Abstract
Recently, frozen raw oysters for consumption have come to be appeared in a market. We investigated the effect of freezing conditions on the extractive components in the frozen raw oysters. Oyster with shell or shucked oyster was frozen individually in liquid nitrogen or ethanol brine below -40°C within 3 min for shucked oyster and 23 min for oyster with shell. Also oyster was frozen at -20, -10 and -5°C in a freezer. The frozen oysters were directly deproteinized with perchloric acid for analysis. After neutralization with a KOH solution, free amino acids, organic acids, and nucleotides in the extracts were analyzed. There was no significant difference in free amino acid contents and organic acids contents in the shucked oysters among different freezing conditions. On the other hand, contents of free amino acids and organic acids in oysters with shell frozen at -5 and -10 °C were significantly lower than the shucked oysters frozen in liquid nitrogen.
