The grape harvest season for most of the United States and Europe is now complete! Grapes are ripe for picking from August through October for vineyards in the Northern Hemisphere. The decision of when to harvest is dependent upon the weather, grape varietal, and vision of a winemaker. For example, lesser-ripe grapes are picked earlier to achieve higher acidity in sparkling wine while overripe grapes are picked later for sweeter dessert wines. Regardless of when a grape is picked, the winemaker must decide how to ferment and mature the wine, and whether to incorporate oak in that process.
For centuries, winemakers have used oak barrels to impart wood influences in a wine’s flavor and color as well as aid in the maturation of the juice. Oak can be implemented in the winemaking process during fermentation, aging, or both. During fermentation, wood is used to stabilize the wine’s color and tone down harsh aromas. Oak nuances do not become as pronounced during this phase because the wine’s yeast cells bind to the oak and are removed after fermentation. During aging, however, the porosity of the barrel introduces oxygen at minimal levels and allows the wine to aerate gradually. Meanwhile, the wood’s tannins protect the wine from harmful oxidation, soften its structure, and impart a depth of flavor. Wines aged in oak have toasty nuances of vanilla, butter, honey, caramel, coconut, toffee, nutmeg and clove, among others. Winemakers have tested other wood types such as chestnut, pine, acacia, cherry, apple, and rauli with significant drawbacks, such as severe porosity and evaporation, loss of barrel shape, or adverse coloring and taste.
White oak is the world’s renowned wood for winemaking due to its durability, resiliency, minimal shrinkage, and pleasant aromas enjoyed by the human palate. The most predominantly used barrels in the wine industry originate from France and the United States. French oak has tighter wood grains and more tannin, which influence a wine more subtly than the stronger, wider-grain American oak. The pungency of American oak decreases a wine’s astringency and intensifies bold flavors in a shorter period of time, making it a preferred choice for maturations of less than one year. The size of a barrel plays a key role in the oak essences a wine will receive. The smaller the barrel, the greater the surface area exposed to the volume of wine; therefore, wine in larger barrels must age for longer periods to attain the same amount of oak exposure.
Oak barrels have an average life expectancy of five years and range in price from $300 to $1,000 each. Wineries also incur a number of related expenses for barrel usage, including maintenance and storage space. The costly and labor-intensive practices of using barrels have led many winemakers to seek alternatives. Barrel substitutes can be implemented in both the fermentation and aging processes. During fermentation, grapes are combined with oak dust to provide color and odor stabilization like the traditional barrel-fermentation method. For the maturation phase, alternatives such as oak chips, blocks, or staves are dropped into enormous stainless steel tanks filled with wine. Ironically, since the chips provide a greater wood to liquid ratio, the oak flavors are intensified in a matter of weeks that could otherwise take a year in a barrel. Pieces of wood floating in a tank, however, are unable to offer the same benefit of aeration as barrel aging, but winemakers have compensated by employing a micro-oxygenation technique where bits of air are pumped into the tank to mimic the barrel’s effects. An advantage of these economical oak chips is they can be toasted to give off specific aromas to cater to the winemaker’s vision for the wine.
Even with its benefits, barrel alternatives have a reputation for lacking authenticity and longevity of aging. On the other hand, some winemakers say it shouldn’t matter whether a wine’s flavor was enhanced by wooden chunks or a wooden cask. Do wineries continue to use traditional barrel practices simply for image or is this truly the ultimate method to produce high-quality wine? I will never forget the impressive sight and intoxicating cold, woody smell the first time I walked into an underground cellar lined with hundreds of oak barrels. The craftsmanship that goes into a bottle of wine begins with the majesty of the oak tree growing for a hundred years that is skillfully handcrafted into a few barrels ready when the juice arrives. Grapes and oak have been winemaking partners for centuries, and winemakers worldwide are perfecting the art of balancing the two while creating quality, affordable wines.