Enhancing protein release and functionality of soy proteins from defatted soy flakes using high-intensity ultrasound-assisted extraction

In addition to evidence regarding their potential for inclusion into functional foods, the effect of the high-intensity ultrasound extraction (HIUE) on the functional properties of soy proteins will be discussed. The aim of this study was to examine the effects of HIUE as a function of the treatment time and ultrasound amplitude, in order to obtain better understanding of physicochemical effects of HIUE on soy protein which may lead to improving its applications in the food industry. For this purpose, samples of the yellow defatted soybean (Glycine max) variety Laura were treated with ultrasound probe system (20±0.2 kHz) by varying the treatment time (30 s, 2, 5, 10, 15 min) and an amplitude (15% and 30%). Functional properties of the obtained samples were characterized in terms of solubility and sulfhydryl content. HIUE resulted in a slight, but gradual decline in solubility with a treatment time, but significant increase (p < 0.05) in acidic environment was observed with the increase of ultrasound amplitude. Sulfhydryl content has been greater influenced with a treatment time for both amplitude applied. The results show that the ultrasound extracted soy proteins were superior to the original (untreated) in the functional properties tested and can be concluded that by combining the treatment time and the ultrasonic power, the samples with enhanced functionalities can be produced enhancing utilization of soy proteins in food products.