Oak has played a fundamental role in winemaking for centuries, first as a storage vessel, and more recently as a way to massage a wine's texture and flavor. These two effects of oak aging have only been well understood for the better part of a century, and the general principles that govern their use are surprisingly simple.

Tight Grain, Medium Grain, and Loose Grain Oak

There are three aspects of oak barrels and oak aging that are worth taking an in-depth look at. Today we will take a look at the different types of woods used to produce barrels for aging wine. The following emails will focus on both the seasoning and toasting of the wood used in the production of barrels, and their effect on the flavor and texture of wine.

Much of this discussion focuses on the difference between what is called French oak, the preferred types of oak around much of the world, and American oak. This is not to say that American Oak is a lesser oak, it simply impacts a wine differently. Wineries, very important ones at that, around the globe rely on the influence of American oak, so each email will also include a pair of specific recommendations to help you further your understanding of the nature of American Oak.

What to expect: American Oak

American Oak barrels have long been thought of as a cheaper, less worthy alternative to French oak when it comes to making barrels for aging wine. This is partially because the American Oak barrel industry was originally based on producing barrels for spirits, where finesse and delicacy took a back seat. As American coopers have adopted the refined techniques perfected over the course of centuries by their European counterparts, their barrels have begun to rival some of the worlds finest. The fact that they can cost half of what Imported French oak barrel costs has also been instrumental in the renaissance of these fine barrels.

How Oak works and why it is not all the same.

Oak barrels are porous. The loss of wine by evaporation, called the angel’s share, and the resulting introduction of oxygen into a barrel allows for complex chemical reactions to take place that can soften the tannins in a wine.  If a wine is stored in an new oak barrel, the wood tannins will leach out of the staves that make up the barrel, and will actually make the wine more tannic, however there comes a time when the oxidative effects of barrel aging soften tannins faster than they are absorbed by the wine.

In plainspeak that merely means that a wine ageing in a barrel can become more tannic as it absorbs wood tannins before softening due to the affects of oxygen. The type of oak can help determine when this point is reached, as one of the great variables among specific types of oak is the tightness of the grain, and thus the rate at which wine evaporates.

Oak is generally broken down into two Groups, American and French, though there are in fact many forests were wood is cut for the use in wine production.

American Oak (AKA Quercus Alba), is a rather wide grained oak with assertive flavors and relatively low porosity. It is high in lactones that can have a sweetening effect on wine. Typical classic descriptors for flavors imparted by American oak include: Coconut, Vanilla and Dill.

French Oak can be broken down into two different species
  • Quercus Robur – Also known as Limousin Oak – a looser grained French Oak
  • Quercus Sessiliflora-  AKA Nerver, Allier or Troncais – A tightly grained French Oak.
Both of these groups tend to impart a subtle spiciness to wines with notes of dried ginger, clove, cedar, and cigarbox being among the most common.

Slavonian – Generally used in the production of large botti, barrels that typically range from 1500 to 8000 liters used primarily in Italy’s Piedmont region. This oak has a tight grain with moderate tannins and limited aromatic compounds. Large Botte are typically used for decades and are prized for their neutral character and ability to slowly, and steadily allow the wine to breath.

Hungarian - Like most forests that fell behind the Iron Curtain, those of Hungary have suffered through several decades of mismanagement but are slowly emerging as an alternative to French Oak. The grain and structure of this type of wood is very similar to that of Nevers Oak but with a more aggressive flavor profile.

Portuguese– In the search for less expensive alternatives to French oak several winemakers have begun experimenting with the oaks of Forests all across Europe. The Portuguese oak produces rather aggressively oaky and spicy wines.

The flavors imparted by oak barrels depend not only on the type of oak used, but also on how the wood was seasoned and even on the specific steps taken to form and complete the barrel. We will take a look at those details in an upcoming email but for now it’s time to turn to a pair of American producers who have used the distinctive quality imparted by American oak barrels as a trademark, helping define their styles and setting them apart from the pack.

This is part three of a four part series.

Read Additional reports in this Series on Snooth.

Part One: Wine 101 - How to speak wine and "Really" taste wine

Part Three: Wine 101 - Oak Structure and Seasoning

Part Four: Wine 101 - Toasty Oak and why it's not all good Coming Soon

American Oak has Helped to Define the Style of many American Wineries

2005 Silver Oak Aleaxander Valley Cabernet Sauvignon
Classic aromas of light dill and oregano, enmeshed in slightly charry, marshmallow/vanilla oak greet the nose. In the mouth this is smooth and velvety with a sweet, easy character and good length to the somewhat simple toasty, black cherry fruit.

2006 Ridge Vineyards Geyserville

Huge, brambly, fruit tones on the nose with hints of dill, cocoa and creamy oak, are followed by a light layer of vanilla and spice over the blackberry, boysenberry fruit on the palate, all cut with a mineral vein and excellent top notes of spicy red berries, leather, and dried floral notes.

Jois us next time when we take a look at how proper seasoning of oak staves makes a difference, and can make or break a wine.