Oct. 1. 1919 Method for Measuring Acidity of Cereal Products 39 



method furnished as accurate a means for measuring grain acidity as has 

 been claimed by its users. Unfortunately, my findings in the above 

 Table I in conjunction with those recorded in the previous paper (7) 

 point to the contrary conclusion.^ 



While for work on freshly ground sulphured or unsulphured oats the 

 Schindler method is clearly inadequate, yet the figures obtained for corn 

 by Besley and Baston (6) would seem to bear a certain relation to the 

 relative age or soundness of the respective samples. But the changes 

 which they have measured can not represent true acidity only. They 

 are doubtless due, in a large measure, to the formation of amphoteric 

 protein cleavage products which cause the titration value to increase 

 suddenly in the presence of alcohol to several times its former mag- 

 nitude.^ 



It was thought advisable that another chemist should examine a 

 number of cereal products for acidity by both the proposed ice-water 

 method and the Schindler method as modified by Besley and Baston. 

 Mr. M. G. Mastin of the Bureau of Chemistry kindly undertook this task, 

 and his findings are given in Table II. 



' In the latest modification of their method Besley and Baston (6) apply an electric mixing apparatus by 

 which they find it possible to reduce the time of extraction in their alcohol method to 30 minutes, as against 

 16 to 18 hours, the time prescribed in their former paper. The introduction of this electrical device, which 

 by the way must be rather ex pensive, is merely an improvement in the technic. Had the authors at the same 

 time abolished the use of alcohol, a real improvement of their method would have been attained. Since in 

 the 18-hour extraction with alcohol the latter had been prescribed for the purpose of preventing bacterial or 

 enzymic action, there seems to be no longer any reason for its use, if the time of extraction is reduced 

 to 30 minutes. From the data given in this and the preceding article, it is evident that the eiTors introduced 

 by the use of alcohol must far outweigh its possible usefulness in a 30-niinute extraction. 



2 One might be tempted to believe that, since by using Besley and Baston's method the acidity values of 

 freshly ground, untreated cereals appear to be always higher than the values obtained by extraction v/ith 

 ice water, it should be possible to calculate the ice-water acidity from the figures published in Besley and 

 Baston's paper (.6). However, this would not be permissible, since the higher values obtained by their 

 method depend not alone on the concentration of the alcohol, which is the same in each case, but also on the 

 nature and concentration of those amphoteric grain constituents which are responsible for the shii't in acidity 

 in the presence of alcohol. The concentration of these bodies naturally varies from case to case. 



