A pH-controlled curcumin-loaded emulsion stabilized by pea protein isolate-maltodextrin-epigallocatechin-3-gallate: Physicochemical properties and in vitro release properties

To improve emulsification properties of pea protein isolate (PPI), PPI-maltodextrin-epigallocatechin-3-gallate (PPI-MD-EGCG) ternary conjugate was prepared for the first time by glycation and then covalent reaction under alkaline conditions. According to structural and physicochemical analysis of PPI-MD-EGCG ternary conjugate by circular dichroism, fluorescence spectroscopy, and Fourier transform infrared spectroscopy, PPI-MD-EGCG ternary conjugate showed the lowest peak intensity and surface hydrophobicity, while the highest emulsification and DPPH radical scavenging efficiency. These confirmed that interactions among protein, saccharide, and polyphenol destroyed the secondary structures of PPI. This may be that combination of glycation and covalent reaction can increase the unfolded conformation and the disordered secondary structures of proteins. PPI-MD-EGCG ternary conjugate was applied in curcumin-loaded emulsion based on ternary conjugate and linoleic acid containing curcumin. Potential of this ternary conjugate as a pH-controlled delivery and release system as well as bioaccessibility of curcumin were evaluated. Curcumin-loaded ternary conjugate emulsion showed the highest loading efficiency of 92.3% and stability. In vitro release properties suggested this ternary conjugate might be a good pH-controlled carrier for curcumin. Therefore, PPI-MD-EGCG ternary conjugate could be used as an effective delivery and release system.