Optimization of ultrasound-assisted extraction of defatted wheat germ proteins by reverse micelles

In this work, an ultrasound-assisted procedure for the extraction of defatted wheat germ proteins by reverse micelles was established. Response surface methodology (RSM) was used to optimize the ultrasound-assisted extraction (UAE) parameters (ultrasonic output power, ultrasonic time and pulse mode) for enhancing the forward extraction efficiency of defatted wheat germ proteins by implementing a three-level, three-variable Box-Behnken experimental design. The independent variable with the largest effect on response was X-2 (ultrasonic time), followed by X, (ultrasonic output power) and X-3 (pulse mode). The optimum extraction conditions were found to be ultrasonic output power 363 W, ultrasonic time 24 min and pulse mode 2.4 s on and 2 s off (2.4 s:2 s). Under these conditions, the forward extraction efficiency of defatted wheat germ proteins can increase from 37% to 57%, and the final protein extraction efficiency by reverse micelles can reach 45.6%, making the advantage of reverse micelles much more obvious than alkaline extraction and isoelectric precipitation, on the separation of protein. (C) 2009 Elsevier Ltd. All rights reserved.