Effects of Ultrasound-Assisted Alkaline Extraction on the Structural and Emulsifying Properties of Chickpea Protein Isolate

This study aimed to investigate the effect of ultrasound-assisted alkaline extraction (UAE) (at 20 kHz and different powers of 0, 200, 300, 400, 500 and 600 W for 10 min) on the yield, structure and emulsifying properties of chickpea protein isolate (CPI). Compared with the non-ultrasound group, ultrasound treatment at 400 W resulted in the largest increase in CPI yield, and both the particle size and turbidity decreased with increasing ultrasound power from 0 to 400 W. The scanning electron microscope results showed a uniform structural distribution of CPI. Moreover, its α-helix content increased, β-sheet content decreased, and total sulfhydryl group content and endogenous fluorescence intensity rose, illustrating that UAE changed the secondary and tertiary structure of CPI. At 400 W, the solubility of the emulsion increased to 63.18%, and the best emulsifying properties were obtained; the emulsifying activity index (EAI) and emulsifying stability index (ESI) increased by 85.42% and 46.78%, respectively. Furthermore, the emulsion droplets formed were smaller and more uniform. In conclusion, proper UAE power conditions increased the extraction yield and protein content of CPI, and effectively improved its structure and emulsifying characteristics.