The acidity influences the wine stability and coloration and it is one of the most important sensory attributes of wines. The total acidity and the pH vary with the salification of tartaric acid and the K content in grapes. This work evaluated the acidity evolution during vinification of three red grape varieties (Merlot, Cabernet Franc and Cabernet Sauvignon) from three viticultural regions of the state of Rio Grande do Sul, Brazil. The vineyards were uniforms and with the same trellising and pruning systems and grafted on the SO4 rootstock. The wines were elaborated by the microvinification process in the 1995 vintage. The evolution of pH, total acidity, tartaric acid and K were evaluated in five vinification phases: 1) immediately after crushing; 2) after draining; 3) after alcoholic fermentation; 4) after malolactic fermentation; 5) after tartrate stabilization. Results show that wines from Sant'Ana do Livramento presented the lowest values of total acidity and the highest increases of pH. The acidity evolution was associated with the initial K and tartaric acid levels found in the grape musts.
wine; chemical composition; wine characterization; enology; potassium
