The effect of distillation methods and stage of plant growth on the essential oil content and composition ofThymus kotschyanus Boiss. & Hohen

Abstract

The essential oils were isolated by steam, hydro and water–steam distillation from the aerial parts of Thymus kotschyanus Boiss. & Hohen in three stages of plant growth (before, at the beginning of and at complete flowering). The oils were analysed by capillary GC and GC–MS. The highest oil yield was obtained by hydrodistillation method and the lowest by steam distillation. The oil yield, related to distillation method and stage of plant growth, was 0.28–1.80% w/w (the highest for complete flowering stage by hydrodistillation method). The main constituents in all of the oils were carvacrol (40.74–61.23%), thymol (7.51–26.92%), γ-terpinene (3.72–8.25%), p-cymene (3.28–6.74%) and borneol (1.33–4.52%). Copyright © 1999 John Wiley & Sons, Ltd.