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

## TL;DR

This study shows that a combination of tea compounds can protect snakehead fish proteins during freezing, reducing oxidation and preserving structure.

## Contribution

The novel finding is that a 3% EGCG-TFO mixture effectively preserves snakehead surimi proteins during frozen storage cycles.

## Key findings

- EGCG-TFO (3%) reduced carbonyl increases and preserved Ca2+ ATPase activity during freezing.
- The mixture maintained Amide I and II structural features by promoting hydrogen and ionic interactions.
- EGCG-TFO (3%) protected microstructural attributes by inhibiting protein coagulation.

## Abstract

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 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.

•The EGCG-TFP mixture was assessed on snakehead protein during FCY.•The EGCG-TFP mitigated the oxidation promoted decline in Ca2 + ATPase and carbonyls.•The EGCG-TFP significantly maintained the Amide I and II associated alterations.•The EGCG-TFP maintained the microstructural attributes of surimi muscles.•Overall, EGCG-TFP (3%) was effective in preserving the snakehead quality.

The EGCG-TFP mixture was assessed on snakehead protein during FCY.

The EGCG-TFP mitigated the oxidation promoted decline in Ca2 + ATPase and carbonyls.

The EGCG-TFP significantly maintained the Amide I and II associated alterations.

The EGCG-TFP maintained the microstructural attributes of surimi muscles.

Overall, EGCG-TFP (3%) was effective in preserving the snakehead quality.