsey’s method.
Table 4. Diastatic activity of flour and starch
dilutions .
Protein content
Diastatic activity
7o
12.6
188
12.0
178
11.0
195
10.0
192
9.0
168
These results, whilst subject to some fluctuation, do
not indicate any significant downward trend with in¬
creasing dilution. This seemed rather surprising, for in
the starch dilutions the amount of diastase present would
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14 -
presumably decrease in the same ratio as the proportion
of flour. The added starch was shown to have no
diastatic activity, and was in addition much more
resistant to diastatic action than the starch which
occurred in the flour. A decrease in diastatic activity
with dilution was therefore certainly to be expected.
Gluten Quality and Decrease in Loaf Volume
per Unit Decrease in Protein Content.
Having established a linear relationship between
protein content and loaf volume for this particular flour,
using E. and A. technical wheat starch as a diluent, the
next step was to apply the dilution procedure to a selected
series of flours. This consisted of flour from three lots of
Marquis wheat, grown at the University of Alberta and having
an identical protein content but showing varying degrees of
frost injury, and also, for comparison, Quaker flour (a
commercial patent), and flour milled from Marquis wheat grown
in Southern Alberta. All but the commercial flour were milled
in the laboratory. The following is a description of the series:
No. 332. Marquis U. of A., after fallow. Injured by
frost, grade No. 6+ . Protein content of
wheat 16.3 per cent, of flour 14.5 per cent.
No. 333. Marquis U. of A., after fallow. Injured by
frost, grade No. 4-. Protein content of
wheat 16.3 per cent, of flour 14.4 per cent.
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- 15 -
No. 335 . Marquis U. of A., after fallow. Injured by
frost, grade "Feed".' Protein content of
wheat 16.3 per cent, of flour 14.4 per cent.
Quaker. Used as standard in baking laboratory.
Protein content of flour 13.0 per cent.
Southern Alberta Marquis . Protein content of
flour 13.9 per cent.
Three dilutions of each sample were made, using E. and A.
technical wheat starch, all percentages being calculated on
the dry basis. Bakings were performed as before with the
results shown in Table 5 and Figure 2.
Table 5. Bakings of starch dilutions of selected series
of flour samples.
Flour
Protein
content
Loaf
volume
Flour
Protein
content
Loaf
vol¬
ume
Flour
Pro¬
tein
con¬
tent
Loai
vol¬
ume
7o
cc .
%
cc .
~
cc .
No. 332
14.5
598
No. 333
14.4
577
No. 335
14.1
597
13.0
521
13.0
531
13.0
553
11.5
475
11.5
466
11.5
494
10.0
428
10.0
404
10.0
413
Quaker
13.0
539
Southern
13.9
479
Alberta
12.0
511
Marquis
13.0
456
11.0
470
11.5
425
11.5
425
10.0
405
Loaf volume Ccc)
15a -
Figure 2. Decrease in loaf volume with dilution of
selected series of flours .
16
Table 6 shows a single-figure estimate1 of the
baking quality of the five original flours, together with
dV/dP, the slope of the line in Figure 2 showing the rate
of falling-off in loaf-volume with decrease in protein
content .
Table 6. Baking quality of flours, and decrease in
loaf volume per unit decrease in protein
content .
Flour
Baking
Quality
av/dp
No. 532
101
38.0
No. 533
98
39.1
No. 335
92
44.1
Quaker
87
33.0
S. Alberta Marquis
57
19.0
It will be observed (from Fig. 2} that in each case
the falling-off in loaf volume with dilution was directly
proportional to the decrease in protein content, or so
nearly so as to make the fitting of a straight line quite
justifiable. In the first three cases (the frost-damaged
samples) , the decrease in loaf volume per unit decrease in
protein content was in the inverse order of the baking
The single-figure estimate of baking quality was computed
as follows:
Loaf volume - 400 x 0.2
Texture score (possible 10) x 3
Crumb color score (10) x 2
Gen. appearance score (10) x 1
Per cent absorption - 60 x 1
Total = estimate of baking quality
1 eti$ to foxx dri-jodf t xcrcX? lacitgjt •xo ©rif to xtllsup
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asw e*zc 3 neq Jhovorm neq- *z:un etit eo non boa
♦ { 33'ixif 'led.fo eoo to 0030 erf 3
loaf volume (cc )
17a -
Figure 3. Decrease in loaf volume with dilution of
flour from wheat grown after Timothy,
Western Rye Grass, Brome Grass and Alfalfa.
18
Table 7 . Dilution bakings of flour from wheat grown
after Timothy, Western Rye Grass, Brome
Grass and Alfalfa.
