Effects of Epigallocatechin-3-Gallate-Bovine Bone Protein (EGCG-BBP) Conjugate on the Structure and Oxidative Stability of Protein in Emulsified Meatballs

To investigate the effects of epigallocatechin-3-gallate-bovine bone protein (EGCG-BBP) on the protein structure and storage oxidative stability of emulsified meat products, the effects of adding different concentrations of EGCG-BBP on the physicochemical and structural properties of myofibrillar protein (MP) in raw meat, and on the oxidative stability of meatballs were investigated. The results showed that the addition of 0.8% EGCG-BBP resulted in the highest content of sulfhydryl group of MP (4.06 nmol/mg protein) in the minced meat, while the carbonyl group and surface hydrophobicity values were lowest, effectively improving the antioxidant capacity of the emulsified meat products. Fourier-transform infrared spectroscopy analysis showed that the wave number corresponding to the peak of the amide A band of MP was significantly increased in the minced meat supplemented with EGCG-BBP compared with the control group, indicating corresponding changes in the secondary structure of MP. The fluorescence spectra showed that there was a significant red shift in the strongest MP wavelength in the control group with a prolongation of the storage time. However, this shift was significantly reduced as the concentration of EGCC-BBP increased. This suggested that the addition of EGCG-BBP changed the tertiary structure of MP. Furthermore, analysis of oxidation indices during storage of the emulsified meatballs showed that the addition of 0.8% EGCG-BBP significantly reduced the values of both PV values and TBARS in the meatballs, thereby improving their oxidative stability. In summary, EGCG-BBP can significantly alter both the secondary and tertiary structures of MP and has good oxidation resistance. This indicates its potential to enhance the quality of emulsified meat products and provides a new choice for the application of antioxidant emulsifiers in meat products.