Grape-derived aroma and flavor precursors exist partially as non-volatile, sugar-bound glycosides. Hydrolysis of these compounds may modify sensory attributes and potentially enhance wine quality. In the first study, four levels of shoot thinning (control, 20, 25, and 30 shoots per meter) with and without basal leaf removal (2-4 leaves per shoot) were established on mid-wire (90 cm), bilateral cordon-trained, mature Cabernet Sauvignon (Vitis vinifera L.) grapevines in eastern Virginia in 1996 to determine the effects on grape chemistry, glycoconjugates, and conjugate fractions. Reduced shoot density generally resulted in higher berry weight and lower soluble solids (°Brix) at each sampling date. Titratable acidity and pH were generally unaffected by shoot thinning. The 25 shoots per meter treatment displayed the greatest rate of increase in total, red-free, and phenolic-free glycoconjugates, expressed as glycosides (μmol).. Leaf removal resulted in increased pH, total phenolics, and total anthocyanins at each sampling date and a higher concentration of total, red-free, and phenolic-free glycosides. In a second study, three crop levels [high (6.4 and 5.3 kg/vine), medium (5.1 and 4.9 kg/vine), and low (3.2 and 2.6 kg/vine) ] were established on mature Cabernet Sauvignon grapevines during the 1995 and 1997 seasons, respectively. Cluster thinning of vines trained to a mid-wire (90cm), bilateral cordon-system was performed by hand three weeks post-bloom to determine the effects on grape glycoconjugates and conjugate fractions (expressed as glycosyl-glucose). In 1995, reduced crop level resulted in higher soluble solids concentration, pH, and total and red-free glycosides but did not affect berry weight or titratable acidity. In 1997, the reduced crop level treatment had higher berry weight and lower soluble solids, sugar per berry, and anthocyanins compared with the high treatment throughout the sampling period. The low treatment had the highest concentration of total, red-free, and phenolic-free glycosides per gram of fresh fruit weight on the last sampling date and the highest total, red-free, and phenolic-free glycosides per gram of fresh fruit weight when compared at similar soluble solids concentrations. Duo-trio significance testing resulted in no sensory differences among the treatments in 1997. In a third study, Pinot noir (Vitis vinifera L.) wines were inoculated with one of six genetically different strains of Brettanomyces intermedius (Ave, M, 216, Vin 1, Vin 4, and Vin5). Wines stored sur lie and those racked immediately following the completion of secondary fermentation were analyzed to determine the influence of B. intermedius strains on total, red-free, and phenolic-free glycoside concentrations (estimated by the analysis of glycosyl-glucose), and on selected free volatiles. Sur lie wines inoculated with strain Vin 4 and racked wines inoculated with Vin 4 and Vin 5 had the lowest total glycoside concentration. Hydrolysis of red-free glycosides appeared greatest in sur lie wines inoculated with Vin 4 and racked wines inoculated with Vin 4 and Vin 5. Wines stored sur lie that were inoculated with M and Vin 1 and racked wines inoculated with Vin 1, Vin 4, and Vin 5 had the lowest concentration of phenolic-free glycosides. Wines were analyzed for volatile compounds known to be produced by Brettanomyces spp. Inoculated wines were found to have detectable concentrations of ethyl-2-methylbutyrate, isoamyl alcohol, ethyldecanoate, isovaleric acid, guaiacol, 2-pheylethanol, 4-ethylguaiacol and 4-ethylphenol. There were significant differences in the concentrations of these compounds among strains. Duo-trio testing demonstrated sensory differences between the control and all inoculated wines. Differences were also found between wines inoculated with strains Ave and Vin 5, strains M and 216, and strains M and Vin 4. / Master of Science

