Effect of Ultrasound Assisted Extraction upon the Protein Content and Rheological Properties of the Resultant Soymilk

The purpose of this study was to determine the effect of ultrasound treatment on the protein content and rheological properties of soymilk extracted from soybeans. Soybean slurry was exposed to ultrasound treatment then filtered. In this work, an ultrasound cleaning bath set with 35 kHz frequency and different treatment temperatures (20 and 40oC) and times (20, 40, and 60 min) was used. Results indicated that ultrasound treatment could significantly (p<0.05) increased the protein content of extracted soymilk by nearly 6.3%. These results were attributed to induced cavitation, which increased the permeability of plant tissues. The flow behaviour of soymilk was observed to be Newtonian for all samples. Viscosity (:) data calculated with a power-law equation (R2 = 0.99) increased slightly but not significantly (p>0.05) after ultrasound treatment. The consistency coefficient (K) did not change after ultrasound treatment. On the other hand, a significant increase in flow-behaviour indices (n) was observed.