Comparison of pennyroyal oils obtained by supercritical CO2 extraction andhydrodistillation

Flowers and leaves of pennyroyal (Mentha pulegium L.) were extracted using supercritical CO2 followed by a two-stage fractional separation technique. Using a flow apparatus with an extraction vessel (11) and two separators (0 .271), the best conditions of extraction (P = 100 bar and T = 50 degrees C) and of separation (P = 80 bar, T = -16 degrees C for the first separator a nd P = 18 bar, T = 0 degrees C for the second) were found and used to inves tigate the effect of different mean particle diameters. The pennyroyal oil obtained under these conditions was compared with that obtained by hydrodis tillation. Twenty-one components were identified by GC-MS and quantified by GC. Both the hydrodistillation and supercritical oils of Mentha pulegium L . contain the oxygenated monoterpenes pulegone (approximate to 80%) and men thone (approximate to 9%) as the main components. The aroma of the pennyroy al oil obtained with supercritical CO2 was closer to that of the starting v egetable material than the aroma of the essential oil produced by hydrodist illation. Copyright (C) 1999 John Wiley & Sons, Ltd.