La vitiviniculture est un secteur économique et culturel important en Bourgogne. L’actuel changement climatique soulève diverses questions notamment sur son impact sur les cultures. Dans cette thèse, l’idée est d’élaborer une méthodologie afin de répondre à la problématique : quels seront les impacts possibles des changements de températures sur la phénologie du Pinot noir en Bourgogne à l’horizon 2031-2048 ?L’évolution des températures en Bourgogne depuis 1961 est caractérisée par un saut positif de température à la fin des années 1980 suivi par une période où la température augmente d’environ 1,5°C.L’un des intérêts de cette thèse réside dans l’élaboration, en suivant une stratégie élaborée durant la thèse, d’une base de données spatialisée réalisée sur la période 1989-2009 afin d’estimer la capacité du modèle WRF à reproduire le climat bourguignon en désagrégeant des données climatiques de large échelle. Le modèle reproduit de façon satisfaisante le cycle saisonnier et la variabilité spatiale climatique globale aux biais près (froid sur les Tx et chauds sur les Tn).Pour régionaliser le changement climatique, WRF a été utilisé pour désagréger des données issues du scénario SRES/A2 sur les périodes 1970-1987 et 2031-2048. Après avoir été évalués et intercomparés trois modèles phénologiques utilisant les données de températures moyennes pour simuler les dates d’occurrence des stages phénologiques du Pinot noir, ont été appliqués sur ces désagrégations.L’impact de l’augmentation des températures à l’horizon 2031-2048 (SRES/A2), estimée à 1,35°C en moyenne, se caractérise par une précocité de la floraison d’au moins 7 jours et une précocité de la véraison d’au moins 15 jours. La durée interstade est également diminuée de l’ordre de 5 jours. / The viticulture is an important economic and cultural sector in Burgundy. The current climate change raises a number of issues including its impact on crops. In this thesis, the idea is to develop a methodology to address the problem: what are the potential impacts of changes in temperature on the phenology of Pinot noir in Burgundy for years 2031-2048?The evolution of temperatures in Burgundy since 1961 is characterized by a positive temperature shift at the end of the 1980s followed by a period where the temperature increases of about 1.5 ° C.One of the interests of this thesis is to develop, following a strategy developed during the thesis, a spatial database conducted over the period 1989-2009 to estimate the ability of the WRF model to reproduce the climate Burgundy by disaggregating large scale data. The model reproduces satisfactorily the seasonal and spatial variability in global climate despite bias (cold on the Tx and hot on the Tn).To regionalize the climate change, WRF was used to disaggregate data from the scenario SRES/A2 on the periods 1970-1987 and 2031-2048. After being evaluated and inter-compared three phenological models, using average temperatures data to simulate the dates of occurrence of phenological stages of Pinot Noir, have been applied to these decompositions.The impact of warming temperatures on the horizon 2031-2048 (SRES/A2), estimated at 1.35 ° C on average, is characterized by an earlier flowering and veraison of about 7 and 15 days respectively. The interstadial duration is also reduced of about 5 days.

Precision agriculture applied to vitiviniculture can bring several advantages to vitis crop production with positive effects on grape and wine quality. This study s objective was to put into practice precision vtiticulture, aiming to improve the administration and management of vinifera grapes. This research was carried out in a commercial vitis cropland with 2.4 ha located in Encruzilhada do Sul (RS) close to RS/BR km 471. In this area, sandy clay loam Palleudult soil prevails. Sampling for the purposes for soil characterisation was carried out in 0-0,2 m depth. The soil attributes determined were: pH, SOM, texture, Ca, Mg, Al, N, MO, K and P, and the plant attributes were: productivity, alcoholic potential and tartaric acid, using a 35 X 35m grid. Data were analyzed through geostatistics by interpolation technique of kriging. The data of yield and enological parameters were obtained by manual harvest in georeferenced points. Grape data were collected during the harvest in 2007 and 2008 seasons. Soil and plant data were submitted to statistical analysis and basic geostatistic. Spatial variability of soil chemical attributes in the area behaved in accordance with the nutrient evaluated. pH showed low variability, clay, Ca, Mg, and N, showed median variability while MO, P and K , a high variability was found, and for Al, very high. In 2007 harvest, tartaric acid and alcoholic potential showed low variability, number of bunches per plant and weight per bunch presented median variability while weight per plant showed high variability. In 2008 harvest, alcoholic potential showed low variability, while tartaric acid, number of bunches per plant, weight