Sophie Tempere

Impact of Perceptive Interactions on Red Wine Fruity Aroma

A preparative HPLC method was applied to aromatic red wine extracts. Twenty-five fractions with various flavors were thus obtained, and several aromatic reconstitutions were produced by mixing some of these fractions. Discriminative tests revealed that the omission of some fractions from the mixture of fruity fractions or the addition of others affected the overall expression of fruity aroma. Sensory profile analyses identified significant differences among aromatic reconstitutions in terms of intensity of black-berry, as well as fresh-, and jammy-fruit descriptors. A fraction with a very low fruity note (fraction 17) had an additive effect on the fresh fruity aroma, while fractions with caramel and lactic notes (fractions 3-5) had a masking effect on this aroma and an additive effect on the jammy-fruit aroma. Further analysis revealed that ethyl 2-hydroxy-4-methylpentanoate was eluted in fraction 17, while diacetyl, acetoin, acetic acid, and γ-butyrolactone were eluted in fractions 3-5. Omissions tests established that ethyl 2-hydroxy-4-methylpentanoate was responsible for enhancing black-berry and fresh-fruit aroma and that a combination of diacetyl, acetoin, acetic acid, and γ-butyrolactone, at levels between 2 and 40% of their perception thresholds, had the same hypoadditive effect on the overall and fresh fruity aroma as fractions 3-5.

Identification of Piperitone as an Aroma Compound Contributing to the Positive Mint Nuances Perceived in Aged Red Bordeaux Wines

Although a sensory definition of the aging bouquet of red Bordeaux wines was recently established, its chemical transcription has only partially been elucidated. A multiple-step approach, combining sensory evaluations of red Bordeaux wines and aromatic reconstitutions of wine extract fractions, was used to identify the molecular markers involved. One wine with a high aging-bouquet score and a mint nuance has received particular attention. Various reconstitution and omission tests highlighted the contribution of two specific fractions to the intensity of the perception of mint aroma. Gas chromatography coupled to olfactometry and mass spectrometry was applied to the targeted fractions to identify molecular marker(s) responsible for the mint nuance in fine red Bordeaux wines. A similar analytical process was applied to selected fractions of essential oils presenting mint odors to characterize them and interpret the mass spectrometry data. This approach resulted in the detection of piperitone, a monoterpene ketone that, to the best of our knowledge, was reported for the first time as a contributor to the positive mint aroma of aged red Bordeaux wines.

Explicit Sensory Training Improves the Olfactory Sensitivity of Wine Experts

Wine quality is first assessed by experts who evaluate the sensory characteristics of the product using sensory skills. Several studies have shown considerable variation in chemosensory human capacities, including wine tasting experts. Some of them show high olfactory detection thresholds for some key compounds of wine. In addition, several authors have observed an induction of sensitivity in subjects with odor-specific hyposmia and increased sensitivity in persons without specific olfactory disorders after repeated exposure to a substance or practice fragrance smell tests. Given these observations, adapted training for professionals in the wine industry may be appropriate. On this basis, we tested a simple sensory training session, that is to say repeated short-term exposures to odorous wine key compounds, with the hope of improving the detection capabilities of wine professionals who need it. Our results show that the sensitivity of these experts can be changed: the olfactory detection thresholds are reduced in the experts trained. This improvement was limited to the odorant used in the training: learning was not generalized but was odorant specific.

Distribution and Organoleptic Impact of Ethyl 3-Hydroxybutanoate Enantiomers in Wine.

Enantiomers of ethyl 3-hydroxybutanoate were assayed in 87 commercial wines from various vintages and origins, using chiral gas chromatography (β-cyclodextrin). Generally, ethyl 3-hydroxybutanoate levels were higher in red than in white wines of the same age. The average S/R enantiomeric ratio of this compound in red wine was approximately 75:25 (± 13), with an average total concentration of ∼ 450 (± 150) μg/L. In red wines, R-form levels increased gradually during aging, but no variations were observed in S-form concentrations. To our knowledge, no previous research had determined the enantiomeric distribution of this compound in wine. The olfactory threshold of the S-form in dilute alcohol solution was 21 mg/L, one-third that of the R-form: 63 mg/L. The S- and R-forms had different aromatic nuances. The olfactory threshold of their mixture (85:15, m/m) was 14 mg/L, indicating a simple additive effect in this binary mixture. Furthermore, the concentrations found in red wines were considerably below the olfactory threshold under the same experimental conditions. Sensory analysis revealed that ethyl 3-hydroxybutanoate (S/R, 85:15, m/m) had an enhancing effect on the perception of fruity aromas in the matrices studied. Sensory profiles highlighted the contribution of ethyl 3-hydroxybutanoate to red-berry and fresh-fruit descriptors, despite its subthreshold concentrations.

