Study on optimization of ultrasound-assisted extraction technology of total flavonoids from green tea by response surface methodology.

In order to optimize the conditions for the ultrasound-extraction technology of total flavonoids from green tea,the Plackett-Burman design was introduced to evaluate the effects of five factors based on single factor test.Ethanol concentration,ratio of liquid to solid and extraction times were found to be the critical for the factors activity of total flavonoids extraction.The optimum conditions for extraction were obtained through Box-Behnken center-united experiment design and Response Surface Methodology with the extraction rate of total flavonoids as the response.The results showed that the optimum extraction conditions are as follows:ethanol concentration 77%,ratio of liquid to solid 42:1 and extraction times 2.Under the above conditions,the experimental value of extraction rate of total flavonoids is 3.76%,and its predicted value 3.79%,which indicated that the combination of Plackett-Burman design and response surface analysis can well optimize the extractive technology of total flavonoids from green tea.