Structure and functional characteristics of rapeseed protein isolatedextran conjugates

The functional properties of rapeseed protein isolate (RPI) has limited its utilization by the food industry. To improve its utilization, RPI-dextran conjugates with different grafting degrees (GD) were prepared by grafting reaction. Grafting reaction was mostly between the dextran and the cysteine (Cys) and lysine (Lys) from 12S globulin, as verified by the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and amino acid composition. The graft treatment changed the molecular structure of RPI, displaying an increase of the surface hydrophility and an unfolding of the secondary structure as confirmed by fourier transform infrared spectrum (FT-IR) and circular dichroism (CD). The graft treatment also made surface structure of conjugates become looser and increased molecular weight, which was more obvious as GD increased. The graft treatment greatly improved the solubility, emulsifying property, and thermal stability of the conjugates. This research successfully improved the utilization value of RPI in the food industry by enhancing its functional properties. (c) 2018 Elsevier Ltd. All rights reserved.