Impact of trypsin on interfacial conformational evolution of soy protein isolate/soy hull polysaccharide emulsion

The impact of trypsin on the demulsification mechanism of soy protein isolate (SPI)/soy hull polysaccharide (SHP) emulsion under trypsin treatment was investigated. We analyzed the conformational evolution of the emulsion interface induced during the bulk demulsification, focusing on the oil-water interface. During the enzymatic treatment for 0-120 min, various spectral analyses including spectrum analyses of Raman, FT-IR, intrinsic fluorescence, and ultraviolet spectral analyses demonstrated gradual hydrolysis and polymerization of protein molecules within SPI/SHP, SPI, and SHP on the oil-water interface by trypsin, particularly noticeable during 30-90 min. Notably, at 90 min, an increase in β-sheet content and a red shift of the IR spectrum from 3400 to 3380 cm^-1 indicated the conjugate effect of small molecules due to large interfacial tension, accompanied by hydrophobic interaction and hydrogen bonding. These alterations in SPI/SHP, SPI, and SHP conformations at the oil-water interface led to droplet demulsification and oil phase release.