Characterization of Seven New Hydrocarbon Compounds Present in the Aroma of Virgin Olive Oils

Abstract

Seven isomeric hydrocarbons were detected in the volatile fraction of three samples of virgin olive oil. Chemical ionization mass spectrometry was used to assign the molecular formulas. Their structures were confirmed by comparison of retention time and mass spectral data with those of a synthetic sample obtained by pentene radical coupling. A final characterization of each chromatographic peak was done by means of a chiral capillary column to distinguish the optically active compounds from the isomers without chiral centers. For the quantitation the recovery factor in the oily matrix during the extraction of the volatile fraction was obtained using a related chemical, the commercially available beta-citronellene. On the basis of the previous literature and the present experiments a tentative rationalization of the involved biochemical pathway is proposed.

Natural Variation of Volatile Compounds in Virgin Olive Oil Analyzed by HS-SPME/GC-MS-FID

“…Three different groupings may be distinguished for the latter (Figure 2, light gray ellipses), which correspond to the C5/LnA alcohols, carbonyls, and pentene dimers, respectively. The group of C5/LnA alcohols is the closest to the C6 compounds, which would indicate a greater metabolic proximity and would support the hypothesis that C5/LnA alcohols would be the first products formed from the homolytic branch of the LOX pathway, which involves the activity of a LOX protein forming an alkoxy radical from a polyunsaturated fatty acid [33], parallel to the pentene dimers formation but in different ways, and finally oxidized enzymatically to C5/LnA carbonyls. Moreover, it was found previously that the pentene dimer content is not related to the contents of the C5/LA carbonyls (5C-14, 5C-15) or alcohol (5C-16), suggesting that pentene dimers are only synthesized from LnA [35].…”

“…Quantitatively, the pentene dimers are the major compounds in this group. They are thought to be produced in the same branch of the LOX pathway as the rest of the C5 compounds [33]. The pentene dimers represented 82% of the C5/LnA content on average (Figure 1), but seem to have a quite low or negligible sensory contribution to the VOO aroma, according to the estimated odor thresholds for these compounds [29].…”

Volatile and Non-Volatile Compounds of Single Cultivar Virgin Olive Oils Produced in Italy and Tunisia with Regard to Different Extraction Systems and Storage Conditions

“…It is well known that volatile and non-volatile components of products of plant origin are dependent on genetic, agronomic and environmental factors. There are few reports (Angerosa et al, 1996(Angerosa et al, , 1998a(Angerosa et al, , 1998b(Angerosa et al, , 1999Morales et al, 1995;Solinas et al, 1998) on the evaluation of the relationships between the aroma components of virgin olive oil with the metabolic pathways and varietal factors. Olive ripening process and, to some extent, the fruit growing environment, affect also the composition of the volatile compounds of the oil (Aparicio & Morales, 1998;De Nino et al, 2000;Guth & Grosh, 1993;Montedoro & Garofalo, 1984;Morales et al, 1996).…”

Olive Oil Composition: Volatile Compounds

“…When the substrate is LnA, LOX catalyses, besides the hydroperoxide formation, also its cleavage, via an alkoxy radical, increasing the formation of stabilized pent-1,3-diene radicals. These compounds can suffer dimerization leading to the production of C 10 hydrocarbons (pentene dimmers) or react with a hydroxyl radical present in the medium, leading to C 5 carbonyl compounds (Angerosa et al 1998b, Pizarro et al, 2011. The most important fraction of volatile compounds, of high quality virgin olive oils, comprises C 6 and C 5 compounds, especially C 6 linear unsaturated and saturated aldehydes.…”