Stag’s Leap Wine Cellars

Collector’s Corner

Stag’s Leap Wine Cellars

Winemaking Articles

Roll Out the Barrels

Certain smells articulate a wine’s beginnings with particular clarity. Flowering grapevines delicately perfume the spring; the heady scent of fermenting grape juice marks the fall. Winter offers my favorite smell. In the wine caves, aromas of Cabernet Sauvignon permeate oak barrels, contrasting powerfully with the cold, crisp, almost sterile air of winter— a visceral reminder that the barrels house a living, breathing product of the grape and a preservation of summer’s abundance. The magnificent blend of toasty oak and ripe, berry aromas is so evocative that it regularly elicits gasps of appreciation from visitors.

The marriage of wine and oak appears to be so natural that we tend to take it for granted. In fact, it was an accidental union, a happy story of form following function.

Barrels were used in ancient times; Herodotus mentions their use for carrying Armenian wine to Babylonia as early as seven centuries BC .(These were probably made of palm wood.) The Iron Age saw widespread use, with barrels’ shape and size allowing for the easy transport and storage of many products.

Over time, barrels came to be recognized as valuable aids to the winemaking process. 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. Many wines benefit from at least partial malolactic fermentation, a secondary fermentation that converts malic acid (the tart acid found in green apples) to softer lactic acid (common in fermented dairy products). For both red and white wines, malolactic fermentation in barrel adds richness and length of flavor on the palate, while softening the oak influence. The small aperture of the barrel allows for a limited amount of oxygen exposure that softens wine tannins and introduces further complexity through oxygen’s reaction to the wood tannins. The controlled amount of oxygenation also allows for the stabilization of wine color.

In the middle of the last century, by which time the use of barrels was limited almost solely to the storage and transportation of wine, winemakers began to value the qualitative virtues that oak bestowed—flavors such as vanilla, spice, smoke, cedar and nut qualities—enhancements that added to a wine’s depth and complexity.

Next to the cost of grapes, barrels are the second highest annual winemaking expense for Stag’s Leap Wine Cellars. Cooperage directly affects wine quality, and our winemakers incorporate the cooper’s art into their own art. We particularly prize French oak. The great forests in France have been carefully managed since Napoleon’s time, when the trees were grown for shipbuilding. Many of the same qualities that made the oak suitable for ships—durability, tight grain, lack of warping—now make it suitable for winemaking. Like grapes, wood character is influenced by environment and therefore 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 flavor and tannins slowly, elegantly balancing the wine. Many of the barrels that we use come from this region, with most coming from Nevers (pronounced ne-vair), a small area within the Center of France. Wood grain varies even within the same area, so we choose barrels from different coopers to achieve a range of grains from which to build layers of flavor and texture.

Barrel expense reflects the time and labor-intensive techniques that have been shown to make the best barrels. The way oak is harvested, seasoned, and shaped all influences its wood expression. As the oak is cut, it is either hand-split or machine-sawn. Hand-splitting follows the grain of the wood and creates softer tannins in the wood, as well as diminishing future leakage. Seasoning the wood prevents future leakage as well as softening wood tannins. The barrels we purchase 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 that allow rich oak aromas to evolve.

Heat application used to bend the staves into the barrel’s characteristics shape also has an effect on wood quality, and therefore on the wine. 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 medium toast provides more toasty, vanilla, and coffee characteristics, with softer tannins. Heavier toasts impart aromas of coffee bean, spice, and cigar box.

Yet another choice the winemaker makes has to do with 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.

Like an artist with a color palette, a winemaker will keep different lots of wine in different kinds of barrels, in order to create the widest range of elements from which to make the finished wine. For the creative 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.