Effects of moderately oxidized lard on myofibrillar protein emulsion gels: Gel-forming properties, water distribution, and digestibility

Emulsion gels were prepared by adding lard with different degrees of oxidation (0, 1, 2, 3, 4, and 5 h, 110 degrees C) to porcine myofibrillar proteins (MP). The findings demonstrated that changes in sulfhydryl content and carbonyl content reflected that oxidized lard induced the oxidation of MP. Compared with the control (CON), moderately oxidized lard (2 h) led to the unfolding of the protein structure, increased beta-sheet content, and exposed hydrophobic groups. These modifications facilitated interactions between the protein and lard at the interface, enhancing the emulsifying properties of MPs. Furthermore, the moderate oxidation of lard (2 h) enhanced the organization of the gel structure and improved the gel performance of MPs, resulting in uniform water distribution. In contrast, the hardness and springiness of MP gel treated with excessively oxidized lard (5 h) were significantly reduced (p < 0.05). The microstructure of MP gel also exhibited irregular aggregation, resulting in a decline in protein digestibility. In addition, lard oxidation (2 h) had a positive effect on maintaining gel stability during storage.