Denis Dubourdieu

Université Victor Segalen Bordeaux 2 | UB2 · Institut des Sciences de la Vigne et du Vin (ISVV)

2022) Recovery after curettage of grapevines with esca leaf symptoms. Phytopathologia Medi-terranea 61(3): 473-489. Summary. Grapevine curettage was reintroduced in France in the early 2000s, and is important for facilitating recovery of plants from esca disease. This surgical practice involves removal of deadwood of vines with leaf symptoms, focus...

The re-emergence of Grapevine Trunk Diseases (GTDs), mainly Esca, has been observed in most of the world’s vineyards during the last two decades. Development of necrosis in grapevine wood, especially white-rot, is typically associated with Esca-diseased plants. One of the different methods being used in attempts to eradicate GTDs is curettage. This...

The re-emergence of Grapevine Trunk Diseases (GTDs), mainly Esca, has been observed in most of the world's vineyards during the last two decades. Development of necrosis in grapevine wood, especially white-rot, is typically associated with Esca-diseased plants. One of the different methods being used in attempts to eradicate GTDs is retaining only...

Six new triterpenoids (1-6), two known genins (7 and 8), and five known functionalized triterpenoids (9-13) were isolated from a Quercus robur heartwood extract. The purification protocol was guided by LC-HRMS by searching for structural analogues of bartogenic acid on the basis of their putative empirical formula. The structures of the new compoun...

Aging in barrel affects the sensory characteristics of wines and modifies the sweet taste in particular. Using an inductive approach, several sweet triterpenes, QTTs, have been identified in oak. Quantitative analysis has shown a significant species effect: sessile oak releases more sweet triterpenes while pedunculate oak is richer in bitter triter...

Background: Fermentation completion is a major prerequisite in many industrial processes involving the bakery yeast Saccharomyces cerevisiae. Stuck fermentations can be due to the combination of many environmental stresses. Among them, high temperature and ethanol content are particularly deleterious especially in bioethanol and red wine productio...

La qualité de l’obturateur conditionne la bonne conservation des vins en bouteille ; il doit assurer une étanchéité parfaite du flacon aux liquides, faire preuve d’innocuité organoleptique et permettre une maîtrise du niveau d’étanchéité aux gaz. Il est désormais acquis que les obturateurs utilisés pour boucher les bouteilles de vin présentent deux...

Background: Fermentation completion is a major prerequisite in many industrial processes involving the bakery yeast Saccharomyces cerevisiae. Stuck fermentations can be due to the combination of many environmental stresses. Among them high temperature and ethanol content are particularly deleterious especially in bioethanol and red wine production....

Eight new triterpenoids (1-8), the known genin (9), and two known functionalized triterpenoids (10 and 11) were isolated from a Quercus petraea heartwood extract. The structures of the new compounds were unequivocally elucidated using HRESIMS and 1D/2D NMR experiments. Sensory analyses were performed in a non-oaked wine on the pure compounds 1-11....

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This work aimed at improving knowledge about sweetness in dry wines. Following on from the empirical observations of winegrowers, we assessed the contribution of grape seeds to wine sensory properties. An inductive fractionation method guided by gustatometry was used to isolate and characterize sweet-tasting compounds from grapes. Fractionation of...

Organic extracts of musts and red wines marked by dried fruit and cooked fruit aromas were analyzed by gas chromatography coupled to olfactometry and mass spectrometry. Thanks to this analytical approach we identified a fragrant lactone corresponding to an odorant zone reminiscent of coconut and dried figs as 5,6-dihydro-6-pentyl-2H-pyran-2-one (C1...

Ethanol is the second major component of wine after water and exhibits important sensory properties. Previous studies suggested that its bittersweet taste varies according to the alcohol content and the matrix. However, the organoleptic impact of ethanol on wine remains largely ambiguous. Various sensory tests were carried out with a trained panel...

