Optimization of extraction process for star anise oil

Response surface methodology was applied to optimize the extraction conditions of star anise oil from Illicium verum Hook.f. . The optimum solvent was obtained. Extracting time, the ratio of solvent to solid and extracting temperature were selected as causal factors. Base on the single factor experiments, a three-factor-three-level experiment design has been developed by Box-Benhken central composite design method. The yield of star anise oil was used as the responsive values. The response surface method was employed to analyze the results of experiments. The results indicate that the optimum conditions for star anise oil are as follows：solvent is acetone, extracting time is 2.3 h, the ratio of solvent to solid is 40︰5.4 (v/w) and extracting temperature is 78.6℃. The predictive maximum yield of star anise oil is 10.49%. The average validation value is 10.56%. The relative error between them is 0.67%.