Optimization of Technology of Microwave Assisted Extraction of Flavonoids from Medicago Sativa by the Response Surface Testing

Technological conditions for microwave assisted extraction of flavonoids from Medicago sativa were optimized by the response surface testing. Single factor experiments were performed for the conditions of ① volume fraction () of ethanol for extraction; ② ratio of mass of Medicago sativa to volume of 60% () ethanol; ③ microwave power; ④ time of microwave treatment and ⑤ number of times of extraction, among which factors ① to ④ were found to have more significant effect on the rate of extraction. Analysis for the interaction and significance of the relating factors was made further by applying the central composite designing principle at 4-factors and 3-levels mode. Optimum conditions found for the extraction of flavonoids were as follows: ① vol. fraction () of ethanol: 60%; ② ratio of mass of Medicago sativa to vol. of ethanol: 1 to 30 (mL·g-1); ③ power of microwave extraction: 450 W and ④ time of microwave assisted extraction: 80 s. The rate of extraction achieved to a max. value of 81.93% under the optimum conditions.