Chardonnay wines impart a unique complex aroma characterized by its buttery, yellow stone fruit, melon, bready and woody notes. Among the terms used in the sensory analysis of these wines, this study investigated hazelnut-like attributes. Multi-dimensional gas-chromatography coupled to olfactometry identified five pyrroles reminiscent of hazelnut:...

Quercoresinosides A and B (1 and 2), two new lignans, were isolated from a toasted Quercus petraea heartwood extract along with a known compound, 3-methoxy-4-hydroxyphenol 1-O-β-d-(6'-O-galloyl)glucopyranoside (3). The purification protocol was based on a taste-guided approach that sought to reveal new bitter compounds released from oak wood into w...

La révélation de la typicité aromatique des cépages est un enjeu majeur de la vinification. Pour certains arômes tels que les thiols volatils (4MSP, 3SH et A3SH), la levure participe à la biotransformation de précurseurs d’arômes contenus dans les moûts en composés très odorants. Initialement identifiés dans les vins de Sauvignon blanc mais présent...

Two main precursors (S-3-(hexan-1-ol)-l-cysteine and S-3-(hexan-1-ol)-l-glutathione) of 3-sulfanylhexanol (3SH, formerly named 3-mercaptohexanol) have been identified so far in grape juice but a correlation between precursor concentrations in grape juices and 3SH concentrations in wines is not always observed. This suggests that there may be other...

Wine taste balance evolves during oak aging by the release of volatile and non-volatile compounds from wood. Among them, an enantiomer of lyoniresinol, (+)-lyoniresinol, has been shown to exhibit bitterness. To evaluate the impact of (+)-lyoniresinol on wine taste, a two-step quantitation method was developed and validated. First, (±)-lyoniresinol...

Oak aging is a crucial step in winemaking during which the organoleptic properties of wine are modified. Various parameters affect the chemical composition of oak wood including botanical origin, which has been previously shown to be a determinant factor. This study focused on the development of a LC-HRMS method to assay four recently discovered ta...

Two grape antioxidants, ascorbic acid and glutathione, and a flavan-3-ol, catechin, were analyzed and related to the production or depletion of volatile compounds (phenylacetaldehyde, methional, and sotolon) that act as markers of premature aging in dry white wines. This research assessed the impact of adding ascorbic acid (AA, 80 mg/L) and glutath...

Wine expresses its beauty by sending a sensory message to the taster through molecules coming from grapes, yeast metabolism or oak wood. Among the compounds released during barrel aging, lyoniresinol has been recently reported as a relevant contributor to wine bitterness. As this lignan contains three stereogenic carbons, this work aimed at investi...

Glutathione (GSH) is a natural tripeptide present in grapes and wines. Its antioxidant properties are particularly useful during winemaking with white varieties like Sauvignon blanc. We examined two winemaking techniques, skin contact and pressing under nitrogen, for their effect on the GSH concentration in the must and wine. GSH was originally rep...

Le choix de la date de récolte constitue un des fondements de la qualité de la vendange et du vin qui en résulte. Comme le remarquaient très justement J. Ribeyrau Gayon et E. Peynaud dans le Traité d’Œnologie « Il est très difficile d’adopter une définition rigoureuse de l’état de maturité du raisin. Tout le monde a la notion du raisin mûr, mais la...

L’équilibre gustatif d’un vin repose non seulement sur sa structure tannique et son acidité, mais également sur sa douceur. Or, l’origine moléculaire de la saveur sucrée des vins secs est demeurée pendant longtemps mystérieuse, en dépit de l’importance de cette perception dans l’appréciation par les consommateurs. Des travaux effectués précédemment...

Two grape antioxidants, ascorbic acid and glutathione, and a flavan-3-ol, catechin, were analyzed and related to the production or depletion of volatile compounds (phenylacetaldehyde, methional, and sotolon) that act as markers of premature aging in dry white wines. This research assessed the impact of adding ascorbic acid (AA, 80 mg/L) and glutath...

