Optimization of Extraction Process of Total Flavonoids from Stems and Leaves of Purple Sweet Potato by Ultrasonic Method

The experiment was to extract the total flavonoids from the stems and leaves of purple sweet potato by ultrasonic assisted ethanol extraction method. First of all,the effects of liquid ratio,extraction time,extraction temperature,ultrasonic power and ethanol volume fraction on total flavonoids in purple potato stem leaves were investigated. Based on single factor experiment,the optimum extraction conditions to flavonoids were determined using response surface methodology. The effects of four crucial parameters,including liquid/material rate,ultrasonic time,ultrasonic power and ethanol concentration. Results showed that the optimum extraction conditions were determined as follows:liquid/material ratio was 18∶1 (g/mL),ultrasonic time was 50 min,ultrasonic power was 200 W,and ethanol concentration was 75%. The actual yield of total flavonoids was 3.46%,which was close to the predicted value of 3.51%. This study provided a reference for the efficient extraction of total flavones and the comprehensive utilization of the purple potato leaf.