A vine physiology-based terroir study in the AOC-Lavaux region in Switzerland

During alcoholic fermentation, nitrogen is one of essential nutrient for yeast as it plays a key role in sugar transport and biosynthesis of and wine aromatic compounds (thiols, esters, higher alcohols). The main issue of a lack in yeast assimilable nitrogen (YAN) in winemaking is sluggish or stuck fermentations promoting the growth of alteration species and leads to economic losses. Currently, grape musts are often characterized by low YAN concentration and an increase of sugars concentration due to global warming, making alcoholic fermentations even more difficult. YAN depletion can be corrected by addition of inorganic (ammonia) or organic (yeast derivatives products) nitrogen during alcoholic fermentation.

One of the major issues for the wine sector is the impact of climate change linked to the increasing temperatures which affects physicochemical parameters of the grape varieties planted in Bordeaux vineyard and consequently, the quality of wine. In some varietals, the attenuation of their fresh fruity character is accompanied by the accentuation of dried-fruit notes [1]. As a new adaptive strategy on climate change, some winegrowers have initiated changes in the Bordeaux blend of vine varieties [2]. This study intends to explore the fruitiness in wines produced from grape varieties adapted to the future climate of Bordeaux. 10 commercial single–varietal wines from 2018 vintage made from the main grape varieties in the Bordeaux region (Cabernet franc, Cabernet-Sauvignon and Merlot) as well as from indigenous grape varieties from the Mediterranean basin, such as Cyprus (Yiannoudin), France (Syrah), Greece (Agiorgitiko and Xinomavro), Portugal (Touriga Nacional) and Spain (Garnacha and Tempranillo), were selected among 19 samples using sensory descriptive analyses. Both sensory and instrumental analyses were coupled, to investigate their fruity aroma expression. For sensory analysis, samples were prepared from wine, using a semi preparative HPLC method which preserves wine aroma and isolates fruity characteristics in 25 specific fractions [3,4]. Fractions of interest with intense fruity aromas were sensorially selected for each wine by a trained panel and mixed with ethanol and microfiltered water to obtain fruity aromatic reconstitutions (FAR) [5]. A free sorting task was applied to categorize FAR according to their similarities or dissimilarities, and different clusters were highlighted. Instrumental analysis of the different FAR and wines demonstrated variations in their molecular composition. Results obtained from sensory and gas chromatography analysis enrich the knowledge of the fruity expression of red wines from “new” grape varieties opening up new perspectives in wine technology, including blending, thus providing new tools for producers.

Un grand nombre de travaux ont été consacrés à la mise en éyidence et à la quantification de l’effet du climat sur la qualité de la production viticole. IIs ont permis de caractériser les grands types de production à une large échelle géographique, et d’en évaluer les variations interannuelles au niveau des millésimes.

The European Landscape Convention (ELC, 2001) defined the landscape as the “part of a
territory as perceived by the population and resulting from the action of natural and/or human factors and their interrelationships”. Wine landscapes, protected or not under figures such as cultural landscapes or Cultural heritage, are a clear demonstration of this definition, denoting the interrelationships of the natural
environment and the action of the human, which modulates the territory to give the different wine
landscapes. This work was focused on the study of the effect of the human factors linked to the cultivation of the vine on the modification of the landscape.

Aims: Agroscope investigated the efficiency of nitrogen fertilization via foliar urea application at veraison with the aim of raising the YAN (yeast assimilable nitrogen) content in the musts. The observations were conducted on the white grapevine cultivar Doral (Chasselas x Chardonnay) in several pedoclimatic conditions of the Leman wine region, Switzerland, in the years 2012 and 2013. Knowing that the YAN in must plays a key role in wine quality, the aim was finding the main parameters affecting the final YAN level in order to better control them.