Efficient binding paradigm of protein and polysaccharide: Preparation of isolated soy protein-chitosan quaternary ammonium salt complex system and exploration of its emulsification potential.

Soy protein isolate (SPI) has good emulsifying ability, but is greatly affected by the environment. The addition of polysaccharides either increases or decreases the stability of SPI. We report and prepared for the first time SPI/HACC complexes with different polysaccharide contents (SPI/HACC ratios are 1:1, 2:1 and 5:1). The binding properties, microstructure and emulsifying properties of the SPI/HACC complexes were determined and analyzed. The results showed that the interaction them is mainly through hydrogen bonding, electrostatic interaction, hydrophobic interaction and steric hindrance effect. The combination of SPI and HACC overcomes their respective limitations and the microstructure is more flat and smooth. It was also found that the emulsifying ability and concentration of SPI showed a certain correlation and the addition of HACC significantly improved the emulsifying ability and storage stability of SPI. This study shows that the prepared SPI/HACC complex has great potential for application in the food industry.