Flour
Protein
Loaf
dV/dP
Flour
Protein
Loaf
dV/dP
content
vol-
content
vol¬
ume
ume
fo
cc .
¥~
cc .
Wheat
17.7
498
Wheat
17.8
505
after
after
Timothy
13.0
586
22.7
W. Rye
Grass
15.0
582
25.8
10.0
515
10.0
519
Wheat
17.0
512
Wheat
16.9
515
after
after
Brome Grass
15.0
401
26.3
Alfalfa
15.0
404
28.4
10.0
528
10.0
519
Starch Dilution and Diastatic Activity.
Although the preliminary experiments indicated that
diastatic activity was unaffected by dilution, it was
suspected that these results were not typical. It
certainly seemed unlikely in the extreme that when, as in
some of the mixtures worked with, over forty per cent of
the flour had been replaced by starch which contained no
diastase at all and in addition was quite resistant to
enzyme hydrolysis, the amount of sugar produced would be
unchanged. Accordingly, the influence of dilution on
diastatic activity was studied in three additional cases;
i '
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- 19
the Quaker and Southern Alberta Marquis flours already-
referred to, and a third, designated "Flour A", which
was available at the time in the laboratory and consisted
of a mixture of residues from trial millings, etc.
The diastatic activity of the original and diluted
flours was determined by the method used before (20), and in
each case a definite downward trend with dilution was
established. In Table 8 the actual decrease in diastatic
activity on dilution is shown, together with a "theoretical"
diastatic activity calculated on the assumption that the
diastatic activity was directly proportional to the amount
of flour (and hence of diastase) in the mixtures. Although
the agreement is far from perfect, there is, nevertheless,
some indication that the diastatic activity is roughly
proportional to the amount of flour in the mixture.
Table 8. Starch dilution and diastatic activity.
Flour
Protein content
Diastatic
activity as
determined
Diastatic activity
calculated from
dilution
Flour A
ah
12.9
155
12.0
131
144
11.0
121
132
10.0
118
120
Quaker
13.0
282
12.0
198
260
11.0
204
239
10.0
179
217
Southern
13.9
149
mm
Alberta
11.5
136
126
Marquis
10.0
121
107
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20
From the foregoing work the following facts emerge :-
1. When flour is diluted with starch, a linear relation
between protein content and loaf volume is obtained.
2. In one case at least (the three frost-damaged samples)
dV/dP, the decrease in loaf volume per unit decrease in
protein content, seems to be related to gluten ty*- .
It was now thought that possibly the diastatic activity
factor should not be ignored after all, even in method (1)
(see page 3} . In the case of the Quaker and Southern Alberta
Marquis flours, wide differences in diastatic activity
(Table 8), and d?/dP (Table 6) occurred, these differences
being in inverse directions. It seemed possible therefore
that the anomalous behaviour of the Southern Alberta Marquis
might be due to its gas production being so low as to be the
limiting factor in loaf volume, protein scarcely coming into
question at all.
In method (2) of course there was no doubt that differ¬
ences in diastatic activity would have to be eliminated.
Sherwood and Bailey (24) concluded from their own and
Rumsey* s (23) work that a diastatic activity of about 250 was
the optimum for bread-making purposes, but for high protein
Canadian wheat flours, forming doughs of greater extensibility,
this would be a somewhat conservative estimate. It seemed
fairly safe to assume, therefore, that in the majority (if
not all) of the flours here dealt with, gas production was a
limiting factor in loaf volume. The gluten was not being
extended to the full amount of which it was capable, and there
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9«d, ,ei ^8o am tt o idw to fnnom Hut ©d* o* ioaOu©**©
21 -
was no reason to suppose that in a series of flours the
ratio of actual to maximum possible loaf volume would be
the same in any two cases.
Further complications became apparent owing to the
fact that on dilution with starch, both the diastatic
activity of a flour and the maximum loaf volume that it
could sustain would be reduced. There seemed to be three
possibilities with regard to the relationship between
actual gas production (governed by diastatic activity)
and the gas production necessary for maximum loaf volume:
(a) both might decrease with dilution by the same
relative amount;
(b) the gas production necessary for maximum loaf volume
might decrease relatively more rapidly than actual gas
production;
(c) actual gas production might decrease relatively more
rapidly than the gas production necessary for maximum
volume .
It seemed quite possible that (c) could be the case in
flours of high diastatic activity, whilst (b) held in those
of very low diastatic activity. In viev/ of these
possibilities and the above mentioned facts it seemed that
perhaps the best way to obtain true comparisons might be
to adjust the diastatic activity of all flours and their
dilutions, so that the maximum possible loaf volume was
produced in every case.
