Feb. 17 , 1923 
Correlations Between Wheat and Flour 
547 
able until after the propagation of the pure strains of wheat has reached 
a certain stage. In order to judge the gluten quality, when only a very 
small sample of grain is available, say the yield of a single plant, or even 
of a spike, use may be made of a rather crude but fairly accurate method, 
the chewing test. The chewing test gives also some approximate idea as 
to gluten content. The gluten content well reflects, in fact, parallelsThe 
crude protein content in the wheat. Furthermore, both the gluten con¬ 
tent and crude protein content are highly correlated with loaf volume. 
From this it would follow that the crude protein content in the wheat 
may, for practical purposes, be substituted for gluten content. Thus 
the crude protein content in the wheat and the chewing test may be ac¬ 
cepted as a practical working index of strength in wheat in the early stages 
of the selection work when the plant breeder is confronted with the task 
of deciding which of the numerous strains to retain and which to discard. 
The information afforded by this index may further be supplemented by 
examining the grain for color and hardness. 
The determination of the crude protein content in the grain of a given 
strain gains in importance and value in view of the accumulating evidence 
which indicates that while the absolute amount of protein in wheat may 
be influenced by environment, yet the protein content of wheat is a 
varietal characteristic, and moreover, that there is a tendency for the 
different varieties and strains to retain their relative rank with respect to 
protein content from one year to the next (18). 
SUMMARY 
The present paper is the result of a study of the relationship of the 
different characters of wheat based upon published data obtained from 
analysis of a number of American wheats. 
Subject to the limitations of the material which have been^pointed out 
in this paper, the following conclusions may be drawn from the data 
herein presented: 
Crude protein content in the wheat is very closely and consistently 
correlated with protein in flour, dry gluten, and gliadin. 
There appears to be practically no relation between crude protein 
content in the wheat and flour yield. 
There is, with some notable exceptions, a high positive correlation 
between the crude protein in the wheat and strength of flour as determined 
by the loaf volume. 
There is generally even a higher, positive correlation between protein 
in the flour and loaf vplume. 
The gluten content of the flour is very closely correlated with loaf 
volume. The intensity of association between these two variables 
appears to be greater than that for protein in flour and loaf volume. 
There is generally a high, positive correlation between wet gluten 
content and loaf volume. 
There is, with some exceptions, a positive, fairly high correlation 
between water absorption of the dough and loaf volume. 
In normal, sound wheat there is apparently no significant correlation 
between flour yield and loaf volume. 
Excepting the data for a few wheat groups, there is a positive and, for 
some wheat groups, a very high correlation between gliadin content and 
loaf volume. 
Dry gluten content is generally highly correlated with gliadin content. 