per plant, weight per bunch and number of gems showed median variability. The 35 X 35 m sampling grid has shown itself adequate for soil attributes excepting clay, which obtained a 30.06 m distance reach. In 2007 harvest, the alcoholic potential was the plant attribute that showed smaller reach n the area, 18.42 m. In 2008 harvest, all the plant attributes studied showed a below 35 m reach. The correlation analysis has revealed itself significant among nitrogen and alcoholic potential in 2007 harvest. In 2008 harvest, phosphorus and potassium showed significant correlation with alcoholic potential. The comparison of the demand for the application of fertilizer at varied rate, with application at steady rate of lime, phosphorus and potassium was based on the soil sampling. In the case of lime, there was a 700 kg saving of it with varied rate application, the same was not observed with phosphorus and potassium, which would increase the product quantity if implemented this way, this happens because the levels of them in the soil are appropriate. The adoption of precision viticulture can help the wine grower to know better and further the productive area, allowing to improve the quality and quantity of the vineyard. / O uso da agricultura de precisão aplicada à vitivinicultura pode trazer benefícios à cultura da vitis e à cadeia produtiva, com reflexos na qualidade da uva e do vinho. O objetivo deste estudo foi aplicar a vitivinicultura de precisão, visando aprimorar a gestão e o manejo de áreas produtivas de uvas viníferas. O estudo foi conduzido em um vinhedo comercial, numa área de 2,4 ha, destinado à fabricação de espumantes situada às margens da RS/BR km 471, em Encruzilhada do Sul-RS. Na área predominam solos classificados como Argissolo Vermelho distrófico. A amostragem para fins de caracterização do solo foram realizadas na profundidade de 0-0,2m. Os atributos de solo determinados foram: pH, SMP, Argila, Ca, Mg, Al, N, MO, K e P, e os atributos de planta foram produtividade, ácido tartárico e potencial alcoólico usando uma malha de amostragem de 35 X 35 m. Os dados foram analisados através da técnica de interpolação geoestatística por krigagem. Os dados de rendimento e parâmetros enológicos foram obtidos por colheita manual em pontos georreferenciados. Os dados de uva foram coletados durante a colheita nas safras 2007 e 2008. Os dados de solo e de planta foram submetidos à analise estatística básica e geoestatistica. A variabilidade espacial dos atributos químicos do solo na área comportou-se de forma distinta de acordo com o nutriente avaliado. O pH apresentou variabilidade baixa, a Argila, o Ca, o Mg, e o N, o apresentaram variabilidade média enquanto que a MO, o K e o P, a variabilidade encontrada foi alta, e para o Al muito alta. Na safra 2007, o ácido tartárico e o potencial alcoólico apresentaram variabilidade baixa, o número de cachos por planta e o peso por cacho apresentaram variabilidade média enquanto que o peso por planta apresentou variabilidade alta. Na safra 2008, o potencial alcoólico apresentou variabilidade baixa, enquanto que o ácido tartárico, o número de cachos por planta, o peso por planta, o peso por cacho e o número de gemas apresentaram variabilidade média. A malha de amostragem de 35X35m se mostrou adequado para os atributos de solo com exceção da argila, que obteve uma distância de alcance de 30,06m. Na safra 2007 o potencial alcoólico foi o atributo de planta que apresentou menor alcance na área, de 18,42 m. Na safra 2008, todos os atributos de planta estudados apresentaram alcance inferior a 35 m. A analise da correlação se revelou significativa entre o nitrogênio e o potencial alcoólico na safra 2007. Na safra 2008, o fósforo e o potássio mostraram correlação significativa com o potencial alcoólico. A comparação da demanda de aplicação de fertilizantes a taxa variada, com a aplicação à taxa fixa de calcário, fósforo e potássio foi feita com base na amostragem de solo. No caso do calcário observou-se uma economia de 700 kg do mesmo com aplicação a taxa variada, o mesmo não foi observado com o fósforo e com o potássio, que aumentaria a quantidade do produto caso fosse aplicado desta forma, isso se dá pelo fato dos teores dos mesmos no solo serem adequados. A adoção da vitivinicultura de precisão pode auxiliar o viticultor a conhecer melhor e mais detalhadamente a área produtiva, permitindo aprimorar a qualidade e quantidade do vinhedo.

