Response Surface Methodology as An Approach to Optimizing Ultrasonic-assisted Extraction of Flavonoids from Navel Orange Peel

The ultrasonic-assisted extraction process of flavonoids from navel orange peel was studied.On the basis of single factor tests,response surface analysis was designed by Design-Expert Software 7.1.3.1,and the effects of extraction time,ethanol concentration,ratio of liquid to solid,and temperature on the yield of flavonoids were investigated.The results showed that the optimum extraction conditions were as follows:with 58.91% ethanol as the extraction solvent and a ratio of liquid to solid of 30.68 ml/g,twice extraction at 75 ℃ for 20.79 min.The predicted yield of flavonoids was 3.298%,close to the practical yield of flavonoids of 3.351%.