Once your juice has been fermented into wine, it’s time to put it into barrels (if that is the aging method you’ve chosen), a process called “barreling down”. Choosing your barrels can be complex, so I’ll go into a little bit about how and why a winemaker makes the choices they do when it comes to oak.
Why use oak barrels? They not only work as vessels to largely protect the wine from oxygen and spoilage while aging, but they add mouthfeel (in the form of wood tannins), depth (from the charred inside of the barrel), and warm, sweet, spicy aromas and flavors that would not otherwise be found in the wines themselves. Many a winemaker has described using oak the way a chef would use seasoning---to simply elevate, without overpowering, what is already there.
First, there are generally three regions of the world that oak barrels for wine are produced: America, France, and Eastern Europe (mainly Hungary). American oak comes from either Minnesota, Pennsylvania, Virginia, or Missouri. French oak comes from regions all over the country, such as Limousin, Vosges, Nevers, or Alliers. Eastern European oak comes from countries such as Hungary, Slovakia, Russia, or Romania. Just like grapes, terroir plays a big part in the effects you get from barrels from different regions. For instance, climate will affect the grain size of a tree, and larger grains will impart more character than tight grains In general, American oak tends to be more heavy-handed, with graham cracker, vanilla extract, or caramel character; French tends to be more subtle, with vanilla blossom, coconut, or butterscotch character; and Eastern European is similar to French but with more herbaceous character.
Within the different regional selections are the stave-aging selections, usually ranging from 1-4 years. Oak staves for barrels are aged outside in stacks for a year or more to cure the wood. Typically, the longer the aging, the harder the wood and more tight and lean the oak tannins will be. There are also different toast levels: anywhere from light to deep/heavy; convection to fire-toasted to steam-bent staves. Modern cooperages literally have this down to a science. You can even specify whether you want the heads of the barrels (the two flat ends of a barrel) to be toasted or untoasted. Untoasted will impart stiff tannins and a bit of a raw wood flavor to the wine. In general, toasting brings out more of the wood sugars, so the heavier the toast, the more charred and caramelized the flavors and aromas will be in the wine. Lighter toasts have more spice, like cinnamon, clove, or pepper; medium has more coconut or vanilla, and medium plus or heavy will have more toasted marshmallow, caramel, or molasses character.
A winemaker also has to decide what percentage of the lot they want to have in new oak, what percentage will be neutral, and what percentage will be somewhere in between. Oak will impart character until about the 4th use of the barrel, when it becomes a neutral vessel. The first use of a barrel will impart the most character, and loses impact each time it is emptied and washed. For this reason, some winemakers choose to use most or all new oak in each vintage of their wines if they want a strong oak character, and some will choose to use a combination of new, slightly used, and/or neutral oak for a more nuanced effect. Because oak barrels cost anywhere from $600-3000+ each, a lot of wineries hold on to their barrels for many years, and use new oak inserts to rejuvenate their neutral barrels for a fraction of the cost of a new one.
All of these factors come into play when choosing oak for each lot of wine, and for each vintage. It’s a good practice to taste and evaluate what your new oak does to each of your lots a few months after barrelling down for each vintage, making adjustments where necessary. That’s the best way to get to know your wines and how they react to certain oak forest sources, toast levels, and even cooperages, so that you can narrow down your barrel choices until you’ve got your style just where you want it.
In the next series installment, we’ll continue the oak discussion with oak alternatives.