Supercritical fluid extraction of essential oils: Results of joint research

Abstract

Peppermint, creeping thyme, and sage herbs, as well as yarrow flowers were extracted with supercritical and liquid carbon dioxide at 9-13 MPa and 25-60?C. Two extraction periods were distinguished except in the case of thyme extraction. Almost pure essential oil was extracted in the first, fast period. The extraction was retarded in the second period controlled by essential oil-matrix interaction, and waxes and water prevailed over the essential oil in the extract. To estimate the effect of essential oil-vegetable oil interaction during the extraction of essential oils from seeds, the limonene + vegetable oil + CO2 equilibrium was investigated using thermodynamic modeling. Changes in the composition of the essential oil in the extracts are demonstrated on the example of sage oil. Compared to hydro distillation, the extracts contained less monoterpenes, the most volatile components, because the separation of the extract from gaseous ??2 in the cold trap was incomplete. The yield of sesqui- and di-terpenes in the extracts, however, was higher than their yield by hydrodistillation. The extraction of sage essential oil was most efficient at 13 MPa and 50?C, when the yield of diterpene manool was more than two times higher than its yield by hydrodistillation.