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22
Experiments Involving the Stimulation of Gas
Production.
In the attempt to eliminate diastatic activity as a
complicating factor, and definitely to establish, if such
existed, the relationship between gluten quality and
behaviour on starch dilution, further experiments were now
designed. In these experiments it was planned to use flour
milled from wheat of four standard varieties, chosen so as
to form a graded series in respect of baking quality. Wheat
of these four varieties, Marquis, Red Bobs No. 222, Huron
and Vermilion, had been grown in adjacent plots at Clover
Bar, near Edmonton, during the summer of 1929. A considerable
quantity of each variety was milled, the protein content of
the flour determined, and dilutions made.
As a first step the original and diluted flours were
baked in the ordinary way and also with the addition of
0.001 per cent of potassium br ornate . This substance acts
as a flour improver, its effect as a rule being more
pronounced the higher the protein content of the flour.
The precise nature of its action is not yet known, -tei
o ordain wo rkers^, Working (27, 28) and Geddes (10), believe
that it affects the physical condition of the gluten,
possibly as the result of a dispersing action on certain
phosphatides intimately admixed with the gluten con¬
stituents, but it still remains to be proved that this
effect alone explains all the changes resulting from its
use. Table 9 and Figures 4, 5 and 6 show the results
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23
thus obtained.
Table 9. Dilution bakes, with and without bromate, of
flour from Marquis, Red Bobs No. 222, Huron
and Vermilion wheat.
Variety
Protein
Loaf
dV/dP
Loaf
Response
content
volume ,
volume ,
to
standard
bromate
bromate
method
method
%
cc .
cc .
cc .
Marquis
18.5
573
748
175
16.0
516
573
57
14.0
470
24.1
518
48
12.0
421
462
41
10.0
371
397
28
Red Bobs No.
17.0
529
644
115
222
14.0
450
24.8
492
42
12.0
405
420
17
10.0
370
400
30
Huron
15.7
480
590
110
14.0
417
30.4
477
60
12.0
372
406
34
10.0
312
358
56
Vermilion
14 .8
337
417
80
13.0
302
16.8
332
30
11.5
287
290
3
10.0
267
269
2
.berried’ do
to t&$BMoidi d*0oxliiw has . Jlv/ ta92± sd noiiuiia . Q 9ldBT
ncmfn tsas , o?[ adoa b©£ tsiirpT8M irio^ri vuiolt
.tfaedvr aotllmieV bn 3
23a -
Figure 4. Decrease in loaf volume with dilution of
flour from Marquis, Red Bohs No. 222,
Huron and Vermilion wheat . Baked by
ordinary method.
Figure 5. Decrease in loaf volume with dilution of
flour from Marquis, Red Bobs No. 222,
Huron and Vermilion wheat. Baked with
the addition of 0.001 per cent potassium
bromate .
Response to inornate tec)
23C
Per cent protein
Figure 6. Variation in response to hr ornate with
dilution of flour from Marquis, Red Bobs
No. 222, Huron and Vermilion wheat.
- 24
With the ordinary baking procedure, the falling-off
in loaf -volume was again proportional to the decrease in
protein content, and in the case of three of the varieties,
namely Marquis, Red Bobs No. 222 and Huron, the slopes of
the curves obtained (Fig. 4), by plotting the loaf volume
against protein content were in the inverse order of baking
quality, although the difference in slope between Marquis
and Red Bobs No. 222 was but slight. Vermilion, however,
which is known to be very inferior in this respect,
although giving a small loaf volume at first did not fall
off to any great extent on dilution, thus behaving in a
similar manner to the Southern Alberta Marquis of a previous
experiment .
It is apparent from Fig. 5, that when these bakings
were performed with the addition of potassium bromate, the
linear relation between protein content and loaf volume
disappeared. The resulting curves do not appear to be
related to gluten quality in any simple manner. The
response to bromate (i.e. the difference between loaf
volume with and without bromate), plotted in Fig. 6, also
fails to reveal any helpful differences between the varieties.
Since it was felt that in all probability these results
were complicated by variations in diastatic activity, an
effort was now made to control this factor. If some fairly
wide range existed over which, owing to its no longer being
a limiting factor, such variations had no appreciable
effect on loaf volume, then it was thought that the problem
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- 25 -
might he fairly readily solved. It should he possible, hy
means of a relatively few experiments, to determine the
amount of some diastatio preparation to add to any flour
of known diastatic activity in order to bring its sugar
production within the desired range.