Investigation and Sensory Characterization of 1,4-Cineole: A Potential Aromatic Marker of Australian Cabernet Sauvignon Wine

This work reports the quantitation and sensory characterization of 1,4-cineole in red wine for the first time. A headspace-solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method was developed to quantitate 1,4-cineole and 1,8-cineole in 104 commercial Australian red wines. 1,4-Cineole was detected in all of the wines analyzed, with concentrations ranging from 0.023 to 1.6 μg/L. An important varietal effect was observed, with concentrations of 1,4-cineole in Cabernet Sauvignon wines (mean of 0.6 ± 0.3 μg/L) significantly higher than in Shiraz (0.07 ± 0.04 μg/L) and Pinot Noir (0.2 ± 0.2 μg/L) wines. Regional variations of both cineole isomer concentrations have been measured between wines originating from different Australian regions. Sensory studies demonstrated that the addition of 0.54 μg/L 1,4-cineole in a Cabernet Sauvignon wine, to produce a final concentration of 0.63 μg/L, was perceived significantly by a sensory panel (p < 0.05). Descriptive analyses revealed that 1,4-cineole and 1,8-cineole may contribute to the hay, dried herbs, and blackcurrant aromas reported in Australian Cabernet Sauvignon wines and may be potential markers of regional typicality of these wines.

The complexity of wine: clarifying the role of microorganisms

The concept of wine complexity has gained considerable interest in recent years, both for wine consumers and wine scientists. As a consequence, some research programs concentrate on the factors that could improve the perceived complexity of a wine. Notably, the possible influence of microbiological factors is particularly investigated. However, wine complexity is a multicomponent concept not easily defined. In this review, we first describe the actual knowledge regarding wine complexity, its perception, and wine chemical composition. In particular, we emphasize that, contrary to expectations, the perception of wine complexity is not related to wine chemical complexity. Then, we review the impact of wine microorganisms on wine complexity, with a specific focus on publications including sensory analyses. While microorganisms definitively can impact wine complexity, the underlying mechanisms and molecules are far from being deciphered. Finally, we discuss some prospective research fields that will help improving our understanding of wine complexity, including perceptive interactions, microbial interactions, and other challenging phenomena.

Masking of Several Olfactory Notes by Infra-threshold Concentrations of 2,4,6-Trichloroanisole

IntroductionAmong wine defects, 2,4,6-trichloroanisole has a specific impact on wine perception. In addition to giving to the wine an unpleasant odor, 2,4,6-trichloroanisole has a masking effect on notes. In this study, the specificity and efficacy of the masking effect of 2,4,6-trichloroanisole was tested at infra- and supra-threshold concentrations. A simplified model of a binary mixture was also studied for in-depth analysis of this phenomenon.MethodsTechniques used included sensory analysis (odor profiling), psychophysical tests (threshold measurement and triangle test), chemical analyses (GC-MS), and a mono/dichorhinic stimulation paradigm, to test the hypothesis of peripheral interaction.ResultsThe results revealed that TCA had a masking effect on a range of aromatic notes, even at infra-threshold concentrations. However, they also showed counteraction of odorant specificity by 2,4,6-trichloroanisole. The origin of this masking effect was also discussed. The results suggested that this interaction can be assumed to take place at receptor level.ConclusionThis study provided experimental confirmation of the widespread idea that constituents in non-perceptible concentrations influence the perceived quality of mixtures of odorous compounds.ImplicationsMoreover, this type of olfactory model may improve our understanding of combinatorial olfactory encoding at the peripheral level.

2-Methylbutyl acetate in wines: Enantiomeric distribution and sensory impact on red wine fruity aroma

Enantiomers of 2-methylbutyl acetate were assayed in red and white commercial wines from various vintages and origins, using chiral gas chromatography (γ-cyclodextrin), revealing the exclusive presence of the S-enantiomeric form. Results also confirmed that (S)-2-methylbutyl acetate levels were generally higher in red than white wines of the same age, and that acetate levels increased gradually during ageing. Olfactory threshold of (S)-2-methylbutyl acetate was evaluated at 313µg/L in dilute alcohol solution (12% v/v) and 1083µg/L in a fruity aromatic reconstitution, reflecting its presence in wines at subthreshold concentrations. At concentrations considerably lower than its olfactory threshold, 2-methylbutyl acetate was associated with blackberry-fruit and banana notes. It was also revealed that, even at subthreshold concentrations, this compound had a modification on the perception of fruity aromas in the matrices studied. Sensory profiles highlighted, for the first time, its specific contribution to black-, fresh-, and jammy-fruit notes, despite its subthreshold concentrations.

Correction to Olfactory Impact of Higher Alcohols on Red Wine Fruity Ester Aroma Expression in Model Solution.

Published: February 1, 2016 Figure 2. Detection probability of fruity reconstitution in different matrices: aromatic impact of higher alcohols at (a) low, (b) medium, and (c) high concentrations added to fruity reconstitution in dilute alcohol solution. ∗, expressed in milliliters of total fruity reconstitution (FR) diluted in 50 mL of matrix. DAS, dilute alcohol solution; HA, higher alcohols. The curves are drawn according to a sigmoid function. Addition/Correction