Optimization on ultrasonic-assisted extraction of anthocyanins from purple yam with response surface analysis

[Objective] purple yam (Dioscoreaceae, Dioscorea alata Linn), as raw materials, can explore the anthocyanins extraction. [Method] ultrasonic-assisted extraction technology was used to extract anthocyanins, the optimum condition was determined through Central Composite center-united experiment design. Based on the single-factor experiments, using solid-liquid ratio, extraction time, ultrasonic frequency and extraction temperature as test factors, the extraction yield of anthocyanins as the response value, a 4-factor, 5-level Control-Composite experimental design was applied. [Result] The results suggest that the optimum extraction condition was as follows: ratio of liquid to solid 36mL/g, extraction time 122s, ultrasonic frequency 63%, extraction temperature 37°C. Under the optimum condition, the anthocyanins yield was 76.35%, The total content of anthocyanins was 46.57 mg/L, namely 4.1mg/g. [Conclusion] Compared with conventional extraction, the anthocyanins extraction rate was significantly increased.