GC-MS in chemical ionization mode (CI) was used as a simple, sensitive method for assaying 3-methyl-2,4-nonanedione (MND) in 67 red wines. MND content was shown to be lower in nonoxidized red wines and higher in oxidized red wines, that is, systematically exceeding the perception threshold (62 ng/L). Concentrations up to 340 ng/L in the most oxidiz...

Winemakers observe a sensory effect of oak ageing in wines, but the phenomenon has never been fully described. The aim of this study was to determine the influence of the ageing container on the sweetness of dry wines and to evaluate the contribution of oak volatile compounds. Both white and red dry wines were produced in various containers, such a...

This work outlines the effects of oxygen exposure during bottling and oxygen barrier properties of different closures (cork, synthetic and screw caps) on wine quality after bottling. The combination of bottling conditions and oxygen transfer rates of closures had a significant effect on the compositional and sensory properties of Sauvignon Blanc du...

The grape berry is the site of biosynthesis and accumulation of compounds that are likely to contribute in wines some of their aromatic characteristics. These compounds have the aromatic potential, and exist in part as volatile forms but mainly as non-volatile aroma precursors that can be released through chemical and biochemical reactions during v...

The grape berry is the site of biosynthesis and accumulation of compounds that are likely to contribute in wines some of their aromatic characteristics. These compounds have the aromatic potential, and exist in part as volatile forms but mainly as non-volatile aroma precursors that can be released through chemical and biochemical reactions during v...

Several studies have reported the beneficial influence of non-Saccharomyces yeasts and their potential applications in the wine industry, mainly in mixed-culture fermentation with S. cerevisiae. The potential impact of 15 non-Saccharomyces strains from 7 species on 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanylhexan-1-ol (3SH) release in mod...

Sweetness contributes notably to the taste-balance of dry wines and increases during oak-barrel aging owing to the release of natural sweeteners from wood. The search for such taste-active molecules, which are sometimes present at very low concentrations in wine or other complex matrixes, requires both reliable purification tools and powerful ident...

A compound associated with oxidized flavor in red wines was recently-identified as 3-methyl-2,4-nonanedione (MND). In order to quantify it, positive chemical ionization (PCI) in an ion trap was studied using conventional liquid reagents such as methanol, acetonitrile, and acetone, as well as non-conventional liquid reagents such as ethyl acetate, d...

Yeast autolysis during lees contact influences the organoleptic properties of wines especially by increasing their sweet taste. Although observed by winemakers, this phenomenon is poorly explained in enology. Moreover, the compounds responsible for sweetness in wine remain unidentified. This work provides new insights in this way by combining senso...

Volatile thiols, compounds that contribute strongly to the varietal aroma, are present in much higher concentrations in sweet wines than in dry wines. This positive effect, due to the presence of Botrytis cinerea on the berries, in fact results from a strong enrichment of cysteine S-conjugate precursors in botrytized berries. In the present study,...

La dégustation d’un vin est un acte complexe, impliquant des mécanismes physiques, physiologiques et cognitifs, au cours duquel le dégustateur construit une représentation d’objets chimiques dans son champ de conscience (1). Cette représentation repose, d’un point de vue sensoriel, sur les paramètres visuels, tactiles, olfactifs et gustatifs du vin...

Sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is a chiral furanone, an aroma compound known to be responsible for premature-aging flavor in dry white wines. Sotolon generally results from mild oxygenation during bottle aging, and until now, its formation pathways had not been elucidated. The ability of the main precursors described in the literat...

Aims: The first aim of this investigation was to determine whether red- and black-berry fruit aromas were specific to red wines. The second aim was to study their contribution to the red Bordeaux wine concept. Methods and results: In experiment 1, red wines were presented to expert assessors in dark, then in clear glasses. Assessors selected wines...

