Barrel aging: the global trend in brewing

Barrel aging: the global trend in brewing
© Stone Brewing

Once upon a time, wooden barrels were simply cheap ways to transport goods. Today, creative brewers let their beers age in these wooden vessels for months at a time to produce complex taste adventures. But they need an array of knowledge and experience to pull off the trick.

Wooden barrels have become a rare sight in the brewing business. The earthy containers, which, according to legend, were developed by the Celts to transport goods, are generally used today as props for festivals or in intimate little taverns. The traditional wooden barrel has been drummed out of service – particularly in industrial beer production – for practical reasons. Metal and plastic barrels make more sense.

“Barrel aging” requires know-how

In their search for the next great taste sensation, craft brewers have rediscovered the qualities of the nearly forgotten wooden barrel. But these brewers are not interested in the eye-catching storage potential of these casks. Rather, they view them as the ideal container in which they can mature their beers and develop complex, completely individual aroma brews. Adventuresome brewers around the world, particularly in the United States, Belgium, the Netherlands and even Germany, are discovering the virtues of barrel-aged craft beers. Particularly now, as winter sets in, such beers – which usually come with an added jolt of alcohol – are the perfect digestif or the ideal fireside companion in the evening.

The art of barrel aging involves something much more than simply pouring the brew into a wooden container. Experts say the art of barrel aging requires a great deal of know-how and can certainly turn out very badly if brewers are not careful. Martin Zarnkow, the Head of the Weihenstephan Research Center for Brewing and Food Quality at the Technical University of Munich, studies the processes and chemical interactions of barrel-aged beer. The scientist describes the work with wooden barrels as a complex way of adding a special aroma to beer and perfecting it. A wide range of processes acts as enhancers. The key one is called microoxygenation. In this process, barrels are never completely sealed, a step that facilitates continuous oxygen transfer through the casks and changes the taste of substances in the beer.

Barrel aging = special aroma

Bold craft-brewing pioneers like to mature their brews in previously used barrels, ones in which traces of their previous occupants like whiskey, rum, brandy or wine still linger. The key players in this special brewing style and the flavors it produces are primarily microorganisms that are left behind by the fermentation process of the previous beverage. As time passes, the barrel-aged beer absorbs the aroma, lending a unique taste to the beer. In essence, barrel aging has a special dynamic of its own, involving factors such as beer type and barrel as well as storage temperature and humidity. The rule of thumb is: The longer a beer is aged, the more explosive its taste. Researcher Martin Zarnkow notes that there is one regrettable aspect to the process: A barrel can be used just once because it has basically been sucked dry of its juices once the job is completed. That means a barrel-aged beer cannot be reproduced by the brewer. These generally therefore head to the shelves as limited edition, high-price specialty beers. This form of barrel aging is the ultimate challenge in the craft brewing industry.

Caramel, vanilla and oak…

The driving forces behind this trend include U.S. brewers like the team of Stone Brewing in Escondido, a group that is hardly like any other producer and ages just about every type of beer in wooden barrels. The California brewers currently have about five such barrel-aged beers in their portfolio. For instance, the Stone brewers mature their mocha Stout called Xocoveza in bourbon barrels to produce a powerful aroma of caramel, vanilla and oak. The Escondido team also creates a Belgian IPA that is aged in tequila casks and a Belgian Style Abbey Ale that is matured in red wine barrels.

Like Stone, the highly respected U.S. brewer Firestone Walker in Paso Robles is committed to barrel aging. In addition to a series with wild ales that aromatically age in French oak barrels – known as barriques – the creative crew at Firestone Walker loves to brew all sorts of special beers in a wide range of American whiskey barrels. The brewing pros use the wooden barrels for brown ales, barley wines, stouts and even a Berliner Weiße wheat beer.

…or rather plums, sugar and chocolate?

Other nations around the world are joining U.S. brewers in the quest to tap the full potential of barrel-aged beers. The Dutch brewers of Brouwerij de Molen just produced a barrel-aged imperial stout called Mooi & Meedogenloos, a brew that was aged in bourbon barrels. To add an extra kick, the brewers tossed in Amarena cherries. The result: a 12-percent brew with hints of plums, brown sugar, vanilla and chocolate. The highly respected Belgian brewer Duvel matures its beer in whiskey barrels. Several versions of them have won international honors that have stoked the team’s passion for brewing. As part of these efforts, Duvel has produced 79,092 numbered bottles in a third batch. The 351 barrels, all of which were at least five years old, came from American bourbon distilleries like Woodford Reserve and Jack Daniel’s.

When the brewer becomes an artist

In Germany, of course, such brews get tripped up by the country’s Beer Purity Law from 1516. Nonetheless, increasing numbers of German brewers are trying their hand at barrel-aged beer. Camba Bavaria brewed in the Upper Bavarian town of Truchtlaching has more than 10 different barrel-aged brews in its portfolio. They include beers aged in rum, cognac, whisky and muscatel barrels. Regional versions are produced in vats with such unusual previous tenants as sloe schnapps as well as Williams pear and plum brandy.

A number of creative German brewers are turning barrel aging into a real art. In Hamburg, the Ratsherrn brewery is experimenting with Madeira and Bordeaux containers. Markus Hoppe of the Upper Bavarian brewery Hoppebräu just issued an imperial stout matured in Oloroso sherry barrels. The Aged Bock made by Schwarzbräu, a brewer in the southern German town of Zusmarshausen, is a true taste sensation. It has already captured a number of honors at international beer competitions. Brewers’ desire to create barrel-aged specialties appears to be unchecked. Many of them view barrel aging as a new challenge that they can seize and surprise their fans with harmonious, complex and highly aromatic beer pleasures.

Mareike Hasenbeck

Mareike Hasenbeck is a freelance journalist with her own craft beer blog (Feiner Hopfen), she is also a beer sommelier and an international expert for beer sensory certified by the DLG (German Agricultural Society).