Abstract: The objective of this work was to investigate the relationship between degradation of fish cytoskeleton protein and textural deterioration during ice-storage by immunohistochemistry, grass carp tissue structure, texture properties, shear force and drip loss. This study would provide theoretical foundation for preservation of fresh fish or its fillets. The results showed that the cytoskeleton proteins were significantly degraded during ice storage. Titin, nebulin, and dystrophin were degraded by 71%, 82%, and 73%, respectively. The ultra-micrograph shows that the light and dark bands of grass carp muscle fibers are unclear within 14 days of ice-storage, Z-band and M-band are destroyed, and 95% of the muscle fiber structure is severely broken. Meanwhile, shear force rapidly decreased from 85 N to 32 N within 10 days. The drop loss rate increased from 1.6% to 10%. Correlation analysis indicated a significant positive correlation between shear force with titin degradation (0.97, P<0.01), a significant positive correlation with dystrophin degradation (0.95, P<0.01). A highly negative positive correlation between drip loss and titin degradation (0.95, P<0.01), a significant negative correlation with dystrophin degradation (0.90, P<0.01). Studies showed that degradation of skeleton proteins may be an important factor of the destruction of muscle fiber and textural deterioration of grass carp during ice storage, and degradation of titin had much more influence on textural degradation than cytoskeleton proteins.

Key words: grass carp, cytoskeleton protein, immunohistochemistry, myofibril structure, texture