主题：小河沿--解惑堂--味精的安全性 -- 虽远必诛

The stability of glutamic acid and monosodium glutamate as regards

pH, temperature and oxygen was studied during storage and two

thermal processings, the residual products and those which appeared

being determined. The initial molecules only change into

pyrrolidonecarboxylic acid, never into glutamine nor y-aminobutyric

acid. Preservation is good in all cases at pH 0 and pH 14, but

glutamic acid is converted to pyrrolidonecarboxylic acid at intermediate

pH values. The change is favored by pH values ranging from

2 - 3, by temperature increase and by oxygen.