Abstract:In order to investigate the structure-function relationship of soybean protein isolate enzymatic hydrolysate(SPIH) under different enzymatic hydrolysis time, the hydrolysis of soybean protein isolate(SPI) was evaluated by measuring the degree of hydrolysis and the mass fraction of polypeptide. The relationship between structure and function was characterized by Fourier transform infrared spectroscopy, endogenous fluorescence spectroscopy, surface hydrophobicity, emulsification, and antioxidant capacity. The results showed that the hydrolysis degree of SPI increased with the prolonged enzymatic hydrolysis duration, while the mass fraction of polypeptide initially increased and then decreased over the duration of enzymatic hydrolysis. Moreover, as the enzymatic hydrolysis time increased, protein unfolding occurred. The protein structure gradually unfolded after enzymatic hydrolysis at 2 h, leading to a red shift in maximum absorption wavelength and enhanced fluorescence intensity. In addition, the secondary structure of SPI was changed by enzymatic hydrolysis, with the β-fold area fraction reaching its peak at 2 h. The surface hydrophobicity, emulsification, antioxidant capacity, ζ-potential and the particle size of the SPIH emulsion were all optimized at 2 h of enzymatic hydrolysis. This study provides the theoretical basis for understanding the changes in structural and functional properties of SPI under different enzymatic hydrolysis durations, thereby expanding its applications in the food industry.
