To oak or not to oak? That is the question today’s winemakers face. Since the advent of concrete and then stainless-steel fermentation and ageing vessels, oak barrels of varying sizes became superbly optional in producing wine. One can make an oaky wine or a vinous delight without a hint of oak.

Before, say, fifty years ago, almost all wine was fermented and aged in wood (although clay vessels like tinajas in Spain and qvevri in Georgia existed). That wood was usually some kind of oak. Exposing the wine to new oak produced one kind of effect (oaky wine), while well-used oak barrels produced another. So, certain places and styles of wine developed, over time, a distinctive flavor associated with oak.

Oaky Flavor Development

Wood, in fact, is essential in the aromas and flavors of not only wines but also spirits, often becoming synonymous with premium quality: the longer a wine, whisky, rum, or tequila ages in barrels, the greater its perceived quality.

You may like oaky wines or you may not. Oaky red wines and oaky white wines also go through fashions, like the wines preferred by wine critic Robert Parker during the 1980s and 1990s. This style became extremely popular, for a while. Now, a lot of people prefer fresher, lighter wines with no oak.

The Big Five white wines and red wines all may be made in an oaky style. These are Chardonnay, Riesling, Chenin Blanc, Pinot Grigio (or Gris), and Sauvignon Blanc for the whites. And Cabernet Sauvignon, Merlot, Pinot Noir, Syrah/Shiraz, and Grenache/Garnacha for the reds. After that, other varieties may or not be made with oak contact.

Torrontés from Argentina, for example, was until recently almost always made with no exposure to oak, but in the past several years some winemakers are successfully experimenting with oak-ageing these white wines. The same is true for Verdejo, whether it’s from Spain or California.

The classic oak barrel stems from that historically used in Bordeaux, France, called a barrique. It holds 225 liters. The size of the barrel affects the infusion of oak compounds based on wine-to-oak surface area. Smaller barrels equals more oaky flavors. Most oaky red wine comes from maturation in barriques.

Tannins and Micro-Oxygenation

Oak vessels impart two elements to both red and white wines. The first is oak tannins, which different from grape tannins in how they taste. Tannins create a drying or rough sensation on different parts of the palate, tongue, and gums. Nick Jackson MW explains that sensing oak tannins occurs mostly on the gums. They “may be perceived by a slight grainy, woody hardness, or even, in bad examples, a sensation of wood splinters hitting the gums.” Grape tannins, by contrast, are more supple. Generally, only new oak vessels will impart substantial amounts of tannins to wine.

The second element is natural micro-oxygenation. This is because oak has pores that allow for some transpiration. The air can and does enter the wine, but slowly in minute quantities. Over time, this process softens the tannins in the wine.

An Oaky History

Over 2,000 years ago, the Gauls stored their alcohol in wood not because they understood science, but because wood was a durable material that could also be rolled for easy transport. When the Romans arrived in 58 BC, they had to admit that this method of storing wines, beers, and other fermented liquids from the pesky Gauls was much more practical, so they adopted it just like they did with the Discobolus of Myron. The Romans realized that these liquids improved in contact with wood, though they didn’t know why, and thus its use spread.

Why is Oak Used?

Wines improve when in contact with wood, but why oak? Many types of wood can be used to age wine (acacia, chestnut, cherry, beech, even pine) but oak is by far the most common owing to its strength. There are various types of oak: Quercus Alba is American oak, very porous, which imparts more intense aromas. Quercus Sessiliflora is French oak, with finer pores, thus offering more subtle aromas. These two are especially used in wines. Oak wood loses its properties over time, so its optimal period for imparting flavors and tannins is during the first three years.

Using Oak is Complex

It’s not just a matter of cutting down an oak, making a barrel, pouring in the white wine or red wine, and letting it age. You may find American Oak used in Europe and French oak used in Napa Valley. After the cooperage, the barrels undergo a preliminary process: they are either toasted or charred. Winemakers use different toasting levels for wine as it adds aromas to the liquid; for spirits, charring is ideal. The charcoal layer inside acts as an active carbon filter, smoothing out the harshness of strong alcohols and rounding them off.

