Abstract
When DMA (dimethylamine) was added to the mixtures of 5 to 7% brewed food such as shoyu (soy sauce), miso (soybean paste), wine, vineger or mirin and nitrite at pH 3.6, the formation of NDMA (N-nitroso dimethylamine) was markedly reduced. Especially, addition of shoyu, miso or acid hydro-lysates of proteins was most effective of all for the suppression of nitrosation ranging from 60 to 70%.
A study was made on the mechanism of the suppression of nitrosation by shoyu, using various methods such as analysis on chemical components of shoyu and fractionation of shoyu components with Amberlite CG-120, IR-45 and ultrafiltration.
Occurrence of Van Slyke reaction between α-amino acid and nitrite in the reaction mixture containing DMA, shoyu and nitrite was confirmed by the decrease of the amino acids in the shoyu, with accompanied formation of α-hydroxy carboxylic acid and nitrogen gas during the reaction. Furthermore, reactivity of glutamic acid as a typical amino acid in shoyu against nitrite was found to be much faster than that of DMA at pH 3.6. It was, therefore, concluded from the the results that Van Slyke reaction suppressed nitrosation by competitively interfering with the reaction of DMA to nitrite.
