Stag’s Leap Wine Cellars

Collector’s Corner

Stag’s Leap Wine Cellars

Winemaking Articles

The Oak and the Vine

The association of wood and wine goes back a very long time. Herodotus recorded the use of wooden barrels as wine containers as early as seventh century B.C., and for most of wine’s history, barrels were the containers of choice for storage and transportation. Over time, winemakers began to also value barrels’ ability to change the taste of the wine inside. Oak barrels came to be favored for imbuing wine with tastes ranging from vanilla, spice, coffee, and caramel to cedar, smoke, and leather.

By the middle of the 20th century oak barrels were also recognized as valuable aids to fermentation and maturation. For white wines, primary fermentation in oak barrels not only increases the range of flavors but also prepares the wine for battonage (lees stirring), which softens and integrates the flavors from the wood and lightens color. For both reds and whites, malolactic fermentation in barrel adds richness and length of flavor on the palate, while softening the oak influence. Barrels also permit a controlled amount of oxygenation, reducing "grapy" aromas, soften tannins, and stabilize color.

Just any oak barrel won’t do, however. Particularly prized is oak from forests in France that have been carefully managed for centuries. The character of the wood varies by region. For example, the soils and closely spaced trees in the area called Center of France produce oak with dense fibers. This tight grain imparts flavors and tannins slowly, elegantly balancing and enhancing the wine. Many of the barrels used at Stag’s Leap Wine Cellars come from this region, with most coming from Nevers (pronounced nevair), a smaller area within the Center of France. Even within Nevers oak there are subtle variations in the wood grain, and we choose barrels from several different coopers (as the makers of barrels are called) to achieve a range of grains from which to build layers of flavor and texture.

Barrels made from too-fresh wood might split and crack as the wood dries out, so the oak must be seasoned. The barrels we purchase for our Napa Valley wines are made from wood that has been dried in the open air for two to three years. Drying wood in a kiln is much faster, but long-term exposure to the natural elements encourages biological and chemical transformations: rich oak aromas evolve, and weathering softens harsh tannins.

The oak is also changed by the heat that is applied to bend the individual staves into the barrel’s characteristic shape.Wood that is toasted, rather than steamed, contributes an even broader range of flavors and textures. In addition, the more the wood is toasted, the less tannin the alcohol in the wine will leach out of the wood. Lightly toasted barrels will impart more tannic, fruity, oaky qualities to wine, while a medium toast provides more toasty, vanilla, and coffee characteristics, with softer tannins. Heavier toasts impart smells of coffee bean, spice, and cigar box.

Yet another choice the winemaker makes concerns the age of the barrels. New barrels provide greater expressions of wood flavor than barrels in which other wines have already aged for a few years. For some lots of wine, the flavor and texture imparted by new barrels is the perfect finishing touch. Other lots may benefit from the slow oxygenation that an older barrel provides without needing so much additional wood influence. For the ambitious winemaker, choosing the oak, the toast, and the age of one’s barrels can be almost as important as choosing the grapes for one’s wine.