Hen egg white lysozyme is a hydrolytic enzyme effective at preventing the growth of Gram positive bacteria by degrading the bacterial cell wall to a point of cell lysis. Investigating lysozyme as a processing tool in wine to control the growth of lactic acid bacteria and malolactic fermentation has significant commercial interest. In this project, the interactions of lysozyme with wine components and wine was evaluated along with the efficacy of lysozyme in preventing malolactic fermentation (MLF) in Oregon Pinot Noir and Chardonnay. The information from this work, together with results from similar projects, will allow the development of guidelines for lysozyme use in commercial wine. Interactions of lysozyme with wine components were evaluated by measurement of enzymatic activity in the presence of wine acids, ethanol, and phenolics. Enzyme inhibition was observed, to various degrees, with all wine components. Crude grape tannin altered the availability of free enzyme by complexing to lysozyme and forming a precipitate. In a model wine system, lysozyme activity was reduced by 50% when tannin was present. Lysozyme addition to red wine resulted in a reduction in pigmented compounds and detectable sensory differences. Wine trials evaluated the efficacy of lysozyme in completely preventing malolactic fermentation (MLF) and terminating MLF midway through fermentation in Oregon Pinot Noir and Chardonnay. Vintages from 1993 and 1994 were treated without SO₂, with SO₂, with SO₂ plus a starter culture of Leuconostoc oenos. Each lot was divided into 0 ppm lysozyme (control), 250 ppm lysozyme, 500 ppm lysozyme, and 1000 ppm lysozyme. Lactic acid bacteria were enumerated monthly, for ten months. Lysozyme prevented malolactic fermentation in all wines at the treatment levels of 500 and 1000 ppm. In the 1993 Pinot Noir, 250 ppm lysozyme prevented MLF but only delayed MLF in the 1994 vintage. Lysozyme effectively terminated MLF at a concentration between 200 and 300 ppm in both Pinot Noir and Chardonnay. / Graduation date: 1996

This research investigated the effects of Pediococcus spp. on Oregon Pinot noir wines. Pediococcus (P. parvulus (7), P. damnosus (1), P. inopinatus (1)) isolated from Oregon and Washington state wines demonstrated differences in their susceptibility to SO��� with some isolates growing well in model media at 0.4 mg/L molecular SO���. All isolates were all able to degrade p-coumaric acid to 4-vinyl phenol. The conversion of p-coumaric acid to 4-VP by pediococci resulted in accelerated production of 4-EP by B. bruxellensis in a model system. Growth of the pediococci isolates in Pinot noir wine resulted in a number of chemical and sensory changes occurring compared to the control. Very low concentrations of biogenic amines were measured in the wines with only wine inoculated with P. inopinatus OW-8 having greater than 5 mg/L. D-lactic acid production varied between isolates with OW-7 producing the highest concentration (264 mg/L). Diacetyl content of the wines also varied greatly. Some wines contained very low levels of diacetyl (< 0.5 mg/L) while others contained very high concentrations (> 15 mg/L) that were well above sensory threshold. Despite suggestions to the contrary in the literature, glycerol was not degraded by any of the isolates in this study. Color and polymeric pigment content of the wines also varied with wine inoculated with OW-7 containing 30% less polymeric pigment than the control. This may be related to acetaldehyde as a number of Pediococcus isolates, including OW-7, reduced the acetaldehyde content of the wine. Sensory analysis revealed differences in the aroma and mouthfeel of the wines compared to each other and to the control. In particular growth of some isolates produced wines with higher intensities of butter, plastic, and vegetal aromas while other also had lower perceived astringency. / Graduation date: 2013

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 92-103). Also available on the World Wide Web.

