Dissertationen zum Thema „Oenologues“
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Loiseau, Gérard. „Obtention d'un marquage mitochondrial de levures oenologiques sélectionnées en Champagne : application au contrôle microbiologique en oenologie“. Montpellier 2, 1986. http://www.theses.fr/1986MON20179.
Der volle Inhalt der QuelleLoiseau, Gérard. „Obtention d'un marquage mitochondrial de levures oenologiques sélectionnées en Champagne application au contrôle microbiologique en oenologie“. Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37599223f.
Der volle Inhalt der QuelleFedoul, Sénia. „Œnologues et sommeliers dans la France du 20e siècle : Une histoire sociale, technique et culturelle de la qualité des vins“. Electronic Thesis or Diss., Lyon 2, 2024. http://www.theses.fr/2024LYO20023.
Der volle Inhalt der QuelleAt the crossroads of a social history of expertise, a cultural and technical history of taste, a historical anthropology of the globalization of French appellation wines in 20th century, this thesis is an open comparative reflection on the systemic dimension of eating and drinking habits. Oenologists and sommeliers are key players in the affirmation of taste as a social value
Schmauch, Grégory. „Interactions tanins-protéines en oenologie“. Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21703/document.
Der volle Inhalt der QuelleFrom wine making to wine tasting, interactions between tannin and protein detain a prominent role in Enology, influencing several wine characteristics like its astringency. Interaction kinetics and precipitation equilibrium between BSA, a model protein, and grape seed tannin have been studied. Variations of initial ratio, pH and ethanol conditions pointed out essential properties of the mechanism. Lack of stoichiometry of the interaction with a linear dependence between initial and final tannin/protein ratio are key points. Kinetic constants are also related to this ratio. Mutual participation of both hydrophobic forces and hydrogen bonds has been shown. Along with these investigations in model solution, tannin and proteins have been followed during wine making and tasting. Disappearance of protein in the must and tannin behaviour can be linked. An HPLC method allowing the titration of saliva with wine indicates a classical behaviour of salivary proteins. Observation of salivary proteins precipitating with tannin thanks to 2D gels shows a non selective precipitation of salivary proteins by wine
Moumeni, Lynda. „Arômes fermentaires : paramètres et cinétiques de production en conditions oenologiques“. Toulouse, INPT, 1997. http://www.theses.fr/1997INPT039G.
Der volle Inhalt der QuelleNoble, Jessica. „Identification des bases moléculaires de propriétés technologiques de levures oenologiques“. Thesis, Montpellier, SupAgro, 2011. http://www.theses.fr/2011NSAM0014.
Der volle Inhalt der QuelleThe molecular basis of technological properties of wine yeasts are not or poorly known. However, this knowledge is required for the improvement of the fermentation capacity and of the organoleptic impact of wine yeasts by breeding strategies and a better exploitation of the yeast biodiversity. This thesis aimed at identifying the genetic bases of several traits of interest such as: sulfite production, fermentation ability in low nitrogen medium or esters formation. A QTL mapping approach has been implemented from a population of meiotic segregants derived from the cross of two strains with contrasting oenological characteristics. Phenotyping of the a population of meiotic segregants was combined with a genotyping to identify QTL for these traits. The involvement of a region of the genome in the control of sulphate assimilation pathway has been demonstrated. This locus is responsible for the phenotypic variation of several metabolites of this pathway and indirectly connected metabolites. Other QTLs have also been demonstrated for the fermentation capacities on a nitrogen limiting medium and production of various volatile compounds. Their analysis revealed several candidate genes whose functions are related directly or indirectly to the studied phenotypes
Maury, Chantal. „Etude des phénomènes impliqués dans les étapes de collage en oenologie“. Montpellier, ENSA, 2001. http://www.theses.fr/2001ENSA0012.
