The inhibition mechanism of nanoparticles-loading oxidized hydroxypropyl starch/carrageenan composite films on texture deterioration of chilled beef from the perspective of protein and exudates changes.

In this work, polyphenol nanoparticles-loaded oxidized hydroxypropyl starch/carrageenan (OC/SPH NPs) films were prepared and applied to the preservation of fresh-chilled beef. The mechanism by which OC/SPH NPs films inhibit quality deterioration in fresh-chilled beef was investigated through analyses of endogenous enzyme activity, protein oxidative degradation, secondary structure, MFI values and TCA-soluble peptides. The results indicated that the active components in the composite film successfully migrated into the beef, while the remaining antioxidant capacity of the film decreased. Endogenous enzymes in the beef gradually release into the exudate over extended storage periods. By day 18, the activities of tissue protease B, L, D, and calpain in the exudate reached 25.42 U/g, 33.97 U/g, 0.73 U/g, and 14.29 U/g, respectively. This indicates that the OC/SPH NPs film significantly inhibited the activity of endogenous enzymes in beef, delayed changes in protein oxidation indicators such as sulfydryl, carbonyl content, Ca2+-ATPase activity, and surface hydrophobicity; simultaneously, it slowed the transition of α-helices to random coils, maintaining the structural stability of myofibrillar protein (MP). Compared with the control film, the MFI value and TCA-soluble peptides of beef treated with the composite film decreased by 32.1% and 27.61%, respectively. After incubation with exudate for 12 h, the degradation extent of MPs was reduced, indicating that the OC/SPH NPs film absorbed exudate and delayed the deterioration of beef texture. The results elucidate that the OC/SPH NPs film protects beef texture stability by reducing endogenous enzyme activation, protein oxidation, and degradation.