FUNCTIONAL AND STRUCTURAL PROPERTIES OF SOYBEAN PROTEIN ISOLATE-GLUCOSE CONJUGATES

The functional properties of soybean protein isolate would be affected by processing conditions,and to overcome this disadvantage,glycosylation was adopted to improve its functional properties.In this study,soybean protein isolate (SPI) was conjugated with glucose through dry maillard reaction under various conditions including different protein and carbohydrate ratios,temperatures,and experimental time.The results indicated that when the mass ratio of protein and glucose was 1:1 at temperature of 55℃,the solubility and emulsion activity of glycated conjugates increased by 56.18% and 28.04% respectively compared with unmodified SPI after 6 hours reaction.Under the same reaction conditions,the emulsion stability could increase by 92.78% compared with native SPI after 8 hours reaction.The changes of grafting degree were measured by the o-phthalic aldehyde (OPA) and the molecular weight changes were analyzed by SDS-PAGE.These indexes confirmed the Maillard reaction of grafted products.The results detected by ultraviolet scanning and fourier transform infrared spectroscopy (FT-IR) also demonstrated that the spatial and secondary structure of the proteins were changed after glycosylation.Our results revealed that glucose grafting could improve the functional properties of SPI,which provides theoretical basis for broadening the application of SPI in food industry.