Protective Effect of EGCG as a Green Cryoprotectant on Protein Structure and Gel Properties of Frozen Grouper Surimi

ABSTRACT This study analyzed the effects of 0.01% (w:v) epigallocatechin gallate (EGCG) on the gel properties and protein structure of frozen grouper surimi. The commercial cryoprotectant (CC: 4% sucrose, 4% sorbitol, and 0.3% polyphosphate) and trehalose composite cryoprotectant (TCC: 4% trehalose, 2% sorbitol, and 4% sucrose) served as controls. Results indicated no significant differences in sensory evaluation among the three antifreeze‐treated surimi samples after 25 days of frozen storage ( p > 0.05). The whiteness value of the EGCG‐treated surimi (68.29) was significantly higher than the other two groups ( p < 0.05), indicating stronger resistance to protein oxidation. The water‐holding capacity (WHC) decline in the EGCG group (4.54%) was smaller than in the other two groups. Low‐field nuclear magnetic resonance (LF‐NMR) analysis further revealed the lowest water migration rate in the EGCG group, indicating its effective inhibition of bound water conversion to free water and enhancement of surimi water retention. Gel strength and microstructure assessments confirmed EGCG's ability to maintain the gel properties and network structure of frozen grouper surimi. In conclusion, since EGCG can simultaneously maintain the WHC, gel properties and protein antioxidant properties of surimi, it shows broad application prospects as a new phosphorus‐free cryoprotectant. Further studies are needed to systematically verify its sensory acceptance and long‐term frozen storage stability in large‐scale industrial production.