Original flavour compounds and the essential oil composition of marjoram (Majorana hortensis moench)

Abstract

The analysis of spice plant flavour compounds usually starts with the so‐called essential oil, which is obtained by steam‐distillation. Comparative investigations of marjoram flavour extracts, separated using different isolation techniques, showed the great influence of the isolation method on the composition of the resulting flavour extract. Experiments with triturations of leaf material under liquid nitrogen, extractions with supercritical carbon dioxide and direct injections of the oil of individual secretory cells demonstrated that cis‐sabinene hydrate and its acetate represent the original flavour compounds in the intact leaf. The great number of monoterpenes described in marjoram essential oils therefore appear to be artefacts, arising from a multitude of rearrangement, hydration and deprotonation reactions from cis‐sabinene hydrate acetate and from an activated precursor form, that possesses the sabinene hydrate skeleton. The nature of these artefact‐forming reactions was investigated by model experiments with synthetic sabinene hydrate and its acetate. The biosynthetic capacity of the marjoram plant with regard to the monoterpenes seems to be confined to the synthesis of the sabinene hydrate skeleton.

Effect of extraction methods on the chemical composition and antioxidant activity of Egyptian marjoram (Majorana hortensis Moench)

“…Terpinene-4-ol and α-terpineol have also been suggested as key components, but they play a contentious role that could be partly decomposition products, thermolabile sabinene hydrates. 20,22 To clarify the efficiency of the extraction techniques on the chemical composition of the marjoram volatile extracts, as well as their antioxidant properties, the identified compounds were classified into four main groups; monoterpenes (M), sesquiterpenes (S), light-oxygenated compounds (LOC) and heavy-oxygenated compounds (HOC) (Figure 2). Monoterpenes constitute the second predominant group of the HD extract (48.32%), but the same class constitutes only 25.3% in the SFE extract.…”

Essential oil compounds in a historical sample of marjoram (Origanum majorana L., Lamiaceae)

“…6,7,26,27 In a solvent extract of the herb, this process of rearrangement is (almost) avoided. The solvent extract of the historical sample, however, more closely resembles the distilled oil than the more native solvent extract of recent marjoram.…”

Enantiomeric composition of (E)- and (Z)-sabinene hydrate and their acetates in ?veOriganum spp.

“…14 (Z)-sabinene hydrate acetate was found in relatively large amounts in solvent extracts 1,2,4,5,15 and in supercritical CO 2 extracts 16 of O. majorana. Elevated temperatures during distillation, even without acid catalysis were reported to be sufficient to form rearrangement products of (Z)-sabinene hydrate acetate.…”

“…The importance of the bicyclic monoterpenes (Z)-sabinene hydrate [(Z)-thujan-4-ol)] and (Z)-sabinene hydrate acetate [(Z)-thujan-4-ol acetate] as the major and original flavour compounds of marjoram (Origanum majorana L.) was intensively discussed by Fischer et al 1,2 and Novak et al [3][4][5] Relatively large quantities of (Z)-and (E)-sabinene hydrate within the genus Origanum have been found in O. heracleoticum, 6 O. majorana var. tenuifolium, 7 O. rotundifolium, 8 O. micranthum, 9 O. ramonense, 10 O. husnucan-baserii, 11 O. microphyllum, 3,12 O. syriacum var.…”