CHARACTERIZATION AND IDENTIFICATION OF YEAST BIOACTIVE PEPTIDES RELEASED DURING FERMENTATION AND AUTOLYSIS IN MODEL WINE

In recent years, consumer demand for products without chemical additives increased, becoming a priority for the wine sector. SO₂ is widely used for its multiple properties including antiseptics, antioxidants and antioxidasics and the strategy of bioprotection in winemaking represents now an alternative to this chemical additive. In oenology, results have highlighted the interest of bioprotection to limit the development of microorganisms like Hanseniaspora uvarum and thus reduce the doses of sulphite. Indeed, this species is considered because of its acetic acid and methyl butyl acetate production, the latter can cover the varietal character of wines.

Cognac is an outstanding french wine spirit appreciated around the world and produced exclusively in the Nouvelle-Aquitaine region, and more precisely in the Cognac area. According to AOC regulations (Appellation D’origine Controlée), the spirit required at least 2 years of continuous ageing in oak barrels to be granted the title of Cognac. The oak wood will import color, structure and organoleptic complexity. The different steps during barrel-making process, such as seasoning and toasting, influence the above quality attributes in both wines and spirits.

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.

Nitrogen (N) nutrition of the vineyard strongly influences the must and the wine compositions. Several chemical markers present in wine (i.e., proline, succinic acid, higher alcohols and phenolic compounds) have been proposed for the cultivar Chasselas, as indicators of N deficiency in the grape must at harvest [1]. Grape genetics potentially influences the impact of N deficiency on grape composition, as well as on the concentration of potential indicators in the wine. The goal of this study was to evaluate if the che- mical markers found in Chasselas wine can be extended for other white wines to indicate N deficiency in the grape must.