With this end in view, varying amounts of each of
two highly diastatic preparations, takadiastase supplied
by the Parke-Davis Co. and malt extract of 200 degrees
Lintner, supplied by Standard Brands Ltd. were added to
each of the four experimental flours and the resulting
changes in diastatic activity determined. (In the case
of the malt, 0.05 per cent of mono-ammonium phosphate,
NH4H2PO4, which acts as a yeast stimulant, was also added) .
The results are summarized in Table 10 and Figures 7 and 8.
With takadiastase the increase in sugar production in each
flour follows a similar law, although the actual amount of
the increase varies in each case, owing probably to
differences in starch resistance. The results obtained
by the use of malt are more irregular. This may be
accounted for, in part at least, by the difficulties in¬
volved in manipulating small amounts of this substance, it
being of a thick syrupy nature. There is also the
possibility of non-homogeneity of the malt, thorough
mixing being impossible. In general, however, the results
seem to be of a somewhat similar nature to those obtained
with takadiastase.
It was also planned to bake loaves containing the
same proportions of these preparations, in order to
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36
determine the region of optimum diastatic activity, as
judged by the attainment of maximum loaf volumes. When
this was attempted, however, it was found that in addition
to being highly diastatic, both the takadiastase and malt
evidently contained proteolytic enzymes. These adversely
affected the gluten during fermentation, resulting in
sticky, "runny" doughs which could not be handled. By
reducing the amount of water added in mixing the dough
(in certain instances by as much as 12 cc.), some loaves
were obtained, and the volumes of these have been
included in Table 10.
Table 10. Results of adding takadiastase and malt
extract to experimental flours.
Flour
Amount of
prepara¬
tion
added
Taka- diastase
Malt extract + 0.0^
ammonium phosphate
Diastatic
activity
Loaf
vol¬
ume
Diastatic
activity
Loaf
volume
~v
cc .
cc.
Marquis
—
140
554
140
554
0.05
273
745
187
642
0.10
318
—
199
661
0.15
350
340
305
687
Red Bobs No. 222
—
184
541
184
541
0.05
358
660
283
570
0.10
431
- —
322
618
0.15
455
—
385
650
Huron
—
131
498
131
498
0.05
268
638
165
544
0.10
301
—
221
584
0.15
332
616
279
582
Vermilion
—
95
450
95
450
0 ,05
154
538
149
512
0.10
172
520
166
522
0.15
208
456
190
520
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- 26a
Figure 7. Effect of addition of varying amounts of
takadiastase on the diastatic activity of
the four experimental flours.
D /astatic activity
26b -
Figure 8. Effect of addition of varying amounts of
malt extract (200 deg. Lintner) on the
diastatic activity of the four experimental
flours .
27
It was realized, however, that owing to their proteo¬
lytic action, as a result of which the physical condition
of the gluten was affected, these preparations were un¬
suitable for use in the present studies, and so some
other method of augmenting sugar production was sought.
The addition of starch which had been finely ground, and
was hence very susceptible to enzyme hydrolysis, in
constant amount in each dilution, although this would
make impossible comparison with the loaf volume of the
original flour, seemed to be a possible line of attack.
A portion of wheat starch was therefore ground for forty
hours in a ball mill, mixed with some of the Marquis
flour, and the mixtures baked. The results given in
Table 11 show that the increase obtained by the use of
the finely-ground starch alone is obviously not of the
required order.
Table 11. Use of wheat starch of low resistance in the
endeavour to stimulate gas production.
Mixture
Loaf volume
cc .
1. Marquis diluted to 16.0% protein with
516
unground wheat starch
2. Marquis diluted to 16.0% protein with
548
finely ground wheat starch
3. As in (1) but with addition of 0.05%
650
Taka-diastase
4. As in (2) but with addition of 0.05%
670
Taka-diastase
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28
These attempts to increase the production of sugar in
the dough by natural means (i.e. enzyme hydrolysis) having
proved impracticable, it was thought that possibly the
desired result might be achieved by the addition, not of
diastatic preparations or readily hydrolysed starch, but
of the product which was actually used by the yeast,
namely maltose. It is true that this might appear to
entail a departure from the conditions usually occurring
in fermenting dough, in which the amount of maltose
produced by starch-splitting is negligible at the
commencement of the fermentation period, but has become
fairly large in the later stages, when it is most needed.
Inasmuch, however, as a considerable quantity of sucrose
(2.5 per cent), which must be in excess of the early needs
of the yeast, is added in the ordinary baking procedure,
it was thought that probably the added maltose would not
lead to over- stimulation of the yeast in the early stages
but would instead ensure the presence of an adequate supply
of sugar during the important final period of fermentation.
