Effect of γ-irradiation on the physicochemical properties of mixed soy protein isolate/starch material

Abstract

To elucidate the effect of γ-irradiation on the molecular structure and mechanical properties of biodegradable material composed by soybean protein isolated (SPI) and starch, SPI and starch were mixed and modified by succinic anhydride and irradiation. Different doses (0 to 50 kGy) γ-irradiation on the elongation, tensile strength, viscosity, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and color of the mixed material were investigated. Gamma-irradiation decreased the viscosity of the material due to cleavage of the polypeptide chains of SPI. Irradiation treatment also increased the yellowness index of the mixed material. This study reveals that γ- irradiation can be applied as a useful cross-linking measure to improve properties of mixed SPI and starch, which provide a valuable chance to replace conventional petroleum-derived plastics, adding more value to this vast agricultural resource.

Key words: Soybean protein isolate, starch, biodegradable material, irradiation.