Determination of 3-methyl-2,4-nonanedione in red wines using methanol chemical ionization ion trap mass spectrometry

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.

Effect of Furan Fatty Acids and 3-Methyl-2,4-nonanedione on Light-Induced Off-Odor in Soybean Oil

Soybean oil is one of the most widely consumed vegetable oils. However, under photooxidative conditions, this oil develops a beany and green off-odor through a mechanism that has not yet been elucidated. Upon photooxidation, 3-methyl-2,4-nonanedione (3-MND) produces a strong aroma. In this study, the effect of furan fatty acids and 3-MND on odor reversion in soybean oil was investigated. Our findings suggest that the observed light-induced off-odor was likely attributable to the furan fatty acids present in the oil through the generation of 3-MND. While 3-MND may not be directly responsible for the development of light-induced off-odor, this compound appears to be involved because off-odor was detected in canola oil samples containing added 3-MND. In addition, in the present work, 3-hydroxy-3-methyl-2,4-nonanedione, which is derived from 3-MND, was identified for the first time in light-exposed soybean oil and shown to be one of the compounds responsible for odor reversion.

Identification and Organoleptic Contribution of (Z)-1,5-Octadien-3-one to the Flavor of Vitis vinifera cv. Merlot and Cabernet Sauvignon Musts

The main goal of this research was to identify key aroma compounds involved in the dried fruits (prune and dried fig) aroma of musts. An odoriferous zone (OZ) was detected by gas chromatography coupled with olfactometry (GC-O) and identified as (Z)-1,5-octadien-3-one (geranium). A quantitation method by SPME-GC-MS (CI, MeOH) was developed and validated for assaying this very fragrant ketone in musts for the first time (LOD, 0.15 ng/L; LOQ, 0.5 ng/L). Concentrations of (Z)-1,5-octadien-3-one in musts marked by dried fruits flavors reached 90 ng/L, thus exceeding its detection threshold (D_th = 9 ng/L). Moreover, sensory experiments showed that this compound contributes to the dried fig nuance at concentrations ranging from 64 to 96 ng/L. Above that level, it contributes to the geranium nuance of the must. Its affinity with sulfur dioxide was also established; 30 mg/L of sulfur dioxide causes a decrease of concentration of 60%.