FAQ: Knock on Wood

Everything you ever wanted to know about wine barrels

FAQ: Knock on Wood
The barrel room at Bordeaux's Château Calon-Ségur in St.-Estèphe (Deepix Studio)
From the Mar 31, 2017, issue

How do you make just about all of the world's finest ageworthy wines? Put some wood to 'em. Oak, specifically. But while barrels are as synonymous with wine as corks, we rarely come face to face with them outside of the occasional garden planter. Take a look at barrels behind the scenes.


Dear Dr. Vinny,
How does aging wine in an oak barrel affect the way the wine tastes?
—D.T., Porter Ranch, Calif.

Dear D.T.,
Wood barrels can be a big part of a wine's profile—they're kind of like the spice rack of winemaking. A barrel can infuse the wine stored in it with different flavors and textures, depending on how old it is, what kind of wood it's made from, how toasted it is, and how long the wine sits in it.

The newer the barrel, the "stronger" it is, and the more flavor it imparts. After three or four years, it tends to lose its potency, becoming what's known as "neutral" oak. The most obvious influence of oak is that it imparts flavors and aromas to a wine: toast, vanilla, cedar, spice and smoke notes are common. Barrels can also impart additional tannins and influence a wine's texture, contributing to complexity.

Most wine barrels are made from 60- to 200-year-old oak trees from France or the United States, but oak from the Slavonia region of Croatia is also highly regarded. Speaking in broad generalities, French oak (Quercus petraea) barrels typically impart more subtle and spicy flavors, offering silky textures, while American oak (Quercus alba) barrels are known for stronger flavors such as vanilla and coconut, resulting in wines with a more creamy texture.
—Dr. Vinny


Do you know your head from your bung hole? You can be sure that a cooper, or barrel maker, does. Let's talk shop.

Head: The two flat sides of the barrel; occasionally repurposed in retirement as serving trays

Hoops: Steel bands secured around the barrel with rivets; hooping was once performed by a cooper's assistant, known as a hooper

Stave: Individual curved slats running lengthwise; typically the only part of the barrel that is toasted

Bilge: The widest section of the barrel, where most of the wine's sediment is collected as it ages

Bung Hole: This opening, sealed with a large cork or other stopper, allows the winemaker to sample an aging wine using a large pipette known as a "wine thief."


During the barrel production process, the barrel's interior is "toasted"—either over an open flame or with an oven. Toasting both mellows the tannins in the wood and augments the flavors the barrel might impart, from raw wood to more spicy, vanilla notes—toasting actually helps release vanillin from the cellulose in the wood. There are varying degrees of toasting, from a light toast to a heavy toast; as the level of toast increases, the resulting aromas and flavors can evolve from baking bread and brioche to vanilla, caramel and butterscotch to coffee, cocoa and dark chocolate.


The high-end, oak-friendly wines of Bordeaux and Napa are most often aged in barriques, as the smaller the barrel, the greater the ratio of wood to wine and, consequently, the more concentrated the oak influence. Prefer a ratio with more wine to wood? The world's largest barrel is Germany's Heidelberg Tun, built in 1751, with a capacity of 220,000 liters. However, it's been used far more often as a dance floor than as a wine barrel.

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