Application of ultrasound treatment to improve the technofunctional properties of hemp protein isolate

The hemp seed protein isolate (HPI) was extracted from defatted hemp seed meal using alkaline extraction (pH = 10.0) acid precipitation (pH = 4.3) method. The effects of ultrasound treatment on its solubility, emulsifying properties, particle size, microstructure, molecular subunits, secondary and tertiary structures, and surface hydrophobicity were determined. Solubility and emulsifying properties of HPI were significantly improved after ultrasound treatment (20 kHz) at 400 W for 12 min. The solubility, emulsion activity, and emulsion stability indices increased by 3.7- 1.7- and 1.5-fold, respectively. The improvement in functional properties correlated with reduced particle size, increased surface hydrophobicity and the alteration in secondary and tertiary structure of HPI. The solubility and emulsifying properties of the ultrasound treated HPI were better than native pea protein isolate but still not as good as those of native soy protein isolate for which further research is needed.