Improving the physical and oxidative stability of emulsions based on the interfacial electrostatic effects between porcine bone protein hydrolysates and porcine bone protein hydrolysate-rutin conjugates

The effect of porcine bone protein hydrolysates (PBPH)-rutin conjugates on the physical and oxidative stability of PBPH-coated emulsions was investigated. The structural changes of PBPH caused by the covalent modification of rutin were confirmed by circular dichroism spectroscopy and fluorescence spectroscopy. The solubility measurement results indicated that covalent conjugation with rutin leads to a change in the charge properties of PBPH. Based on layer-by-layer electrostatic deposition, emulsions were prepared with PBPH and different concentrations of PBPH-rutin conjugates at pH 5.0. The results revealed that the emulsion with 2.5 mg/mL PBPH-rutin conjugates had the highest emulsifying stability, which corresponded to the highest zeta-potential, smallest droplet size, and most uniform droplet distribution. The addition of PBPH-rutin conjugates could effectively delay lipid oxidation of emulsions. In addition, transmission electron microscopy revealed that the network structure formed by PBPH-rutin conjugates at the interface appeared to provide crucial protection against droplet aggregation and lipid antioxidants. In conclusion, the physical and oxidative stability of PBPH-coated emulsions can be enhanced via the interaction of PBPH with PBPH-rutin conjugates at the interface.