Postharvest ozone treatment in grapevine white cultivars: Effects on grape volatile composition

STICS est un modèle de culture développé à l’INRA (France) depuis 1996. Il simule les bilans de carbone, d’eau et d’azote dans le système culture-sol, piloté par des données climatiques journaliéres. Il calcule à la fois des variables agricoles (rendement en quantité et qualité) et environnementales (pertes en eau et en azote). Une des originalités de STICS est son adaptabilité à de nombreuses cultures (herbacées, ligneuses, annuelles, pérennes) rendue possible par le choix de paramètres génériques et d’options de formalismes. Le travail présenté traite, dans un premier temps, des spécificités de STICS pour la vigne en terme de bilan trophique, de fonctionnement énergétique et hydrique et d’estimation des teneurs en sucre en en eau du raisin. Nous montrons ensuite diverses sorties du modèle qui permettent de caractériser des terroirs du vignoble des Côtes du Rhône.

Bacterial malolactic fermentation (MLF) has a considerable impact on wine quality. The yeast strain used for primary fermentation can consistently stimulate (MLF+ phenotype) or inhibit (MLF- phenotype) malolactic bacteria and the MLF process as a function of numerous winemaking practices, but the molecular evidence behind still remains a mystery. In this study, such evidence was elucidated by the direct comparison of extracellular metabolic profiles of MLF+ and MLF- yeast phenotypes. Untargeted metabolomics combining ultrahigh-resolution FT-ICR-MS analysis, powerful machine learning methods and a comprehensive wine metabolite database, discovered around 800 putative biomarkers and 2500 unknown masses involved in phenotypic distinction.

Context description and research question: an increasing number of farmers are considering the impact of conservation practices on soil health to guide sustainable management of vineyards. Understanding impacts of soil management on soil organic carbon (SOC) is one lever for adoption of agroecological practice with potential to help maintain or improve soil health while building SOC stocks to mitigate climate change (Amelung et al., 2020).

AIM Astringency is described as a ‘dry puckering‐like sensation’ following consumption of tannins1 that affect consumer preference of foods and beverages, including red wine2. To improve the understanding of astringency, which is a complex interaction due to multiple mechanisms occurring simultaneously, further studies are needed. In this view, oral tribology is considered a useful technique for beverage study to evaluate the thin-film lubrication properties of saliva resulting in oral friction‐related sensations3. The aim of this study was to examine the film behavior of selected protein-based fluids under controlled friction conditions, to understand polyphenol-protein interactions involved in the sensation of astringency.

Mannoproteins (MPs) are released from the yeast cell wall during alcoholic fermentation and aging on the lees, and influence aspects of wine quality such as haze formation and colour stability. Yet, as this is a slow process with microbiological and sensory risks, the exogenous addition of extracted MPs poses an efficient alternative. While Saccharomyces cerevisiae has long been studied as a prominent source for MPs extraction, their structure and composition greatly differ between yeast species. This may influence their behaviour in the wine matrix and subsequent impact on wine properties. However, although wine yeast species other than S. cerevisiae possibly present an untapped source of MPs, they are still ill-characterised in terms of chemical composition and influence on wine.