When we think of the cellar in a winery and imagine vintage upon vintage of lovely wine aging and refining itself, a clear image comes to mind: oak barrels. The image is so pervasive that some people are surprised to learn of the role of other methods such as stainless steel fermentation tanks or clay amphora in some wineries. 

Regardless of what technology throws our way, the oak barrels remain ubiquitous. They have played a starring role in winemaking for centuries, and will likely remain so for a long time to come. 

“Oak tends to “soften up” a wine, making it smoother, less harsh and more quickly drinkable,” say the writers at Main Brew, “Oak can turn an ordinary wine exceptional, and can make a below-average wine taste much better.”

It was the special privilege of the Wine Revealed crew to visit the cellars where many fine wines are made. Again and again, we saw oaken barrels employed in the aging of these wines, from French barriques to large casks.

Prior to the 1600’s, wines were usually aged and stored in clay or glass vessels. Both are effective, with clay being a bit more porous and allowing some oxygenation of the wines. But there is a big problem with these materials: breakability. 

Thus the transition to oak barrels began. They had been widely used throughout Europe as general-purpose shipping containers, and goods were stored and moved from place to place in them with relative ease. Employing them for wine became an easy choice for people at the time. 

Then something amazing happened: people discovered that oak added flavor to wine, and they grew to appreciate it very much! It added one more dimension to an already beautiful thing by contributing aromas and flavoring, even adding lovely nutty, smokey, or vanilla notes to the wines within them. 

The oak added a bit of tannins to allow for longer aging, balanced out strong fruity flavors, and made the overall wine drinking experience more nuanced and pleasurable. It was clear from the beginning that oak was here to stay. 

So powerful is the love for oak on our palates, that oak chips or dust are added to steel fermentation tanks, and even the most rudimentary of wine production often involves a step to at least add that flavor to the wine. 

Choosing which kind of oak to use is an important decision to be made in the elaboration of wines. Federica Mascheroni Stianti of Castello di Volpaia winery, Tuscany explained to us how her team tasted wines from different barrels, but liked the French oak the best, so all their oak is French. 

Cecilia Leoneschi of Castiglion del Bosco, Tuscany, showed us her winery’s barriques, large casks, and cement tanks. She explained that they chose to use French oak because France has the perfect climate to grow the oaks and age the wood. 

Leoneschi added that the barriques allow more oxygen to get to the wine. This affects the color and roundness of the wine. The large casks allow less oxygen and age the wine more slowly. 

French oak is known to impart hazelnut and smoke flavors, while American oak gives notes of coconut and vanilla. Slavonian oak is another popular option that we frequently encountered in Italy, and it is used throughout Europe. It is harvested from forests from Slovenia, Bosnia, Croatia, Hungary, and other areas. It is noted for its more subtle flavors and softer tannins.

Oak has a certain amount of porosity which can contribute to the oxygenation of the wine. Some oaks are more porous than others, so the decision of which oak to use should be carefully weighed in consideration of the end goal. For long aging, less oxygenation is desirable, while for a wine meant to be drunk young, a little more is beneficial. 

Cask size must also be taken into consideration. A smaller cask allows for more direct contact between wood and wine, while larger casks will allow for less direct contact. Likewise, the age of a cask is important to consider. Newer oak will impart stronger flavors, while older barrels will become more and more neutral over time.

Often when barrels are built, the oak on the inside is toasted to add new flavors and enhance existing ones. The process is simple: some sort of open flame or blow torch is used, and the desired amount of toasting – from light to dark – is evenly applied. 

This process adds some wonderful flavors that carry over into the final product: clove, cinnamon, honey, caramel, coffee, cocoa, and molasses are just some of the flavors imparted by this process. These flavors differ depending on the intensity of toasting, and winemakers choose accordingly when matching the flavors to the desired end product. 

People have come to expect the taste of oak in many wines, and some are even disappointed or feel a wine is incomplete if they don’t taste the oak. However, it is worth trying wines that have not been oaked to see how they compare. 

Many wineries are releasing unoaked Chardonnays, for example, so that the fruit and acidic qualities of the wine can shine through. An oaked Chardonnay will have toasted and nutty aromas and flavors, while the unoaked will be more fruit-forward, and flavors like peach, apple, and pear will be noted. These are gaining in popularity and appreciation, and are a testament to the wide variety of personal tastes that wine consumers may have.

If you are curious about the oak used in your favorite wine, the winery’s website will likely contain helpful information about the type of oak and even the degree of toasting it has undergone. Start looking for and noting the corresponding aromas and flavors as you taste the wine, and jot your impressions down in your tasting journal. Oak is a delicious new avenue to explore as your love of wine tasting grows!