Der volle Inhalt der QuelleThe aim of that work was to better understand the behaviour of gelatines to better control this step, to estimate the potential of: plant proteins in wine fining and to understand the impact of fining treatment on wine astringency. Phenolic compounds were analysed before and after fining treatment of a model wine and six different wine with gelatines having different MW and plant proteins. Simple phenolic compounds precipitated, neither with gelatines, nor with plant proteins. Results of condensed tannins analysed by thiolysis showed that aIl gelatines precipitate the same level of condensed tannins. They selectively precipitated highly polymerised and highly galloylated tannins. Moreover, the more hydrolysed gelatines precipitated tannins which were more polymerised than those precipitated by the less hydrolysed one. The plant proteins tested in that work (wheat, rice and lupinus), precipitated a lower level of tannins than gelatines. Their selectivity for tannins was dependent of the protein used, but sorne of them were as selective tan gelatines. Polysaccharides and glycerol do not precipitate but influence the level of precipitation and the selectivity of proteins for polymerised tannins. Our results showed the presence of residual fining pro teins in wine after fining, Presumably as soluble tannins-proteins and tannins-proteins-polysaccharides complexes. Comparison between sensory evaluation and tannins analysis suggested than the reduction of astringency by fining treatment is due to the removal of highly polymerised. And highly galloylated tannins which are responsible for astringency, or to the presence of soluble tannins-pro teins complexes which reduce tannins-salivary proteins interaction, thus diminishing the astringency perception
Bezenger, Marie-Claude. „Incidence de l'azote sur le déroulement de la fermentation alcoolique en oenologie“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb376029757.
Der volle Inhalt der QuelleCadière, Axelle. „Ingénierie de la voie des pentoses phosphate chez la levure Saccharomyces cerevisiae : applications en œnologie“. Thesis, Montpellier, SupAgro, 2010. http://www.theses.fr/2010NSAM0009.
Der volle Inhalt der QuelleThere is an ever-growing interest in the development of S. cerevisiae wine yeast strains with reduced ethanol yield. We proposed a novel approach based on rerouting the carbon flux towards the pentose phosphate (PP) pathway. First, we showed that the flux through the PP pathway is limited both by the absence of a mechanism for reoxidation of NADPH and by the intrinsic capacity of the pathway. We also showed that the transcription factor Stb5 plays a key role in maintaining a basal flux through the PP pathway to meet the requirements for NADPH and biosynthetic precursors. Over-expression of STB5 is a potentially useful strategy for increasing the flux through the PP pathway, provided that an alternative system of reoxidation of NADPH is expressed. In parallel, we investigated an evolutionary engineering strategy based on long-term batch culture on gluconate, a substrate poorly assimilated by S. cerevisiae cells and metabolized by the PP pathway. We selected strains that had evolved a greater gluconate consumption capacity after 70, 180 and 240 generations. During wine fermentation, these evolved strains produced similar amounts of ethanol as the parental strain but displayed completely novel phenotypes, including higher fermentation rates, lower nitrogen requirements, lower levels of acetate production, and enhanced production of aroma compounds. 13C flux analysis and transcripomic analysis of one of these strains, ECA5, showed a greater flux through the PP pathway consistent with the observed increased expression of GND1 and TKL1. The expression of genes associated with nitrogen metabolism, the Ehrlich pathway, proton homeostasis and glycolysis was stronger than in the parental strain, whereas genes involved in stress response and respiration were down-regulated, in agreement with the phenotypes of ECA5. In addition to providing strains with considerable potential for wine making, this work sheds new light on the operation of PP pathway and its links with central and secondary metabolism
Ayoub, Marie-José. „Diversités moléculaire et phénotypique de souches autochtones oenologiques de Saccharomyces cerevisiae isolées au Liban“. Phd thesis, Institut national agronomique paris-grignon - INA P-G, 2006. http://tel.archives-ouvertes.fr/tel-00136103.
Der volle Inhalt der QuelleMonteiro, Centeno da Costa Filipe. „Procédé d’immobilisation de levures pour applications oenologiques. Etudes des paramètres du procédé. Validations experimentales“. Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0061.
