Effect of surface changes of soy protein materials on water resistance

Abstract The water resistance properties of unmodified soy protein isolate (SPI1) materials and modified soy protein isolate (SPI2) materials were investigated. The surface morphology and surface composition of the materials were also identified by Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The average roughness of materials reduced from 14.362 nm to 8.672 nm. The N/C ratio of surface was decreased from 0.078 to 0.055, and the content of C1 reduced from 45.0% to 53.7%. Results indicate that the modification of SPI changes the surface morphology and surface composition of materials, showing higher water resistance.