Search

International audience; BACKGROUND Today, many agricultural products claiming a link to their origin and typicity receive a warm welcome on the market. Nevertheless, the notion of typicity is blurred for consumers and needs to be objectified for communication purposes. This study aims at formalizing a methodology for studying typicity of terroirs, with PDO wines as an example, using a participatory approach with professionals of the wine sector from terroirs, using focus group and tasting. The vision of typicity of terroirs by professionals outside of these terroirs has been studied by a free word association task.RESULTS This study allowed a clear distinguishing of the typicity of the studied terroirs. Professionals from terroirs identified the global conceptual typicity of their terroirs using various factors, mainly soil, geography and grape variety, whereas professionals outside terroirs expressed their visions of terroirs by reputation or sensory characteristics of wines. Tasting results showed a discrimination of wines based on their typicity and highlighted descriptors involved in sensory perceptual typicity for each studied terroir.CONCLUSIONS Professionals from terroirs share a common vision of their typicity and identify more typicity factors than professionals outside terroirs. Sensory typicity has been highlighted for five of the six terroirs studied, according to the various descriptors. The study of two populations, from and outside terroirs, shows the gap between the typicities identified by professionals from terroirs and those perceived by professionals outside terroirs. (c) 2020 Society of Chemical Industry

A strong blackcurrant aroma was recently perceived in some red wines originating from the same appellation. Varietal thiols such as 4-mercapto-4-methyl-2-pentanone (4MMP), 3-(mercapto)hexyl acetate (3MHA) and 3-mercapto-1-hexanol (3MH) are compounds potentially responsible for the development of this aroma. In order to demonstrate the correlation between thiols concentrations in red wines and blackcurrant aroma intensity, a multiple variable analysis was realised with thiols concentrations obtained by chemical analysis and blackcurrant aroma intensities obtained by descriptive sensory analysis. The 4MMP concentration was very well correlated to the blackcurrant aroma, and 3MHA and 3MH present at high concentrations act as enhancers of the perception of this aroma. This correlation was further supported after performing a sensory comparison by classification test. The different factors that could impact on the development of blackcurrant aroma in red wine were discussed.

Varietal Thiols in Wine: Discovery, Analysis and Applications Aur elie Roland, R emi Schneider,* Alain Razungles, and Florine Cavelier* Interloire, 12 rue Etienne Pallu, BP 1921, 37019 Tours Cedex 01, France UMR 1083 Sciences pour l’!nologie, INRA, SupAgro, Universit e Montpellier I, 34060 Montpellier Cedex 01, France Institut Franc ) ais de la Vigne et du Vin, at UMR 1083 Sciences pour l’!nologie, INRA, 34060 Montpellier Cedex 01, France IBMM, UMR-CNRS 5247, Universit es Montpellier I et II, Place Eug ene Bataillon, 34095 Montpellier, France

The isotopically labelled S-3-(hexan-1-ol)-glutathione d 2 /d 3 (G3MHd 2 /d 3 ) was synthesized with a strategy based on acid-labile protecting groups. The natural analogue of this compound could be a precursor of 3-mercaptohexanol, a varietal thiol reminiscent of grape fruit, released during alcoholic fermentation. In a first time, deuterated glutathione conjugate was used to perform identification and quantification by stable isotope dilution assay of G3MH in musts from several varieties: Sauvignon, Riesling and Gewurztraminer. In a second time, synthetic and natural musts (Sauvignon Blanc) were spiked by G3MHd 2 /d 3 at different levels from 12 to 150 μg L −1 to demonstrate the relationship between 3-mercaptohexan-1-ol (3MH) and G3MH. GC–ITMS/MS analysis of the resulting wines clearly showed the formation of the corresponding deuterated 3MH, that proves the direct connection with G3MH under enological conditions. In Sauvignon Blanc grape juice, a conversion yield of 4.4% was found in duplicate for an initial spiking of G3MH d 2 /d 3 equivalent to 12 μg L −1 .

International audience; Thiol precursor content in Melon B. and Sauvignon blanc grape juices obtained under vacuum was determined by quantifying cysteinylated and glutathionylated conjugates of 3-mercaptohexan-1-ol (3MH) and 4-methyl-4-mercaptopentan-2-one (4MMP). This characterization allowed the study of thiol precursor evolution during ripening of Sauvignon blanc grapes in several viticultural situations together with grape reaction product (GRP) and the main substrate of polyphenoloxidase, that is, caftaric acid. Concentration of precursors greatly increased during ripening except for the cysteinylated conjugate of 4MMP. Precursor evolution was also monitored during the oxidation of grape juice. Addition of oxygen to a grape juice set off the enzymatic oxidation of hydroxycinnamic acids but did not negatively affect precursor concentrations. Part of the glutathionylated precursor of the 3MH was produced during prefermentative operations (up to 140% in Sauvignon blanc). Consequently, this precursor naturally occurring in grapes was also formed during prefermentative operations. The proportion of biogenetic and prefermentary formation of the glutathionylated precursor of 3MH was different under industrial conditions depending on the grape variety considered. Addition of glutathione and hexenal in grape juices of Melon B. and Sauvignon induced an increase of the production of 3MH and consequently of its acetate in the resulting wines. Residual glutathione in must has to be preserved to enhance the aromatic potential of grapes

