Response Surface Methodology as an Approach to Optimization of Supercritical CO_2 Extraction and Chemical Composition Analysis of Volatile Oil from Flowers of Chrysanthemum morifolium

The optimal conditions (namely extraction pressure, temperature and time) for the supercritical CO2 extraction of volatile oil from the flowers of Chrysanthemum morifolium were investigated using response surface methodology (RSM) based on a 3-variable, 3-level Box-Benhnken experimental design leading to 15 experiments. Meanwhile, the extracted volatile oil was analyzed for chemical composition. Computer generated response surfaces, canonical analysis and contour plot interpretation revealed that the optimal values of extraction pressure, temperature and time were 25 MPa, 74.9 ℃ and 186.3 min, respectively. Under such conditions, the experimental and predicted values of volatile oil yield was 3.464% and 3.51% and the former was 1.28% lower than the latter. Totally 44 compounds were identified by GC analysis in the extracted volatile oil and their total content was determined by the area normalization method to be 72.3%, of which, 20 exhibited a relative content of more than 1%.