Differences and mechanisms of color deterioration in three types of ready-to-eat shellfishes during storage

Ready-to-eat (RTE) abalones, scallops and oysters were prepared through a process of cooking, drying, vacuum packaging, and high-temperature sterilization, and were subjected to accelerated storage. Upon storage, the three RTE shellfishes all showed color deterioration, as indicated by darker color, decreased L* and W* values, and increased a* value. In contrast, the color deterioration of RTE oysters was more pronounced. Meanwhile, oxidation reactions occurred during storage, which were manifested as increased peroxide value, thiobarbituric acid reactive substances value and aldehyde content. Correlation analysis showed that the color indexes (L* and W*) of the three RTE shellfishes were negatively correlated with the contents of 5-hydroxymethylfurfural, hydrophilic pyrroles, hydrophobic pyrroles and quinones, suggesting that Maillard/Maillard-like reactions and phenolic oxidation reaction contributed to the color deterioration. The higher contents of reducing sugar, lipids and transition metal ions in RTE oysters make it more prone to non-enzymatic browning reactions, causing faster color deterioration.