Study of the concentration effect by rheological measurements for ultrasound and heat-treated native soy protein isolate

Abstract

Ultrasound is a highly effective, environmentally friendly technique for inducing structural changes in soy protein isolates.When combined with simultaneous heating, this process can produce synergistic or additive effects. Previous studies onnative soy protein isolates focused on foamability and viscoelasticity, correlating these properties with particle size distribution and surface charge at 2, 4, and 6% (w/w) protein concentrations. Building on this, the current work investigatedthe combined effect of ultrasound and temperature on these same concentrations. We found a clear correlation betweenprotein concentration and the functional properties. The objective of this study was to determine the impact of a combinedultrasound and temperature treatment on the solubility, viscosity, surface hydrophobicity, and gelling properties of nativesoy protein isolates at these concentrations. Our findings indicate that the treatments promoted concentration-dependentchanges in these functional parameters. Although solubility magnitude depends on the storage conditions of the flour, theeffects of the treatments can be identified as an interaction between ultrasound and temperature for all concentrations. Itwas seen that ultrasound promoted an increase in solubility while temperature generated a reduction in solubility at thesame time. Viscosity increased at high temperatures or in the combined treatment, most markedly at 2% due to the formation of soluble aggregates. In contrast, at 6% of protein concentration, gelling properties showed a stronger dependenceon surface hydrophobicity and solubility. Thus, the combined technology, through a synergistic effect, depended on theprotein concentration, a revelation that is highly important for various food processing applications.