Effect of Different Drying Methods and Development Stages on the Essential Oil Chemical Composition of Aerial Parts of Origanum vulgare L. subsp. hirtum (link) Letsw

In this study, the effects of different methods of drying (sun, shade, and oven-drying at 45 degrees C for 12 hours) and development stages (pre, full, and post-flowering) on the essential oil composition and yield ratio of aerial parts of Origanum vulgare L. subsp. hirtum (Link) letsw. was investigated. The essential oil from dried samples were obtained by hydrodistillation for 4 hours, using a Clevenger-type apparatus. The chemical composition of the essential oil was analyzed using Thermo Scientific TSQ GC-MS/MS. Total percentages of the determined compounds of O. vulgare subsp. hirtum ranged from 79.1 to 99.9 %. Thirty-seven components were identified in the essential oil of O. vulgare subsp. hirtum mostly consisted of phenolic compounds and monoterpene hydrocarbons. The highest essential oil yield was observed in the full-flowering period and oven-drying method at 45 degrees C for 12 hours, (2.8 %), matched against shade-drying (2.5 %) and sun-drying (2.4 %) methods. A phenolic compound carvacrol (49.2-64.7 %) was detected as the main component of the essential oil followed by gamma-teipinene (6.0-14.6 %) and p-cymene (6.8-14.0 %). These results indicated that chemical composition and yield ratio of the O. vulgare subsp. hirtum essential oil varies according to drying methods and development stages.