Key odorants of industrially-produced Helichrysum italicum subsp. italicum essential oil

To better characterize the constituents responsible for the specific odor of Helichrysum italicum subsp. italicum, the key odorants of a sample of commercial essential oil produced industrially were identified by Gas Chromatography-Olfactometry (Aroma Extract Dilution Analysis) (GC-O AEDA). These compounds were characterized, together with 82 constituents, by careful fractionation procedures and Gas Chromatography-Mass spectrometry and GC-O analyses applied to the entire oil and to its fractions. Several authentic samples of reference constituents (purchased commercially or synthesized by original procedures) were co-injected to confirm some identifications. The most odor-active constituents perceived by all the panelists and showing the highest mean Flavor Dilution factor were 4,6-dimethyloctan-3,5-dione, 1,8-cineole and nerol. Many other constituents in low or, even, in trace amounts, also participate to the global odor of the essential oil.