Effect of partial grape drying on the Cabernet Sauvignon grapevine on the wine characteristics: first results in Brazil

Abstract

Cabernet Sauvignon grapes in general do not reach their physiological maturation in the southern regions of the country, which is due to the adverse climatic conditions. This situation induces scientific organizations to develop research, as partial grape drying on the grapevine to improve grape quality. The results of this first experiment conducted during the 1999 vintage have showed that partial grape drying caused a linear increase in the variables related to sugar and acidity of the must. Indeed, the ºBrix increased from 18,8 in the control grapevines to 25,6 in the 10 days dried grapes, which means an average increase of 0,36ºBrix/day. The wine composition elaborated with partial 10 days dried grapes compared to the control ones had higher levels of alcohol (+24.0 p. cent), volatile acidity (+55.6 p. cent), pH (+5.0 p. cent), dry extract (+50.4 p. cent), reducing sugars (+160.6 p. cent), ashes (+34.5 p. cent), ashes alkalinity (23.2 p. cent), tannins (+100.0 p. cent), anthocyanins (+22.2 p. cent), tannins/anthocyanins ratio (+63.2 p. cent), OD 420 (+48.0 p. cent), OD 520 (+38.0 p. cent), and proline (+123.8 p. cent) ; minerals also increased their concentrations, like P (+90.0 p. cent), K (+23.7 p. cent), Ca (+34.7 p. cent), and Mg (+44.2 p. cent) ; the same occurred with the volatile compounds ethyl acetate (+105.4 p. cent), methanol (+85.4 p. cent), 2-methyl-1-propanol (+39.1 p. cent), and the sum of the higher alcohols (+16.41 p. cent). Sensory analysis showed that better wines were obtained with partial dried grapes, where wines from the 4 days dried grapes had a score of 89.4/100 and from the 10 days dried grapes of 79.4/100 while those from control grapevines reached only 69.4/100. Mots-clés : passe