Study of grape-ripening process variability using mid infrared spectroscopy

STICS est un modèle de culture développé à l’INRA (France) depuis 1996. Il simule les bilans de carbone, d’eau et d’azote dans le système culture-sol, piloté par des données climatiques journaliéres. Il calcule à la fois des variables agricoles (rendement en quantité et qualité) et environnementales (pertes en eau et en azote). Une des originalités de STICS est son adaptabilité à de nombreuses cultures (herbacées, ligneuses, annuelles, pérennes) rendue possible par le choix de paramètres génériques et d’options de formalismes. Le travail présenté traite, dans un premier temps, des spécificités de STICS pour la vigne en terme de bilan trophique, de fonctionnement énergétique et hydrique et d’estimation des teneurs en sucre en en eau du raisin. Nous montrons ensuite diverses sorties du modèle qui permettent de caractériser des terroirs du vignoble des Côtes du Rhône.

In the last few decades, minor vine genotypes traditionally cultivated on the Mount Etna slopes, have attracted the interest of both researchers and vine growers, as they offer an interesting oenological profile.

Under standard wine tasting conditions, volatile organic compounds (VOCs) responsible for the wine’s bouquet progressively invade the glass headspace above the wine surface. Most of wines being complex water/ethanol mixtures (with typically 10-15 % ethanol by volume), gaseous ethanol is therefore undoubtedly the most abundant VOC in the glass headspace [1]. Yet, gaseous ethanol is known to have a multimodal influence on wine’s perception [2]. Of particular importance to flavor perception is the effect of ethanol on the release of aroma compounds into the headspace of the beverage [1].

Germicidal ultraviolet-C (UV-C) light has shown promising results for suppression of several plant-pathogenic microorganims, including Erysiphe necator, which attacks grapevine. In Washington State the majority of winegrape production is in a semi-arid steppe environment, with historically low powdery mildew disease pressure, making it a promising area to deploy UV-C as a disease management tool. Trials focusing on UVC application timing and frequency will assist in developing regionally-appropriate application recommendations for eastern Washington State.

Climate change has become a reality that is becoming more and more apparent every day, with changes in the physico-chemical composition of grapes and an increase in the alcohol content of finished wines. These higher alcoholic degrees are not without consequences for the success of alcoholic and malolactic fermentation. Correcting the alcohol content (-20% of the initial alcoholic strength) is also part of an approach designed to meet consumer expectations for healthier, lighter or lower-alcohol wines (9 to 13% vol.). Correcting the alcohol content of wines also rebalances the mouthfeel by reducing the alcohol’s burn.