Amino acid changes in fermented oyster (Crassostrea gigas) sauce with different fermentation periods

Fermented oyster sauce (FOS) was prepared with 25% NaCl (w/w) at 20 °C with different fermentation periods. Biochemical changes during the fermentation were investigated. Results revealed that, during fermentation, protein contents were increased whereas carbohydrate contents were decreased. Amino acid composition showed that the contents of aspartic acid, lysine, glutamic acid, glycine and alanine were higher than other amino acids. Free amino acid contents of FOS fluctuated during the fermentation period but most of the free amino acids increased. Particularly, the contents of taurine, glutamic acid, lysine, glycine and alanine were high, which may contribute to the taste and flavour of FOS.