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Aroma compounds are secondary metabolites that play a key role in grape quality for enological purposes. Terpenes, C13 -norisoprenoids, phenols, and non-terpenic alcohols are the most important aroma compounds in grapes and they can be found as free volatiles or glycoconjugated (bound) molecules. The non-volatile glycosylated group is the largest, and it is present in all varieties of Vitis vinifera (L.), the most widely used species for wine production. These aroma precursors represent the reserve of aroma molecules that can be released during winemaking. Their relative and absolute concentrations at fruit ripening determine the organoleptic value of the final product. A large range of biotic and abiotic factors can influence their biosynthesis in several ways. Agronomic practices such as irrigation, training systems, leaf removal, and bunch thinning can have an effect at plant level. The spraying of stimulatory compounds on fruit at different developmental stages has also been shown to modify metabolic pathways at fruit level with some impact on the aroma composition of the grapevine fruit. Viticulturists could act to promote aroma precursors to improve the aromatic profile of grapes and the wine ultimately produced. However, agronomic practices do not always have uniform results. The metabolic and physiological changes resulting from agronomic practices are unknown because there has not been sufficient research to date. This review presents the state of the art regarding the influences of vineyard agronomic management on the biosynthesis of grape aroma compounds. Although literature regarding the topic is abundant there are still many unknown biological mechanisms involved and/or that have been insufficiently studied. The aim of this work is therefore to find the gaps in scientific literature so that future investigations can focus on them.

Les réactions d'oxydation impliquant les composés phénoliques semblent induire des modifications non négligeables du profil chimique et sensoriel des vins. Les travaux concernent l’étude des mécanismes réactionnels impliquant certains thiols volatils, contributeurs de l’arôme distinctif et de la complexité des vins des différents cépages avec les composés phénoliques oxydés des vins blancs, principalement les flavan-3-ols. En solution modèle de composition proche du vin, une réactivité différente des thiols volatils selon leur nature chimique vis à vis des formes oxydées des flavan-3-ols a été établie. La synthèse et la caractérisation des adduits par RMN entre les principaux composés phénoliques des moûts et des vins blancs et le 3-sulfanylhexanol, présentant des nuances d’agrumes, a ensuite été réalisée en conditions d’oxydation chimique et enzymatique. La suivi cinétique de la formation des adduits par CLHP-ESI-SM a permis de mettre en évidence une réactivité du thiol spécifique vis à vis d’un substrat polyphénolique, d’établir le rôle catalytique des métaux (Fe2+) et la capacité antioxydante du dioxyde de soufre vis à vis de ces mécanismes réactionnels. La compréhension de mécanismes fondamentaux de la réactivité de la (+)-catéchine et de la (-)-épicatéchine en conditions œnologiques avec les thiols volatils nous a permis de décliner les travaux à l’étude de l’influence de la présence des flavan-3-ols au cours de la vinification et de l’élevage des vins sur ces composants de l’arôme des vins blancs., Oxidation reactions involving phenolics might change wines chemical and sensory profile. The present work concern the study of reactional mechanisms implying certain volatile thiols, responsible of distinctiveness and complexity of various wines, with white wines oxidized phenolic compounds, mainly flavan-3-ols. In a model wine solution, a different volatile thiol reactivity pattern according to their chemical nature with respect to oxidized flavan-3-ols forms was established. The adducts synthesis and characterization by NMR between the principal white musts and wines phenolic compounds and the 3-sulfanylhexanol, presenting citrus fruits nuances, were carried out under chemical and enzymatic oxidation conditions. Their formation monitoring by HPLC-ESI-MS highlighted a specific reactivity of thiol with polyphenolic substrate and established the catalytic role of metals (Fe2+) as well as, the antioxidant effect of sulphur dioxide into these mechanisms. The comprehension of fundamental mechanisms for the reactivity of (+)-catechin and of (-)-epicatechin with volatile thiols in oenological conditions enabled us to elucidate the influence of flavan-3-ols into white wines aroma compounds during wine making and ageing.

La saveur sucrée est à l’origine de l’équilibre gustatif des vins secs. On observe uneaugmentation de son intensité au cours de la macération post-fermentaire et de l’élevage enbarrique. Nous montrons que ces phénomènes sont respectivement liés à la libération depeptides de la levure et de composés non-volatils du bois de chêne dans les vins.Le rôle de la protéine Hsp12 de S. cerevisae sur le gain de sucrosité est établi enutilisant des techniques de biologie moléculaire et d’analyse sensorielle.Le développement d’un couplage chromatographie de partage centrifuge –gustatométrie permet de fractionner un extrait de bois de chêne et de purifier plusieurscomposés sapides. L’utilisation de la LC-FT/MS et de la RMN nous a permis d’identifierquatre nouvelles molécules, appelées quercotriterpénosides (QTT), deux d’entre elles (QTTI et III) possédant une saveur douce. Les seuils de perception du QTT I et d’un lignane amer,le lyonirésinol, sont respectivement 590 μg/L et 1.52 mg/L.La mise au point d’une méthode de quantification de ces composés en LC-FT/MS nous apermis de démontrer l’impact organoleptique du lyonirésinol dans les vins.Il est probable que les QTT I et III contribuent, directement ou indirectement, au gain desucrosité conféré par le bois de chêne., Sweetness contributes to the balance in taste of dry wines. An increase in sweet taste isobservable during post-fermentation maceration and oak-barrel aging. We have revealed thatthese phenomena are respectively due to the release in wines of yeast peptides and nonvolatileoak wood compounds.The role of Hsp12 protein from S.cerevisae on the increase in sweetness is establishedwith both molecular biology and sensorial analysis techniques.The development of a method coupling centrifugal partition chromatography andgustatometry has enabled us to fractionate an oak-wood extract and to purify several sapidcompounds. Thanks to both the LC-FTMS and the NMR spectroscopy methods, we havehighlighted four new molecules, called quercotriterpenosides (QTT), out of which QTT Iand III are responsible for a sweet taste. The perception thresholds of QTT I and a bitterlignan, lyoniresinol, are respectively 590 μg/L and 1.52 mg/L.LC-FT/MS method has been used to develop a quantification method for these compoundsand we have demonstrated the organoleptic impact of lyoniresinol in wines.QTT I and III are likely to contribute, directly or indirectly, to the increase in sweetnessconsecutive to barrel aging in dry wines.