For millennia, the question of what to ferment, age and transport wine in has plagued the minds of winemakers around the world. Over time, winemakers have learned that the role a vessel plays in the winemaking process is much more than just providing a watertight space. Instead, the various different materials, which can be used to manufacture such vessels, including clay, oak, concrete and later stainless steel, have a varying influence on the flavor and style of a wine.
If you’ve ever taken the time to visit a winery, a wine tasting event, or even just read the label on the back of a bottle of wine, it’s almost certain that you’ve come across references to such vessels.
In particular, it’s likely that you’ve come across a reference to oak barrels, usually American or French, and how they’ve influenced the wine that you’re about to drink. But does it really make that much of a difference? And if so, why?
American vs Eastern European vs French Oak
There are, in fact, three major types of oak barrels used in the production of wine, American oak, French oak and Eastern European oak. The type of barrel chosen by a winemaker depends on a number of factors including the influence that they want it to have on their wine and how much it’s going to cost them.
The difference between each type of barrel comes from the species of oak used to produce the barrel and the climate in which the tree survived.
The main species of oak used for American barrels is the white Quercus alba, which is grown in the Eastern United States. Meanwhile, in France and Eastern European nations such as Romania, Croatia and Hungary, both the Quercus robur (common oak) and Quercus petraea (white oak) species are grown and used in barrel-making, with Quercus petraea considered the superior of the two.
Generally speaking, the French Oak species are much more expensive than the American counterpart owing to the amount of usable wood per tree. There is a much higher “wastage” (technically nothing is wasted, instead we are referring to the percentage which can be used for barrel-making) associated with French Oak, which consequently pushes prices up.
A Question of Grains
One of the main distinctions between the different species of oak, when it comes to winemaking, is the space between grains (annual growth rings of a tree).
Quercus robur and Quercus petraea have finer grains, which stop wine from penetrating too deep during the maturation period. This provides a smaller surface area with which an aging or fermenting wine has contact with, resulting is a subtler influence and altogether smoother flavor. (See also "How Do All Those Aromas and Flavors Get Into Wine?")
Quercus alba, on the other hand, has a wider grain, allowing more interaction with wine. This increased surface area enables a bolder influence on wine, with a stronger extraction of flavors and tannins from the oak.
Where is French Oak Grown?
Around a quarter of France (approx. 14 million ha) is comprised of forestland, which accounts for nearly half of all forest in Europe. Roughly one-third of this forest area in France is comprised of oak trees.
The oak used for in the production of barrels comes from one or more of the country's major forests: Allier, Limousin, Nevers, Tronçais and Vosges. The wood from these regions has different characteristics, which are also influenced by the amount of toasting received during barrel production.
When selecting barrels, winemakers must take into account the species of oak, where it was grown and the degree of toasting when predicting how it will influence their wine.
Oak Barrel Toasts Levels
There are five main kinds of toast levels:
Light toast is used for wines that need fewer aroma enhancements and have higher tannin content.
Medium Plus (+)
Heavy toast breaks down the complete chemical components in the oak and creates more complexity in aroma and flavor. There are fewer tannins to impart to the wine structure, and wines aged in these barrels possess notes of campfire, smoked meat or jerky, coffee and dark chocolate.
Toasted heads require that only the tops and bottoms of the barrel are toasted, allowing for greater consistency for red wines with less tannin. The tops and bottoms of barrels are called "heads".
The Major French Oak Forests
Limousin (li-moo-sahn) is a forest in the central region of France. Both the Quercus robur and Quercus patraea species are grown here, though barrels made in this region are not commonly used in winemaking, as the relatively wide grain of the oak here imparts flavors, which are considered too bold and simple. Instead, these barrels are used in the production of Brandies in Cognac and Armagnac.
Nevers (ne-vere) is also located in the central region of France, North East of Limousin. Oak grown here tends to be medium-to-tight grained and barrels made using Nevers oak are renowned for contributing spicy, almost cinnamon-like flavors.
Allier (ah-leay) is situated between Nevers and Limousin. The oak here is fairly similar to that of Nevers, though it has an even tighter grain structure. Barrels made using Allier oak are well regarded for the finesse in which they impart spicy flavors and aromas, which can otherwise dominate and ruin wines.
Tronçais (tron-say) is a renowned subsection of the Allier forest, which produces grand oak trees of impressive size and a prized tight grain. Troncais oak is considered one of the finest woods to make barrels from, and barrels produced here are used for the aging of the finest and most expensive Bordeaux wines.
Vosges (vohj) is located in Eastern France in a low mountain range of the same name. The oak here is tight-grained and similar to the wood from Never and Allier, though slightly wider-grained. Vosges imparts a little color and very smooth tannins to wine and is often used for Chardonnay and Pinot Noir wines.