Impact of grape maturity on esters content and sensory characters in wines fermented with yeast strains of different genetic backgrounds

Under the pressure of global warming, several wine grape growing regions around the world are increasingly suffering from advanced and compressed phenology; endangering wine character while also creating serious logistic problems. From a physiological standpoint, the issue of delaying ripening is not simple as, in several instances, only a few processes must be delayed (i.e. sugar accumulation into the berries) while other events such as pigmentation and accumulation of other important phenolic compounds should proceed at a normal rate. Thus, the issue of decoupling technological maturity from phenolic maturity is another important consideration. Over the last decades, several research groups have endeavored to establish alternate cultural practices aimed at addressing this decoupling. In some cases, special applications of quite robust and well known practices regarding physiological principles have been utilized, however some completely new techniques are also being studied. In figure 1 of the review, we offer a panorama of the available tools and in the text we elaborate on those having provided most reliable and consistent results under an array of genotypes and environmental conditions. Among these, primary focus is given to post‐veraison—apical to the cluster—leaf removal (that can also be suitably replaced by applications of anti‐transpirants); the use of kaolin against multiple summers’ stresses; and a drastic version of late winter pruning having the potential to postpone ripening into a cooler period with improved grape composition and a limited negative impact on yield and storage reserves replenishment. 

The METAPIWI project advances viticulture research by examining microbial communities in PIWI (fungus-resistant) grapevines compared to traditional Vitis vinifera. It investigates how these microbes influence spontaneous fermentation and the production of distinct metabolites and aromas.

Il a été souvent démontré (Seguin, 1970), que les meilleurs terroirs sont ceux qui présentent pendant la période de maturation du raisin, une régulation et une limitation de l’alimentation hydrique de la vigne. Si on s’intéresse aux facteurs influençant ce régime hydrique, on constate le rôle prépondérant du taux d’éléments grossiers non poreux qui limitent la réserve utile du sol en diminuant le taux de terre fine. De plus, ces éléments grossiers jouent également un rôle au niveau du pédo-climat thermique car leur conductivité thermique et leur chaleur spécifique sont plus élevées que celles de la terre fine. Ainsi le sol se réchauffera et se refroidira plus rapidement (Saini et McLean, 1967), (Gras, 1994).

Glutathione plays a key role in preventing some oxidative processes during winemaking. This molecule limits the must enzymatic oxidation, reacts with caffeic acid and generates a colourless compound that prevents subsequent browning. It also has a protective effect on wine aroma, preventing the oxidation of the volatile compounds with a high sensory impact.

Climate change constitutes an enormous challenge for humankind and for all human activities, viticulture not being an exception. Long-term strategic changes are probably needed the most, but growers also need to deal with short-term changes: summers that are getting progressively warmer, earlier harvest dates and higher pH in musts and wines. In the last 10-15 years, a relevant corpus of research is being developed worldwide in order to evaluate to which extent extreme canopy management operations, aimed at reducing leaf area and, thus, limiting the source to sink ratio, could be useful to delay ripening. Although extreme canopy management can result in relevant delays in harvest dates, longer term studies, as well as detailed analysis of their implications on carbohydrate reserves, bud fertility and future yield are desirable before these practices can be recommended.