Acta Pharm. 51 (2001) 305-310

Extraction of thyme oil: Comparison between hydrodistillation and
supercritical CO₂ extraction

SLAVCO A. ALEKSOVSKI,^1*  HELENA SOVOVA  and   FILIMENA A. POPOSKA

slavcho@ereb.mf.ukim.edu.mk

¹Department of Chemical and Control Engineering, Faculty of Technology and Metallurgy, Skopje, Macedonia
²Institute of Chemical Process Fundamentals, Academy of Sciences CR, Prague, Czech Republic

Supercritical fluid extractiuon (SFE) with carbon dioxide and hydrodistillation (HD) were compared as methods to isolate essential oil from thyme herb (Thymus serpyllum, L.). The SFE extraction was performed in a semibatch apparatus and the rate of extraction was found dependent on the extraction pressure and temperature and on the amount of carbon dioxide passed through the extractor. The most suitable conditions for the extraction were 11 MPa and 50 °C. The compounds exctracted by both SFE and HD were identified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The difference in the aroma of the products was quite noticeable and can be attributed to qualitative and quantitative differences in the extracts and hydrodistillates. Predominance of aromatic alcohols carvacrol and thymol and their biosynthetic precursors p-cymene and gama-terpinene was revealed in both SFE extracts and HD oil. The SFE extracts also contained water and cuticular waxes; longer extraction times and higher pressures resulted in a higher percentage of water and waxes in the extract.

Keywords: Thymus serpyllum, L. (Lamiaceae), supercritical fluid extraction, essential oil, hydrodistillation, carvacrol, thymol, p-cymene, gama-terpinene