Abstract: The microwave-ultrasonic synergism (MUS) was applied in the glycosylation of rapeseed protein (RP) and the functional properties and molecular structure of RP-dextran conjugates were investigated. The results indicated that the grafting degree of RP was up to 67.1% under the following reaction conditions: microwave power 500 W, ultrasonic power 300 W, and treatment time 7 min, which was even higher than that obtained by wet heating and microwave methods. Therefore, the combined treatment could significantly increase the efficiency of glycosylation reaction. Compared with rapeseed protein and the RP-dextran conjugates prepared by other methods, the solubility, emulsifying activity, foaming capacity, and foam stability of the RP-dextran conjugates prepared by MUS were significantly improved to 55.7%, 13.9 m2/ g, 50.0% and 80.0%, respectively. The results of surface hydrophobicity and circular dichroism (CD) spectroscopy indicated that combined microwave and ultrasonic treatment led to protein unfolding and increased the molecular flexibility of RP, thereby promoting the glycosylation reaction of RP and improving the functional properties of RP-dextran conjugates.

Key words: microwave-ultrasonic synergism, glycosylation, rapeseed protein, functional property, molecular structure