Use of pectinolytic yeast in wine fermentations

Climate influence on grapevine physiology is prevalent and this influence is only expected to increase with climate change. Although governed by a general determinism, climate influence on grapevine physiology may present variations according to the terroir. In addition, these site-specific differences are likely to be enhanced when climate influence is studied using farm data. Indeed, farm data integrate additional sources of variation such as a varying representativity of the conditions actually experienced in the field. Nevertheless, there is a real challenge in valuing farm data to enable grape growers to understand their own terroir and consequently adapt their practices to the local conditions. In such a context, this article proposes a framework to site-specifically study climate influence on grapevine physiology using farm data. It focuses on improving the analysis of time series of weather data. The analytical framework includes the synchronization of time series using site-specific thermal indices computed with an original method called Extended Growing Degree Days (eGDD). Synchronized time series are then analyzed using a Bayesian functional Linear regression with Sparse Steps functions (BLiSS) in order to detect site-specific periods of strong climate influence on yield development. The article focuses on temperature and rain influence on grape yield development as a case study. It uses data from three commercial vineyards respectively situated in the Bordeaux region (France), California (USA) and Israel. For all vineyards, common periods of climate influence on yield development were found. They corresponded to already known periods, for example around veraison of the year before harvest. However, the periods differed in their precise timing (e.g. before, around or after veraison), duration and correlation direction with yield. Other periods were found for only one or two vineyards and/or were not referred to in literature, for example during the winter before harvest.

In a recent study several genes controlling the acidification properties of the wine yeast Saccharomyces cerevisiae have been identified by a QTL approach [1]. Many of these genes showed allelic variations that affect the metabolism of malic acid and the pH homeostasis during the alcoholic fermentation. Such alleles have been used for driving genetic selection of new S. cerevisiae starters that may conversely acidify or deacidify the wine by producing or consuming large amount of malic acid [2]. This particular feature drastically modulates the final pH of wine with difference of 0.5 units between the two groups.

Climate change will increase the frequency of water deficit experienced in certain european regions, due to increased evapotranspiration and reduced rainfall during the growing cycle. We therefore need to find ways of adaption, including the use of more drought-tolerant planting material. In addition to the varieties used as grafts and involved in the wine ypicity of our wines, rootstocks selection is a relevant way of adapting to more restrictive environmental conditions.

As the quality and typicity of wine are influenced by the climate, it is essential to have a good knowledge of climate variability, especially with regard to temperature, which has a great impact on vine behavior and grape ripening.

Aim: Geographical Indications-GI are commonly used to protect territorial products around the world, such as cheese and wine. This qualification is useful because it improves the producer’s organization, protects and valorizes the distinct origin and quality of the product, increases recognition and notoriety, and adds value for products. Tropical wines are mainly produced in Brazil, India,