ULTRASOUND INDUCED FUNCTIONALIZATION OF SOY PROTEIN CONCENTRATE

Abstract

Processing conditions for the fabrication of soy protein concentrates (SPCs) have a profound impact on the tightly packed, globular structure of soy proteins, which is reflected in the weakening of structural and functional properties, limiting their use in food systems. Many scholars have investigated the modification of soy protein, but this is the first time that high-intensity ultrasound technology has been used to address its limitations through improvement of the physicochemical properties of SPC. Therefore, the aim of this study was to develop an ultrasound-based method capable of producing SPC with improved functional properties making it a multifunctional ingredient for food systems intended for human consumption. The effects of high-intensity ultrasonication (20 kHz; 30% for 0.5; 2; 5 or 10 min) on the solubility, emulsifying properties, hydrophobicity, oil and water binding capacities and color of commercially available SPC were investigated. Ultrasonic cavitation induced the restructuring of SPC, which was confirmed by significant changes in functional and structural properties. After ultrasonic treatment (30% amplitude for 5 min), the most significant shifts in solubility were observed. The emulsion fabricated with this restructured SPC was firm, stable, without perceptible phase separation, with emulsifying activity and emulsion stability of 1024.4 ± 10.6 m2/g and 836.3 ± 12.2 h, correspondingly. Ultrasonic treatment of 30% amplitude for 2 min enabled SPC with best oil (3.26 ± 0.4 goil/gprotein) and water binding capacity (5.04 ± 0.9 gwater/gprotein). Furthermore, the results additionally revealed that with the increase in sonication time the surface hydrophobicity of SPC increased first and then decreased. The value of a* and b* decreased significantly with the ultrasonic treatment time increment, while lengthened ultrasonic cavitation increased the L* value. In conclusion, the functional and structural improvement of SPC endorsed the adequacy of ultrasonic cavitation in SPC modification.