Sweet wines made from botrytized grapes contain much higher concentrations of volatile thiols, especially 3-sulfanylhexan-1-ol (3SH), than dry white wines. Three new specific volatile thiols (3-sulfanylpentan-1-ol (3SP), 3-sulfanylheptan-1-ol (3SHp), and 2-methyl-3-sulfanylbutan-1-ol (2M3SB) were recently identified in Sauternes wines. Like most vo...

Among Saccharomyces yeast, S. cerevisiae and S. bayanus var. uvarum are related species, sharing the same ecosystem in sympatry. The physiological and technological properties of a large collection of genetically-identified S. bayanus var. uvarum wine strains were investigated in a biometric study and their fermentation behavior was compared at 24...

Wine has very rich and complex aromas but is paradoxically obtained from grape juice that has very little odour itself. This aromatic transformation is mainly due to the action of yeasts during the alcoholic fermentation. First, yeasts produce secondary metabolites that give to wines its basic 'winy' characteristic. Second, some enzymatic activitie...

This work outlines the results from an investigation to determine the effect of the oxygen dissolved at bottling and the specific oxygen barrier properties of commercially available closures on the composition, color and sensory properties of a Bordeaux Sauvignon Blanc wine during two years of storage. The importance of oxygen for wine development...

Use of a URE2 mutant yeast having a loss-of-function mutation in the URE2 gene for increasing the release of aromatic volatile thiol by yeast during fermentation.

Nelson Sauvin (NS) is a unique hop cultivar that gives a specific flavor (exotic fruit-like, Sauvignon Blanc wine-like) to finished beers. We have attempted to identify the specific flavor compounds derived from NS. First, isobutyric esters, including 2-methylbutyl isobutyrate (2MIB), have been found in the beers used with NS (NS product). These co...

During red wine fermentation, high temperatures may cause stuck fermentation by affecting the physiology of fermenting yeast. This deleterious effect is the result of the complex interaction of temperature with other physicochemical parameters of grape juice, such as sugar and lipid content. The genetic background of fermenting yeast also interacts...

The most famous sweet wine in France is made from botrytised grapes in the Sauternes region. Its distinctive, complex aromas are undoubtedly due to noble rot as a result of Botrytis cinerea development on perfectly ripe Sauvignon blanc and Semillon grapes. The contribution of volatile thiols in botrytised wine aroma was recently reported. The objec...

A preparative HPLC method, which preserves wine aromas and isolates fruity characteristics in specific fractions, was applied to red wine aroma extracts. Various odor-active zones were detected in typical fractions by GC-O analysis of their extracts. Through further GC-MS analyses, the aromatic compounds responsible for 15 of these odoriferous zone...

2-Furanmethanethiol, a compound contained in many kinds of food, was identified for the first time in five types of miso fermented soybean paste (red salty rice miso, thin-colored salty rice miso, weak salty rice miso, barley miso, and soy miso) by specific extraction of volatile thiols using p-hydroxymercuribenzoate. In the triangle test with red...

Nelson Sauvin (NS) is a unique hop cultivar that was bred and grown in New Zealand. This hop gives a specific flavor (exotic fruit-like, white wine-like) to finished beers. However, the key compounds of this flavor have not yet been identified. We have attempted to identify the specific flavor compounds derived from NS. We focused on certain volati...

Sulfur compounds, and especially volatile thiols, are extremely odoriferous molecules, which contribute to the aromas of many fruits, plants, and foods (Shankaranarayana et al. 1982). For example, certain thiols contribute to the characteristic aroma of blackcurrant (Rigaud et al. 1986), grapefruit (Demole et al. 1982; Buettner and Schieberle 1999)...

6 Villenave d'Ornon cedex, France, and Unit e Mixte de Recherche 1219 nologie, Facult e d'nologie, and Ecole 7 Nationale d'Ing enieurs des Travaux Agricoles de Bordeaux, France 8 9 A preparative HPLC method, which preserves wine aromas and isolates fruity characteristics in specific 10 fractions, was applied to red wine aroma extracts. Various odor...