A few preliminary experiments demonstrated that
considerable increases in loaf volume could be obtained
with maltose, added in solution to aid in thorough
mixing. In addition, the texture of the loaves thus
obtained was superior to that of the original flour, whereas
those resulting from the use of Taka-diastase or malt were
impaired in texture. Maltose and 0.05 per cent ammonium
phosphate, it was found, gave better results than maltose
alone. Thus Marquis flour baked with the addition of
- 83
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29
2.0 per cent maltose gave a loaf volume of 642 oc . , whereas
with 2.0 per cent maltose and 0.05 per cent ammonium
phosphate, a volume of 668 cc . was obtained.
It was decided, therefore, to investigate the effect
of adding varying proportions of maltose to flour, in order
to determine whether, with increasing concentration, the
loaf volume rose to a sharp maximum and then fell off
again, or whether any considerable region of Optimum con¬
centration" existed. A number of bakings of the four
experimental flours (Marquis, Red Bobs No. 22, Huron and
Vermilion) were made with the addition of varying amounts
of this sugar and 0.05 per cent of ammonium phosphate, the
results being included with those of subsequent work in
Table 12 and Figs. 9, 10, 11 and 12. In each case a
maximum loaf volume was obtained, but whilst with Red
Bobs No. 222 no significant change in volume occurred
over a range of concentration extending from four to
six per cent, the volumes given by the other three flours
increased to well defined maxima and then fell off again
with varying degrees of abruptness.
As no gen era!” optimum zone” of maltose concentration
had been established for the undiluted flours, the
foregoing procedure of baking with the addition of
varying amounts of maltose was applied to the various
starch dilutions. The loaf volumes obtained are shown
in Table 12 and the accompanying Figures 9, 10, 11 and 12.
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30
Table 12. Loaf volumes obtained by the addition of
varying amounts of maltose + 0.05 per cent
ammonium phosphate .
Flour
Protein
content
Maltose
added
Loaf
vol¬
ume
Flour
Protein
content
Maltose
added
Loaf
vol¬
ume
%
i ■
cc .
$
c c .
Marquis
18.5
0
573
Red Bobs
17.0
0
529
2
627
No. 222
3
571
3
648
4
620
4
663
5
623
5
639
6
616
Marquis
16.0
0
516
Red Bobs
14.0
0
450
4
604
No. 222
4
517
5
600
5
565
6
628
6
567
7
614
7
565
Marquis
14.0
0
470
Red Bobs
12.0
0
403
4
578
No. 222
3
480
5
615
4
494
6
577
5
508
6
507
7
490
Marquis
12.0
0
421
Red Bobs
10.0
0
370
4
455
No. 222
5
404
5
546
6
460
6
480
7
453
7
452
8
390
Marquis
10.0
0
371
3
370
4
384
5
370
6
423
7
400
8
402
Huron
15.7
0
480
Vermil¬
14.8
0
5537
3
553
ion
2
489
4
577
3
534
5
582
4
510
6
554
. ric ed$ vd bottladtio ^osmjL^r 'Zjc.I
■
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SI elcfaT
Table 12 (cont’d.)
Flour
Protein
content
Maltose
added
Loaf
vol¬
ume
Flour
Protein
content
Maltose
added
Loaf
vol¬
ume
%
%
cc .
%
7o
cc .
Huron
14.0
0
417
Vermilion
13.0
0
302
4
520
3
472
5
518
4
472
6
536
5
468
7
551
6
471
8
552
Huron
12.0
0
372
Vermilion
11.5
0
287
4
479
4
451
5
470
5
462
6
497
6
460
7
477
7
466
8
452
Huron
10.0
0
312
Vermilion
10.0
0
267
4
397
3
420
5
450
4
423
6
435
5
430
7
435
6
452
7
438
The curves obtained by plotting loaf volume against
concentration of added maltose are of some interest. In
general there is an increase, with dilution, in the amount
of added sugar necessary to produce maximum loaf volume.
There are also marked differences in the types of the curves
themselves. In the case of the Marquis, for example, the
loaf volume of the three highest dilutions (lowest protein
contents) rises sharply to a maximum, and then falls off
again; with the original flour and the first dilution,
however, there is no such peak.
X.
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Lou/ volume (cc)
3la -
figure 9. Loaf volumes obtained by the addition of
varying amounts of maltose + 0#05 per
cent ammonium phosphate to the original
and diluted flour - Marquis.
- 3lb -
Figure 10. Loaf volumes obtained by the addition of
varying amounts of maltose + 0.05 per
cent ammonium phosphate to the original
and diluted flour - Red Bobs No. 222.
