Effects of combined treatment with ultrasound and pH shifting on foaming properties of chickpea protein isolate

In this study, the foaming properties of chickpea protein isolate (CPI) subjected to different pH shifting treatment were investigated. It was found that the foaming ability (FA) of CPI, CPI subjected to treatment with pH shifting at pH 2 and pH 12 (CPI2 and CPI12), CPI subjected to combined treatment of ultrasound with pH shifting at pH 2 and pH 12 (CPI2-U and CPI12-U) were 81.1%, 180%, 225.5%, 212.1%, and 263.3%, respectively, while the foaming stability (FS) of these CPI did not change significantly. These results indicated that pH shifting under extreme acid or alkaline pH condition significantly enhanced the foaming properties of CPI, while the use of ultrasound further intensify this change. The best foaming properties of CPI12-U was ascribed to its smallest particle size, zeta potential, interfacial tension, the largest solubility and surface hydrophobicity. Besides, the free sulfhydryl content of CPI subjected to these treatments increased significantly, facilitating their adsorption to the air-liquid interface. Moreover, the increased content of alpha-helixes for CPI subjected to these treatments contributed to the formation of more stable interfaces. So this study provided a convenient means to significantly improve the foaming properties of CPI.