WHICH TERROIR-RELATED FACTORS INFLUENCE THE MOST VOLATILE COMPOUND PRODUCTION IN COGNAC BASE WINE?

The interactions between geographical and biotic factors, along with the winemaking process, influence the composition and sensorial characteristics of wine¹. In addition to the primary end products of alcoholic fermentation, many secondary metabolites contribute to wine flavor and aroma and their production depends predominantly on the yeast strain carrying out the fermentation. Commercially available strains of S. cerevisiae help improve the reproducibility and predictability of wine quality. However, most commercial wine strains available on the market have been isolated from Europe, are genetically similar, and may not be the ideal strain to reflect the terroir of Canadian vineyards².

Fruity notes play a key role in the consumer’s appreciation of Bordeaux red wines. If literature provides a lot of knowledge about the nature of volatile compounds involved in this fruity expression, the sensory phenomena involving these compounds in mixture still need to be explored. Considering previous sensory works about the impact of esters and some overripening compounds, the goal of this work was to study the implication of perceptual interactions involving red wine odorant compounds of diverse origins and described as potentially affecting fruity aromatic expression.

Light-struck taste (LST) is a wine fault that can occur in white and sparkling wines when exposed to light. This defect is mainly associated to the formation of methanethiol and dimethyl disulfide due to light-induced reactions involving riboflavin (RF) and methionine [1]. The presence of RF in wine is mainly due to the metabolism of yeast [2] which fermenting activity can be favoured by using yeast derivative products (YDPs) as nutrients. Nonetheless, a previous study showed the addition of YDPs before the alcoholic fermentation (AF) led to higher concentrations of RF in wines [3]. Due to the widespread use of YDPs in the winemaking process, this study aimed to understand the possible relation between the content of RF in wine and the YDP adopted as nutrient for AF.

Brettanomyces bruxellensis is an ubiquitous yeast associated with different fermentation media such as beer and kombucha, where its presence is beneficial to bring an aromatic typicity. However, it is a main spoilage yeast in wines, in which it produces volatile phenols responsible for organoleptic deviations causing significant economic losses (Chatonnet et al., 1992). Cellar and winery equipment’s are considered as the first source of contamination, during fermentation and wine ageing process (Connel et al., 2002). Indeed, it is possible to find B. bruxellensis in the air, on walls and floors of the cellars, on small materials, vats and barrels.

Wine production is a complex biochemical process that involves a heterogeneous microbiota consisting of different microorganisms such as yeasts, bacteria, and filamentous fungi. Among these microorganisms, yeasts play a predominant role in the chemistry of wine, as they actively participate in alcoholic fermentation, a biochemical process that transforms the sugars in grapes into ethanol and carbon dioxide while producing additional by-products. The quality of the final product is greatly influenced by the microbiota present in the grape berry, and the demand for indigenous yeast starters adapted to specific grape must and reflecting the biodiversity of a particular region is increasing. This supports the concept that indigenous yeast strains can be associated with a “terroir”.