The Interaction Between Soybean Protein Isolate and EGCG and Tea Polyphenols: Effects on Protein Structure and Binding of Key Beany Flavor Substances

This study investigated the effects of epigallocatechin gallate (EGCG) and tea polyphenol treatments at varying concentrations on soybean protein isolate (SPI), with particular focus on SPI's structural modifications and its subsequent interactions with characteristic beany flavor compounds. Treatment with EGCG and tea polyphenols significantly decreased SPI's adsorption capacity for characteristic beany flavor compounds (hexanal, benzaldehyde, 1-octen-3-ol, and 2-nonanone), while markedly enhancing adsorption of 2-pentylfuran. EGCG/tea polyphenol treatment improved the solubility of SPI and enhanced the fluorescence quenching effect. Additionally, as EGCG, the α-helix and β-turn structure in SPI changed to a β-sheet and random coil structure, reducing surface hydrophobicity. The molecular docking results indicate that the interactions between SPI and EGCG or tea polyphenols are primarily hydrogen bonding and hydrophobic interactions. The sensory evaluation demonstrated that EGCG and tea polyphenols effectively mitigated the unpleasant fatty flavor characteristics of SPI.