Analysis of influence mechanism of grinding on the gel properties of soybean protein isolate based on the changes of its structure and solubility

The compact spherical structure of soy protein isolate results in low protein flexibility and poor functional properties. In this study, the influence mechanism of grinding on its gel properties was analyzed according to the changes of soy protein isolate structure and solubility after grinding. The results indicated that at 15 min of grinding, β-sheet of the soy protein isolate decreased from 38.54% to 29.15%, the particle size became smaller, and the original solid sphere became a hollow sphere, the protein had a more disordered secondary structure, and the solubility increased to 28.24%. The glucono-δ-lactone-induced cold-set gel of this protein exhibited higher water holding capacity (76.37%), storage modulus (G') and loss modulus (G″). Creep recovery test showed that this gel had better elasticity and rigid structure at 15 min of grinding. This study could lay a theoretical foundation for research on improving the gel properties of soy protein isolate by mechanical modification in future.