Protective effect of covalently coupled polyphenols on hydroxyl radical-damaged potato protein isolate: laccase-mediated functional modification of resveratrol and luteolin

Potato protein isolate (PPI) is a major byproduct of potato starch processing, and its effective utilization is of great significance in reducing waste, conserving resources, and promoting environmental sustainability. However, the functional characteristics of PPI, such as solubility and emulsifying properties, are insufficient. This study explores a novel enzymatic strategy that utilizes laccase catalysis to covalently couple PPI with polyphenols (resveratrol, luteolin), aiming to simultaneously enhance the functional properties and antioxidant capacity of PPI. This modification increases the solubility of PPI in the critical acidic pH range (3–5); At low polyphenol levels, the emulsifying activity index increased by 12.4–35.4 %. Importantly, covalent binding of polyphenols provides synergistic antioxidant protection, effectively reducing the levels of protein oxidation markers induced by hydroxyl radicals. This study successfully demonstrated that laccase mediated covalent coupling of polyphenols is an effective means of converting PPI into components with enhanced functionality and strong antioxidant activity, providing an important foundation and promising solution for its application as antioxidants in protein based health food systems.