Concentration effects of proanthocyanidins on protein oxidation and quality deterioration of refrigerated golden pompano (Trachinotus blochii) fillets: Insights from metabolomic analysis.

This study investigated the effects of different proanthocyanidins (PA) concentrations (0-4.0 g/L) on protein oxidation, physicochemical quality, and metabolomic changes in refrigerated golden pompano (Trachinotus blochii) fillets. The results showed that PA exhibited concentration-related protective effects against quality deterioration, primarily by inhibiting lipid and protein oxidation. Notably, 2.0 g/L PA exhibited superior protective effects, suppressing the increase in free-radical intensity, carbonyl content, and disulfide bond content, while retaining more sulfhydryl content. Furthermore, myofibrillar proteins showed enhanced structural stability, characterized by higher α-helix content, stronger intrinsic fluorescence, and reduced aggregation. PA at 2.0 g/L also more effectively maintained muscle integrity, water-holding capacity, texture, and color during storage. Metabolomic analysis further revealed that this treatment downregulated metabolites associated with lipid oxidation, microbial spoilage, ATP degradation, and protein oxidation. However, at a higher concentration (4.0 g/L), PA exhibited pro-oxidative behavior, accelerating oxidative deterioration and compromising preservative efficacy. These results provide mechanistic evidence supporting the potential of PA as a natural preservative for fish and offer mechanistic support for its practical application in aquatic products.