Protein structural changes, volatile flavor evolution and microbial community succession in Opsariichthys bidens during simulated natural refrigerated transport: a correlation analysis

Chinese hook snout carp (Opsariichthys bidens) deteriorates readily during postharvest transport, yet the interplay between muscle protein degradation, volatile flavor formation, and microbial metabolism under realistic transportation conditions remains poorly understood. This is the first study to systematically investigate the correlation between protein structural changes and microbial metabolism in Chinese hook snout carp during refrigerated transport simulating natural conditions at 4 °C, 16 °C, and 32 °C. Elevated temperatures accelerate myofibrillar protein denaturation. Compared with fresh samples, α-helix content decreases by approximately 8.5% under 32 °C for 24 h, while random coil content increases by 12.3%, accompanied by reduced water-holding capacity (moisture content declining from 81.64% to 74.92%). Flavor profiles are dominated by aldehydes at 4 °C, whereas sulfur compounds, indole, and pyridines gradually accumulate with rising temperature, and severe flavor deterioration occurs within only 12 h at 32 °C. Low-temperatures enriched psychrotrophic Acinetobacter and Pseudomonas, whereas elevated temperatures promoted diverse mesophilic spoilage bacteria with enhanced amino acid, lipid, and carbohydrate metabolism. Transport temperature serves as the primary driver of quality loss, with storage duration exerting cumulative amplification effects. Our findings provide correlation-based insights into temperature-dependent quality deterioration that can inform cold-chain optimization strategies.