The article discusses the use of a directed breeding program to improve wine yeast strains. It says temperature is one of the essential parameters in winemaking due to its effect on fermentation kinetics and the chemical quality of the resulting wine. It offers an assessment of the capacity of nine commercial strains commonly used in red winemaking...

Nelson Sauvin (NS) is a unique hop variety that was bred and grown in New Zealand. This hop gives a specific flavor (exotic fruit-like, white wine-like) to finished beers. However, the key compounds of this flavor have not yet been identified. We have attempted to identify the specific flavor compounds derived from NS. We first compared the GC-MS p...

GC-MS in electron ionization mode (EI) was used as a simple, sensitive method for assaying sotolon [4,5-dimethyl-3-hydroxy-2(5)H-furanone] in various dry white wines. The impact of barrel-aging conditions, that is, whether yeast lees were present or not, on the formation of sotolon in dry white wines was then studied. The sotolon content was highes...

Sulfur dioxide is now considered to be a toxic chemical by most world health authorities. However, it remains an irreplaceable additive in enology for wine conservation, combining antioxidant and antibacterial properties. Sweet white wines from botrytized grapes retain particularly high SO 2 levels due to their high sulfur dioxide binding power. Th...

The premature aging of red Vitis vinifera L. wines is mainly associated with the formation of an intense off-flavor reminiscent of prunes. The compounds responsible for this deterioration in red wine flavor have not previously been identified. Sensory descriptive analysis associated with a gas chromatography-olfactometry (GC-O) technique was first...

Aims: It is well known that vine nitrogen deficiency can negatively impact on aroma in white wines. Soil nitrogen fertilization enhances aroma expression, but it also increases vine vigour and susceptibility to grey rot. The aim of this work was to investigate the impact of foliar nitrogen as well as foliar nitrogen and sulphur applications on arom...

Volatile thiols such as 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanylhexan-1-ol (3SH) are aromatic molecules having an important organoleptic impact on white wines. These components are produced from inodorous nonvolatile cysteinylated precursors by Saccharomyces cerevisiae metabolic activity during alcoholic fermentation. Here we provide a...

4-Methyl-4-sulfanylpentan-2-one (1; 4MSP) provides a characteristic aroma compound of wines made from Vitis vinifera L. cv. Sauvignon blanc. 4MSP has a strong box-tree odor with a very low perception threshold and is derived from the cysteinylated precursor S-(1,1-dimethyl-3-oxobutyl)cysteine (4; P-4MSP). P-4MSP is transformed into 4MSP during alco...

GC-MS in electron ionization mode (EI) was used as a simple, sensitive method for assaying sotolon [4,5-dimethyl-3-hydroxy-2(5) H-furanone] in various dry white wines. The impact of barrel-aging conditions, that is, whether yeast lees were present or not, on the formation of sotolon in dry white wines was then studied. The sotolon content was highe...

The enantiomers of sotolon, a flavor compound typical of oxidized white wines, were separated by preparative HPLC to determine their perception thresholds and distribution in wines. The enantiomeric ratios of chiral sotolon were evaluated in several dry white wines using gas chromatography and a chiral column (beta-cyclodextrin) connected to a 2 m...

Conventional wine yeasts produce high concentrations of volatile acidity, mainly acetic acid, during high-sugar fermentation. This alcoholic fermentation by-product is highly detrimental to wine quality and, in some cases, levels may even exceed legal limits. In this study, a non-conventional species, Torulaspora delbrueckii, was used, in pure cult...

The diastereoisomeric distribution of S-3-(hexan-1-ol)cysteine (P-3SH), the cysteinylated precursor of 3-sulfanylhexan-1-ol (3SH) in Vitis vinifera grape juice, was determined by a new method. This procedure is based on the purification of P-3SH in a small volume of must (500 microL) by affinity chromatography, followed by the separation of chiral...

Sweet white wines from botrytized grapes present high SO2 levels because of their high sulfur dioxide binding power. The objective of this work was to develop a new method for reducing this binding power by partially eliminating the carbonyl compounds naturally present in these wines that are responsible for this phenomenon. A selective liquid-soli...

