Lotte Peplow, the Brewers Association’s American craft beer ambassador for Europe, takes a deep dive into barrel-ageing in the American craft brewing world

Photograph: Nic Crilly-Hargrave

The practice of fermenting beer in wooden vessels has been around for hundreds of years, but it wasn’t until the 1990s that American craft brewers started experimenting with ageing beer in used spirit barrels.

Today, barrel-aged beer styles produced by American craft brewers regularly win top honours in prestigious international beer competitions. It’s yet another example of American craft brewing’s relentless innovation.

Worth seeking out for their incredible complexity, depth of flavour, and subtle nuances of character, barrel-aged beers lend themselves perfectly to the cold winter months.

A variety of beer styles are suitable for barrel-ageing in wood, but sour beers and beers with high alcoholic strength are the most common. Barrels for sour or ‘wild’ beer may be used several times over, while barrels that formerly held spirits, such as bourbon, tequila, or gin, are rarely used beyond their first or second fill.

Many American craft brewers consider barrels to be the fifth ingredient of beer and not simply a storage vessel. They source barrels with as much care and attention as selecting their annual hop varieties. Each barrel is unique, which means experimentation and flexibility is an essential part of the barrel-ageing process.

Most distilleries or vintners will sell used barrels, but brewers will go to great lengths to secure the barrels they have in mind for a particular project. The Bruery, a craft brewery in Orange County, California, buys barrels by the truckload and selects the exact barrels for each project depending on the sensory analysis of the barrel.

Brewers from Great Divide Brewing Co, in Denver, Colorado, have been known to travel overseas (to Ireland) to hand pick barrels for their partner programme with Jameson whiskey, while Eric Ponce, barrel program manager at Firestone Walker Brewing Co, in Paso Robles, California, has been sourcing different types of spirit barrel from around the world for many years. “Every barrel needs to meet our requirements, as in the distillery we choose, how long the spirit was matured in barrel, barrels should not be rinsed after emptying, etc,” he says.

Oak is full of flavoursome, aromatic compounds that can add another level of depth and complexity to a beer, making it the preferred wood for barrel-ageing for many brewers. Jeremy Grinkey, director of production at The Bruery, explains: “Oak is easy to work with, compared to palm and other woods. It’s fairly common across Europe and has very tight grains, lending to its liquid holding properties. Having said that, we’ve used cherry and acacia barrels, too, for fun.”

Equally important to the flavour of the barrel is the art of blending different beer together to create a desired result. A number of base beers may be ageing in different barrels, some of which may be fresh barrels, to give a high intensity of oak/spirit flavour, while others may have been used before to give a lower intensity of flavour. It is the skilful blending of these beers by the brewer that creates the alchemy.

Other flavours may be added along the way, such as cocoa, coconut, or coffee beans, to add further levels of complexity. Eric, at Firestone Walker, explains: “Blending starts with the flavour of the barrel. If the barrel is not quality and does not impart the flavours and aromas we are expecting, that particular barrel will be discarded, but that predicament doesn’t happen often.”

So how much time should a beer spend aging in a barrel? There is no definitive answer and it depends on when the beer is ready.

“It’s all about taste,” says Eric. “We have a concept of how long, depending on the base beer and type of spirit barrel, plus we measure liquid from each barrel to get analytical and micro specs, but overall it’s about taste.”

At the Bruery, sours age anywhere from six months to four years, and stouts, barley wine etc will age between one and three years. Some beers are ‘double barrel-aged’, which means the beer has been moved into a fresh bourbon barrel after about a year for extra extraction.

Simply leaving a beer in a barrel and hoping for the best is not going to cut it. Barrel-ageing presents a number of challenges, as Bryan Slekes, senior director of finance at Great Divide, acknowledges. “Time, consistency, and efficiency are the key challenges in barrel-ageing. Beer often takes a year in the barrel before we get what we want out of it. Every barrel is different and sometimes individual barrels don’t work out.”

Jeremy Grinkey, at The Bruery, adds: “Planning and understanding the risk factor is huge. It’s hard to know what something will taste like in two years’ time. Just because beer is put in a barrel doesn’t always make it better.”

Fortunately for beer lovers in the UK, barrel-aged beers from Firestone Walker, Great Divide, and The Bruery, among others, are available from select independent bottle shops and online retailers.

About the Brewers Association

The Brewers Association (BA) is the not-for-profit trade association dedicated to small and independent American brewers, their beers and the community of brewing enthusiasts.

The BA represents 5,400 US breweries. The BA’s independent craft brewer seal is a widely adopted symbol that differentiates beers by small and independent craft brewers.

The BA organises events including the World Beer Cup, Great American Beer Festival, Craft Brewers Conference and BrewExpo America, SAVOR: An American Craft Beer and Food Experience, Homebrew Con, National Homebrew Competition and American Craft Beer Week.

The BA publishes The New Brewer magazine, and Brewers Publications is the largest publisher of brewing literature in the US.

Beer lovers are invited to learn more about the dynamic world of craft beer at CraftBeer.com and about homebrewing via the BA’s American Homebrewers Association and the free Brew Guru mobile app.