An evaluation of the physiological responses of young grapevines planted and maintained under water constraint 

Tannins are a heterogenous class of polymeric phenolics found in grapes, oak barrels and wine. In red wine tannins are primarily responsible for astringency, though they also have an important role in reacting with and stabilizing pigments. There are numerous sub-classes of tannins found in wine but they all share structural heterogeneity within each sub-class, with varied polymer composition, configuration and length.

Numerous methodologies exist for the quantification of tannins, however, protein precipitation using bovine serum albumin has proved itself useful due to its strong correlation to the sensory perception of astringency and the basic instruments required for the method. Though the method can yield valuable insights into tannin composition, it cannot be automated easily and necessitates well-trained personnel.

Grapevine Red Blotch disease (RB) is a recently discovered disease that has become a major concern for the viticulture and winemaking industry in California, USA. The causal
agent, Grapevine Red Blotch Virus (GRBV) was identified in 2011 and its presence was confirmed in several states in the US, in Canada, and in Switzerland. It has been demonstrated that RB compromised the regulation of ripening by suppressing specific ripening events, altering the expression patterns of transcription factors and causing hormonal imbalances in Zinfandel.

During wine aging, several complex phenomena of gas transfer take place in barrels due to the wine/oak contact. The efficiency of this gas transfer varies according to oak wood’s intrinsic physical properties. This research aims to better understand oxygen transfer phenomena through dry oak staves and especially through stave gaps, in order to reevaluate the importance of barrel-making on a barrel’s supply of oxygen. Experimentation was based on the development of an innovative permeameter of laboratory scale, for which the principal operating conditions concerning applied pressure, the choice of liquid phase/gas phase, and the grain type of oak are taken into account and investigated. With a specially developed tightening system, the existing pressure at stave gaps in a barrel could be reproduced on a laboratory scale in order to estimate its influence on oxygen transfer efficiency.

Le climat a de fortes implications sur le bon fonctionnement physiologique de la vigne et a besoin d’être quantifié afin de déterminer l’aptitude des régions à la culture de la vigne. Une méthode, qui pourrait éventuellement servir à prévoir l’aptitude des régions à la culture de la vigne, est proposée.

The components and methodology for characterization of the terroir have been described by Gómez-Miguel & Sotés (1993-2014, 2003) and Gómez-Miguel (2011) taking into account the full range of environmental factors (i.e: climate, lithology, vegetation, topography, soils, altitude, etc.), landscape variables (derived from photo-interpretation and a digital elevation model), and specific variables to the country’s viticulture (i.e: size and distribution of the vineyards, varieties, phenology, productivity, quality, designation regulations, etc.).