Mechanism of freshness-lock during the quality determination period of farmed turbot Scophthalmus maximus revealed by foodomics

A series of biochemical changes occur in the muscles of postmortem fish, resulting in an extremely easy decline in freshness. The early stage of postharvest can be regarded as the quality determination period (QDP) oficeice seafood. The QDP handlings influence the final quality of fish product. Bleeding at ice seawater was conducted to lock the freshness of farmed turbot. The pH, ATP-related compounds and K values were measured. A non-target metabolomics technique was used to elucidate the mechanism of freshness-lock. The results showed that the levels of pH and ATP-related compounds were decreased slowly in the fish of freshness-lock, while K values were lower than those in no freshness-lock fish during cold storage. The metabolomics analysis revealed that 25 metabolites were significantly changed in the muscles of turbot after 2 d of cold storage. After freshness-lock treatment, 6 metabolites reversed in the muscles of turbot, with the rises in glycerol 3-phosphate, dihydroxyacetone phosphate, and decanoyl-l-carnitine and the drops in pyruvaldehyde, D-lyxose, and d-ribose. This study indicates that locking freshness during QDP of fish has a delayed effect on the quality deterioration and can prolonging the shelf-life of fresh product. •Locking freshness during QDP of fish has a delayed effect on the quality deterioration.•After bleeding in the iced seawater, the pH and ATP-related compounds were decreased slowly, and K values were lower.•There were 25 metabolites significantly changed in the muscles of turbot after 2 d of storage.•Six biomarkers were reversed in the muscles of turbot after freshness-lock treatment.