Structural and physicochemical properties of pea protein isolate/catechin/sodium alginate ternary complex and its...

This study aimed to investigate the structural and physicochemical properties of pea protein isolate (PPI)/catechin (CA)/sodium alginate (SA) ternary complex and its application as a Pickering emulsion stabilizer. PPI/CA/SA ternary complexes at different concentrations (0, 0.002, 0.01, and 0.05% w/w) of CA were prepared and used as an emulsifier to prepare Pickering emulsion. The polyphenol binding capacity increased from 75.87 nmol/mg protein to 133.53 nmol/mg protein with increasing CA concentrations from 0% to 0.05%. Intrinsic fluorescence spectra and surface hydrophobicity measurements revealed structural modifications in PPI and enhanced molecular interactions among PPI, CA, and SA. XRD analysis confirmed the amorphous nature of the ternary complexes, suggesting effective binding or encapsulation of CA within the PPI/SA matrix. FT-IR analysis showed that structural alterations in the protein were occurred in the PPI/SA complex upon CA incorporation. FE-SEM images showed that increasing CA concentration was associated with the appearance of particles with relatively smoother surfaces, which may reflect enhanced molecular interactions and reduced surface hydrophobicity. The antioxidant activity of the complexes, measured by ABTS assay, increased with CA concentrations. Pickering emulsions stabilized with ternary complexes exhibited higher storage and thermal stability as the CA concentrations increased, which may be attributed to the enhanced viscoelastic properties of the interfacial layer.