Evaluate the freshness and shelf life of refrigerated salted perch (Perca fluviatilis) focusing on the flavor change

Steamed perch is a favorite dish in China, and salting is a necessary step before steaming. Due to the abundance of microorganisms in freshwater fish, the cold storage time during the sales stage after salted affects its flavor and safety. This study investigated the dynamic changes in the freshness of the salted perch (salt, 2 %, w/w) during cold storage (0–8 days), and evaluated the shelf life by the conventional methods (TVB-N, TVC, and K-values) (before steaming) and the sensory method (after steaming). The results showed: (1) As refrigeration time extended to 8 days, the freshness of salted perch declined significantly, with TVB-N content increasing to 16.5 mg/100 g, TVC to 5.9 log CFU/g, and K-values to 38.61 %; (2) The optimal shelf life for sensory evaluation was 2 days, which was 6 days shorter than the shelf life obtained by the conventional method; (3) The changes in some flavor compounds might be the main contributors to flavor deterioration and could serve as potential markers for decreased freshness. These compounds include a significant reduction in tartaric acid and inosine-5′-monophosphate (IMP) content (P < 0.05), an increase in the level of bitter amino acids, and alterations occurring in the 18 major key flavor compounds, such as 1-octen-3-ol, methyl trans-9-octadecenoate, hexanal, and nonanal. This research offers novel insights into evaluating the shelf life of aquatic-prepared dishes.