Effect of high-intensity ultrasonic treatment on the physicochemical, structural, rheological, behavioral, and foaming properties of pumpkin (Cucurbita moschata Duch.)-seed protein isolates

Pumpkin-seed protein isolates were treated with high-intensity ultrasound (HIU). The effects of different ultrasound powers at the same treating time on the physicochemical, structure and foaming properties of pumpkin-seed protein isolates (PSPIs) were investigated. The results showed that the ultrasound treatment transformed the PSPI aggregates into smaller aggregates with a more uniform distribution. When the pH value increased, the solubility and foaming ability of the protein also increased significantly. Increasing the ultrasound power also increased the surface hydrophobicity of the PSPIs and the total sulfhydryl contents, while the active sulfhydryl content decreased. The most significant effect on the total sulfhydryl content occurred when 500 W ultrasonic power was used. The ultrasound treatment also had a significant effect on the chromaticity and turbidity of the pumpkin-seed protein isolates. With an increase in ultrasonic power, scanning electron microscopy (SEM) showed that the sizes of particles decreased as their distribution increased. Moreover, ultrasound treatment was found to be beneficial for enhancing and improving foaming performance. Ultrasound modification affected the protein's physicochemical properties and structure, which contributed greatly to the corresponding functional and nutritional properties of the protein. It would be, therefore, useful to develop and utilize plant protein and to improve its added-value.