Distribution and Sensory Impact of (2E,4E,6Z)-nonatrienal and Trans-4,5-epoxy-(E)-2-decenal in Wines and Spirits.

This study reports the distribution of (2E,4E,6Z)-nonatrienal (1) and trans-4,5-epoxy-(E)-2-decenal (2) in wines and spirits. We validated a quantification method using solid-phase extraction (SPE) and negative chemical ionization (NCI, NH3) gas chromatography-mass spectrometry (GC-MS) analysis. Both were identified for the first time in wines and spirits from different grape varieties and raw materials. Their olfactory detection thresholds (ODTs) were 16 and 60 ng/L, respectively. Analysis of 66 wines showed that the highest levels of (1) (441.3 ng/L) and (2) (386.5 ng/L) were found in red and white wines, respectively. At these levels, they modify the balance of the fruity expression of red (fresh to cooked fruits) and white (vegetal/green hazelnut nuance) wines. Similar quantitative and sensory analyses were conducted in spirits. With ODT estimated at 500 and 400 ng/L and concentrations ranging from trace amounts to 1.1 and 2.4 µg/L respectively, (1) and (2) can contribute directly to the aroma of spirits.

Identification and Distribution of New Impact Aldehydes in Toasted Oak Wood (Quercus petraea).

The purpose of this study was to identify aroma compounds associated with the toasting intensity of oak wood (Quercus petraea). Crude organic extracts from oak wood samples (toasted at different temperature-time couples) were analyzed by a sensory-guided approach using GC-O-TOFMS, followed by purification with semipreparative HPLC (reverse phase). This approach revealed two specific odorous zones (OZs) reminiscent of metal and puff pastry. The first OZ was identified as trans-4,5-epoxy-(E)-2-decenal (1) by coinjection of the commercial product, whereas identification of (2E,4E,6Z)-nonatrienal (2) associated with puff pastry OZ was validated by a multistep chemical synthesis approach (Wittig reaction) followed by semipreparative HPLC purification (chiral phase). Their detection thresholds in model wine solution were 60 ng/L (1) and 16 ng/L (2). Their distribution in toasted oak wood samples [GC-NCI-MS (NH3) analysis] ranged from some ng/g to 210 ng/g for (1) and 85 ng/g for (2). Finally, additional sensory experiments demonstrated the impact of newly identified aldehydes in toasted oak wood.

Contribution of Volatile Odorous Terpenoid Compounds to Aged Cognac Spirits Aroma in a Context of Multicomponent Odor Mixtures.

Cognac spirit aromas result from the presence of a wide variety of volatile odorous compounds associated with the modalities of spirit distillation and aging. However, very few studies have been carried out on aging notes of Cognac spirits. An HPLC fractionation approach was used in order to evidence fractions of interest recalling the specific aromatic nuances of aged Cognac. Then, a GC-O/MS analysis of the selected fractions allowed one to detect odorous zones and identify several volatile compounds. Among them, various well-known volatile compounds representative of the terpenoid family were highlighted, such as geraniol, α-terpinene, nerol, α-terpineol, 1,8-cineole (eucalyptol) and, particularly, piperitone, santalol, and α-campholenal, which have not previously been cited in Cognac. These compounds were quantitated and their detection thresholds were determined. Geraniol, α-terpinene, α-terpineol, and 1,8-cineole concentrations increased while spirits were more aged, while nerol tends to decrease. A sensory contribution of terpenes was observed through perceptual synergic effects, along with ß-damascenone and whisky lactone.