• supercritical fluid extraction;
  • natural vitamin E;
  • wheat germ;
  • central composite rotate design;
  • response surface analysis

ABSTRACT: Natural vitamin E was extracted by supercritical fluid extraction of carbon dioxide (SFE-CO2) from wheat germ. Several SFE-CO2 parameters, such as extracting pressure, extracting temperature, and flow rate of carbon dioxide were examined as the independent variables of central composite rotate design (CCRD). Through the response surface methodology (RSM), the optimal processing conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The results demonstrated that the extracting pressure, temperature, pressure × temperature interaction, and flow rate of CO2 significantly affected the yield of the natural Vitamin E's extraction, while two interactions containing the flow rate of CO2 had no significant effect on the yield of natural vitamin E. The optimal processing conditions of the extraction of natural vitamin E in wheat germ by SFE-CO2 were: extracting pressure 5000 PSI, extracting temperature 316 K, and flow rate of carbon dioxide 1.7 ml/min. Optimum value predicted by RSM for the concentration of natural vitamin E was 2307 mg/100g. Close agreement between experimental and predicted values was obtained.