An investigation of CO<inf>2</inf> extraction of marigold (Calendula officinalis L.)

Abstract

Essential oil content (0.05 %) of marigold (Calendula officinalis L.) was determined using the official steam distillation procedure. High-pressure CO2 extraction of plant material under supercritial (100, 200 and 300 bar and 40 °C) and subcritical (60, 90 and 120 bar and 15 °C) conditions for 3 h was investigated. It was found that the increase in the pressure promoted an increase in the yield. The essential oil contents obtained from the investigated CO2 extracts by steam distillation were significantly higher (1.52-2.70 times) and increased with pressure. Major constituents of the oil, identified using GC-MS and GC-FID, were α-cadinol (26.54 %), T-cadinol and T-muurolol (9.80 %), γ-cadinene (2.99 %), hexadecanoic acid (2.95 %), and ledane (2.45 %). In addition, the essential oils of the CO2 extracts contained δ-cadinene (6.50-19.87 % under supercritical and 16.09-19.41 % under subcritical conditions), which was not found in the essential oil obtained from the plant by steam distillation. The extraction kinetics was investigated at 200 bar and 40 °C. The total extract obtained after 10 h of extraction was 6.54 % and essential oil content in it, refering to plant material, was 0.209 %, which is 4.16 time more than the one determined by the standard steam distillation procedure.