Loaf volume (cc)
- 3lc -
Figure 11. Loaf volumes obtained by the addition
of varying amounts of maltose + 0*05
per cent ammonium phosphate to- the
original and diluted flour - Huron.
- sia -
Figure 12. Loaf volumes obtained by the addition
of varying amounts of maltose + 0.05
per cent ammonium phosphate to- the
original and diluted flour - Vermilion.
Loaf vo/ume ( cc )
- 3le -
Per cent protein
Figure 13 . Maximum loaf volumes obtained by the
addition of maltose + 0.05 per cent
ammonium phosphate to the original
and diluted experimental flours,
plotted against protein content.
'
- 32 -
This ’’peak" in the loaf- volume curve occurs to a
varying degree in the higher dilutions of all the varieties.
The fact that a similar type of curve was obtained with the
undiluted Vermilion flour suggests that it is possibly an
indication of ’’weakness”, although the other curves
furnish several exceptions to such a generalisation.
The maximum loaf volumes of the various flours and
their dilutions obtained with the addition of maltose and
ammonium phosphate have been plotted against protein content
in Fig. 13. Whilst gas production as a limiting factor
has now undoubtedly been eliminated, the resulting curves
do not appear to lend themselves to any simple quantitative
estimation of gluten quality. As a matter of fact three
different types of curves are obtained from the four
varieties. The Marquis curve is concave downward, Red
Bobs No. 222 and Huron give practically straight lines,
and Vermilion a curve concave upward. The Marquis curve
may perhaps be explained on the assumption that, owing
to the good quality of the gluten, considerable
quantities of starch can be added to the flour without
causing any great decrease in loaf volume, but that when
a certain critical decrease in protein content has been
effected, the cumulative effect of the added starch results
in a sudden large diminution. Similarly the relatively
large initial decrease with dilution in the loaf volume of
Vermilion may be taken as evidence of inferior gluten quality.
The subsequent "flattening-out" of this curve is not,
however, so easy to explain.
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tdcn ax ©vino sirtj lo "dno-^ninedd-Bll” d-nenpaadjja edT
* ’ ::-X c. ;Boe 03 viovewod
32a -
Figure 14. Loaf volume obtained by the br ornate
method, minus maximum loaf volume
obtained by the addition of maltose
and ammonium phosphate, plotted
against protein content.
The differences between the loaf volume obtained by
the bromate method (Table 9) and the maximum obtained by
the addition of maltose and ammonium phosphate (Table 12)
are plotted for the various flours and their dilutions in
Figure 14. There seems to be no systematic difference in
the curves given by the different varieties. It is
worthy of note, however, that in the case of the four
undiluted flours, Marquis, Red Bobs No. 222 and Huron
gave a greater, and Vermilion a lesser, loaf volume by
the bromate method than with the addition of maltose.
The magnitude of the differences, it will be noted, is
precisely in the order of baking quality of the
original flours. The ability to give a greater loaf
volume with bromate than can be obtained by the addition
of maltose and ammonium phosphate would therefore appear
to be correlated with baking quality. Some confirmation
of this hypothesis was obtained by baking a sample of
pastry flour, known to be of inferior bread-making
quality, by the ordinary method, with the addition of
bromate, and with the addition of maltose. By the
ordinary method a volume of 430 cc . was obtained. This
was only increased to 440 cc . by the addition of 0.001
per cent potassium bromate, but with 5 per cent maltose
a loaf of 502 cc . resulted.
From the nature of the curves in Figure 14, however,
it appears that this relation does not necessarily hold
when a number of flours are brought to some similar
protein content by the addition of starch.
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DISCUSSION OF RESULTS, AND CONCLUSIONS.
In the preliminary discussion, attention was directed
to the fundamental difference between the method here
employed and that used by some British millers as an
index of flour strength. In the latter, the greater
the difference between the strong Canadian flour and
the weak flour with which it is being mixed, the greater
is the improvement effected. In the former, on the other
hand, it was assumed that the greater the difference in
properties between the flour to be tested and the starch
added to it, the smaller would be the resulting
impairment.
Emphasizing this fundamental difference, two
opposing tendencies seem to be discernible in the
results of those experiments in which no attempt was
made to stimulate gas production. These are:
(a) The better the quality of the gluten, the
greater the resistance of the flour to reduction in
loaf-volume by starch dilution.
(b) The poorer the gluten, the less the difference
in properties between flour and added starch, and hence
the less the change on dilution.
It would appear that in flours with good quality
gluten, tendency (a) is dominant, and that differences
in gluten quality can be detected by the starch dilution
method. In those of a markedly inferior nature, however,
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35
(b) seems to become increasingly dominant, rendering
comparison with superior flours impossible. On this
account the method cannot be capable of any general
application in the estimation of gluten quality.
