Abstract: Response surface methodology(RSM)was used to optimize the refluxing extraction process of anthocyanins from purple sweet potatoes as a result of getting the optimum technology. The results of single-factor test showed that the best ethanol concentration was 70%, extraction temperature was 60℃, extraction time was 60 min, liquid-material ratio was 7∶1. Based on these results, the significant parameters were further optimized using Box-Behnken design, RSM and regression analysis. The optimum parameters were ：ethanol concentration 74%, extraction temperature 66℃, extraction time 56 min, liquid-material ratio 8∶1. Under such conditions, the extraction efficiency could reach 4.64 mg/g, and have a smaller relative error at 0.85% compared with the theoretical value(4.68 mg/g). The study showed that the processing parameters achieved from these experiments were accurate and can be applied to the extraction and production of anthocyanins from purple sweet potatoes.

Key words: Purple sweet potatoes, Anthocyanin, Refluxing extraction central, Composite design, Response surface methodology