Protein structural and textural characteristics of sous-vide cooked rainbow trout (Oncorhynchus mykiss) meat

The global consumption of seafood is increasing, drawing attention to its high nutritional value. Sous-vide cooking minimizes nutrient loss and reduces heat-induced browning, making it a promising method for the future expansion of fish meat cooking. This study aimed to elucidate the details of temperature-dependent protein changes during sous-vide cooking of fish meat and to examine their relationship with texture. In our results, the hardness of rainbow trout meat decreased by heating, with the lowest hardness observed in meat cooked sous-vide at 50°C. Biochemical analyses of proteins, including SDS-PAGE, immunoblotting, microscopic observation, and peptidomic analysis, revealed temperature-specific collagen denaturation, actin solubilization, sarcoplasmic protein aggregation, and myofibrillar protein degradation. Additionally, biophysical analyses using DSC and FTIR, confirmed thermal myosin denaturation above 40°C and sarcoplasmic protein aggregation. Furthermore, a regression analysis of the hardness of rainbow trout meat as a function of sous-vide cooking temperature was conducted based on quantified protein changes. The regression model indicates that the progression of actin solubilization, collagen solubilization into cooking loss, collagen degradation, and myosin thermal denaturation contribute to softening of rainbow trout meat during sous-vide cooking. On the other hand, thermal aggregation of sarcoplasmic proteins, collagen thermal denaturation, and actin thermal denaturation may promote its hardening. These findings contribute to a more comprehensive understanding of the mechanism underlying textural changes of fish and meat depending on sous-vide cooking temperature. • Texture of sous-vide cooked fish meat depends on cooking temperature. • Protein changes during sous-vide cooking exhibit temperature specificity. • Thermal protein changes reducing myofiber integrity contribute to softening.