Extraction of fennel (Foeniculum vulgare Mill.) seeds with supercritical CO2: Comparison with hydrodistillation

Ground fennel (Foeniculum vulgare Mill.) seeds, growing wild in Montenegro, were extracted with supercritical CO2 (SC-CO2) at a flow rate of 0.2 kg CO2/h under varying extraction conditions in order to determine yield, composition and organoleptic characteristics of extract. The extracts obtained were compared to fennel seed oil isolated by hydrodistillation. In the SC-CO2, extracts as well in the hydrodistilled oil, the major compounds were trans-anethole (68.6-75.0%) and (62.0%), methylchavicol (5.09-9.10%) and (4.90%), fenchone (8.40-14.7%) and (20.3%), respectively. With pressure varying from 80 to 150 bar and temperature varying from 40 to 57 °C, it was found that, for the selected herb material, the optimal conditions of SC-CO2 extraction (high percentage of trans-anethole, with significant content of fenchone and reduced content of methylchavicol and co-extracted cuticular waxes) are: pressure, 100 bar; temperature, 40 °C; extraction time, 120 min. Organoleptic tests confirmed that hydrodistilled oil possessed a less intense fennel seed aroma than extracts obtained by SC-CO2.