Comparison of Oxidation Extent, Structural Changes, and Oxidation Modification Types of Myofibrillar Protein Treated by Hydroxyl Radical and Peroxyalkyl Radical Oxidation System

Protein oxidation is a major contributor to food quality deterioration and has attracted increasing attention in recent years. Dityrosine, as a potentially toxic protein oxidation product, is readily formed during the processing and storage of high-protein foods. Following ingestion, dityrosine can induce oxidative stress and may contribute to the onset and progression of multiple diseases. To investigate the effects of different free radicals on the generation of foodborne dityrosine, this study compared the differences in side chain modification, cross-linking aggregation, structural changes, and oxidation sites of oxidized proteins induced by hydroxyl radical oxidation system (HOS) and peroxyalkyl radical oxidation system (POS) and attempted to discuss potential mechanisms. Overall, POS can markedly promote dityrosine formation, consistent with greater oxidative damage to myofibrillar protein (MP), as evidenced by the generation of more carbonyl compounds. POS also substantially disrupted the tertiary structure of MP, exposing internal hydrophobic groups and thereby increasing the diversity of oxidative modifications. Under POS conditions, MP underwent irreversible covalent cross-linking and formed high-molecular weight aggregates. In contrast, HOS exhibited weaker effects on side-chain modification, cross-linking and aggregation, and structural disruption. However, HOS more strongly promoted the decay of thiol groups, which likely facilitated the disulfide-mediated covalent cross-linking of MP. Collectively, these comparations identify an appropriate simulated oxidation system for investigating dityrosine generation during food processing. PRACTICAL APPLICATIONS: This study identifies POS as a suitable model for inducing dityrosine formation in meat protein systems. POS can be applied in meat protein antioxidation research to evaluate the inhibitory effects of different antioxidants on the formation of the toxic oxidative product dityrosine. These findings provide a practical basis for selecting appropriate oxidation systems when studying protein oxidation in high-protein food products during processing and storage.