Abstract: Diosgenin was extracted by grinding starch pretreatment and ultrasonic extracting method from Dioscorea zingiberensis C.H.Wright. The effects of grinding starch time, ultrasonic extraction time, ethanol concentration, ratio of material to solvent and number of extractions times on extraction yield were investigated. By employing response surface methodology, the relationship of grinding starch time, ultrasonic extraction time, ratio of material and solvent and extraction yield was founded. The parameters of extraction process were optimized, so the optimal experiment parameters are: grinding starch time 5 min, ultrasonic extraction time 50 min and the ratio of material and solvent 1:18, extraction yield of ultrasonic wave extraction method increased 19% compared with the traditional method. The method is energy-saving, of low pollution and better efficiency.

Key words: Dioscorea zingiberensis C.H.Wright, grinding starch, ultrasonic extraction, diosgenin, response surface methodology(RSM)