Modification of Physicochemical and Functional Properties of Pumpkin Seeds Protein Isolate (PsPI) by High-Intensity Ultrasound: Effect of Treatment Time

High-intensity ultrasound (HIUS) is reported to modify tecno-functional properties of proteins. This study aimed to investigate the effect of HIUS treatment times on pumpkin seeds protein isolate (PsPI) suspensions as a function of pH, by evaluating particle size, zeta potential, and emulsion and foam properties. Results showed that 5 min of HIUS treatment caused a reduction in the average hydrodynamic diameter of the particles from 5.63 +/- 0.08 mu m (control) to 1.68 +/- 0.15 mu m. In addition, an increase of zeta potential in the pH range around the isoelectric point of PsPI was found in all treated samples. However, prolonged HIUS treatment favored the formation of molecular aggregates, and 5 min treatment with HIUS was sufficient to achieve a significant increase in foaming and emulsifying ability compared to the untreated control, especially in the pH range of 2.5-6.5. Thus, the use of HIUS was proved to be an excellent treatment method for enhancing the functional properties of PsPI.