Red wine oxidation study by accelerating ageing tests and electrochemical method

The phenolic composition of red grapes is one of the most important quality parameters.

Color is one of the main qualitative parameters of a wine. As a matter of fact, immediately after having opened a bottle of wine, color, even before aroma and taste, is the first sensorial parameter to be evaluated by the consumer It can change according to various factors depending on the characteristics of the grapes or on the different production and storage processes.

Harvesting grapes at adequate maturity is key to the production of high-quality red wines. Enologists and wine makers define several types of maturity, including technical maturity, phenolic maturity and aromatic maturity. Technical maturity and phenolic maturity are relatively well documented in the scientific literature, while articles on aromatic maturity are scarcer. This is surprising, because aromatic maturity is, without a doubt, the most important of the three in determining wine quality and typicity (including terroir expression). Optimal terroir expression can be obtained when the different types of maturity are reached at the same time, or within a short time frame. This is more likely to occur when the ripening takes place under mild temperatures, neither too cool, nor too hot. Aromatic expression in wine can be driven, from low to high maturity, by green, herbal, fresh fruit, ripe fruit, jammy fruit, candied fruit or cooked fruit aromas. Green and cooked fruit aromas are not desirable in red wines, while the levels of other aromatic compounds contribute to the typicity of the wine in relation to its origin. Wines produced in cool climates, or on cool soils in temperate climates, are likely to express herbal or fresh fruit aromas; while wines produced under warm climates, or on warm soils in temperate climates, may express ripe fruit, jammy fruit or candied fruit aromas. Growers can optimize terroir expression through their choice of grapevine variety. Early ripening varieties perform better in cool climates and late ripening varieties in warm climates. Additionally, maturity can be advanced or delayed by different canopy management practices or training systems.

The Grenache observatory was created in 1995. The object of this 24 parcels network, covering main Rhone Valley soils, is to state the effect of pedo-climatic conditions on plant physiology and wine characteristics. The results concerning colour and tanins show a very important diversity in Grenache behaviour.

The Douro demarcated region constitutes just over 50% of the area of mountain vineyard in the world, i.e., vineyards with slope gradients of 30% or above. Among the different (terraced) vineyard layouts, the formerly preferred wider terraces supporting two rows of vines and the currently advocated narrower single vine row, dominate the vineyards’ planting layout. The slope of these terraces, in other words, the supporting earth ramp, is a key element in these vineyards’ construction.