Der volle Inhalt der QuelleThe study and development of yeast immobilization processes for wine fermentations started in the mid 80’s. Even though this technology could be of great benefit for the oenological sector very few process left the laboratory or pilot scale and those which arrived to industrial scale didn’t have the ambitioned success due to technical or economical constraints. The first goal of this work was to develop an industrial process for yeast immobilisation with emphasis on the most sensitive aspects which required further studies. The second objective of this work was to characterise the fermentation kinetics of immobilised yeasts cells during the production sparkling wines and during the deacidification of grape must. Whenever possible the wines produced were also characterised from a sensorial point of view. The third and last goal was to evaluate the use of immobilised yeast cells for continuous fermentation of grape must. For that we have used continuous fixed bed and fluidized bed fermenters
Monteiro, Centeno da Costa Filipe. „Procédé d’immobilisation de levures pour applications oenologiques. Etudes des paramètres du procédé. Validations experimentales“. Electronic Thesis or Diss., Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0061.
Der volle Inhalt der QuelleThe study and development of yeast immobilization processes for wine fermentations started in the mid 80’s. Even though this technology could be of great benefit for the oenological sector very few process left the laboratory or pilot scale and those which arrived to industrial scale didn’t have the ambitioned success due to technical or economical constraints. The first goal of this work was to develop an industrial process for yeast immobilisation with emphasis on the most sensitive aspects which required further studies. The second objective of this work was to characterise the fermentation kinetics of immobilised yeasts cells during the production sparkling wines and during the deacidification of grape must. Whenever possible the wines produced were also characterised from a sensorial point of view. The third and last goal was to evaluate the use of immobilised yeast cells for continuous fermentation of grape must. For that we have used continuous fixed bed and fluidized bed fermenters
Lurton, Luc. „Etude de la protéolyse intervenant au cours du processus d'autolyse chez Saccharomyces cerevisiae : applications oenologiques“. Dijon, 1987. http://www.theses.fr/1987DIJOS060.
Der volle Inhalt der QuelleRossignol, Tristan. „Analyse de l'expression du génome des levures oenologiques en fermentation alcoolique par des approches post-génomiques“. Montpellier 2, 2004. http://www.theses.fr/2004MON20033.
Der volle Inhalt der QuelleDelsart, Cristele. „Champs électriques pulsés et décharges électriques de haute tension pour l’extraction et la stabilisation en oenologie“. Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21982/document.
Der volle Inhalt der QuelleThe wine industry needs to find solutions in the coming years to reduce its carbon footprint by 20% and quickly propose alternatives to sulphur dioxide usage. This work on pulsed electric fields offers wine professionals an eco-innovation that could help to address these two issues. Eco-innovation is increasingly seen as the key to future competitiveness in the context of sustainable development. However, before being integrated in wine production, eco-innovation must demonstrate its performance and efficiency without compromising product quality and consumers safety so that it could be approved by government authorities (OIV, EU ...). As such, this thesis has received a joint financial support from the CIVB and the ADEME. The principle of Pulsed Electric Field (PEF) is to apply to a product; electrical pulses of a few kilovolts in a very short period time (a few microseconds) and then repeated n times. During treatment (grapes, grape must or wine) cells transmembrane potential increases till the induction of pores in the membranes. The irreversibility of the pores leads not only to the extraction of cellular components but also cell death. Thus, depending on the time of this technology application in winemaking and operating parameters, allows the extraction of sensory interests compounds such as polyphenols or the inactivation of microorganisms. PEF takes into account three important aspects to the sustainability of a technology: environment, economy and quality. This technique has a number of advantages for wine producers: clean, fast, inexpensive, efficient, industrializable and automated. Compared to other treatments such as pasteurization, sterile filtration, thermovinification, hot or cold maceration, cryoextraction or flash-release, its energy consumption is low (a few tens of kWh / tonne). PEF technology is environmentally friendly, as it requires little energy and no chemical inputs. It is fast and efficient because the processing time is only a few tens to hundreds of milliseconds. Finally, this technique is a non-thermal and therefore does not degrade the heat-sensitive molecules such as flavours. The objectives of this research work was to understand the effect of PEF on the cells, to determine the processing parameters during the extraction of compounds of interest grapes and to inactivate microorganisms in order to stop alcoholic fermentation of sweet wines and stabilize microbiologically red wines before bottling maintaining the quality of the processed product
Girond, Sylvie. „Influence de quelques pesticides sur les levures oenologiques : étude du mécanisme de résistance vis à vis du mancozébe“. Toulouse, INPT, 1989. http://www.theses.fr/1989INPT018A.
