The effect of ultrasonication power and time on extraction of protein isolate from sprouted mung bean

In this research, the extraction of protein from sprouted mung bean was conducted by the combination of ultrasound pretreatment, alkaline extraction and acid precipitation processes and the effects of sonication power (0, 50, 100, 150, 200, 250 and 300 W) and sonication time (10, 20, 30 and 40 min) on the structural and functional properties of the sprouted mung bean protein isolate (SMPI) were investigated. The results showed that the maximum extraction yield, protein solubility, water holding capacity (WHC), oil absorption capacity (OAC) and foaming capacity (FC) were reached in sonication power and the extraction time of 300 W and 30 min, respectively. Fourier transform infrared (FTIR) spectroscopy of the extracted proteins showed no destruction of the functional groups of the extracts during the sonication process. In addition, differential scanning calorimeter (DSC) analysis showed that longer sonication time and higher power of sonication led to more denaturation of proteins. Scanning electron microscopy (SEM) images illustrated considerable inter space and pores in the remaining sprouted mung bean cake at longer time and higher power of sonication. Based on the results, the functional properties of SMPI for use as a food ingredient could be enhanced by sonication, which is a green extraction process.