Optimization of anthocyanins extraction conditions of purple eggplant-peel by response surface methodology

Using purple eggplant-peel as the research object, organic solvent extraction as the method, with the anthocyanin solution absorbance as a measure indicator. Response surface analysis method was used to optimize the extraction condition of purple eggplant-peel anthocyanins. On the basis of single factor experiments, extraction temperature, liquid-solid ratio (mL/g) and extraction time were chosen as arguments and A525V/m (V:extracting agent, m:the sample quality) as response value. The interaction of the respective variables and their influence on the extraction rate were studied by using Box-Benhnken central composite design and response surface analysis theory. Under the condition of 70% ethanol (containing 0.05% hydrochloric acid, V/V) , the optimum extraction condition for extraction was obtained. Results showed that optimum conditions were:the temperature was 38℃, liquid-solid ratio was 19∶1, extraction time was 95min. Under these conditions, A525, the effect of anthocyanins extraction was 12.752. Comparing with the theoretical value 12.876, the relative error was 0.124. Results indicated that the equation derived by response regression equation had some practical significance.