A barrel-aged beer is a beer that has been aged for a period of time in a wooden barrel. Typically, these barrels once housed bourbon, whisky, wine, or, to a lesser extent, brandy, sherry, or port. There is a particular tradition of barrel ageing beer in Belgium, notably of lambic beers. The first bourbon barrel-aged beers were produced in the United States in the early 1990s.
Beers can be aged in barrels to achieve a variety of effects, such as imparting flavours from the wood (from tannins and lactones) or from the previous contents of the barrels, or causing a Brettanomyces fermentation. Oak remains the wood of choice, but other woods are in use as well. Chestnut, ash, poplar, cedar, acacia, cypress, redwood, pine, and even eucalyptus have been used for barrel-ageing with varying success.
The flavours imparted by oak barrels differ widely depending on the oak species, the growing area, and how the wood has been treated. New oak barrels can be used for ageing beer, but they are not common due to high costs. Some flavours that new oak will contribute are wood, vanilla, dill, spice, and toastiness.
History
Lambics have been brewed in Belgium's Zenne Valley and Pajottenland since the 13th century. There were at least 300 lambic makers in the region in 1900, both in Brussels and in the countryside. Timmermans is one of the oldest existing breweries, dating back to 1702, and the production of the blended lambic derivative gueuze is believed to have started in the same year.
Eugene Rodenbach started brewing Flanders red ale in the 19th century, after learning how to "ripen" beer in oak barrels in England. Rodenbach Classic contains a blend of young beer with beer matured on oak for two years, whereas Rodenbach Vintage consists entirely of beer that has matured for two years in one selected foeder. Another Belgian sour beer style, Oud bruin is not typically barrel-aged, although there are some examples from both Belgium and North America.
In the German town of Bamberg, smoked beer or Rauchbier has been tapped directly from oakwood casks at the Schlenkerla tavern since the 15th century.
Greene King's Strong Suffolk Ale is an example of an 18th century "country beer". It is blended from Old 5X, which is aged for two years in oak tuns. Large oak vats were once the norm for fermentation and storage of beer in England, a fact made notorious when one of these burst in London in 1814, killing eight people.
In the United States, the historic Ballantine Brewery aged their beer in wooden vats for up to a year. They were originally made of oak, and later of cypress wood. 20th century beer writer Michael Jackson characterised Ballantine IPA as "wonderfully distinctive, an outstanding American ale unique in its fidelity to the East Coast tradition of Colonial ales."
In the era of craft beer, some breweries produce exclusively barrel-aged beers, notably Belgian lambic producer Cantillon, and sour beer company The Rare Barrel. Others also specialise in barrel-ageing particular beer styles, such as Põhjala which has a focus on Baltic porters and Jester King with its Méthode Traditionnelle. International craft brewer, Mikkeller operates a custom barrel-ageing facility at an old shipyard in Copenhagen, Denmark.
In 2016, Craft Beer and Brewing wrote that "barrel-aged beers are so trendy that nearly every taphouse and beer store has a section of them. Food and Wine wrote in 2018: "A process that was once niche has become not just mainstream, but ubiquitous."
Lambic beers of Belgium
Lambics are fermented and aged in wooden barrels similar to those used to ferment wine. The microflora from the wood contribute to a spontaneous fermentation and brewing activity was concentrated on the colder months of the year to avoid spoilage. The barrels used by traditional Belgian lambic breweries can be up to 150 years old, and the lambic ageing process typically lasts from one to three years. Willem Van Herreweghen of Timmermans said: "We have oak and chestnut barrels. Chestnut is neutral and imparts no taste to the lambic. Oak gives a vanilla-like flavour usually described as 'oaky' and, of course, this is the most common type of wood used by lambic makers."