Saccharomyces cerevisiae yeast strains exhibit a huge genotypic and phenotypic diversity. Breeding strategies taking advantage of these characteristics would contribute greatly to improving industrial yeasts. Here we mapped and introgressed chromosomal regions controlling industrial yeast properties, such as hydrogen sulphide production, phenolic o...

Botrytized wines (BW) are famous for their distinctive, complex aromas. To date, only a few studies have analysed the volatile compounds involved in their typical flavours. In this paper, GC–O was applied to BW and dry white wines (DW) made from the same grape varieties to characterize the main odorants responsible for their sensory differences. Su...

Nelson Sauvin (NS) is a unique hop variety that was bred and grown in New Zealand. This hop gives a specific flavor (exotic fruit-like, white wine-like) to finished beers. However, the key compounds of this flavor have not yet been identified. We have attempted to identify the specific flavor compounds derived from NS. We first compared the GC-MS p...

Natural Saccharomyces cerevisiae yeast strains exhibit very large genotypic and phenotypic diversity. However, the link between phenotype variation and genetic determinism is still difficult to identify, especially in wild populations. Using genome hybridization on DNA microarrays, it is now possible to identify single-feature polymorphisms among d...

Commercial Albariño wines from different subzones of Certified Brand of Origin ‘Rías Baixas’ (NW Spain) were analysed over four consecutive harvests. The contents of monoterpenes, volatile phenols, alcohols, sulphur compounds, acetates, fatty acids and ethyl esters were determined by gas chromatography (flame ionisation detector and flame photometr...

Nelson Sauvin (NS) is a unique hop variety that gives a specific flavor (exotic fruit-like, wine-like) to finished beers. We have attempted to identify the specific flavor compounds derived from NS. First, isobutyric esters (isobutyl isobutyrate, isoamyl isobutyrate and 2-methylbutyl isobutyrate) have been identified in the beers used with NS. Thes...

Specific extraction of volatile thiols using sodium p-hydroxymercuribenzoate revealed the presence of three new sulfanylalcohols in wines made from Botrytis-infected grapes: 3-sulfanylpentan-1-ol (II), 3-sulfanylheptan-1-ol (III), and 2-methyl-3-sulfanylbutan-1-ol (IV). The first two have citrus aromas, whereas the third is reminiscent of raw onion...

Glutathione (GSH) was assayed in must and wine using capillary electrophoresis coupled with laser-induced fluorescence (LIF) detection. Sample preparation involved conjugating thiols with monobromobimane (MBB) in a 2-(N-cyclohexylamino)ethanesulfonic acid [CHES] buffer (179mM). The electrophoretic conditions were 30kV with a capillary length of 105...

The Saccharomyces bayanus var. uvarum yeasts are associated with spontaneous fermentation of must. Some strains were shown to be enological yeasts of interest in different winemaking processes. The molecular typing of S. bayanus var. uvarum at the strain level has become significant for wine microbiologists. Four microsatellite loci were defined fr...

The enantiomeric distribution of 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) in Vitis vinifera wines was determined by combining two techniques: specific purification of volatile thiols from the wines using p-hydroxymercuribenzoate and separation of the chiral molecules by gas-phase chromatography on a cyclodextrin capillary colum...

Clarity and stabilityThe colloidal stateColloid reactivityProtective colloids and gum arabic treatmentReferences

IntroductionOxidative defectsEffect of various forms of bacterial spoilageMicrobiological origin and properties of volatile phenolsCork taintSulfur derivatives and reduction odorsPremature aging of white wine aromaOrganoleptic defects associated with grapes affected by various types of rotMiscellaneous defectsReferences

IntroductionGlucose and fructoseOther sugarsChemical properties of sugarsSugar derivativesPectic substances in grapesExocellular polysaccharides from microorganismsReferences