Effect of super-chilling storage on maintenance of quality and freshness of the Pacific oyster (Crassostrea gigas)

The quality changes of shelled Pacific oysters (Crassostrea gigas) were examined in relation to the effects of superchilling storage at -1 degrees C for 28 d by measuring changes in biochemical properties (microbial analysis, adenosine triphosphate (ATP)-related compounds, pH, free amino acids) and sensory evaluations in this study. The results indicated that microorganism growth was significantly inhibited during superchilling storage. Adenosine diphosphate (ADP) and adenosine monophosphate (AMP) accumulated while ATP rapidly decreased in the adductor muscle. ATP and ADP were the primary components in the other 3 tissues including mantle, gill, and body trunk of oysters, and they remained -relatively stable over time. The pH and adenylate energy charge in the adductor muscle could be utilized as freshness indicators for shelled oysters. However, there were no significant differences (P>0.05) among the free amino acids during whole storage. According to the sensory evaluations, oysters could be alive and tolerated up to 21 d at -1 degrees C storage. The study demonstrated that superchilling storage at -1 degrees C could better maintain the eating quality of shelled oysters and the shelf life was extended to 21 d.