Oak Barrels for Wine – Part Three
Different barrels from different oak sources and cooperages are often called the “winemakers’ spice rack.” From experience, a winemaker learns what barrel types best impart desired aromas and flavors into different varieties and styles of wine. New barrels impart far more flavor into a wine than a used barrel. Typically a new barrel gives up 55-65% of its flavoring components during the first use. Second use can impart 20-35% flavoring while third and fourth use impart 15-25% and 10-15%, respectively. Over time oak flavoring properties are "leached" out of the barrel and less wood flavoring is available for the vintage of wine stored in the barrel.
Over time, with successive use of a barrel, layers of natural deposits (primarily potassium bitratrate, or wine diamonds) build up to limit oxygen transport through the wood, an important part of the wine maturation process. There are procedures that can remove significant portions of these deposits, thus refreshing the oxygen transport properties of a barrel. In this way, older, very neutral barrels can continue to have utility in the winery. Selective use of different types, styles and sources of oak barrels, as well as new vs. older barrels, provides the winemaker a wide range of flavoring options.
Other types of wood, such as chestnut, redwood, acacia and pine, have been used for winemaking, but none have been as successful as white oak. Chestnut is too tannic. Redwood is too rigid to make small barrels and imparts an unpleasant flavor. Acacia imparts a yellow tint and some bitter notes to the wine. There are examples of large chestnut and redwood vats, especially in Europe and older CA wineries, but these vessels have long since lost the capacity to impart wood character to the wine inside. These wooden vats lend “romantic charm” to a winery, but they really represent simple neutral tankage, harder to clean and cool than SS tanks, but still with some porosity that allows aeration to help wines mature as they age.
The oak barrel aging process is best monitored via frequent tasting by the winemaker. As flavors from the barrel are incorporated into the wine, and the inherent wine aromas and flavors are modified by time and exposure to wood and oxygen, the winemaker must be diligent in determining when enough is enough. Often during the first 6-12 months of aging, different batches or varieties wine are blended together from barrels into tank and then returned to barrels for further aging. Mixing different varieties at this stage is common practice to create blends that are further aged for better overall flavor integration. Also, wines can be moved from new to older barrels, or vice versa, or into SS tanks, in order to adjust and moderate the final level of oak influence on a wine.
The cost of oak barrels will influence their use. American oak barrels typically cost $400-650 apiece. Oak from cooler climates grows more slowly and has a tighter grain. This not only improves the flavor characteristics in a wine, but increases the cost. French oak barrels, with their more wasteful production method, tight grained wood structure and delicious flavoring characteristics, are significantly more expensive, ranging from $900-1,300 apiece. Barrels from other European oak sources are available today that closely mimic the flavor profiles from French oak and at somewhat reduced cost. Most winemakers carefully consider the flavoring impact desired in a wine, as well as the eventual retail price, when deciding on American vs. French (or other European) oak barrels. Besides the cost of new barrels, judicious use of new and older oak barrels is also important in controlling costs in a modern winery’s oak program.