Note: Effects of Oak Wood on the Aromatic Composition of Vitis vinifera L. var. treixadura Wines

Treixadura wines from the 1998 vintage were obtained from traditional vinification in a winery. After alcoholic fermentation, the wine was subjected to ageing in oak barrels for three months. One part of the wine is placed in barrels of American oak and the other part in French oak (Allier oak). Wine stored simultaneously in a stainless steel tank was used as a control. Chemical composition and volatile compounds of wines were analysed. There were no appreciable differences in alcohol and tartaric acid among the wines stored under different conditions, but differences were observed in pH, total and volatile acidity, reducing sugars, malic and lactic acids. Ageing in oak barrels resulted in an increase in volatile acidity and Folin—Ciocalteu index, and a decrease of free and total sulphur dioxide. Various monoterpenes, norisoprenoids, hexenols, sulphurs, volatile phenols, acetals and lactones increase their content notably when aged in barrels of both American and French oak. On the other hand, some acetates, ethyl esters and fatty acids were present in higher concentrations in the wine stored in stainless steel tank. Sensory results indicated that the wine aged in French (Allier) oak was better scored than when aged in American oak, as it provided subtle and delicate nuances of wood, which did not mask the fruity aroma of the Treixadura wine but contributed to its aromatic complexity.