Chemical composition and yield of essential oils from Bakhtiari savory (Satureja bachtiarica Bunge.) under different extraction methods

Bakhtiari savory is a perennial aromatic herb distributed in Zagros mountain range, southwestern Iran. To determine the effect of extraction methods on qualitative and quantitative characteristics of the essential oil of Bakhtiari savory was extracted by different methods. Conventional methods [hydrodistillation by two Clevenger-type apparatus: British Pharmacopeia (HDBP) and Research Institute of Forests and Rangelands, Iran (HDRIFR), and traditional steam and water distillation (TSWD)], an innovative technique steam distillation (SDinnov), microwave-assisted steam hydro-diffusion (MSHD 400 and 800W), and microwave-assisted hydro-diffusion (MHD 400 and 800W) were used to extract essential oil from the aerial parts of savory and their results were compared. The essential oils of all samples were analyzed using GC-FID, GC/MS, and for comparison, a sample was analyzed using head space solid-phase microextraction (HS-SPME). The highest essential oil yields were obtained from two methods, including HDBP, and MSHD 400W. Significant differences occurred among the major constituents in essential oils from extraction methods, including thymol, carvacrol, p-cymene, and)gamma-terpinene. The highest amounts of thymol and carvacrol were obtained from MHD (800 W) method in comparison other methods. The highest content of monoterpene hydrocarbons was obtained from HS-SPME, whereas the highest percentage of oxygenated monoterpenes was achieved from MHD (800 W) method. In conclusion, extraction of the essential oil from Bakhtiari savory with microwave-assisted hydro-diffusion (MHD) was better in terms of energy saving, extraction time, oxygenated fraction (thymol and carvacrol), and product quality. (C) 2015 Elsevier B.V. All rights reserved.