Physicochemical Properties of Soy Protein Concentrate Treated with Ultrasound at Various Amplitudes

Abstract

This research was conducted to investigate the influence of ultrasound amplitude on thephysicochemical properties of soy protein concentrate. Soy protein concentrates (SPC, Acron SM) were treatedwith a frequency of 20 kHz ultrasound and three different amplitudes of 50, 80, and 100% for 5 min. Untreated andultrasound-treated soy protein concentrate samples were evaluated in terms of recovery of soluble protein, particlesize, surface hydrophobicity, free sulfhydryl groups, turbidity and microstructure. The environmental scanningelectron microscope images of the treated and untreated soy protein concentrate samples were taken in order toanalyze the microstructure of the samples. The findings showed that the ultrasound treatment have a significanteffect on all physicochemical characteristics (p<0.05). All ultrasound treated samples showed significantly highersolubility compared to the untreated soy protein concentrates. In addition, the highest protein solubility wasdetermined for the samples treated with 100% amplitude. Ultrasound treatment reduced the size of all proteins.The sample which has the highest solubility also showed the lowest particle size compared to the others. Moreover,ultrasound treated (100% amplitude) soy protein concentrate was resulted with highest surface hydrophobicity andfree sulfhydryl groups. Microscope images of the soy protein concentrates showed a spherical morphology withparticle diameters which closely corresponding to the results obtained by dynamic light scattering. It was clearlyseen that increasing ultrasound amplitude enhance the functionality of soy protein concentrates.