Der volle Inhalt der QuelleGrassin, Catherine. „Recherches sur les enzymes extracellulaires secrétées par Botrytis cinerea dans la baie de raisin applications oenologiques et phytopathologiques /“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37605577j.
Der volle Inhalt der QuelleBoudaoud, Nawal. „Potentialités d'utilisation du nez électronique à spectromètre de masse pour la caractérisation de la fraction volatile du liège oenologique“. Phd thesis, INAPG (AgroParisTech), 2006. http://pastel.archives-ouvertes.fr/pastel-00001930.
Der volle Inhalt der QuelleSalmon, Jean-Michel. „Mise en évidence d'un rôle anabolique de l'acide L-malique chez Saccharomyces cerevisiae en anaérobiose et en conditions oenologiques“. Montpellier 2, 1986. http://www.theses.fr/1986MON20153.
Der volle Inhalt der QuelleBidard, Frédérique. „Clonage et analyse d'un gène de floculation FLOS de "Saccharomyces cerevisiae" : introduction du caractère floculant dans des levures oenologiques“. Montpellier 2, 1993. http://www.theses.fr/1993MON20043.
Der volle Inhalt der QuelleSalmon, Jean-Michel. „Mise en évidence d'un rôle anabolique de l'acide L-malique chez Saccharomyces cerevisiae en anaérobiose et en conditions oenologiques“. Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb376010269.
Der volle Inhalt der QuelleRemize, Fabienne. „Ingénierie de la production de glycérol chez "Saccharomyces cerevisiae" en oenologie. Régulation, surproduction et maîtrise des effets secondaires“. Montpellier 2, 1999. http://www.theses.fr/1999MON20016.
Der volle Inhalt der QuelleGeraudie, Vincent. „Système d'aide à la conduite des procédés viticoles et oenologiques, basé sur l'utilisation d'un capteur piéton de suivi de maturité“. Montpellier SupAgro, 2009. http://www.theses.fr/2009NSAM0025.
Der volle Inhalt der QuelleRachidi, Najma. „Etude de la structure du chromosome III de levures oenologiques "Saccharomyces cerevisiae" et évaluation de la spécificité d'expression en fermentation alcoolique“. Montpellier 2, 1998. http://www.theses.fr/1998MON20087.
Der volle Inhalt der QuelleFornairon-Bonnefond, Caroline. „Réactivité post-fermentaire de saccharomyces cerevisiae vis-à-vis de l'oxygène en conditions oenologiques : application à l'élevage de vins sur lies“. Montpellier 2, 2000. http://www.theses.fr/2000MON20169.
Der volle Inhalt der QuelleClement, Tiphaine. „Utilisation d'un fermenteur continu multi-étagé pour la compréhension des mécanismes d'adaptation de la levure à des ajouts d'azote en conditions oenologiques“. Thesis, Montpellier, SupAgro, 2012. http://www.theses.fr/2012NSAM0017/document.
Der volle Inhalt der QuelleWe set up a multi-stage continuous fermentor (MSCF) to mimic the conditions of alcoholic fermentation. In this bioreactor, the yeasts are in a steady and well controlled state representative of the growth and stationary phases of the batch. The ability of the MSCF to reproduce batch fermentation was assessed using an integrated approach (measurement of kinetic parameters, intra and exo-cellular metabolites and gene expression). We then used the MSCF to study the impact of nitrogen supplementation performed during the stationary phase, on yeasts metabolism. Several original results were obtained, concerning the TCA cycle, the transport of nitrogenous sources and the synthesis of higher alcohols and esters. This work points out the interest of using the MSCF to assess the effect of medium perturbations during alcoholic fermentation, especially during the stationary phase. More generally, the accuracy of the MSCF and the originality of the data obtained open new prospects for a better understanding of yeasts metabolism and regulation mechanisms
Ghanem, Chantal. „Study of the impact of oenological processes on the phenolic composition and biological activities of Lebanese wines“. Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/17853/1/GHANEM_C.pdf.
