Abstract: The cryoprotective effect and underlying mechanism of epigallocatechin gallate (EGCG) on frozen tilapia surimi were investigated by assaying gel properties and physicochemical indicators of myofibrillar protein as well as using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that addition of EGCG had a cryoprotective effect on tilapia surimi, with a significant difference being observed compared to the blank control group. After freezing, the salt solubility and total sulfydryl content of myofibrillar protein in the control group decreased by 68.2% and 62.9% compared to 54.5% and 49.2% with the addition of 0.01% EGCG, respectively. EGCG could significantly delay the generation of protein carbonyl. In addition, the gel strength and water-holding capacity of surimi in both the presence and absence of EGCG decreased gradually with the prolongation of storage time, and excess EGCG accelerated gel degradation. SDS-PAGE showed that EGCG could effectively inhibit the degradation of myofibrillar protein, and that it was the most effective when added at a level of 0.01%. EGCG, which can delay the denaturation and degradation of myofibrillar protein and the oxidative degradation of surimi, is expected to be a new antifreezing agent for surimi.

Key words: surimi, cryoprotectant, myofibrillar protein, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel properties