Development of an oil-in-water emulsion stabilized by a black bean protein-based nanocomplex for co-delivery of quercetin and perilla oil

An oil-in-water (O/W) emulsion stabilized by a protein-based nanocomplex was developed for the co-delivery of quercetin (Q) and perilla oil. Several nanocomplexes, synthesized by exploiting noncovalent interactions between black bean protein (BBP) and Q, were evaluated using fluorescence and Fourier-transform infrared (FTIR) spectroscopies. Thermodynamic analysis (Delta H > 0, Delta S > 0) indicated that the interactions between BBP and Q were mainly hydrophobic in nature, and FTIR spectroscopy suggested that the BBP-Q complexes, particularly BBP-Q3 (BBP:Q = 10:1, v/v), contained several alpha-helix structures and many beta-sheet secondary structures. Compared with the emulsion stabilized by BBP alone, the BBP-Q3-nanocomplex-stabilized O/W emulsion featured a smaller particle size (278.7 nm), lower viscosity, better emulsifying properties, and significantly reduced Q and perilla oil release during gastrointestinal digestion. These findings indicate that BBP-Q nano-complexes can act as effective O/W stabilizers for the co-encapsulation of polyphenols and oils in emulsions.