Abstract: Effects of heat treatment temperature (30–90 ℃) and time (0–60 min) on the thermal aggregation behavior of myofibrillar proteins (MPs) from mirror carp (Cyprinus carpio) were studied by measuring changes in protein solubility, turbidity, surface hydrophobicity, sulfhydryl content, Fourier transform infrared spectrum and the rupture force of heat-induced MP gels. The results showed that the heat-induced aggregation of MPs strongly depended on temperature. After heat treatment at 30 ℃, the degree of protein denaturation became smaller, and the active sulfhydryl content increased, while the total sulfhydryl content remained unchanged without the formation of any disulfide bonds. In this case, protein aggregation mainly depended on the surface hydrophobic interaction. As heating temperature increased, surface hydrophobicity, β-sheet content, turbidity and the rupture force of heat-induced gels increased, and sulfhydryl content, α-helix content, and solubility decreased. These results corroborated that the increase of temperature could lead to high aggregation ability of proteins. All the tested indexes changed significantly (P < 0.05) during heat treatment from 0 to 15 min and remained stable from 30 min onward. In addition, the highest heat-induced gel strength (1.07 N) was obtained upon heat treatment at 70 ℃ for 30 min. Collectively, the above results suggest that protein thermal aggregation behavior is significantly affected by heat treatment conditions, and it can be regulated by controlling heat treatment condition.

Key words: heat treatment conditions; mirror carp; myofibrillar proteins; thermal aggregation behavior