Der volle Inhalt der QuellePeltier, Emilien. „Étude des causes génétiques de la plasticité phénotypique par une approche de cartographie de QTLs : cas de la levure oenologique Saccharomyces cerevisiae“. Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0945/document.
Der volle Inhalt der QuelleThe yeast S. cerevisiae is the only species able to complete the alcoholic fermentation of grape must which is the main step of the wine-making process. Because of the high technological variability found in this species, selection work is carried out with the aim of using efficient yeasts for the industry. These strains show important differences both in their fermentation kinetics and their metabolite yield which affects the wines quality. In addition to these important phenotypic variations, the phenotypic response of yeasts varies considerably and not homogeneously against environmental variations. Understanding the genetic mechanisms that explain these differentiated responses to environmental variations is a non-trivial scientific question. This is of particular importance in oenology, where the winemaking conditions are highly variable (vintages, grape variety, terroirs, oenological practices...). In order to obtain yeasts ensuring the success of the fermentations under a wide range of conditions, we propose here to better understand these mechanisms of interaction Gene x Environment in an oenological context. The identification of genetic locus (Quantitative Trait Loci (QTL)) controlling quantitative characters is made possible by QTL mapping approaches. These approaches require the study of a large progeny in segregation that must be characterized genetically and phenotypically. The establishment of a statistical link between genotype and phenotype allows the localization of QTLs that have an impact on phenotyped characters. During this thesis a phenotyping method that allows us to follow the fermentations of several hundred individuals has been developed. Thanks to it, two progenies genotyped by whole genome sequencing have been phenotyped in different environmental conditions. This lead to the identification of many QTLs and to the estimation of their impact in strain robustness. The implication of the alleles of 3 genes showing a strong interaction with environment and pleiotropic effects linked to the SO2 metabolism has been proved molecularly. The results achieved are discussed in the context of QTL exploitation for the selection of more efficient yeast
Mestres, Jean-Paul. „Contribution à l'étude du traitement informatique des données d'analyse : applications dans le domaine des analyses oenologiques et au calcul du mouvement des polluants dans les nappes“. Montpellier 1, 1988. http://www.theses.fr/1988MON13516.
Der volle Inhalt der QuelleFuentes, Espinoza Alejandro. „Vin, réchauffement climatique et stratégies des entreprises : comment anticiper la réaction des consommateurs ?“ Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0150/document.
Der volle Inhalt der QuelleIt’s commonly accepted that global warming will have important consequences formany vineyards throughout the world, with impacts on wine production, on grape quality andtherefore on wines quality. In Bordeaux and other regions, warming is partly the cause of achange in the chemical composition of the grapes harvested under conditions of excessivematurity. The wines resulting from their vinification are richer in alcohol, less acidic andmarked by aromatic characteristics reminiscent wines produced in warmer and dryer latitudes.In this context, global warming will involve important economic stakes in wine consumption,and it may be useful to know the capacity of consumers to accept these wines durably. Theobjective of this thesis work is both forward-looking in relation to global warming and itsconsequences on wines quality and at the same time on the sustainable match between supplyand demand.The analysis methodology is an experimental market coupled with a sensory analysis.Experiences with consumers showed the influence of the characteristics of global warmingwines on consumer’s preferences and the wines valorisation on the market. Finally, the resultsshow that consumers have differentiated valorizations for oenological processes aimed atcorrecting the negative effects of global warming
Winstel, Delphine. „Recherches sur les composés du bois de chêne modulant la saveur des vins et des eaux-de-vie“. Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0409.
