Optimization on response surface models for the optimal extracting conditions of anthocyanin from purple yam

The anthocyanin was extracted by traditional solvent method. The pH differential method was used to determine the content of anthocyanin. Response surface methodology was used to optimize the extraction technology of anthocyanin from purple yam. Based on single-factor experiments, citric acid concentration, extraction time, material-liquid ratio and extraction temperature were selected as influencing during extraction.The experiment mathematical model was arranged according to Box-Behnken central composite experiment design, which studied each variable and their interactions on the yield of anthocyanin. The quadratic multinomial model on the yield of anthocyanin and each influence factor of extraction anthocyanin was established by using the Design-Expert software. The optimal extraction conditions were obtained after 2.5h extraction with 3.0%citric acid at the material-liquid ratio of 1∶20.0g/mL and the extraction temperature was 65.0℃, under these conditions estimated value and verified value being of 0.586% and 0.574%, respectively.