Ultrasonic-assisted extraction and functional properties of wampee seed protein

The wampee seed protein (WSP) was extracted by the ultrasonic and alkaline solution. Response surface methodology was used to optimize the extraction parameters for obtaining the highest protein yield, and the protein's functional properties such as protein solubility, water and oil holding capacity, and emulsifying and foaming properties ware studied in comparison with soy protein isolate (SPI). The results showed that ultrasonic time and pH significantly influenced the yield, and the optimal extraction conditions were achieved when solid-solvent ratio, ultrasonic time and pH were 1:29 g/mL, 64 min and 12, respectively, under which the yield was 15.06%. The functional property tests revealed that the WSP's solubility was higher than that of SPI and its isoelectric point was near 3.0. Compared with SPI, the oil holding capacity, emulsion activity index and emulsion stability index of WSP were significantly higher, but its water holding capacity, foaming capacity and foaming stability were significantly lower.