Der volle Inhalt der QuelleDuring barrel aging, wines and spirits undergo organoleptic changes caused by the release of aroma and taste molecules. While the key aromatic compounds released from oak wood have been identified, the bitter and sweet molecular determinants remain largely unknown. The first objective of this work was to bring new insights on the families of molecules already identified in oak wood: lignans and coumarins. First, a significant impact of (±)-lyoniresinol on spirits bitterness has been demonstrated. Then, sensory analysis showed the contribution of six coumarins to bitter taste of wines and spirits by synergistic effect. Fraxetin was identified for the first time in all three matrices of the study. In the second part of this work, the contribution of oak wood toasting to wine sweet taste has been studied, which allowed to confirm and to interpret empirical observations. Indeed, the aim of this study was to isolate new taste-active compounds, according to two different methods. For the first one, a fractionation protocol of oak wood extracts has been established. Separation techniques coupled with gustatometry allowed the purification of eleven taste-active compounds. Their identification has been carried out by HRMS and NMR. For the second method, a targeted approach has been used following a metabolomic screening by HRMS on several eaux-de-vie of Cognac. Two new taste-active molecules have been purified. These new markers have been quantified in several oak wood extracts, wines and spirits. The influence of oenological parameters on its content has been studied
Malherbe, Sophie. „Modélisation de la fermentation alcoolique en conditions oenologiques : élaboration du modèle à partir des principaux mécanismes limitants de la cinétique fermentaire, validation et application au contrôle des fermentations en cave (cuverie et besoins énergétiques)“. Montpellier 2, 2003. http://www.theses.fr/2003MON20133.
Der volle Inhalt der QuelleDambrouck, Thierry. „Contribution à l'étude des protéines des moûts et des vins de Champagne : détermination de leur origine, étude d'une glycoprotéine majeure, l'invertase de raisin : thèse pour le doctorat en sciences spécialité Biologie et Biochimie Appliquée, option Oenologie“. Reims, 2004. http://theses.univ-reims.fr/exl-doc/GED00000027.pdf.
Der volle Inhalt der QuelleThis work is a contribution to the study of proteins of musts and Champagne wines. The objective of the first part of this study was to analyse the origin of proteins of a Chardonnay wine. Results obtained using specific antibodies indicate that most of the wine proteins came from grapes and many of them were glycoproteins. Some proteins of this Chardonnay wine came from yeast; they were released during the alcoholic fermentation and consisted of high molecular weight glycoproteins. In contrast, no bacteria proteins were detect in this Chardonnay wine. The second part is a study of a major glycoprotein from Champagne wines, the grape invertase. Results showed that invertase from Chardonnay must were expressed of the GIN1 isogene. The sequon with the Asn-101 seems to be not glycosylated. Invertase showed a high heterogenous glycosylation, however, the paucimannosidic type was identified as the major N-glycan in grape invertase. An enzyme-linked immunosobent assay (ELISA) technique was developed and used to quantify the grape invertase after fining treatment. Results showed that fining treatment induced a loss of grape invertase correlated with a loss of proteins. This loss of proteins (e. G. Invertase or total proteins) was correlated with a modification of the foaming parameters of these treated wines
Laboyrie, Justine. „Composition et origine du bouquet de vieillissement des vins rouges de Bordeaux. Influences du terroir dans l'expression aromatique des vins vieux“. Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0228.
