SIMPLE METHOD FOR MEASURING THE ACIDITY OF 

 CEREAL PRODUCTS: ITS APPLICATION TO SUL- 

 PHURED AND UNSULPHURED OATS^ 



By Victor Birckner 



Mycologist in Fermentation Investigations, Bureau of Cliemistry, United States 

 Department of Agriculture 



INTRODUCTION 



Much attention has been given during recent years to acidity deter- 

 minations in connection with the analysis and valuation of cereals and 

 their various products. Some of the newer literature on this subject 

 is reviewed in a recent article by Liiers and Adler {ii)."^ Of the 

 methods proposed by various investigators, that of Schindler {12) has 

 been rather extensively used in this country (5, 8, 18), especially in work 

 with com {Zea mays). Its use is also recommended in a recent French 

 paper by Leprince and Lecoq (9). 



Besley and Baston (5) alone have investigated approximately 10,000 

 samples of com by means of a modification of Schindler's method; and 

 the acidity values thus obtained are considered by Winton and his 

 coworkers "the best chemical means of detecting actual spoilage, or at 

 least a tendency in that direction" {18, p. i). The method involves extrac- 

 tion of the material for 16 to 18 hours at room temperature with neutral 

 alcohol (specific gravity 0.86) and titration of the alcoholic extract with 

 standard alkali. The acidity is stated in terms of cubic centimeters 

 of normal alkali required to neutralize the acidity of the extract from 

 1,000 gm. of material. The acidity figure 30 is taken as an arbitrary 

 limit, beyond which the value should not rise for sound corn. 



This alcohol extraction method has several weak points, as will at 

 once become apparent if we consider for a moment the nature and 

 mode of formation of the acids present in grain extracts. Liiers and 

 Adler (ii) have shown conclusively that in extracting barley or malt, 

 acid-forming ferments come into play, and that it is therefore necessary 

 to make a distinction between the original acidity of the material and 

 the acidity formed during extraction. According to the same authors, 

 the acidity of barley or malt extractions is due mostly to acid phos- 

 phates, which are partly present as such and partly are formed during 

 extraction from organic phosphorus complexes through the action of 

 specific ferments, to which they give the name phosphatases. The 



'An abstract of this paper was read before the thirty-third annual convention of the Association of Official 

 Agricultural Chemists at Washington, D. C, in November, 1916. 

 2 Reference is made by number (italic) to " Literature cited," p. . 



Journal of Agricultural Research, Vol. XVIII, No. i 



Washington, D. C. Oct. i, 1919 



sj Key No. E-ii 



(33) 



