At harvest, when the fruit arrives at a winery, the winemaker begins making dozens of decisions that will affect the final product. Foremost is deciding upon the container in which to age the wine when fermentation is complete, and for how long. The ageing process will last anywhere from several months to several years and will significantly affect the final profile of the wine.
Stainless steel vats are often used by winemakers seeking to preserve fresh fruit flavors in a wine. The vats prevent the wine from interacting with oxygen and their temperature is easily controlled, which also helps achieve the goal of preserving fruit flavors.
These days more and more winemakers are utilizing containers known as eggs—a reference to their round, oblong shape—that are made of concrete. The material doesn’t impart any flavor to the wine, but it does allow the wine to “breathe” just a little bit. This small amount of oxygen can help dissipate sulfuric aromas and release compounds responsible for more pleasant aromatic qualities. Additionally, the spherical shape of concrete eggs keeps solids in the wine suspended, which can add both flavor and texture.
Still, when many wine drinkers think of a winery, a room full of oak barrels comes to mind. If one heads up to Napa or is lucky enough to visit another world-class region such as Burgundy or Bordeaux in France, small, oak barrels will seem ubiquitous. However, purchasing new, sweet-smelling oak barrels every year is wildly expensive and is actually quite rare. There are a couple of different reasons for this.
A new French oak barrel costs at least $1,000 and as much as $4,000 with shipping factored in. From a financial standpoint, this means it is only suitable for wines that can fetch very high prices in the marketplace. Beyond the price tag, new oak barrels impart significant amounts of flavor to a wine. During the first vintage in use, the freshly toasted barrel will give off notes of vanilla, cinnamon, clove, and toast that could overwhelm many styles of wine. Once the barrel has been used for at least a year, this effect will begin to diminish. After about three years, the barrel will be considered neutral, meaning it will still let the wine interact with small amounts of oxygen, but it won’t impart any more flavor to a wine that goes inside of it. In some regions, wine producing families are known to keep the same barrels in their cellar for up to one hundred years! When barrels are used so extensively, particles from the wine accumulate and adhere to the inside surface, creating an almost glass-like coating and minimizing the effect of ageing the wine in oak.
While the condition of the barrel determines how much flavor it will add to the blend, the size of the barrel determines how much oxygen will come into contact with the wine. This has to do with the surface-to-volume ratio. The smaller the volume, the greater the exchange of oxygen between the staves and through the wood grain will be. This micro-oxygenation process softens the structure of the wine. The barrels we might be most familiar with hold about two hundred and twenty-five liters. Two-thousand-liter barrels are not uncommon and some are even much larger, minimally affecting the profile of the wine.
The age and size of the barrel are only two factors that influence the style of the wine. The origin of the wood is important. too. Barrels from different forests in France are said to have their own characteristics. Barrel staves are dried and toasted prior to finishing. Both of these processes change the characteristics of a barrel, and thus, a wine. America also produces oak barrels. The wider grain of the oak means it gives an especially brash flavor to the wine. For this reason it is most suitable for full, bold wines and has been traditionally used for wines such as Rioja from Spain, Australian Shiraz, and California Zinfandel. Croatia and Hungary also craft oak barrels with unique flavor profiles. Acacia barrels have experienced a recent renaissance amongst winemakers around the globe. They are especially useful for adding spice to Sauvignon Blanc where oak might overpower it.
To ensure a wine is not overpowered by oak flavors or not subjected to too much oxidation during the ageing process, it is common for winemakers to employ a variety of ageing vessels, made of different materials and sizes. Wine from each of these is then blended before bottling. Depending on the style, the wine may now be ready to drink, or still require several years in the cellar, depending on another complex set of factors. Patience really is a virtue.