A global and regional study on winegrowers’ perceptions and adaptations to climate change

The French “Coteaux du Layon” Appellation of Origin has built its Jarne on the production of sweet white wines. A network of experimental plots, based on the “terroir” concept, was established in 1990; it allows for the follow-up of the overripening behaviour of the grapes in relation with the agroviticultural parameters.

The diversity of potential sources of damage to the terroir of an appellation (physical, aesthetic, ecological damage, damage to the image, to collective representation or even, in a broad concept which will not be retained here, to the geographical name identifying the terroir) is accompanied by a fragmentation of the legal sources allowing its protection.

Fermenting grape juice represents one of the oldest continuously maintained anthropogenic microbial environments and supports a well-mapped microbial ecosystem. Several yeast and bacterial species dominate this ecosystem, and some of these species are part of the globally most studied and best understood individual organisms. Detailed physiological, cellular and molecular data have been generated on these individual species and have helped elucidate complex evolutionary processes such as the domestication of wine yeast strains of the species Saccharomyces cerevisiae. These data support the notion that the wine making environment represents an ecological niche of significant evolutionary relevance. Taken together, the data suggest that the wine fermentation ecosystem is an excellent model to study fundamental questions about the working of microbial ecosystems and on the impact of biotic selection pressures on microbial ecosystem functioning. Indeed, and although well mapped, the rules and molecular mechanisms that govern the interactions between microbial species within this, and other, ecosystems remain underexplored. Here we present data derived from several converging approaches, including microbiome data of spontaneous fermentations, the population dynamics of constructed consortia, the application of biotic selection pressures in directed laboratory evolution, and the physiological and molecular analysis of pairwise and higher order interactions between yeast species. The data reveal the importance of cell wall-related elements in interspecies interactions and in evolutionary adaptation and suggest that predictive modelling and biotechnological control of the wine ecosystem during fermentation are promising strategies for wine making in future.

Having the possibility to use a wide spectrum of elecromagnetic waves, dielectric spectroscopy is a technique commonly used for electrical characterization of dielectrics or that of materials with high energy storage capacity, just to name a few. Based on the electrical excitation of dipoles (polymer chains or molecules) or ions in relation to the characteristics of a weak external electric field, this method allows the measurement of the complex permittivity or impedance of polarizable materials, each component having a characteristic dipole moment.In recent years, the food industry has also benefited from the potential offered by this technique, whether for the evaluation of fruit quality or during the pasteurization of apple juice [1-3]. As the tests are fast and do not destroy the products, dielectric spectroscopy proved to be an experimental tool suitable for online measurements as well as long-term monitoring.

Among red wines ethyl esters, those from short hydroxylated and branched-chain aliphatic acids constitute a family with a particular behavior and sensory importance. They have been previously discussed in the literature [1] and recent studies have established that some of them were strongly involved in of red wines’ fruity aroma [2]. As some among them have an asymmetrical carbon atom, it seemed important to separate their different enantiomers to obtain an accurate assessment of their organoleptic impact. Three chiral esters have been identified, presenting alkyl and/or hydroxyle substituants: ethyl 2-hydroxy-4-methylpentanoate, ethyl 2-methylbutanoate, and ethyl 3-hydroxybutanoate.