Design of Soy Protein Isolate/Chitosan/EGCG Ternary Complexes to Reduce Beany Flavor and Improve Emulsifying Properties

The beany flavor of soy protein isolate (SPI) reduces consumer acceptance of plant-based foods. This study aimed to develop ternary complexes with reduced release of beany flavor compounds and enhanced emulsifying properties. Effect of different assembly sequences (SPI-chitosan (CS)-epigallocatechin gallate (EGCG), and SPI-EGCG-CS) and EGCG concentrations on the structural characteristics of ternary complexes were investigated. Results showed that both SPI-CS-EGCG and SPI-EGCG-CS significantly reduced the release of beany flavor compounds, with SPI-EGCG-CS showing a better effect. Furthermore, the ternary complex showed a stronger inhibitory effect on the release of beany flavor with the 2.0 mg/mL EGCG. Additionally, the ternary complexes all showed the higher emulsifying activity compared with SPI-CS and SPI. Fourier-transform infrared (FTIR) spectroscopy demonstrated that hydrogen bonding and hydrophobic interactions played pivotal roles in governing the formation of the ternary complex, concomitant with SPI shift toward a more flexible and disordered conformation. The formation of the ternary complexes reduced the exposure of hydrophobic groups on the SPI surface. Moreover, the modification of surface charge and particle size in the ternary complexes was highly dependent on the order of component assembly, with SPI-EGCG-CS being significantly altered and SPI-CS-EGCG remaining largely unchanged. • SPI-EGCG-CS showed the strongest inhibition of beany flavor release. • EGCG at 2.0 mg/mL greatly enhanced mitigation of off-flavor compounds. • All ternary complexes exhibited higher emulsifying activity than SPI and SPI-CS. • Hydrogen bonding and hydrophobic forces dominated complex formation and structure.