Why is oak significant to wine?

One of the largest influences winemakers can have on the flavor and characteristic of a wine is choosing the type of material the wine is aged in during the bulk aging stage. In fact, taste is the most important reason that oak is used to make wine barrels. It contributes positive flavor characteristics that are either leached from the wood itself or produced through the process of oxidation. Most wines that are aged in wooden barrels are aged in oak. Barrels made from wood were first utilized by Roman winemakers to store and age wines. Chestnut, pine redwood, apple wood, cherry wood, have been used to make wine barrels, but none of them have the same combination of properties that make oak such a viable material for aging and storing wine. Often these other woods will leach excessive tannins or off-putting flavors or colors into the wine. Through thousands of years of trial and error, oak has come to be the standard type of wood used to make wines for some major reasons.

In fact, in terms of physical properties oak is a hard wood and can stand up to significant abuse. It is nonporous so it will not leak; yet it still allows a small amount of oxygen to penetrate into wine, causing a maturing effect. It contains tannins, which can add texture and structure to wines, and it is malleable or flexible under the right conditions, since the staves or boarders that make up the rounded curves of a barrel are not carved into that shape, but bent into it.

Availability is another important factor as to why oak is so valuable. Old grown forests and major barrel-making facilities (called cooperages) are found in two of the world’s top five wine-producing counties: France and The United States. This means the barrels are made relatively close to where the wineries need them. French oak is far more commonly used for higher-quality wines. It contributes elegant vanilla notes and flavors of baking spices like cinnamon, cloves, and nutmeg. American oak is not as widely used, because it has more aggressive flavors like strong vanilla character, toasted coconut, and dill. In some cases winemakers will use barrels from sources other then France or The United States to age their wines. For instance, Slovenia and other Eastern European regions also provide oak barrels for wine making with more neutral character and comparatively inexpensive supply of oak barrels. Due to different growing conditions, the actual source of wood used for a barrel can play into the types of flavor it might contribute.

Also, the most important flavors from oak aging are those associated with the wood itself and with how the barrels are made. General wood flavors would include those reminiscent of oak, cedar, sawdust or a cigar box. Depending on where the oak for a barrel is grown, it might contribute flavors such as cinnamon, cloves, nutmeg, black paper, toasted coconut, or even dill. It is crucial to know that, the fewer times a barrel is used, the more flavor it has to contribute. As wine ages in a oak barrel, it pulls flavor from inside of the barrel, subsequent wines in the same barrel simply have much less access to flavor, as it has already been leached away. Therefore, multiple and significant decisions must be made by a winemaker who decides to age his or her wines in oak barrels.