The conflation of the word “barrel” and “aged” is so maddeningly thorough that Matt Brynildson, head brewer at California’s Firestone Walker Brewing Co., isn’t sure if anyone understands that the brewery’s award-winning ales are the result of fermentation―not aging―in wood. It’s a process where the brewer employs the powerful flavor effects of wood early in the beer-making process, not during aging. As such, the effect is potent and swift.
Brynildson won’t say Firestone Walker is unique in fermenting in wood―though he’d like to: “A lot of these guys doing Belgian-style brewing may be doing some or all of their fermentation in oak, so I can’t say we’re the only American brewery doing primary fermentation in oak. But what I do say is that we’re one of only two breweries left in the world using a Union set.”
A “Union set” is a reference to the Burton Union fermentation system, now only used by the Marston’s brewery at the iconic source of British pale ale, Burton-on-Trent. The archaic approach to brewing was the one that inspired David Walker and Adam Firestone to create the patented Firestone Union fermentation system.
In both fermentation systems―the original Burton and Firestone―wooden vessels are linked together in a yoke of connected vessels. As fermentation proceeds, excess yeast and beer are pushed out of the barrel, up a swan’s neck connection (an air lock of sorts) and into a common trough. From there, the beer is channeled back into one of the barrels, mingling the beers somewhat―hence the “union” of the name, Brynildson guesses―and vigorous yeast can be harvested.
In the Marston’s brewery, every attempt is made to minimize the influence of wood on the flavor of Pedigree, the renowned beer brewed on this system. Coopers on the brewery staff repair and recondition old wooden tanks, to preserve the flavor neutrality achieved over long use. By contrast, Firestone Walker has harnessed the union system to take advantage of the unique flavors this “athletic fermentation” causes and add wood character to their beers.
“In our system, we’re looking for an oak effect,” explains Brynildson. “We’re selecting new American oak, and we’re having barrels built to our specifications to obtain oak flavor. American oak happens to be the less expensive medium to build barrels, but, more importantly, American oak has a little more aggressive attack when it comes to oak character.
“Among winemakers, French barrels are coveted and are considered to have a softer effect on the finished product. It’s a little like comparing noble hops versus American hops: French oak is though to have a more “noble” effect on the character. But we found that there are too many other flavors in our beer―the hops, the heavy malt character―the assertive attack of American oak works perfectly.”
The Firestone Union system consists of 40 oak barrels. Every week, a batch of the brewery’s Double Barrel Ale is brewed on the Union system. Each week, a new, properly toasted oak barrel is rotated into the system, and the oldest barrel is rotated out. Even with that moderate amount of oak influence―the output from 40 barrels, from brand new to 10 months in age, are blended together―the influence of new oak at the lively fermentation state is so dominant that all the brewery’s flagship beers are blends of oaked and stainless-steel fermented beers―except in the brewery’s taproom, where an 100-percent oak-fermented Double Barrel Ale is always available.
A Celebration of Barrels
“A barrel is its own little ecosystem,” observes Jeff Sparrow. The Chicago-based brewer and author helps to organize the annual Festival of Wood and Barrel-Aged Beer, hosted by the Illinois Craft Brewers Guild, and now in its seventh year.
“Is it a new barrel, where you need to be very careful of the strong wood character? Is it a used barrel, what was in it before, what’s going to grow in it now depending on its history and what you do to it next?” he asks.
Over the years, Sparrow has watched brewers who are intrigued with the influence of wood on beer move away from barrel alternatives―toasted oak chips, spirals, oak “beans” soaked in bourbon―to employ true barrels.
“I think there’s the coolness factor,” he explains. “You walk into Russian River, and Vinnie has his barrels on prominent display. Pete [Crowley, Rock Bottom’s Chicago brewer] has them stuck downstairs, Goose Island has barrels in whatever spare corner they can find. If people see a beer with wood chips floating in it, well … but when you see a barrel, it attracts so much more attention.”
Over and above the impression a rack of barrels makes on a visitor, there are chemical interactions going on inside a barrel that no wooden substitute can duplicate―and no brewer can fully control.
The wooden walls of the barrel are slightly permeable, allowing the modulated exchange of gases with the world outside. And the size of the barrel governs the surface-to-air ratio, which sets the pace of chemical interactions within the barrel: smaller barrels are more active; reactions in larger barrels are slower and may lead to more flavor complexity. After experimenting with smaller barrels, New Belgium’s Peter Bouckaert has converted the brewery’s barrel program largely to huge foeders, where microorganisms can work at a more leisurely pace.
With the return of wood to the brewing process, the brewer is incorporating yet another variable―and a less predictable one, at that―to the brewing regime. Not surprisingly, given that every barrel has its own history (its cask character), a new skill is required in the brewery: that of artfully blending the products of different barrels to obtain the desired balance of flavors in the finished beer. The job of blending is a long tradition among lambic and sour ale brewers in Belgium. It will no doubt become a specialization on the American craft brewing scene if the infatuation with barrels continues to grow.
Are there “new” frontiers in the old craft of barrel-influenced beer? Other species of wood have been tapped for flavor: Hitachino Nest Japanese Classic Ale is aged in cedar casks, borrowing from the sake tradition; and Dogfish Head Craft Brewery has constructed huge tanks from palo santo, an aromatic hardwood from Paraguay.
The permutations are endless: delicate beers soured in chardonnay barrels; fruited porters aged in bourbon barrels; barley wines seasoned in former sherry casks―all relying on the talents of the brewer and subject to the mysteries of a wooden barrel. Who ever dreamt so many new possibilities could flow from such an old source?