Changes in Viability and Taste Compounds of Crassostrea gigas during Depuration and Waterless Live Storage

To explore the changes in the viability and taste compounds of Crassostrea gigas at different circulation stages after harvesting, the oysters were sampled at different times of depuration, induced dormancy and waterless live storage for evaluation of viability changes in terms of adenosine triphosphate (ATP) related compounds, adenylate energy charge (AEC) and free amino acids and evaluation of flavor quality changes with respect to contents and taste activity values (TAV) of taste compounds. The results showed that the viability and taste compounds of C. gigas were significantly influenced by postharvest transportation and environmental stress. All viability indicators were significantly restored by 24 h depuration, with ATP, AEC and the content of total free amino acids being significantly higher than before depuration (P < 0.05), indicating that the viability reached new levels. During the process from induced dormancy to waterless live storage, more energy substances were required to maintain the balance of the organism under low temperature and hypoxia stress, so all viability indicators were significantly lower than before depuration (P < 0.05) and remained stable at a lower level. Among the taste compounds, the content of umami amino acids increased and the content of bitter amino acids decreased in C. gigas after depuration, and the content of taste amino acids decreased slowly as the waterless live storage time increased. The umami?nucleotides inosine 5’-monphosphate (IMP) and adenosine 5’-monophosphate (AMP) were accumulated throughout the circulation process (P < 0.05); the total amount of organic acids showed a fluctuant downward trend, with the amount of lactic acid being significantly higher after than before depuration (P < 0.05) and showing a decreasing trend from dormancy to the end of waterless live storage (P < 0.05), while the amounts of succinic acid and malic acid showed an increasing trend during waterless live storage (P < 0.05). The levels of Na+ and K+, which play an auxiliary role in the umami taste of C. gigas, were higher after 9 days of waterless live storage than before depuration. The total amount of taste substances did not change overall. The TAV of taste compounds showed that Asp, Glu, Arg, Ala, IMP, lactic acid, succinic acid, Na+ and K+ contributed significantly to the taste of C. gigas. In conclusion, the viability and taste substances of C. gigas can be maintained at a high level by depuration for 24 hours + gradient cooling to induce dormancy + ecological ice temperature waterless live storage for 9 days after harvesting.