British Food Journal Volume 13 Issue 6 1911

Abstract

In the second part of this report the action of nitrogen peroxide on flour is discussed at some length in an account of a series of researches that have been carried out by DR. MONIER‐WILLIAMS. His conclusions may be briefly stated as follows. The maximum bleaching effect is obtained when each kilogram of flour is treated with from 30 to 100 cubic centimetres of nitrogen peroxide. The bleaching effect becomes more pronounced after keeping for several days. The amount of nitrous acid or nitrites that are present in bleached flour corresponds to about 30 per cent. of the total nitrogen absorbed, the proportion of nitrites present remaining nearly constant after the lapse of several days in the more slightly bleached samples. After the lapse of a short time it is still possible to extract about 60 per cent. of the nitrogen absorbed by the flour by means of cold water, but after several days the nitrogen that can be extracted by this means decreases. This may perhaps be attributed to the “absorption” of nitrous acid by the glutenin and gliadin. In highly bleached flour (300 cubic centimetres of nitrogen peroxide per kilogram of flour) a considerable increase in the amounts of soluble proteins and soluble carbohydrates takes place. In highly bleached flour, after some time, about 6 or 7 per cent. of the nitrogen introduced as nitrogen by the nitrogen peroxide is absorbed by the oil, which acquires the characteristics of an oxidised oil. No evidence is forthcoming as to the formation of diazo compounds nor the production of free nitrogen. Bleaching was found to exercise an inhibitory action on the salivary digestion of flour.