Influence of the year and the environmental factors on condensed tannins from Cabernet franc grapes

Grape canes are a non-recycled byproduct of wine industry (1-5 tons per hectare per year) containing valuable phytochemicals of medicine and agronomical interest. Resveratrol and wine polyphenols are known to exert a plethora of health-promoting effects including antioxidant capacity, cardioprotection, anticancer activity, anti-inflammatory effects, and estrogenic/antiestrogenic properties (Guerrero et al. 2009). Additionally, resveratrol is a major phytoalexin produced by plants in response to various stresses and promotes disease resistance (Chang et al. 2011). Our project aims to develop polyphenol-rich grape cane extracts to fight phytopathogenic or clinically relevant fungi. We initiate the project with the development of analytical methods to analyze resveratrol mono- and oligomers (dimers, trimers and tetramers) from grape canes and we evaluate their potential activity against clinically relevant opportunistic fungal pathogens (Houillé et al. 2014).

Climate change (CC) is altering grape/wine composition, challenging wine sensory quality. Rising temperatures increase grape sugar levels, with higher wine ethanol (EtOH) contents, reduce total acidity (TA) converging with increased pH and lead to the accumulation of CC odorous markers such as γ-nonalactone (γ-C9) and massoia lactone (ML).

The use of oenological tannins is authorized for many years by the OIV and advised for color stabilization. For this reason, winemakers look for a better understanding of tannins/anthocyanins interactions to produce deeply colored wines with great color stability during aging.

L’appellation d’origine contrôlée repose sur une définition précise de l’aire de production du raisin. Cette délimitation définie par l’Institut National des Appellations d’Origine est proposée par des experts choisis pour leurs compétences dans le domaine de la connaissance de la relation terroir – vins, après avis du syndicat de défense de chaque AOC.

In viticulture, the concept of terroir is often used to enlighten the environmental-based typicity of grapevines grown in a local area however its scientific basis remains under debate. Grape polyphenols as key player of the plant defense system enables adaptation to environmental changes and so far, form a unique metabolic component to investigate the terroir influence.