Chitosan mitigates the beany flavor and improves the functional properties of soy protein isolate via the electrostatic interaction

Soybean protein isolate, as the most representative plant-based protein, has severely limited the acceptance of consumers due to its beany flavor. Conventional physical or chemical methods to remove the beany flavor often impair the functional properties of SPI. The effect of different coacervation ratios and chitosan molecular weight with soy protein isolate (SPI) via coacervation on the functionalities and beany flavor were studied. Results showed that the low molecular weight CS (LC) was more effective in decreasing the beany-flavor and increasing the emulsifying stability and antioxidant capacity of SPI. Compared with the LC, high molecular weight CS significantly enhanced the emulsifying activity. Additionally, the complex ratio of 30:1 was more effective in improving functionalities and flavor attributes of SPI simultaneously. The results of hierarchical cluster analysis and principal component analysis indicated that the flavor compounds between SPI-CS coacervates and SPI could be well distinguished. Additionally, the representative beany-flavor compounds of SPI obviously alleviated after coacervated with the CS. The ζ-potential, particle size and FTIR result illustrated the complex coacervates of SPI-CS via electrostatic interaction and hydrogen bonds. The surface hydrophobicity result illustrated that the CS moderately modified the structure of SPI via coacervation. The secondary structure content showed that the α-helix and β-turn content of SPI-CS increased, and the β-sheet decreased remarkably. Additionally, LC was more easily coacervated with the SPI than that of medium/high molecular weight CS. This work may provide an effective methodological and theoretical basis for further improving the functionalities and flavor profile of plant-based protein.