Effect of climate change on the polyphenolic composition of the main varieties of grape from La Rioja (Spain) and new oenological strategies to correct these effects on the quality of red wine

Abstract

Even though grapes grow all around the planet those aimed for high quality wine production occur in areas with very specific climate conditions. Moreover, each individual variety of grape requires conditions that are even more particular. Thus, any change on the climate or meteorological patterns can affect the chemistry of the grape and the final quality of wine. Recent studies have explored the impact of climate change on the worldwide production of grape, and some highlight an advance on the vintage date associated with a temperature increase, this being for instance, 18-21 days in the South of France from 1940 to 2000. Regarding the chemical composition of wine, anthocyanins and condensed tannins are the main type of polyphenolic compounds found in red wine. Anthocyanins are the main pigments of red grapes whereas tannins play an important role on the astringency and bitterness of wine. During wine making process, both types of compounds undergo chemical transformations leading to more stable polymeric pigments. The mechanisms of these reactions and the structures of these derivative pigments have been a recurrent topic of study. With the advances on the analytical techniques, some of these structures have been elucidated, discovering products of the direct and indirect condensation of anthocyanins and tannins. Additionally, anthocyanins have been found to react with other minor components present in wine, yielding a new class of compounds called pyranoanthocyanins and producing changes in the hue of the wine [3]. A better knowledge of the formation kinetics and evolution of these pigments during wine production will allow the producer to adapt the oenological practice to control and optimise the final quality of red wine. This work is aimed towards the study of climate influence on the polyphenolic composition of must and wine from Tempranillo grape cultivar, the main variety of grape in La Rioja (Spain), and its evolution during wine production.