Effects of Portulaca oleracea Extracts on Gelation and Emulsification Properties of Pork Myofibrillar Proteins

This study aimed to investigate the effects of Portulaca oleracea extracts (PE) on the gelation and emulsification properties of pork myofibrillar proteins (MPs). A myofibrillar protein-Fenton oxidation system (0.0049 g/L FeCl₃, 0.0176 g/L ascorbic acid, 5 mmol/L H₂O₂) was established, and different concentrations of PE (0.00, 2.00, 4.00, 8.00 mg/mL) were added. The changes in gelation and emulsification properties of MPs were analyzed to assess the impact of PE on the functional characteristics of MPs in pork tenderloin under oxidative conditions. The results demonstrated that PE significantly reduced the cooking loss of the gel (P<0.01) and improved its water-holding capacity (P<0.01) compared with the oxidation control group. Specifically at a concentration of 4.00 mg/mL, the addition of PE resulted in a 6.72% decrease in cooking loss and a 11.98% increase in water-holding capacity compared with the oxidation control group. However, the addition of PE led to a significant decrease in the whiteness of the gel (P<0.05), with the degree of whiteness being inversely related to the concentration of PE. Furthermore, the addition of PE increased the storage modulus (G') and loss modulus (G'') of the gel. At a concentration of 4.00 mg/mL PE, the microscopic structure of the gel exhibited greater regularity and order than that after oxidation, with an increase of 10.10% in hardness and 7.16% in elasticity. SDS-PAGE results indicated that the cross-linking between PE and proteins could be reduced, and PE significantly enhanced the emulsifying activity and emulsifying stability of the proteins (P<0.01). Overall, based on the comprehensive findings, it can be concluded that 4.00 mg/mL PE effectively inhibits the oxidation of MPs and improves the functional characteristics of proteins.