Optimization of ultrasound-microwave assisted extraction of proanthocyanidin from brown rice by response surface methodology

In order to improve the yield of brown rice, ultrasonic wave and microwave were used to strengthen extraction of proanthocyanidin from brown rice.On the basis of single factor tests,the method of the central composite experimental design (BOX-Behnken) was used to optimal of ultrasound-assisted extraction of proanthocyanidins form brown rice by four factors and three levels.The results indicated that the extractive conditions were optimized as follows:ethanol volume fraction 50%; ratioof liquor to solvent,22 (mL/g); ultrasonic power 400W; ultrasonication time 33 min; microwave power,350 W; subsequent microwave treatment 3.3 min; and.The extraction yield was 7.09%±0.01%.