Grape composition and wine quality of Muscat Hamburg cultivar after a specific inactivated dry yeast application as adaptation strategy to climate change

In recent years, resistant varieties have returned to the attention of the wine sector as a response to climate change and the reduction of pesticides in grapevine management, which is the main culprit of pesticide use in European agriculture. In this context, the production of sparkling wines could be strongly influenced due to its requirements for a particular balance between sugars and acidity, and the necessity of sound grapes to ensure wine quality. However, these parameters are not the only ones that define the suitability of a grape variety to produce sparkling wine.

European regulations describe what elements must be given in the specifications of DPO determination ; mainly production conditions, links between quality and products characteristics and the physical traits of the production area. These elements are given in the “link to terroir” paragraph relating natural and human factors, detailed product characteristics linked to the geographical area and at last interactions between product originality and the geographical area.

Oxidation in wine is mostly related to the Michael addition of nucleophiles on two quinones formed from the oxidation of ortho-diphenols. In wine this mechanism is responsible for the increase of the yellow hue and aroma loss. Glutathione exerts its antioxidant activity throughout its competitive addition onto quinones, but many other compounds can have the same behavior: sulfanyl
compounds, amino acids, etc. Addition of yeast derivates during the winemaking process can increase the level of those nucleophilic compounds and then confer to the wine a higher resistance

Climate is one of the main components that defines the development and behavior of the plant, conditioning the health status and the final quality of the grapes. In temperate coastal climates such as in Uruguay (latitude 35° S, longitude 55° O), precipitations during the growing season present high interannual variability, with a average of 100 mm per month. This variability means that plants must adapt to conditions from one year to the next.

The Grenache Noir grape variety, due to its originality and its representativeness, contributes very directly to the quality and typicality of the wines of the Rhône Valley. It is generally appreciated for its varied aromatic palette and for the roundness and suppleness it gives to wines. Since 1995, the Rhodanien Institute has set up a network of reference plots representative of the different types of terroir present in the southern zone of the Côtes du Rhône Appellation (TRUC, 1997; VAUDOUR et al, 1996 ) . Publications on the aromatic composition of grapes and wines are very abundant, but only a few articles have appeared on the Grenache grape variety PAUMES et al., 1986).