Epigallocatechin Gallate Combine with Ice Glazing:\nA Promising Way to Preserve the Quality of Frozen Eriocheir\nsinensis

The quality of frozen Eriocheir sinensis plays an important role in influencing consumer preference. Polyphenol\noxidase (PPO) activity changes are commonly used to evaluate melanosis\nin aquatic products. In this study, we examined the interactions between\nepigallocatechin gallate (EGCG) and PPO. Further, we investigated\nwhether treatment with EGCG in combination with ice glazing could\nrestrict melanosis in E. sinensis during\nfrozen storage and maintain its quality. The results demonstrated\nthat EGCG inhibited PPO activity in a dose-dependent manner and firmly\nbinds to the active pocket of PPO, thereby altering its tertiary structure.\nThe melanosis and oxidation of E. sinensis in frozen storage were significantly reduced by adding 0.1 g/L EGCG\ncombined with ice-glazing treatment (EGCG + IG). EGCG + IG improved\nthe melanosis score of E. sinensis after\nsix-week storage by 77.17%, and reduced protein and lipid oxidation\nby 10.80% and 62.46%, respectively, compared with untreated specimens.\nMoreover, the umami and sweet amino acids were better retained. Among\nthe combined treatments, ice glazing effectively inhibited oxidation,\nwhereas EGCG significantly inhibited melanosis. In summary, EGCG combine\nwith ice glazing, is an effective way to maintain the quality of frozen E. sinensis and could also be studied to store other\naquatic products.