Irrigation effect on the sensory profile of wines from two red grapevine cultivars autochthonous from D.O. Ribeiro (northwest Spain)

Abstract

The effects that irrigation may have on the enological response of Galician traditional red grapevine cultivars are not well known. However, the actual global change context has increased the interest of winemakers in knowing how irrigation could affect wine sensory perception. In this context, the aim of this study was to assess the effect of irrigation on the sensory profile of wines from two Galician autochthonous red grapevine cultivars in the Ribeiro Designation of Origin (D.O.). The field experiment was carried out during 2011 at the research farm of the Estación de Viticultura e Enoloxía de Galicia (EVEGA), located within the D.O. Ribeiro, where Brancellao and Sousón (two Galician red grapevine cultivars) were subject to two irrigation managements: a rainfed control and an irrigation to 70% of potential evapotranspiration. Grapes were manually harvested and transported to the EVEGA cellar where separate microvinifications (three repetitions for each treatment and cultivar, thus, 12 tanks) were performed. A pannel of 8 judges tasted the wines in two sessions (one per cultivar) for evaluating their sensory profile. Wine samples were coded to avoid judges from knowing the sample origin. Seven wines were served each session: three from the rainfed treatment, three from the irrigation treatment and one repeated from the others in order to test the repeatability in judge’s response. Data were analysed through the ANOVA of Friedman and a hedonic index was computed. General parameters of wines (titratable acidity, pH, alcoholic grade) did not differ between treatments for each cultivar. A different set of sensory descriptors for each cultivar differed between treatments. In the case of Brancellao, five descriptors were significantly different between treatments: colour depth, colour hue, alcohol, green and mature tannins. For Sousón, only two descriptors differed between treatments: aroma intensity and fruity odour. Several descriptors contributed to the calculation of the hedonic index. These descriptors differed between wines from Brancellao and Sousón; however, six descriptors were common for both cultivars: astringency, dark fruits, bitterness, structure, persistence and global quality of the wine. In conclusion, Brancellao wines from the rainfed treatment received higher marks than those from the irrigation treatment; whereas for Sousón no significant differences were observed.