A STUDY OF THE NON-PROTEIN NITROGEN OF 
WHEAT FLOUR.* 
By M: J BUISH. 
(From the Chemistry Department of the Montana Agricultural Experiment 
Station, Bozeman.) 
(Received for publication, December 26, 1917.) 
Preliminary to a projected investigation concerning the more 
important biochemical changes which occur when wheat is 
frosted, as well as the relation of these changes to bread-making 
value, and particularly in order to study the effect of premature 
freezing on the nitrogen compounds of the wheat kernel, it has 
been found desirable to develop a more satisfactory method for 
the separation of protein from non-protein nitrogen compounds 
in wheat flour than an examination of the literature has revealed. 
A number of methods have been developed for the separation of 
protein from non-protein nitrogen in almost all kinds of bio- 
logical products, and several of these appear to be satisfactory 
for their purposes. With cereals, however, none of these methods 
seems to answer the purpose since cereals contain alcohol-soluble 
proteins, which are not encountered in any other plant or animal 
tissues. 
Reagents ordinarily used for precipitating proteins, such as 
alcohol, acetic acid, trichloroacetic acid, salts of heavy metals, 
colloidal iron, aluminum hydroxide cream, phosphotungstic acid, 
and tannic acid, are for various reasons unsatisfactory for re- 
moving gliadin from water extracts of flour. 
Ritthausen,! 40 years ago, advocated the quantitative removal 
of the proteins from milk, by alternately adding to the protein in 
solution dilute copper sulfate and potassium hydroxide until the 
proportions were such that the copper precipitate would no longer 
redissolve. The insoluble copper-protein compounds were then 
* Published with the approval of the Director of the Montana Agri- 
cultural Experiment, Station. 
1 Ritthausen, H., J. prakt. Chem., 1872, v, 215. 
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THE JOURNAL OF‘BIOLOGICAL CHEMISTRY, VOL. XXXIII, NO. 3 