Memoria para optar al título de Ingeniero en Alimentos / Se obtuvo vino tinto a partir de uvas viníferas variedad Pinot Noir por medio de fermentación con cepas de Saccharomyces cerevisiae UCH-M4 y UCH - M3, seleccionadas del Valle del Maule, Área de San Javier, Región del Maule, Chile. Los vinos presentaron valores de pH, acidez total, acidez volátil, anhídrido sulfuroso total, anhídrido sulfuroso libre, grado alcohólico y rendimiento dentro de las normas legales chilenas y conceptuales, siendo muy similares a los obtenidos por la levadura control Lalvin QA23. La velocidad de fermentación fue muy similar en todas las cepas de levaduras. Los mostos fermentados con la levadura UCH – M3 seca presentaron la mayor concentración de polifenoles totales. La capacidad antioxidante de los polifenoles de los mostos fermentados con levadura UCH – M4 fue mayor que la de los demás mostos, pese a tener una menor cantidad de polifenoles totales. Por lo tanto se determinó que la actividad antioxidante de los polifenoles no tiene relación con la concentración de éstos, si no que tiene que ver con la calidad del polifenol. El color de todos los vinos fue evaluado como rojo rubí, y sus matices e intensidades colorantes correspondieron a vinos tintos de un año. En la evaluación sensorial, los vinos no presentaron diferencias estadísticamente significativas, siendo calificados en general con buena apariencia, poco dulces, acidez y astringencia normal y de buen sabor. El aroma fue calificado como normal, predominando las frutas ácidas y los berries, así como también el olor a alcohol. Respecto a la calidad general, los vinos se evaluaron por sobre la calificación “ni bueno ni malo”. Con esta investigación se concluyó que las cepas UCH-M3 y UCH-M4 pueden ser utilizadas en la producción industrial de vinos tintos Pinot Noir / Red wine from Pinot Noir wine grapes strains was obtained through fermentation process using two strains of Saccharomyces cerevisiae (UCH-M3 and UCH-M4). The strains were obtained from the Maule Valley, Area of San Javier, Maule Region, Chile. The wine parameters such as pH, total acidity, volatile acidity, total sulfur dioxide, sulfur dioxide-free, alcohol content and performance meet the Chilean legal regulations and conceptual characteristics. The results were similar to those obtained by using the QA23 control yeast. The rate of fermentation was very similar for all yeast strains. The highest concentration of polyphenols was obtained when the UCH - dry M3 yeast was used. The antioxidant capacity of the musts fermented with yeast UCH - M4 was greater than the others, in spite of a lower content of total polyphenols. Therefore, the antioxidant activity of polyphenols is not related with its concentration, but with the quality of polyphenol. The color of all wines was evaluated as ruby red, and hues and color intensities were similar to one year old red wines. The sensory evaluation showed no significant differences between wines. The evaluation gave as result good appearance, low sweetness, normal acidity and astringency and good taste. The aroma was found normal with marked acid fruits and berries flavour, as well as alcohol odour. The overall quality of wines was evaluated above the score of "neither good nor bad". With this research it can be concluded that the UCH-M3 and UCH-M4 strains can be used for the production of industrial Pinot Noir wines

This research investigated yeast populations and diversity during pre-fermentation cold maceration and alcoholic fermentation of Vitis vinifera L. cv. Pinot noir grapes from a commercial vineyard (Dayton, OR). Fermentations were conducted at the Oregon State University research winery in 100 L tanks while grapes from the same vineyard lot were fermented at a commercial winery. Samples were taken daily during pre-fermentation maceration (9°C) and alcoholic fermentation (27°C) and plated on WL and lysine media to determine Saccharomyces and non-Saccharomyces populations and diversity. Total non-Saccharomyces populations increased from 1 x 10³ cfu/mL to 1 x 10⁵ cfu/mL during pre-fermentation cold maceration and reached a maximum of 1 x 10⁷ cfu/mL during alcoholic fermentation. Thirteen distinct yeast species were tentatively identified based on appearance on WL media and were initially screened for β-glucosidase activity using 4-methyllumbelliferyl-β-D-gluconopyranoside (4-MUG) plates. The identity of the isolates screening positive for β-glucosidase activity was determined by sequence analysis of the D1/D2 domain of the 26S rDNA gene. The five isolates identified