Abstract: The changes of rheological property of soybean protein isolated (SPI) after ultrasonic treatment were studied. According to the results, after 20min treatment with 25kHz and 400W ultrasonic treatment, the apparent viscosity of 10.0% and 12.5% were reduced to 3.2% and 6.5% of the control respectively. The flow behavior indexes were increased to 0.81and 0.78, from the control as 0.66 and 0.44 respectively. The storage modulus G′and the loss modulus G″were lowered to ten percent of the control after sonication. Sonication effect would lower G″value more than lowering of G′value. However sonication had little effect on the tanδvalue. The Braband viscosity was also reduced markedly after ultrasonic treatment.

Key words: ultrasonic treatment, soybean isolated protein, rheological property