Abstract: The changes in muscle pH and rigor index during ice storage of big head carp and their effects on heat-induced gel properties of salt-soluble proteins from big head carp were determined. The experimental results indicated that the muscle pH of the fish obviously decreased from 7.26 to 6.51 after 10 h of post-mortem ice storage and then began to increase after 48 h. The rigor index began to increase after 19 h of post-mortem ice storage, and reached its maximum value after 48 h, 72.1%. The lowest gel strength was observed for heat-induced gels from salt-soluble proteins extracted from big head carp muscle ice-stored for 1h.The gel strength was found to increase with increasing rigor index and they reached their maximum levels at the same time. The gel strength slowly decreased as the rigor index began to decrease.

Key words: rigor index, salt-soluble protein, gel, big head carp