Refrigeration-reheating induced fishy odor in cooked Chinese mitten crab (Eriocheir sinensis): Formation and intrinsic factors.

This study investigated odor changes in cooked Chinese mitten crab (Eriocheir sinensis) during refrigeration and reheating, with an emphasis on volatile flavor compounds and lipid oxidation. Sensory evaluation indicated that fishy odor emerged during refrigeration and persisted after reheating. A total of 52 odor compounds were identified, mainly aldehydes, alcohols, and ketones, with nonanal and 1-octen-3-ol increasing during refrigeration. Odor activity value (OAV) analysis and partial least squares discriminant analysis (PLS-DA) identified nonanal, hexanal, and (E)-2-octenal as key differential fishy odor compounds. Lipid oxidation indices, including peroxide value (POV) and thiobarbituric acid reactive substances (TBARS), increased, accompanied by decreases in unsaturated and polyunsaturated fatty acids, particularly C18:2n-6, C20:5, and C22:6. Correlation analysis showed that C18:2n-6 degradation was negatively associated with nonanal, while oxidative degradation of C20:5 and C22:6 correlated with nonanal, hexanal, and (E)-2-octenal. This study provides insights into the formation of fishy odor in cooked E.sinensis.