The stimulation of gas production, in order to
obtain the maximum possible loaf volumes, has led to
more complicated, rather than simpler, results. No
explanation of these, other than that already suggested,
can be offered here, though in view of the fact that
loaf volume is largely governed by physical factors, the
possible effect of st&rch dilution on the physical
properties of the dough (apart from mere reduction in
protein content) should not be overlooked. Certain facts
of interest have emerged however .
(i) The unsuitability of at least two commercial
diastatic preparations as agents for the stimulation of
gas production in flours has been demonstrated. These
results, together with those of Collatz and Racke (7)
and Sherwood and Bailey (24) indicate the necessity of
devising some method for the purification of preparations
of this enzyme. On the other hand, it has been shown
that by the addition of maltose and 0.05 per cent of
ammonium phosphate, loaf volume could be increased to a
maximum.
(ii) As already suggested, one way of interpreting
the results might be to compare the maximum loaf volume
which the various flours in a test series were capable of
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attaining when all had been reduced to some similar
protein content. From Figure 13 it will he seen that
there is a considerable range of protein contents over
which the loaf-volumes at any given protein content
would be in the order Marquis, Red Bobs No. 222, Huron
and Vermilion; that is, in the order of gluten quality.
Owing, however, to the differing rates of decrease in
loaf volume with dilution exhibited by the four varieties,
the quantitative results obtained from such a procedure
would vary with the protein content chosen. The loaf
volumes though they fell in the order of gluten quality,
could not be said to be proportional to it.
(iii) The variations in the response to potassium
bromate and maltose are of considerable interest. It is
believed that the response due to bromate is related to
both quantity and quality of gluten. The discovery that
in "strong” flours the loaf-volume obtained with the
addition of 0.001 per cent potassium bromate was
greater than the maximum obtained with the addition of
maltose, whilst in "weak" flours the reverse was true
seems further corroboration of this view, since the
maltose presumably acts solely as a yeast stimulant.
It is disappointing, however, to observe the irregular
nature of the results obtained when this procedure is
applied to the diluted flours.
(iv) The nature of the curves obtained by plotting
loaf volume against concentration of added maltose has
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37
already been noted. A sharp maximum is, in general,
associated with lo w concentration or inferior quality
of gluten. This is analagous to the well-known lack
of stability and narrow range of fermentation tolerance
in weak flours .
SUMMARY.
1. The purpose of this investigation has been to ascer¬
tain whether the baking behaviour of flours when brought
to a series of definite and comparable protein contents
by dilution with starch could be used to estimate gluten
quality.
2. When flours are diluted with starch, the rate of
decrease in loaf volume per unit decrease in protein
content has no general application as a measure of
gluten quality. This is true whether the baking is
performed with or without the stimulation of gas
production.
3. Diastatic activity is reduced by starch dilution to
an extent roughly proportional to the decrease in the
amount of flour in the mixture .
4. The addition of maltose to increase gas production
has proved more satisfactory than the use of diastatic
preparations, o?/ing to proteolytic enzymes being con¬
tained in the latter.
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. -xattBl exit ii danxst
38
5, The maximum volumes which a series of flours are
capable of attaining when all have been brought to the
same protein content by starch dilution seem to be in
the same order as, though not necessarily proportional
to, gluten quality, provided that the degree of
dilution is not too high.
6. "Strong" flours give a greater loaf volume when
baked with the addition of 0.001 per cent potassium
bromate than can be obtained by the use of maltose
to increase gas production. With "weak" flours the
reverse is true. When a number of flours are reduced
to the same protein content by the addition of starch,
however, the differences between loaf-volume by the
bromate and maltose methods are not necessarily in the
order of gluten quality.
7 . When successive increments of maltose are added to
a "weak" flour, in general the loaf volume increases to a
well-defined maximum and then falls off again. With
"strong" flours on the other hand, the maximum is less
pronounced, and tends to broaden out into an "optimum
zone" .
ACKNOWLEDGEMENTS .
The author wishes to thank Dr. Robert Newton, who
suggested the problem, for his constantly helpful criticism
and advice, and Mr. G. D. Macmillan for his valuable technical
assistance .
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- 39 -
REFERENCES .
(1) BAILEY, C. H. The Chemistry of Wheat Flour. Chemical
Catalog Co., New York. 1925.
(2) _ , and LE VESCONTE, A. M. Physical tests
of flour quality with the Chopin extensimeter .
Cereal Chem. 1(1): 38-63. 1924.
