Vol. XVI Washington, D. C, January 6, 1919 No. i 



DETERMINATION OF ACIDITY AND TITRABLE NITRO- >^ew Y&r- 

 GEN IN WHEAT WITH THE HYDROGEN ELECTRODE ■.--.> 



By C. O. SwANSON, Associate Chemist, and E. L. TaguE, Assistant Chemist, Department 

 of Chem,isiry, Kansas Agricultural Experiment Station 



Acidity in wheat flour is usually determined by making a water extract 

 of the flour at a definite temperature for a definite time and titrating this 

 extract with a standard alkali, using phenolphthalein as an indicator. 

 Since the quantity of alkali neutralized is governed to a considerable 

 extent by the temperature and duration of extraction, a large number of 

 workers extract at 40° C. for two hours. This method can also be used 

 for wheat {Triticum aestivum), the grain being first finely ground. 



Because wheat contains the enzym phytase, as has been shown by 

 several investigators,^ it is to be expected that the duration of extraction 

 and the temperature used will influence the amount of standard alkali 

 neutralized. 



Acidity in wheat or wheat flour is not due to the presence of free acids 

 as that term is ordinarily understood. The varying amounts of alkali 

 neutralized in different samples are supposed to be due to the presence 

 of phosphates in less or greater amounts. This statement is supported 

 by the fact that the greater the acidity the greater the amount of phosphor- 

 us in the extract.^ 



Water extracts of wheat and wheat flour as ordinarily made are 

 slightly turbid. This turbidity depends to some extent on the nature 

 of the flour. Extracts from wheat and low-grade flour give clearer 

 extracts than those from high-grade flour. This is probably due to the 

 presence of greater amounts of electrolytes in the ground wheat and low- 

 grade flour, as these would help to coagulate the turbid or colloidal 

 matter. 



Because of the turbidity and the colloidal nature of wheat and flour 

 extracts, absorption plays a part in the determinations of acidity when the 

 colorometric method is used. 



' Anderson, R. J. concerning the organic phosphorus compound of wheat bran and the 

 HYDROLYSIS OFPHYTIN. N. Y. State Agr. Exp. Sta. Tech. Bui. 40, 31 p. 1915. 



' Swansom, C. O. acidity in WHEAT flour; its relation to phosphorus and to other constitu- 

 ents. Jn Jour. Indus, and Engin. Chem., v. 4, no. 4, p. 274-278. 1912. 



Journal of Agricultural Research. (l) Vol. XVI, No. i 



Washington, D. C. Jan. 6, 1919 



qv Key No. Kans.-i8 



