Optimization of ultrasound-microwave synergistic extraction of total saponins from lily residue by response surface methodology

The residue of the by-products in the starch production process of Yixing lily was analyzed as the extracted material to study the optimum procedures of the ultrasound-microwave synergy extraction method.Effects of thanol concentration, liquid-solid ratio, microwave power and extraction time on yield of total saponins were determined. Based on the results of single factor test, as well as Box-Behnken experiment principle, the four factors and three levels response surface method (RSM) test was designed and the yield of total saponins was determined as response value. The optimum extracting parameters to achieve the highest total saponins yield of 6.59‰ was obtained as follows:ethanol concentration (v/v) of 77%, liquid to solid ratio of 11∶1 (mL/g) , microwave power of 503W, and extraction time 139s. The ultrasound-microwave synergy extraction technique combined with the advantages of microwave and ultrasonic was a new method of higher efficiency, lower temperature and less time consumption.