(3) BLISH, M. J. On the chemical constitution of the
proteins of wheat flour and its relation to
baking strength. J. Ind. Eng. Chem. 8:138-144.
1916.
(4) _ and PINCKNEY, A. J. The identity of
gluten proteins from various wheat flours.
Cereal Chem. 1( 6) : 309-316 . 1924.
(5) _ , and SANBSTEDT, R. M. Viscosity studies
with Nebraska wheat flours. Ibid. 2( 4) : 191-202 .
1925.
(6) CHOPIN, M. Determination of baking value of wheat
by measure of specific energy of deformation
of dough. Ibid. 4(1): 1-13. 1927.
(7) COLLATZ, F. A., and RACKE, D. C. Effects of
diastase and malt extract in doughs. Ibid.
2(4): 213-227. 1925.
(8) COOK, W. H. The bound water of wheat-flour
suspensions in relation to baking strength.
Univ. of Alberta, M.Sc. thesis, (unpublished).
(9) CROSS, R. J. and SWAIN, R. E. The amino acid
distribution in proteins of wheat flours.
Ind. Eng. Chem. 16:49-52. 1924.
(10) GEDDES, W. F. Chemical and physico-chemical changes
in wheat and wheat products induced by
elevated temperatures. III. The influence
of germ constituents on baking quality and
their relation to improvement in flour induced
by heat and chemical improvers. Can. Jour.
Res. 2(3) : 195-213. 1930.
(11) GORTNER, R. A. Viscosity as a measure of gluten
quality. Cereal Chem. 1(2): 75-81. 1924.
(12) _ . Correlation of loaf volume with the
peptizing action of salts on wheat flour proteins.
Proc. Soc . Exp. Biol, and Med. 24:530-532. 1929.
:m©ilO
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■
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40
(13) _ and DOHERTY, E. II. Hydration
capacity of gluten from "strong" and "weak"
flours. Jour. Agr. Res. 13(8) : 389-419 . 1918.
(14) _ , HOFFMAN , W. F., and SINCLAIR, W. B.
The peptization of wheat flour proteins by
inorganic salt solutions. Cereal Chem.
6(1) : 1-8 . 1929.
(15) GREIYE, E. and BAILEY, C. H. The concentration of
glutenin and other proteins in various types
of wheat flour. Ibid. 4( 3) : 230-247 . 1927.
(16) HERTZ, E. The determination of the gluten con¬
stituents in flour and their relation to
bread-making qualities. Miller’s Review
35(6) : 170-171. 1916.
(17) JOHNSON, A. H., and BAILEY, C. H. Gluten of flour
and gas retention of wheat flour doughs. Cereal
Chem. 2(2): 95-106. 1925.
(18) LARMOUR, R. K. Relation between protein content and
quality of wheat as shown by different baking
methods. Ibid. 7(l}:35-48. 1930.
(19) _ , and MACLEOD, A. G. A study of the
basic, bromate, and blend baking formulae as
means for determining wheat quality, with
special reference to low grade wheat of the
crop of 1928. Sci. Agr. 10(1): 1-22. 1929.
(20) MALL0CH, J. G. Modifications of Rumsey’s method for
the determination of di astatic activity in flour.
Cereal Chem. 6(3) : 175-181 . 1929.
(21) _ . Studies on the resistance of wheat
starch to diastatic action. Can. Jour. Res.
1(2): 111-143. 1929.
(22) RASK, 0. S., and ALSBERG, C. L. A viscosimetric
study of wheat starches. Cereal Chem.
1(1) : 7-26 . 1924.
(23) RUMSEY, L. A. The diastatic enzymes of wheat flour
and their relation to flour strength. Amer .
Inst. Baking. Bui. 8. 1922.
(24) SHERWOOD, R. C., and BAILEY, C. H. Control of
diastatic activity in wheat flour. I.
Production of diastatic flour and effects of large
dosages. Cereal Chem. 3( 2) : 107-136 . 1926.
. .
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(25) WELLS , H. G. , and OSBORNE, T. B. The biological
reactions of the vegetable proteins. I.
Anaphylaxis. J. Infect. Dis. 8:66-124. 1911.
(26) _ . Is the
specificity of the anaphylaxis reaction
dependent on the chemical constitution of
the proteins or on their biological relation?
The biological reactions of the vegetable
proteins. Ibid. 12:541-558. 1915.
(27) WORKING, E. B. The action of phosphatides in
bread dough. Cereal Chem. 5(5) : 225-254. 1928.
(28) . Some oxidising effects of flour
bleaching. Ibid. 5(5) : 451-455. 1928.
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