A Comparative Study of Headspace and Hydro-Distillation Techniques for Volatile Compounds in Thyme Species across Drought Stress and Phenological Stages

Abbasi, Shahrbanoo; Houshmand, Sadollah; Ahmadi, Tayebeh

doi:10.22034/jmpb.2025.370397.2032

A Comparative Study of Headspace and Hydro-Distillation Techniques for Volatile Compounds in Thyme Species across Drought Stress and Phenological Stages

Articles in Press

Document Type : Research Paper

Authors

¹ Department of Plant Breeding and Biotechnology, Shahrekord University, Iran

² Department of Medical Laboratory Science, College of Science, Knowledge University, Kirkuk Road, Erbil 44001, Iraq

10.22034/jmpb.2025.370397.2032

Abstract

Variations in essential oils and phenolic compounds of T. daenensis, T. armeniacus, and T. vulgaris were investigated at two phenological stages: 50 and 100% flowering. The volatile components of these species, extracted using headspace and hydrodistillation techniques were analyzed via gas chromatography-mass spectrometry (GC-MS) under two water stress conditions (90 and 50% field capacity). GC-MS analysis identified the major constituents, including thymol (5.175–51.53%), carvacrol (1.77–24.52%), γ-terpinene (3.95–23.66%), and p-cymene (3.35–24.50%), in the three species using the hydrodistillation method. Maximum thymol content of 51.53% and 43.20% was recorded in T. daenensis during 100% flowering under 90 and 50% FC conditions, respectively. A decline in thymol content in T. daenensis and T. vulgaris was recorded as a decrease from 90 to 50% FC, while T. armeniacus showed an increase. In the headspace method, different compounds were identified as the primary components. Notably, thymol (7.68–54.34%) was identified as the dominant compound in T. daenensis. Drought stress significantly increased thymol composition at the 50% flowering stage but reduced it at the 100% flowering stage. Hierarchical clustering and principal component analysis revealed three distinct groups, separating the compounds identified by the headspace and hydrodistillation methods. The findings suggest that hydrodistillation is more reliable for determining the true concentrations of compounds.

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