The Influence of Oak on Wine

Once in awhile you’ll purchase a wine that says it was aged in oak, but why do they do that? How does that impart flavor into the wine you’re drinking? Last month, we discussed the influence of oak on wine within the Women’s Wine Alliance of San Diego.

Wine is generally aged in three different types of oak: American, French, and European. White oak is used because it is hard and water tight, whereas red oak is porous and could let air or other contaminants into the wine. Oak has a natural affinity for wine and originally it was used as a transport and storage vessel.

(Two similar Sangiovese wines that were aged in different oak from Altipiano Vineyards)

American oak is most widely used for aging wine because it is the most available. Sometimes wine is aged in new oak barrels, but from time to time vineyards will also age wine in old bourbon barrels. Bourbon can only be aged in new oak and in the 1980’s, bourbon sales were starting to decrease, while California wine sales were starting to increase, so vineyards were buying up all the old bourbon barrels to impart a different flavor into their wines. Today, you’ll usually find American oak barrels used in US, Spanish, and Australian wines.

France has a large growing area of oak. 40% of forests in the EU are in France and 1/3 of France’s forests are oak. At least 200,000 barrels of French oak are sold every year and the US is the primary customer.


(Me, standing in front of oak wine barrels at Ramona Ranch Vineyard)

European oak generally comes from Hungary, Poland, Czech Republic, Russia, and Slovenia. Hungarian and Baltic oak was used in Bordeaux prior to World War I, but its use continues to grow because of availability. Slovenian oak is usually used by Italian producers.

Though wine producers love to use oak in their wine making, there are risks. Oxidation can occur if the wine barrels aren’t topped off. Also, if batonnage, which is the stirring of wine sediment back into the wine, is excessive. The wine could also suffer from brettanomyces which is a microbiological fault caused by rogue yeast.


Toasting a wine barrel during its construction can help impart different flavors to the wine. A lightly toasted barrel can add oaky, woody, and vegetal flavors. A medium toast can add a vanilla or coffee flavor and a heavily toasted oak barrel can add toasty or spicy flavors to the wine.

Certain chemical compounds in the oak can also impart different aromas in the wine. Cis-lactone imparts the aroma of raw oak, trans-lactone of coconut, vanillin of vanilla, eugenol and isoeugenol of spice and cloves, guaiacol and 4-methylguaiacol of smoke, spice, and bacon and furfural and 5-methylfurfural of caramel, burnt sugar, butterscotch and almond.

Depending on your goals, there are alternatives to using oak barrels in wine. There are oak chips, oak inserts and oak essences or powder. Oak chips are usually French or American and have a range of toasts. They are most effective when added at fermentation. They are also 1/20th of the cost of an actual oak barrel. Oak inserts are placed in inert tanks during fermentation or maturation. Oak essences or powder are usually from French and American oak and specific tannins are usually targeted, but there could be problems with clarification and sustainability over time.

So the next time you’re enjoying a glass of oak aged wine, you can smile, knowing why they may have used oak to age your wine and think about what flavors and aromas you’re experiencing.





(Information provided by the Women’s Wine Alliance of San Diego)


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