Characterizing the molecular basis of the differences in aromatic precursors found in commercial clones of Vitis vinifera cv. Tannat

A multidisciplinary approach aiming at studying the grape-growing areas also referred as “Terroir” was initiated a few years ago in Switzerland.

Galicia, a region sited in the northwest of Spain, is one of the most important wine production area, with five Appellations of Origin Controlled (AOC).

Climate change is leading to a rise in average temperature and in the frequency and severity of heatwaves, and is already significantly disturbing grapevine phenology and berry composition. With the evolution of the weather of Australian grape growing regions that are already warm and hot, flavonoids, for which biosynthesis depends on bunch microclimate, are expected to be impacted. These compounds include anthocyanins and tannins which contribute substantially to grape and wine quality. The goals of this project were to determine if berry tannin accumulation is sensitive to high temperature and to enhance knowledge on upper temperature limits for viable wine production, in turn informing critical timing for mitigation strategies.

Polyphenols are important compounds involved in many chemical and sensory wine features. In winemaking, adding oenological tannins claims to have positive impacts on wine stability, protection from oxidation and aroma persistence. Polyphenols are antioxidant compounds by either scavenging reactive oxygen and nitrogen species or chelating Fe2+ ions (1). However, as tannins oxidation leads to the formation of highly reactive species (i.e. ortho-quinones), it is still unclear if they have an effective role toward oxidation of wine aromas (2). In this work, we aim at studying the effect of two commercial tannins (proanthocyanidins, ellagitannins) on red wine flavour (mainly aroma) before and after air exposition.

L’aire d’AOC Ribeira Sacra s’étend sur plus de 200 km au large des versants escarpés du Miño et du Sil, dans la Galice (Espagne).