Abstract: Objective: To optimize the process of supercritical CO2 fluid extraction of the aniseed oleoresin from aniseed powder; Method: An effective two-phase statistical approach to enhance extracting rate. In the first phase, Plackett-Burman design was undertaken to evaluate the effects of the seven factors: namely material size, CO2 flow rate, extracting pressure, extracting temperature, extracting time, separating pressure and separating temperature. By regression analysis, extracting pressure, extracting temperature and extracting time were found to be important for extraction of aniseed oleoresin. In the second phase of the optimization process, a three-level three-factor Box-Behnken design was used to optimize the above critical internal factors. Results: The results showed that the maximum experimental extracting rate of aniseed oleoresin (8.29%) can be obtained in 1.82 ～2.85 h, with the extracting pressure 27.2 MPa and extracting temperature 33.5～44.9 ℃; Conclusion: The maximum predicted aniseed oleoresin extracting rate 8.52% was obtained by solving the quadratic regression equation. In this situation, the optimum conditions are: extracting pressure, 29.31 MPa; extracting temperature, 44.87 ℃ and extracting time 2.30 h.

Key words: supercritical CO2, aniseed oleoresin, Plackett-Burman design, Box-Behnken design