TMT-Based Quantitative Proteomics Reveals the Molecular Mechanism Underlying Quality Deterioration of Refrigerated Northern Pike (Esox lucius)

This study aimed to elucidate the characteristics of protein changes and their relationship with physicochemical properties during the quality deterioration of refrigerated Northern Pike (Esox lucius). We employed tandem mass tag (TMT)-based quantitative proteomics, combined with physicochemical indicators, including surface hydrophobicity, carbonyl content, sulfhydryl content, and myofibrillar fragmentation index (MFI), to systematically analyze protein alterations during cold storage. The results showed that with prolonged cold storage, the surface hydrophobicity, carbonyl content, and MFI of Northern Pike samples exhibited an increasing trend, whereas the sulfhydryl content decreased. Proteomic analysis identified a total of 563 differentially expressed proteins (DEPs) between fresh and cold-stored states, of which 293 were upregulated and 270 were downregulated. Furthermore, by integrating COG/KOG functional classification, subcellular localization, and GO enrichment analysis, the functional characteristics of the DEPs and their potential involvement in biological processes were systematically characterized. Correlation analysis revealed that six DEPs were significantly correlated with the changes in physicochemical indices of Northern Pike during cold storage, namely fructose-bisphosphate aldolase encoded by ALDOA, Nesh-SH3 domain-target protein, keratin, neurofilament heavy polypeptide, serine/arginine repetitive matrix protein 2-like, and asymmetrical bis(5′-nucleosidyl) tetraphosphatase. By integrating analyses of differentially abundant proteins and protein oxidation, this study suggests potential molecular mechanisms potentially responsible for quality loss in northern pike under chilled storage, offering a theoretical foundation for its preservation and quality assessment.