Synergistic effect of tea epigallocatechin gallate and tea flower-derived oligosaccharides on frozen storage cycles inducing oxidation and microstructural alterations of snakehead surimi proteins

The synergistic effect of epigallocatechin gallate (EGCG) and tea flower oligosaccharides (TFO) was analyzed in snakehead during different 8 frozen storage cycles (FCY). Four different protein groups were prepared: C (no additives), K (conventional combination (4% sucrose+4% sorbitol)), EGCG-TFO (1%), and EGCG-TFO (3%). FCY accelerated the oxidation, especially C, where decreases in total sulfhydryl (54.68 to 34.70 mmol/kg) and Ca²⁺ATPase (0.518 to 0.304 mmol/g) were observed, as well as an increase in surface hydrophobicity. The K samples showed better stability against FCY-induced oxidative modifications than EGCG-TFO (1%). Meanwhile, EGCG-TFO (3%) restricted the FCY accelerated increase in carbonyls from 1.56 to 5.17 nmol/mg. Moreover, the Amide <i>I</i> and II regions were preserved by promoting hydrogen and ionic interactions, as well as securing the α-helix in the myosin region, as evidenced by molecular simulation. EGCG-TFO (3%) also protected the microstructural attributes owing to its inhibitory role in protein coagulation and interaction forces.