Quality assessment of soy sauce using underivatized amino acids by capillary electrophoresis

Fermented soy sauce was identified by determining underivatized amino acids through the proposed capillary electrophoresis-ultraviolet method coupled with sweeping technology for the first time, based on the coordination interaction between amino acids and Cu²⁺. The essential amino acids pattern was used to the evaluate quality of soy sauce of different grades, the results showed that the quality of special grade soy sauce was higher than that of others. The sample S13 had the highest quality according to the analysis of the 12 kinds of soy sauce by principal component analysis. According to the method of Taste Activity Value, glutamic acids, lysine, alanine, and aspartic acid were considered to be the main taste amino acids in soy sauce.