Optimization of ultrasound-assisted extraction of flavonoids from sesame leaves using response surface method

The optimum conditions for the ultrasound-extraction of crude flavonoids from sesame leaves were determined using response surface methody (RSM). A central composite design was used to investigate the effects of four independent variables, namely ethanol concentration,the liquid to solid ratio,extraction time and ultrasonic power on the response, yield of flavonoids. Data were analyzed using SAS8.1 software. Canonical analysis of surface responses revealed that the stationary surface was a maximum. The coefficient of determination was 0.9007. Analysis of the regression coefficients showed that ethanol concentration was the most important factor that exerted a highly significant influence (p0.001) on the dependent variables. The optimum extraction conditions were: ethanol concentration 56%, the liquid to solid ratio 25∶1, extraction time 36 min, ultrasonic power 330 W. Under the optimum conditions, the extraction yield of flavonoids was 3.460%.