Fruity expression of red wines resulting from varieties adapted to climate change. A comparative study with the "traditional" grape varieties planted in Bordeaux

Currently, one of the major issues for the wine sector is the impact of climate change linked to the increasing temperatures recorded and expected in the upcoming years. The vegetative cycle of the grape varieties authorised and planted in the Bordeaux wine region is tending to shorten, affecting the physicochemical parameters of the grapes and, consequently, the quality of the wines. In some varietals, the attenuation of their fresh fruity character is accompanied by the accentuation of dried-fruit notes [1]. As of today, winegrowers must implement adaptive strategies to continue producing high quality wines in a climate that is becoming warmer and drier. Some winegrowers have initiated changes in the mix of vine varieties [2]. This study intends to explore the fruitiness in wines produced from grape varieties adapted to the future climate of Bordeaux. Indeed, Bordeaux wines currently have a recognized fruity typicity [3], that it is imperative to preserve to maintain its reputation and avoid economic and, therefore social consequences. For that, commercial single–varietal wines from 2018 vintage made from the main grape varieties grown in the Bordeaux region (Merlot and Cabernet-Sauvignon) as well as from indigenous grape late-ripening varieties from the Mediterranean basin were collected, such as France (Cabernet-Franc, Cabernet-Sauvignon, Merlot and Syrah), Greece (Agiorgitiko, Xinomavro), Portugal (Touriga Nacional) and Spain (Garnacha and Tempranillo). Wines were evaluated sensorially: a sorting task was instructed to the panel and descriptive analyses of all wines were recorded with descriptors related to the fruity character of each wine. To study their fruity aroma expression, samples were prepared from wine, using an HPLC method which preserves wine aroma and isolates fruity characteristics in 25 specific fractions [3]. A trained panel evaluated sensorially the fractions. The descriptors characterising each wine matched those attributed to the different fractions. Then all fractions with intense fruity notes were selected for each wine and the comparative study of their fruity expression highlighted some fractions of interest. Aromatic reconstitutions were realised by mixing fractions with a fruity aroma (“fruity pool”) in ethanol and microfiltered water to obtain an ethanol level of 12% (v/v). By comparing the fruity expression of each fruity aromatic reconstitution (FAR) made from the different late-grape varieties previously selected, 3 distinct groups were highlighted. FAR of wines made from late-grape varieties from Spain (Garnacha and Tempranillo) were gathered into the group 1 with the FAR of the wine made from a grape variety from France (Syrah). The group 1 was characterised by “red-berry”, “black-berry” and “exotic” fruits notes. The group 2 was composed by FARs of wines made from two grape-varieties from France (Cabernet-Sauvignon and Merlot) and two grape-varieties from Greece (Agiorgitiko and Xinomavro). This second group was mainly described as “red-berry”, “black-berry”, “candy”, “amylic” and “artificial” fruits notes. Finally, FAR of the wine made from grape variety from Portugal (Touriga Nacional) was classified into the group 3 with the FAR of the wine made from the last grape variety from France (Cabernet-Franc). The group 3 was mainly characterised by “freshness”, “mint” and “eucalyptus” notes. These results open up new prospects for the preparation of aromatic reconstitutions [4] from several fractions in order to study the impact of perceptive interactions on wine fruity aroma expression after the integration of wines from "new" late-ripening varieties in Bordeaux blends.