Gas chromatography–mass spectrometry analysis of free and glycoconjugated aroma compounds of seasonally collected Satureja montana L.

Abstract

The present work examines the content and composition of glycoconjugated and free volatile aroma compounds in the plant material of savory, depending on the stage of plant development. Free volatile compounds (essential oil) as well as volatile aglycones obtained after the enzymatic hydrolysis of isolated glycosides were analyzed by coupled gas chromatography–mass spectrometry (GC–MS). Thirty-six compounds were identified in the essential oil and 17 compounds among the volatile aglycones. The main components of essential oil (yield 0.80–1.46% w/w, SD=0.02–0.03) were thymol (30.88–46.02%, SD=0.40–0.45), p-cymene (7.10–13.48%, SD=0.19–0.27), γ-terpinene (7.57–9.74%, SD=0.19–0.23) and carvacrol (3.81–6.86%, SD=0.05–0.07). The main aglycones (yield 58.4–95.6 mg kg −1, SD=1.5–3.0) were: thymoquinone (27.55–32.93%, SD=0.38–0.40), eugenol (8.35–19.44%, SD=0.06–0.23), cis-3-hexene-1-ol (2.38–9.73%, SD=0.04–0.22) and thymol (4.07–7.81%, SD=0.05–0.06). Other aglycones in lower percentages were p-cymen-8-ol, α-terpineol, geraniol, benzyl alcohol, 2-methoxy-4-ethyl-6-methylphenol, 1-octen-3-ol, methyl salicylate, 3,5,5-trimethyl-4-(3-hydroxy-1-buthenyl)-2-cyclohexene-1-one, carvacrol and other compounds. The results show moderate similarity in the chemical composition of oil and volatile aglycones. In the aglycones fraction, the contents of thymoquinone and thymol decreased with maturation of the plant, and contents of eugenol, nerol, geraniol, increased in the same time. This is mainly in agreement with seasonal variations of the main oil components.