Mechanism, Conformation And Functional Properties Of Soy Protein-Saccharide Grafts Synthesized By Microwave

In this paper, the soy protein isolate (SPI), lactose and soluble starch (SS) were used as the main materials, and SPI-saccharide grafts were synthesized by the microwave radiation. The main analytic methods, conditions, mechanism of the reaction, and the physicochemical characteristics, conformation and functional properties of grafts were studied systematacially in order to research the SPI-saccharide graft modification, find the functional properties of the products, and gain the new and more effectively reactive ways, which could supply the technical foundation for the industry in some degree.The OPA method was selected as the analytic methods of the active position, which is the free amino groups, in the SPI-saccharide graft reaction, and was improved. The way of determining the concentration of the SPI solution was based on both the trace Kiadhal and UV methods.Microwave could improve the rate of the SPI-saccharide graft reaction greatly. And, in the same heating way, the inclosed manner seemed good for the reaction, but the reaction rate was not enhanced evidently. The factors that affect the reaction were analyzed and the conditions were optimized.Compared to SPI, the relative molecular weight (MW) of the SPI-lactose graft was not changed by gel chromatography in Sepharose CL-6B, and the composition 1 (MW>440kDa) was not detected in the SPI-SS graft. Moreover, the results of HPLC analysis showed that the content of SPI-saccharide grafts during the MW 10-80kDa was higher than SPI.After SPI grafted with saccharide, the total content of its saccharide rose obviously, and its intrinsic viscosity also be enhanced, but the heat-denaturalization temperature, and the lysine and arginine in it decreased. In addition, by the analysis of fluorescence, the maximal fluorescence intensity (FI) of SPI was at 450nm, however, that of grafts was at 430nm, which accorded with the fluorescent characteristic of the Maillard-type products.According to the analysis of SDS-PAGE, the bands of the graft subunits decreased, but the glycosyl bands were seen more clearly, with the degree of graft (DG) increasing. Grafts with higher DG, which were analyzed further by HPCE, were found that the subunit MW of the SPI-SS graft rose, and there was no crosslink between the subunits of the SPI-lactose graft.By the analysis of RP-HPLC, 6 main components were detected in the SPI and SPI-lactose graft, however, only 4 were found in the SPI-SS graft, and moreover,the polarity of the graft...