Inhibitory effect of aqueous extract of Allium species on endogenous cathepsin activities and textural deterioration of ice-stored grass carp fillets

Abstract

Cysteine cathepsin-associated degradation of muscle proteins have been assumed to be crucial to the softening of chilled fillet. The effect of aqueous extract of Alliums on cathepsin-induced proteolysis and texture deterioration of ice-stored carp fillets was evaluated. Among all treatments, extracts of scallion and garlic were the most effective inhibitor of cathepsin B, reducing the enzyme activity by more than 40 % after storage of 3 days, whereas extracts of scallion and leek had the greatest inhibitory effects on the cathepsin L activity, resulting in corresponding reduction in enzyme activity of 65 and 57 %, respectively. Extracts of scallion and garlic were the most effective treatments in impeding accumulation of TCA-soluble peptides and breakdown of myofibrillar proteins as validated by SDS-PAGE pattern. After storage of 21 days, the shear force of fillets treated with scallion and garlic extracts were approximately 30 % higher than those of control, whereas the treatments with other Allium extracts showed no inhibitory effect on textural deterioration. The results demonstrated that the treatment of grass carp fillets with extract of scallion and garlic has the potential to mitigate the endogenous cathepsin-induced softening of ice-stored grass carp fillets.