Mechanism of purslane extract inhibiting oxidation and modifying physicochemical properties of pork myofibrillar proteins under oxidation system

The research aimed to elucidate how purslane extract (PE) inhibited pork myofibrillar proteins (MPs) oxidation and modulated the physicochemical properties in the Fenton oxidation system. This study employed UHPLC-QE-Orbitrap-MS/MS to comprehensively analyze the PE constituents and evaluate their antioxidant properties. Furthermore, the effects of various PE concentrations (0.05, 0.10, 0.15, 0.20, and 0.40 mg/mL) on the structural characteristics of pork MPs in a hydroxyl radical oxidation system were evaluated. The findings indicated that PE was rich in phenolics, with luteolin, kaempferol, genistein, rutin, diosmetin, morin, kaempferol-3-O-rutinoside, isoquercitrin, and isorhamnetin-3-O-neohesperidoside being the nine most prevalent compounds. These compounds contributed to the extract's strong free radical scavenging activity. Experimental results demonstrated that adding 0.20 mg/mL PE significantly reduced the carbonyl content compared with oxidized MPs while increasing total thiol, free thiol, and free amino group levels ( P  < 0.05). The protective effect of PE on MP amino acid side chains was superior to that of Butylated hydroxyanisole (BHA). Moreover, PE addition protected the secondary structure of MPs and minimized the α-helix loss caused by oxidation. In addition, PE decreased the intrinsic fluorescence intensity of MPs, enhanced their surface hydrophobicity, and reduced their solubility. SDS-PAGE results indicated that oxidation and PE addition induced MP aggregation, with most of it being reversible. These findings support the potential of PE as a natural antioxidant in meat products and offer a theoretical basis for its functional applications in meat processing.