EXPERIMENTAL MILLING AND BAKING. 27 
flour that produces the best bread in the testing laboratory is most 
likely to produce the best quality of bread when baked with com- 
mercial formulas and equipment. 
CHEMICAL DETERMINATIONS. 
In connection with the milling and baking experiments described 
above, certain chemical determinations are made. These determina- 
tions are essential for several reasons. In the first place, they show 
the investigator whether the differences in flour strength indicated 
by the baking test are true or are due to the treatment received by 
the wheat during milling or in the subsequent baking process. In 
milling the same sample of wheat into more than one grade of flour 
there will naturally be a difference in the composition of the flour as 
a result of the distribution of the flour yielding material in the wheat 
kernel. It is essential in making comparative studies that the com- 
position be known so that the same grade of flour be used throughout. 
Comparative results from studies on patent flours, for instance, 
should by no means be included with data from studies on straight 
or other grades of flour. 
Second, the results of chemical studies offer constructive sugges- 
tions to the miller in the matter of handling wheat at the mill and to 
the baker in handling flour in the bakery. Third, inasmuch as no 
chemical test or group of tests has been developed which will give 
conclusive evidenre as to the kind of bread which may be produced 
from any given lot of wheat or wheat flour, the correlation of the 
results of chemical and physical determinations with the results of 
baking and milling tests throws light upon some of the causes for 
differences in the strength of wheats, and may eventually lead to the 
development of simple chemical tests for determining flour strength. 
There is no unanimity of opinion in answer to the question as to 
what chemical constituents are of principal importance in regulating 
the baking strength of flour. Current among the factors associated 
with quality of flour are: The proteins of the flour, the nature and 
quantity present ; the influence of acids, bases, and salts upon the 
physical properties of the proteins; the acidity of the flour; the 
nature and amount of the mineral salts already present; and the 
kind of food supplied the yeast plant during the fermentation of the 
dough, as well as the nature of the fermentation products (sugars and 
proteins) developed by diastatic or proteolytic enzyms. 
Wheat flour contains five distinct proteins: An albumin, a glob- 
ulin, a prolamine (gliadin), a glutelin (glutenin), and a proteose. 
In addition to these compounds, amino acids are also found in the 
wheat and to a lesser extent in the flour. Albumin, globulin, and 
amino acids are found chiefly in the embryo. Their presence in flour 
is due to the impossibility of entirely separating the germ from the 
endosperm during the process of roller milling. The gliadin and glu- 
tenin constitute from 85 to 88 per cent of the total protein of high- 
grade flour. The proportion of gluten to crude protein in whole 
wheat is somewhat lower than this. When wheat flour is made into 
dough these two compounds, commonly called gluten, absorb approxi- 
mately two to three times their combined weight of water, forming 
a more or less coherent or tenacious mass. It is the expansive force 
of the gas generated by the yeasts during the fermentation of the 
