Evaluation of sustainable technological alternatives to produce differentiated red wines

Doctoral thesis abstract

Abstract

The climatic variability during the grapevine cycle and especially during the ripening affects the oenological potential of the grape and the quality of the wine. The increase in interannual climate variation due to climate change makes it essential to adopt winemaking management measures to produce quality wines. The production of red wines with body and intense color requires harvesting the grapes in an advanced state of maturity and an intense extraction of phenolic compounds during winemaking. Grapes with advanced maturity have high concentrations of sugars and high pH, causing alcoholic wines and stability problems. This doctoral project focused on studying winemaking alternatives that allow regulating the alcohol content and the pH of the wines without affecting their phenolic concentration, as a tool to mitigate the effect of interannual climate variability. In particular, the substitution of ripe grape must for immature grape must, and the pre-fermentation hot maceration in the Pinot noir and Tannat cultivars in the 2016, 2017 and 2018 harvests were evaluated. Additionally, another trial was carried out where the aggregate and replacement with water or white grape must as alternatives for reducing the alcohol content of the wines. The oenological potential of the grapes harvested, and the general composition, color, phenolic composition, and polysaccharides of the wines were determined. Sensory evaluations of the wines were also carried out. Through the winemaking techniques proposed, it was possible to produce wines with lower alcohol content and pH without negatively affecting their color or phenolic concentration and in polysaccharides of the wines. The effect of these techniques depended strongly on the cultivation and the oenological potential of the grapes in each harvest. The results obtained suggest that these winemaking techniques can minimize the effects of interannual climate variability on the composition of the wines, being tools that contribute to improving the sustainability of the national wine sector.