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

Le sol est un facteur important permettant la croissance de la vigne. Les propriétés physiques et chimiques, mais aussi microbiologiques ont une influence sur beaucoup des fonctions du sol comme la structure, le drainage, la fertilité, déterminant la vigueur des plantes et le potentiel œnologique des raisins.

For a long time environment was known as one of the most important factors to characterize the quality of wines but at the same time it appears very difficult to distinguish inside the “terroir” the role of the single factor. These remarks partially explain why methods for viticultural evaluation are often quite different (Amerine et al., 1944; Antoniazzi et al., 1986; Asselin et al., 1987; Astruc et al., 1980; Bonfils, 1977; Boselli, 1991; Colugnati, 1990; Costantinescu, 1967; Costantini et al., 1987; Dutt et al., 1981; Falcetti et al., 1992; Fregoni et al., 1992; Hidalgo, 1980; Intrieri et al., 1988; Laville, 1990; Morlat et al., 1991; Scienza et al., 1990; Shubert et al., 1987; Turri et al., 1991).

This study evaluated the levels of trans-resveratrol in commercial wines made from Cabernet Sauvignon grapes from different valleys of Chile stilbenes. The Cabernet Sauvignon is the most planted variety in Chile, being 38% of the total vineyard country. Chile is the fourth largest wine exporter in the world, so it is important to evaluate the Cabernet-Sauvignon wines in their concentration levels of trans-resveratrol and its relation to the benefits provided to human health in moderate consumption. Evaluation comprises commercial wines from different valleys of Chile and its relationship with climatic characteristics, soil and vineyard handling.

Wine regions are getting warmer as average temperatures continue raising affecting grape growth, berry composition and wine production. Berry quality was evaluated in plants of Vitis vinifera cv Syrah grafted on two rootstocks, Paulsen (PL1103) and SO4, and grown under two salinity concentrations (LS:0.7dS/m and HS:2.5dSm-1) in combination with two irrigation regimes (HW:133% and CW:100%), being the seasonal water application 483mm (control, 100%). Spectrophotometer measurements from berry skin during veraison and harvest stages and from “young” wine samples, were indicative of the stressors effect and the mediation of the rootstocks. At veraison (i) total phenolics content were high under LSHW (0.7dSm-1 and high water conditions) for SO4 and PL1103.

Vineyards are strongly exposed to fungal diseases, attacks from insects and competition with weeds. Most treatments used on grape vines contain synthetic active substances, which may be transferred to the wine. Such pesticides have a negative image because many active substances are potential health hazards. A specific oenological treatment allowing the reduction of pesticide residues in wine based on activated vegetable fibres (AVF) is under examination by the International Organisation for Vine and Wine. This technique works efficiently and alters the wine only little (Lempereur et al. 2014).