Study of soybean gel induced by Lactobacillus plantarum: Protein structure and intermolecular interaction

The change of protein structure and intermolecular interaction during the formation of soy protein isolate (SPI) gel induced by Lactobacillus plantarum ( L . plantarum ) were investigated. In the present study, the peak value of UV–Vis spectra decreased gradually with the prolongation of fermentation time. Fermentation treatment resulted in α-helix content decreasing by 60.16%, while β-sheet content increased by 68.15% (P < 0.05). The surface hydrophobicity was decreased by 62.31% (P < 0.05) due to the molecular aggregation of SPI. Correspondingly, the free sulfydryl group content decreased by 58.48% (P < 0.05). These results highlighted that the protein structure and intermolecular interaction of SPI could be significantly changed by L . plantarum fermentation. The main intermolecular interactions maintaining the fermentation-induced gel were hydrophobic interactions and disulfide bonds. This work provided theoretical support for the establishment of the mechanism of fermentation-induced gel and the rational application of L . plantarum in soybean products.