Contribution of wine microorganisms to the aroma composition of wine and its sensory impact

The different odor and flavor nuances of a wine are caused by between 25 and 50 different odor chemicals present at concentrations above olfactory thresholds. The final flavor perception is the result of a subtle perceptual balance between the primary sensory outputs triggered by those molecules in the olfactory, taste and trigeminal receptors. Most of those odor chemicals are by-products of yeast metabolism and their levels in wine are determined by the interaction between the grape must composition, the specific genetic characteristics of the yeast and environmental and technological conditions.

The main objective of this PhD is to gain knowledge in our understanding of the role of the yeast characteristics on the wine aroma composition and sensory properties. In the first part of the work we will seek to measure the variability in aroma composition linked to the specificity of yeast and to their interaction with the must composition. We will further develop mathematical models able to predict for a given yeast species, the production of aroma compounds and of the corresponding wine sensory properties as functions of must composition.

A special focus is given on the distinction of non-Saccharomyces yeast originated from the vineyard and Saccharomyces yeast either added or inoculated from strains present in the wine cellar. Mathematical models should be used to relate specific genetic characteristics of yeast with their formation of aroma compounds and sensory properties evoked by the specific aroma composition. In collaboration with the other partners of the project, we will try to establish links between all three concepts.

Further information

• Laboratory for Aroma Analysis and Enology (LAAE), University of Zaragoza
• Viticulture and Oenology Department (VOD), DLR-Rheinpfalz