Studies on Oyster Meat Extracts I. Seasonal Change of Nitrogenous Components

Abstract

Seasonal change in content of free amino acids (FAA), trimethylamine oxide (TMAO) and non protein nitrogen (NPN) was investigated in the shucked whole body and adductor muscle of the cultured oyster Crassostrea gigas. The whole body was abundant in FAA such as glutamic acid, glycine, alanine, proline and taurine. The adductor muscle contained glutamic acid, glycine, alanine, β-alanine, proline, arginine and taurine in relatively high contents. Levels of TMAO were negligible in both the whole body and adductor muscle. In the whole body, contents of proline and glycine were lowest in summer. In the adductor muscle, the aforementioned FAA except alanine and taurine also showed the lowest values in summer. NPN contents in both the whole body and adductor muscle were lowest in this season. The seasonal change in content of the FAA was discussed in relation to the paratability of oyster meats.