Barrel-Aged Beer: Bourbon Barrels, Wood and Time

Barrel-AgedBeer

Barrel-aged beer is beer that has rested in a wooden barrel, usually oak, long enough to pick up flavor from the wood and often from whatever the barrel held before. The most famous version uses barrels that previously held bourbon, which add vanilla, caramel, toasted oak and a distinct whiskey character to the beer.

It is one of the slowest corners of brewing. A barrel-aged beer typically spends months in wood, and the brewer cannot rush or fully predict what each barrel will give.

Oak changes beer in a few ways at once.

Flavor from the wood itself. Fresh oak can taste raw or like fresh-cut lumber. Barrels made from toasted or charred oak contribute gentler, sweeter notes: vanilla, caramel, butterscotch, toasted bread or nuts, and sometimes cocoa or coffee. The heavier the toast or char, the more of those dessert-like flavors you get.

Tannins and texture. Wood tannins add structure and a slight dryness, and some astringency is normal.

Slow oxygen exposure. A wooden barrel is not perfectly airtight. Over months, small amounts of oxygen enter, which can help soften rough edges in strong beers. Too much becomes a flaw: the BJCP guidelines treat excessive oxidation or unplanned sourness as faults in a wood-aged beer.

Darker color. Toasted and charred wood often darken the beer a shade.

Not every wood-aged beer uses a whole barrel. Brewers also use oak chips, cubes, spirals or staves inside a tank, which gives wood character with more control and less time.

Under US rules, bourbon must be aged in charred new oak containers. Once a barrel has held bourbon, it cannot be used to age bourbon again. That leaves a steady supply of used barrels, many of which historically went to Scotch whisky makers and other spirits producers, and some of which now go to breweries.

A freshly emptied bourbon barrel still holds whiskey soaked into the wood. Fill it with beer and that residual spirit comes out along with the char and oak flavors. The BJCP guidelines say the spirit character in these beers should be noticeable but balanced, not like drinking a shot.

Brewers use other spirit and wine barrels too: rye whiskey, rum, tequila, brandy, port, sherry and wine casks all show up. Each adds its own signature. For more on the overlap between beer and spirits, see beer and bourbon cask finishes.

Big, rich beers handle wood best. A light lager would be flattened by bourbon and char; an imperial stout or barleywine has enough malt, alcohol and body to stand up to them. Common choices:

• Imperial stout: the classic. Roast and chocolate meet vanilla and bourbon. See porter vs stout.
• Barleywine and old ale: caramel and dried fruit flavors pair naturally with oak.
• Strong Belgian-style ales: see Belgian tripel and dubbel.
• Sour and wild ales: some styles, such as Flanders red and lambic, have wood built into their tradition and are judged separately from wood-aged beer.

For centuries, wooden casks were simply how beer was stored and shipped, and wood flavor was usually incidental rather than the goal. The modern idea of aging beer in wood specifically for flavor is much newer.

The American barrel-aged movement is usually traced to Chicago. Goose Island has long dated its Bourbon County Stout to 1992, though research by beer writers points to 1995 for its first public appearance. The barrels reportedly came from Jim Beam after a beer-and-bourbon dinner, with Master Distiller Booker Noe sending empties to the brewery. Around the same time, Samuel Adams released Triple Bock in 1994, a very strong beer aged in whiskey barrels. Whichever came first, bourbon-barrel stout took off and became one of the most sought-after categories in American craft beer.

Most barrel-aged beers are strong, so they are usually poured in small servings and sipped slowly. A slightly warmer serving temperature brings out the vanilla and oak; see beer serving temperature. A snifter or tulip helps with aroma; see beer glassware.

Many strong barrel-aged beers age reasonably well in cool, dark, stable storage, though hop-forward beers do not. See how to store beer.