Abstract: This paper deals with the optimization of the process conditions for the microwave-assisted extraction of total flavonoids from Fructus Aurantii Immaturus using response surface methodology (RSM). Based on one-factor-at-a-time experiments, a quadratic regression model indicating the individual and interactive effects of microwave power, extraction time and ethanol concentration on the yields of naringin and hesperidin was established using a Box-Behnken experimental design. From the response surface and contour plots drawn for the model, the optimal extraction conditions were obtained as follows: size reduction ratio 40－60 mesh, liquid/solid ratio 100:1, ethanol concentration 58.8% (V/V), microwave power 447 W, and extraction time 3.9 min. Under these conditions, the experimental yields of naringin and hesperidin were 50.21 mg/g and 4.96 mg/g, respectively, which were in substantial agreement with the theoretically predicted values.

Key words: Fructus Aurantii Immaturus, total flavonoids, microwave-assisted extraction, response surface methodology