Abstract: Soybean protein isolate (SPI) was subjected to ultrasonic pretreatment and then dry-heated with xylose (XYL) at a mass ratio 4:1 at 90 ℃ for 6 h to obtain Maillard reaction products (MRPs). The MRPs were subsequently used as the emulsifier and soybean oil was used as the dispersed phase to prepare emulsions in order to investigate the effect of ultrasonic treatment of SPI on its Maillard reaction with XYL and emulsifying properties of the resultant MRPs. The results indicated that ultrasonication of SPI significantly enhanced its Maillard reaction with XYL and improved the Zeta potential, fluorescence intensity and emulsifying activity of the MRPs. Measurements of particle size and creaming index illustrated that ultrasonication decreased the aggregation degree of MRPs-stabilized emulsions under varying conditions of ionic strength, temperature, and pH, but could not weaken the creaming of the emulsions as compared with native SPI.

Key words: soy protein isolate, Maillard reaction, ultrasonication, emulsion stability