Oak consists of molecules like cellulose, hemicellulose, and lignin. Despite being hydrophobic, these activate with toasting, releasing compounds affecting wine tastes such as dimethylpyrazines (adding cocoa or coffee notes); phenolic aldehydes (imparting vanilla aroma); furans (contributing toasted almond aromas); and maltol (responsible for caramel aromas). The tannins in the wood activate with oxygenation, producing bitterness, astringency, longevity, and color. Other oak components, like gallic and ellagic acids, coumarins like scopoletin and aesculin, and flavanols like catechin, may add subtle amounts of astringency, acidity, and bitterness to the wine.

Physically, wine stored in a barrel undergoes evaporation, concentrating aromas and flavors. Evaporation largely depends on the humidity level in the cellars, so it must be carefully controlled. Lastly, a slight precipitation of color molecules like anthocyanins stabilizes its visual appearance.

Moreover, the exposure time remains crucial: the longer the liquid is exposed to these processes, the more they impact it.

What Does an Oaky Wine Taste Like?

Oak contains and imparts vanillin, which as the name suggests, tastes like . . . yes, vanilla. Other flavors that impartedby oak include, butter, mocha, caramel, toffee, and honey aromas or flavors.  Vanilla will stand out in both red wines, like Cabernet Sauvignon or Syrah, and white wines, like Chardonnay or Sauvignon Blanc. Remember, you may well also feel those oak tannins on your gums in combinations with the flavors.

Bevinars’ resident expert and wine professor Mark Oldman comments provocatively that “Oak in wine can be slutty,” when its overdone. But, “When it is in the right proportion, a wine’s contact with oak barrels adds a creamy, vanilla-tinged dimension to a wine, whether white or red.” Your wine should taste like an oak two-by-four, unless you’re really an oaky fan.

The best way to tell if you like oak or not is to seek out one oaked Cabernet Sauvignon and one not as well as one oaked Chardonnday and one not. Taste them side by side. You will immediately detect the consequences of oak ageing. Then, making your future buying decisions on that basis, while also considering any possible food and wine pairings. French oak and American oak can also impart distinct flavors.

Winemakers need to proceed with care when adding oaky elements to lighter wines, red and and especially white. Oak can be overpowering and may also mask other flavors. Most rosé wines are not oaked, with a few excpetions.

Finally, here’s are chart for wine lovers of the oakiest of oaky wines, starting with those that can hold up to the most amount of oak contact. This chart is for oaked wines, indicating the likely level of oak compounds like vanillin and tannins that the wines can manage while remaining aestheitcally appealing. Always check the label to see if the winemaker used French oak barrels or American oak, or even an Eastern European oak.

Oak level Red Wine White Wine
High Napa Cabernet Sauvignon California Chardonnay
High Bordeaux blends Bordeaux Sauvignon Blanc
High Rioja Reserva and Gran Reserva Traditional Rioja Whites
High Argentine Malbec Australian or California Viognier
Medium Grenache/Garnacha Chenin Blanc
Medium Tempranillo Pinto Grigio
Medium Shiraz/Syrah Dry Riesling
Medium GSM blends Godello
Medium California Zinfandel Semillon blends
Medium Carmenere Rhone white blends
Medium Merlot Bourgogne whites
Medium Sangiovese Torrontes
Medium-Low Pinot Noir Gewutztraminer
Low Mencia Fiano
Low Rioja Joven Gruner Veltliner
Low Modern, fruity Grenache Pinot Blanc
Very Low Gamay Noir Albariño

Charlie Leary

A member of the Circle of Wine Writers, Charlie Leary has directed restaurant wine programs in the US, Canada, Costa Rica, and France. In the mid 1990s, while earning a PhD from Cornell University, he made artisanal cheeses and counted among the first North Americans inducted into the Guilde International des Fromagers; he later planned, planted, and managed an IGP vineyard in Andalusia.

His book-length guide to worldwide wine education programs (Leary’s Global Wineology) was first published in 2022, in part based on his experience earning numerous wine certifications. His feature articles have appeared in Decanter magazine, Jane Anson’s Inside Bordeaux, JancisRobinson.com, Sommelier Business, Hudin.com, and Tim Atkin MW’s website, among others. He recently consulted for the wine metaverse startup Second Winery and wrote a detailed report on the history of wine sensory analysis for the Wine Scholar Guild. Charlie now lives in Panama, where he offers wine classes, and is writing a book on the philosopher Montesquieu as an eighteenth century winegrower. IG: @bacopty