Chitosan Mitigates Functional Deterioration of Myofibrillar Protein After Chlorogenic Acid-Induced Oxidation: Structure Restoration and Interfacial Regulation

Chlorogenic acid (CA) exhibits robust lipid antioxidant activity within meat matrices. However, excess CA generates quinones that alter and damage porcine myofibrillar protein (MP). This study investigated the restorative effects of chitosan (CS) on MPs suffering from CA-induced oxidative damage. Three CA concentrations (0, 50, 100 μmol/g protein) and five CS dosages (0.125–1.0 g/g protein) were used to evaluate conformation, turbidity, surface hydrophobicity, solubility, emulsification, rheology, and gel properties. CA-oxidative damage to MP triggered protein unfolding, thiol depletion and aggregation, greatly lowering solubility, emulsifying capacity, viscoelasticity and water retention. CS exerted biphasic effects on turbidity, surface hydrophobicity, tertiary structure, and solubility only under severe CA-induced oxidative modification (100 μmol/g CA): low-to-medium CS aggravated adverse changes, while 1.0 g/g CS partially reversed such damage. For conformational, emulsion and gel parameters, CS consistently alleviated structural disorder caused by CA-induced oxidative damage across all treatments, with 1.0 g/g CS optimally mitigating α-helix loss and uneven emulsion droplets. Significant CA × CS interactions were detected for conformation, turbidity, surface hydrophobicity, solubility, emulsification and rheology (p < 0.001). Gel strength, water-holding capacity and water distribution exhibited non-significant interactions (p > 0.05), revealing independent additive effects of CA and CS on gel networks. Overall, high-dose CS partially ameliorates structural and functional defects of MP caused by CA-induced oxidative damage, which provides theoretical support for the combined application of polyphenols and polysaccharides in meat protein regulation.