were Metschnikowia pulcherrima, Hanseniaspora uvarum, Kluveromyces thermotolerans, and two Saccharomyces cerevisiae isolates. β-glucosidase activity was further characterized and quantified using a liquid media representing grape must conditions (pH 3.5, 20° Brix) at two temperatures (25°C and 8°C). While increasing sugar concentration suppressed the β-glucosidase activity of H. uvarum (-99%), β-glucosidase activity still remained relatively high for M. pulcherrima, S. cerevisiae isolate 1, and S. cerevisiae isolate 2. At 8°C, β-glucosidase activity was reduced for M. pulcherrima compared to activity at 25°C, but activity increased for K. thermotolerans, S. cerevisiae isolate 1, and S. cerevisiae isolate 2. The yeast isolates possessing β-glucosidase activity were used in fermentations of Vitis vinifera L. cv. Pinot Noir grapes. The grapes were treated with high hydrostatic pressure (HHP) to inactivate naturally occurring yeast and bacteria. All yeast isolates grew during pre-fermentation cold maceration (7 days at 9°C) and populations increased 3 to 4 logs. Following pre-fermentation cold maceration, all ferments were warmed to 27°C and inoculated with S. cerevisiae RC212. Alcoholic fermentations were all complete within eight days and after pressing wines were analyzed for volatile aroma compounds by SPME-GC-MS. The presence of different yeast isolates during pre-fermentation cold maceration resulted in wines with unique aroma profiles. Ethyl ester concentrations were highest in the wine that did not undergo a pre-fermentation cold maceration, while concentrations of branch-chained esters were higher in the treatments with yeast present during pre-fermentation cold maceration. Pre-fermentation cold maceration with yeast isolates demonstrating β-glucosidase did not affect the concentration of β-damascenone or β-ionone. Wines that had undergone pre-fermentation cold maceration with S. cerevisiae isolate 1, S. cerevisiae isolate 2, and a combination of all isolates resulted in over twice the concentration of β-citronellol over wines that did not undergo a pre-fermentation cold maceration. / Graduation date: 2013

L'objectif premier de ce travail de thèse était de développer des analyses métabolomiques non ciblées de vins en bouteilles afin de déchiffrer les informations chimiques relatives à l’évolution de leurs compositions avec le temps. Cette recherche initiale était fondée sur l'hypothèse que, lors de l'analyse, les vins en bouteilles gardent une mémoire chimique des paramètres environnementaux à l’œuvre au moment de leur élaboration (gestion du vignoble, pratiques œnologiques, climat, terroir). Une seconde hypothèse reposait sur la nécessité d’étudier le passé pour anticiper l’évolution de la qualité du vin du point de vue de sa composition chimique. À cet effet et pour la première fois dans la science du vin, la Spectrométrie de Masse à Résonance Cyclotronique des Ions et à Transformée de Fourier (FTICR-MS), la Chromatographie Liquide couplée à la Spectrométrie de Masse (UPLC-Q-TOF-MS), la spectroscopie de Fluorescence d’Excitation et d’Émission (EEMF) et les statistiques multivariées ont été combinées. Le développement méthodologique a révélé l'avantage de coupler les mesures de masses exactes par FTICR-MS à la discrimination des isomères par UPLC-Q-TOF-MS afin d'étendre la gamme des métabolites détectables. Ces outils ont été appliqués à l'identification de marqueurs de vieillissement sur des séries verticales de vins rouges et blancs de Bourgogne, y compris sur des vins très anciens (millésimes inconnus) considérés comme des points extrêmes d'évolution, introduisant ainsi la notion de verticalomics. La caractérisation d'une série de vins blancs de Bourgogne (Chardonnay) a révélé que les espaces chimiques spécifiquement liés à des pratiques œnologiques (SO2 ajouté lors du pressurage, niveau de débourbage ou perméabilité du bouchon) pourraient être déchiffrés, bien que les signatures de millésimes étaient les plus significatives. Des expériences similaires sur les vins de Champagne (Chardonnay, et mélanges de Chardonnay, Pinot noir et Pinot Meunier) après la prise de mousse et le vieillissement sur lattes ont mis en évidence l'effet d'hormesis associé à l'oxygénation du vin. Enfin, les analyses non ciblées d'extraits de raisin et des vins correspondants provenant de différentes appellations et élaborés par le même vigneron ont révélé qu’il était possible de lire des signatures liées au terroir, en particulier après quelques années de vieillissement en bouteille. Plus largement, nos résultats fournissent