Qualitative evaluation of aromatic herbs by direct headspace GC analysis. Applications of the method and comparison with the traditional analysis of essential oils

Abstract

SummaryGC headspace analyses of various aromatizing herbs have been compared with those relating to the essential oils, obtained by steam distillation, of the same plants. In this way it was possible to establish the most significant differences between the composition of a herb flavor and that of its essential oil. In particular, we observed some very volatile compounds in the headspace samples which were absent from the essential oil; these components may make an important contribution to the herb flavor. The identification of these substances is still in progress.

Odor Thresholds of Various Unsaturated Branched Esters

“…In contrast to the methyl, ethyl and propyl esters, substitution of a trans double bond in the 2 position resulted in a four-fold decrease in the odor threshold to 4.2 µL/10 3 L. Similar to the propyl ester, the cis butyl isomer had a higher odor threshold than the trans isomer (13 µL/10 3 L vs. 4.2 µL/10 3 L). Roman chamomile flowers (9) and Roman chamomile essential oil (16) are again reported as sources of butyl angelate. Butyl tiglate has been reported in Alphonso mango (Mangifera indica) by Idstein and Schreier (17).…”

Lessons Learned from Herbal Medicinal Products: The Example of St. John’s Wort

“…Assuming that there were additional active compounds, we investigated this fraction further phytochemically; subfraction IIIc1 was obtained containing some procyanidins, in particular, procyanidin B2 (11). However, this subfraction did not show any activity in the FST, but when pure hypericin (1) was combined with subfraction IIIc1, significant activity was observed in the FST, in doses ranging from 0.009 to 0.9 mg hypericin/kg (Table 2).…”

Biologically Active and Other Chemical Constituents of the Herb ofHypericum perforatumL.

“…The hyperforins are lipophilic and unstable toward heat and light either on storage or in solution. One of the products of degradation is 2-methyl-3-buten-2-01 (17) probably generated by oxidative cleavage of the isoprenyl side chains of 14 and 15 (Chialva et al 1982;Maisenbochet;. The same product is observed when hop (Hurnulus lupulus, Cannabidaceae) bitter acids are oxidatively degraded (Wohlfart et al, 1982).…”