Analysis of Interfacial Mechanical Properties and Functional Response Mechanisms of Protein–Polyphenol Composite Systems

Protein–polyphenol composite systems have gained attention for their ability to regulate protein structure and functionality. Catechin interacts with oyster water-soluble proteins through non-covalent and covalent pathways, forming composite systems with distinct structural features. Spectroscopic, microscopic, and physicochemical analyses reveal clear structural and interfacial changes. Non-covalent interactions cause partial unfolding of protein molecules, thereby improving dispersion stability, interfacial adsorption, emulsifying properties, and foaming performance, with representative systems showing increases of approximately 20–40% in emulsifying activity and up to 80–90% radical scavenging capacity. In contrast, covalent interactions induce crosslinking, forming more compact structures with greater stability but reduced flexibility. These structural differences also influence antioxidant activity and enzyme inhibition capacity. Overall, the findings show that the binding mode plays a key role in determining interfacial mechanical behavior and functional responses in protein–polyphenol systems.