une description globale sans précédent de la composition chimique du vin et de sa modification par le vieillissement. / The main objective of this work was to develop non-targeted metabolomics analyses of bottled wines in order to decipher chemical informations from the time-related evolution of their composition. This original research was based on the hypothesis that, when analyzed, bottled wines would still hold chemical memories of envionmental parameters (vineyard management, oenological practices, climate, terroir…) at the moment of their elaboration, even after several years of ageing. A second hypothesis was that in order to anticipate the future evolution of the wine quality in terms of chemical composition, it is necessary to know what it was in the past. To that purpose, and for the first time in wine science, Fourier Transform Ion Cyclotron Resonance – Mass Spectrometry (FTICR-MS), Liquid Chromatography coupled with mass spectrometry (UPLC-Q-ToF-MS), Excitation Emission Matrix Fluorescence (EEMF) and multivariate statistics were used in combination. Methodological develoments revealed the advantage of coupling exact mass measurements by FTICR-MS to isomeric discrimination by UPLC-Q-ToF-MS in order to extend the range of detectable metabolites. Such tools were applied to the identification of ageing markers in vertical series of red and white wines from Burgundy, including very old wines (unknown vintages) considered as evolution end points, thus introducing the concept of verticalomics. The characterization of series of white wines from Burgundy (Chardonnay) revealed that chemical spaces specifically related to eonological practices (SO2 addition at pressing, settling level, and permeability of the stopper) could indeed be deciphered although the vintage signatures were confirmed to be the most significant. Similar experiments on Champagne wines (Chardonnay, and blends of Chardonnay, Pinot noir and Pinot Meunier) after the "prise de mousse" and the ageing "sur lattes" further highlighted the hormesis effect associated with the oxygenation of wine. Finally, non-targeted analyses of series of grape extracts and corresponding wines from different appelations – though elaborated by the same winemaker – revealed that terroir-related signatures could be indeed read in wines, in particular after a few years of bottle ageing. Altogether our results provide an unprecedented comprehensive description of the chemical composition of wine and its modification through ageing.

Fermentation of the grape must into wine is one of the most important steps in winemaking. Selected yeast strains of Saccharomyces cerevisiae have been used for many years to ensure complete and even fermentations. The formation of volatile compounds also occurs during fermentation and will influence the sensory perception of the wine. The main objective of the research was to study the sensory and chemical composition of 1992 Oregon Riesling, Chardonnay and Pinot Noir wines fermented with different commercial S.cerevisiae strains. In the first study, Free-Choice Profiling was used to study the sensory profiles of all three varieties after 7 and 20 months of aging. This method was used in order to utilize a panel of expert winemakers for the tastings. The sensory data analyzed through Generalized Procrustes Analysis showed that some strains were similar while others were different in terms of aroma and flavor at 7 months of age. After 20 months of aging, differences and similarities were still present although the sensory profiles were different from the young wines. This last finding showed that differences are still present after a period of aging. In the second study, the chemical composition of all three varieties and the volatile composition of selected wines of Riesling and Chardonnay were studied. In both white varieties, statistical differences in titratable acidity, residual sugar, volatile acidity and malate content resulted from fermentation with different yeast strains. The volatile composition was qualitatively similar, but some quantitative differences, as relative concentration, were found. Whether or not those differences had a sensory impact was not investigated. Results of the present study showed the need for further studies in order to understand the role of yeast in flavor development. Relationships between sensory profiles and volatile composition could help winemakers to understand the influence of a selected strain on a particular variety and to select yeast strains to optimize wine quality. / Graduation date: 1995