MICHIGAN ACADEMY OF SCIENCE. 
75 
THE PROTEID CONTENT OF WHEAT AS AN INDEX TO ITS 
BREAD MAKING QUALITIES. 
A. J. PATTEN. 
The proteid content of wheat in relation to its bread-making value 
has been studied by a number of investigators, and it is a matter of 
regret, that as yet, no more definite knowledge on this particular sub¬ 
ject has been obtained. 
While unquestionably the proteid content of wheat determines in no 
uncertain degree its value for bread-making purposes, still we are un¬ 
able to say just why one particular Hour is capable of producing bread 
of better quality than another flour when chemical and physical analyses 
show no differences in the two flours. For a clearer understanding of 
the subject it is necessary to know something of the several proteids 
found in wheat. They have been classified by Osborne and Voorhees 
briefly as follows: 
(1) A globulin, soluble in salt solutions, and not coagulated at 
temperatures below 100° C. 
(2) An albumin, which is coagulated at 52° C. and differs from 
animal albumin in several important respects. 
(3) A proteose, precipitated (after removing the globulin by dial¬ 
ysis and the albumin by coagulation) by saturating the solution with 
common salt. 
(4) Gliadin, soluble and dilute alcohol, and forming nearly half of 
the whole proteid matter of the kernel. 
(5) Glutenin, insoluble in water, salt solutions and dilute alcohol, 
soluble, however, in very dilute acids and alkalies. 
THE TOTAL PROTEID CONTENT IN RELATION TO THE BREAD-MAKING VALUE OF 
WHEATS AND FLOURS. 
The proteid content of wheats varies quite materially. Some samples 
contain as low as 8 per cent, others as high as 18 or 20 per cent of total 
proteid material. For purposes of nutrition, those wheats containing 
a maximum amount of proteid material, provided it is in the best form 
for bread-making purposes, are most valuable. Unfortunately, however, 
it is very often true that wheats with a maximum proteid content 
produce flours of poor bread-making qualities. 
Wheat containing a high percentage of proteid material may or may 
not produce flour with a correspondingly high proteid content, because 
the nitrogen of the wheat may be variously distributed; for example, 
in one sample, a majority of the nitrogen may be in the endosperm and 
less in the germ and bran, in which case the resultant flour would be 
relatively high in proteid material; on the other hand, a majority of 
the nitrogen may be in the offal parts and less in the endosperm or 
