Comparative study of hydro- and steam-water distillation for isolation of essential oils from needles of Cupressus torulosa D. Don

Abstract

Cupressus torulosa, a large aromatic evergreen conifer tree widely distributed in the northwestern Himalayan region of India, holds various traditional uses of its aerial parts. The objective of this study was to compare the essential oil content and chemical composition of C. torulosa needles obtained using two distinct distillation methods: hydro-distillation (HD) and steam-water distillation (SWD). Gas Chromatography with Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS) techniques were employed to determine the compositions of the oils. The results indicated that the hydro-distilled essential oil (HDEO) exhibited significantly higher content (0.73±0.09%) compared to the steam-water distilled essential oil (SWDEO, 0.19±0.02%). Additionally, the HDEO and SWDEO exhibited notable differences in their chemical composition. The HDEO was primarily rich in oxygenated monoterpenes (58.45%), with terpinen-4-ol (29.09%) and umbellulone (21.29%) identified as the major constituents. On the other hand, the SWDEO was dominated by monoterpene hydrocarbons (73.75%), with α-pinene (22.19%), δ-3-carene (19.98%), and limonene (14.7%) as the main components. The findings from this study can assist in selecting the appropriate distillation technique to obtain essential oils with desired chemical compositions for various end-use applications.