PHYSICOCHEMICAL COMPOSITION OF CABERNET-SAUVIGNON WINE MADE FROM GRAPES AFFECTED BY GRAPE RIPE ROT

Aim: In the last years, grape ripe rot has been one of the most important diseases of the Serra Gaacha vineyards, RS, Brazil. In order to determine its influence on wine quality, we studied the physicochemical composition of must and wine made from affected Cabernet-Sauvignon grapes. Methods and results : The experimental design was a randomized complete block, with six treatments - musts containing 0, 2.5, 5, 7.5, 10, and 20 % of affected grapes - and three replications. Grape musts were extracted from ripe fruits and wines were made in 20-L glass recipients. Polynomial regression analysis showed that ripe rot significantly increased the degrees Brix, density, pH, and degrees Brix/total acidity ratio of grape must. In wine, increases were observed for most variables evaluated except for density, absorbance at 520 nm, color intensity, and anthocyanins, which decreased. Conclusions: These results show that grape ripe rot affects must and wine composition. The effect is more striking in wine, where it significantly reduces color. In this way, grape ripe rot should be prevented or controlled in the vineyards. Significance and impact of the study: These results are important because they show the negative effect of grape ripe rot on wine composition and quality.