International audience; The contribution of dimethyl sulfide (DMS) to the aroma of Syrah and Grenache Noir wines from the Rhone Valley of France was investigated by sensory analysis, and its levels in these wines were measured. The potential DMS in the corresponding grapes and wines, susceptible to release during wine aging, was evaluated. Free DMS and potential DMS assessed by a heat-alkaline treatment were measured in grape juices and wines by SPME-GC-MS using methods previously reported and slightly modified. A relationship between potential DMS from grapes and the total DMS levels in wine was demonstrated. Furthermore, a linear regression between the ratio of free DMS levels to these total DMS levels in wine and time of storage was found. Free and potential DMS levels in grapes and wines depended on grape variety, vintage, and vine location. DMS imparted a noticeable and complex contribution to the aroma of the wines investigated, depending on the mode of sensory perception used, either before or after glass swirling. It significantly enhanced the fruity notes of the wines, and additional truffle and black olive notes

The aromas of six Merlot and three Cabernet Sauvignon wines of the 1996 vintage from the Bordeaux region were evaluated by sensory analysis. A panel of selected enology students was trained to assess 20 attributes previously generated for these wines by enologists of Bordeaux. Using statistical methods, this 20-attribute list was reduced to a 12-attribute list. The aroma profiles of the wines of Merlot and Cabernet Sauvignon were very close. Differentiation of the wines of these two varieties was significant only for the caramel descriptor, which was rated higher in the Merlot wines. Gas chromatography/olfactometry (GC/O) and GC/MS analyses were used to detect and identify the potent odorants with the caramel odor in the two most differentiated samples for this attribute, a Merlot wine and a Cabernet Sauvignon wine. Two odorant zones with this odor resulted in identification of 4-hydroxy-2,5-dimethylfuran-3(2H)-one (HDMF) and 4-hydroxy-2(or 5)-ethyl-5(or 2)-methylfuran-3(2H)-one (HEMF). Aroma extract dilution analysis (AEDA) method showed a higher dilution factor (FD) for HDMF in the Merlot wine extract than in the Cabernet Sauvignon extract. The HDMF levels determined in the wines studied using a stable isotope dilution assay (SIDA) method were consistent with the results found by sensory analysis and GC/O; i.e., higher HDMF levels were present in the Merlot wines than in the Cabernet Sauvignon wines.

The presence of β-carotene and a precursor of lutein is described in wood for the first time. These compounds were found in the wood of sessile oak, pedunculate oak, American white oak, chestnut, and beech. The levels were generally low and varied considerably from one tree to another. Among the European oaks, sessile oak was significantly richer in lutein than pedunculate oak. Sessile oaks from Jupilles forest contained the highest β-carotene levels. The position of the wood sample in the trunk affected the carotenoid content, and barrel wood is taken from a zone that is fairly rich in these compounds. Keywords: Carotenoids; oak wood; age of wood; European oak; American oak

Aims: The aim of this study was to demonstrate the impact of the volatile compounds, arising from glycosidic precursors contained in the berries of Vitis vinifera L.cv Syrah and Grenache noir varieties, on wine aromas from these varieties.Methods and results: The sensory analysis was used to compare Grenache noir and Syrah wines. The role played by the glycosidic precursors on the future odorant profile of the wines from both varieties was demonstrated in an experiment by increasing their natural content in glycosides. Then, odorant compounds were generated by aging treatments, heating at 45 °C for 3 weeks, preceded or not by enzyme addition, or natural aging for 18 months. The wines were then submitted to a selected and trained panel. Samples were compared using triangular test. Furthermore, a quantitative descriptive analysis was carried out to determine the aroma attributes describing and discriminating the wines from the two varieties.Conclusion: The glycoconjugates increased the global aromatic complexity, and enhanced the fruity aromas in Grenache wines and the leather or olive aromas in Syrah wines. The use of glycosidase enzymes led to a stewed fruit character in Grenache wines, whereas in Syrah wines, the samples enriched with glycosides differed according to the « terroir ».Significance and impact of study: This study showed the impact of the glycosidic fraction of the grapes on the varietal aroma of wines. Furthermore, comparisons of the results obtained by both aging techniques highlight the experimental interest of the aging model but also its limits.