Contribution of dominant spoilage bacteria to quality deterioration of refrigerated large yellow croaker (Pseudosciaena crocea): myofibril proteins degradation.

This research evaluated the effects of three specific spoilage organisms (SSOs)-Shewanella baltica, Pseudomonas brenneri and Pseudomonas psychrophila- on quality deterioration and myofibrillar proteins (MPs) degradation in chilled large yellow croaker fillets. The SSOs were found to expedite the conversion of umami/sweet amino acids to biogenic amines (BAs), reduced water holding capacity and textural deterioration. This altered taste activity value (TAV) of representative amino acids and increased the equivalent umami concentration (EUC). SSOs exacerbated MP conformational changes from ordered rigid to disordered flexible structures, enhancing protein solubility and tyrosine content. Findings from SDS-PAGE and TEM indicated significant degradation of myosin, actin, and tropomyosin, and disruption of sarcomere structure. Correlations between quality traits and MPs stability were established. Spoilage impact ranked: Shewanella baltica > Pseudomonas brenneri > Pseudomonas psychrophila. This study highlights the importance of preventing SSOs colonization in delaying quality deterioration and provides comprehensive insights into MPs degradation in SSO-induced spoilage.