Der volle Inhalt der QuelleAmong wines, those which impart the most pleasure and magic to amateurs are very often aged wines. These are bottles preserved for many years in the hope of a great tasting. Upon opening, the taster will expect to discover the complexity and elegance of the wine's aging bouquet. This olfactory concept, in which aromas produced during bottle aging blend harmoniously with those of the wine's youth, is the gift offered by great wines to epicureans. The expression of the bouquet is purported to be very closely linked to the terroir and the vintage, both revealed during the course of aging. This thesis work is essentially devoted to demonstrating and detailing this empirical knowledge.Firstly, quantitative analysis was carried out on several molecules linking the composition of grape berries to fermentation activities and to aging. Eighty wines of different vintages from several Bordeaux vineyards “Châteaux” were studied. Analysis of the results showed that the wines each have their own molecular identity despite variability due to vintage and age. The presence of terpene compounds, derived from plant metabolism, is fundamental in the construction of this identity. This differentiation of the wines at a molecular level shows the importance of grape composition and the expression of terroir on the identity of old wines.Secondly, the parameters of the terroir (water status, nitrogen status, and grape variety, for example) were compared to the concentrations of the aromas studied, which were measured using gas chromatography techniques. This work required the development of analytical tools as well as the designing of several experiments on various scales (from laboratory to wine production units). Finally, with the aim of obtaining tools that could help predict the aging potential and the emergence of the bouquet, an additional study focusing on the precursors of bouquet aromas was initiated. Among the compounds that influence the expression of the bouquet, dimethyl sulfide (DMS) has multiple organoleptic characteristics, contributing to the “fresh fruit” and “truffle” characters of old wines. The influence of wine-growing parameters on the levels of DMS precursors (pDMS) was studied. The modulation of its levels was also explored. DMS levels, determined through the measurement of its potential, are largely influenced by the conditions of the vintage and by the stage of ripeness of the grape. However, fermentation conditions constitute a real issue for its preservation during winemaking and therefore its management at bottling. The release of DMS during aging depends on the matrix since interactions with grape tannins take place. In that context, the behavior of the DMS during tasting was clarified. The DMS could therefore be a good marker both of the terroir and the management of fermentation, as well as the way of serving old wine. This thesis presents many questions on the molecular origins of other compounds of interest, and the influence of fermentation and wine aging conditions on the aging potential and aromatic character of old wines
Vignault, Adeline. „Tanins œnologiques : caractéristiques, propriétés et fonctionnalités. Impact sur la qualité des vins“. Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0263.
Der volle Inhalt der QuelleThe use of oenological tannins is a common practice worldwide in winemaking. However, up to date this use, is only authorized by the OIV to facilitate wines and must clarification. Nevertheless, oenological tannins are used for several reasons, explaining the existence of diverse tannins on the market. For all these reasons, OIV has begun few years ago to create a working group in order to conduct a large study on oenological tannins. Thus, the aim of this research was to carry out an exhaustive study to determine firstly the chemical composition and the richness in tannins of the oenological tannins. Secondly, their potential functionalities were studied, focusing on their antioxidant activity, their ability to stabilize and improve wine color and finally, their antioxidasic activity. Concerning chemical composition, the principal tannins monomers, dimers, trimers and tetramers were identified and quantified by HPLC-MS and LC-QTOF. The abundance in tannins was estimated by different methods: TPI, Bate-Smith, Methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The antioxidant capacity was measured 5 methods (ABTS, CUPRAC, DPPH, FRAP and ORAC) meanwhile the oxygen consumption was measured using a non-invasive method based on luminescence. Antioxidasic property, was achieved by measuring first the laccase activity in winemaking, then by determined inhibition type and finally by laccase characterization precipitation by electrophoresis SDS-PAGE. The oenological tannins ability to stabilize the color was determined by their bathochromic and hyperchromic effect and by the calculation of the copigmentation index. Their color stabilization effect was evaluated during several days, different ethanol content and pH level. The results confirm that oenological tannins and specifically, ellagitannins, really protect wine against oxidation either because they exert antioxidant capacity and/or they consume directly oxygen. Moreover, oenological tannins can improve and stabilize red wines color acting as copigments, with gallotannins being the most efficient ones. In addition, oenological tannins, particularly grapes tannins, can be a new tool to inhibit the laccases produced by B. cinerea. As a fruit of these results, the OIV resolutions OENO-TECHNO 17-612 and OENO-TECHNO 17-613, just accepted, proposed to include two new functionalities of tannins uses in musts and wines:• Contribute to the antioxidant protection of must and wine components• Promote the expression, stabilization and preservation of color