Solera Beer

For Jason Kahler, falling in love with sour beers was a wallet-emptying predicament. “I was really into gueuze and lambic, but as a young brewer I did not have $35 to drop on a beer,” recalls Kahler, who began his brewing career at Fitger’s Brewhouse in Duluth, Minnesota.

What makes Belgium’s spontaneously fermented sour beers so pricey is time—the bacteria and wild yeast take years to impart the desired pucker—and Kahler had plenty. So he decided to brew his own sour and wild ales. Over the course of a decade, he filled his rural home near Mt. Hood (he had relocated to Hood River, Oregon, in 2000 to work for Full Sail) with several dozen stainless-steel kegs—the containers teeming with colonies of wild Brettanomyces yeast and souring Lactobacillus andPediococcus bacteria—cramming them in the laundry room and kitchen and clustering them around the wood-burning stove in winter.

Eventually, though, Kahler’s patience wore thin. “It took too long to get the qualities I wanted,” he says. Not ready to give up, he figured out a runaround for Father Time. He drew off a fraction of his souring brew, added fresh wort (the sugary grain broth that becomes beer) and blended the batches together, seeking the perfect acidic pop. “I could get it every two months instead of waiting two years,” says Kahler, who had stumbled upon a modified version of a centuries-old process: solera. Kahler’s homespun experiments led him to launch Solera Brewery in Parkdale, Oregon, in 2012.

Traditionally, solera refers to a collection of wooden barrels—it’s also the name of the oldest barrel or barrels in the group—and the criadera, or nursery. As the older barrels are tapped, they’re fed by younger liquids, which marry with the elder vintages and create a more homogenous, blended flavor. (Solera derives from the Spanish suelo or Latin solum, meaning floor or soil. The final blend is typically taken from barrels nearest to the floor.) The method originated in Spain during the 19th century as a commercial system for maintaining consistency in sherry production—separate vintages were replaced with a steady flavor.

In addition to sherry, the process can be used to age port, Marsala wine (its method is called perpetuum), balsamic vinegar, rum, and even whiskey and bourbon. Over the last decade, craft brewers have enlisted the solera technique to create both sour and aged beers of uncommon complexity. Each year, The Bruery in California’s Orange County releases a blend of its increasingly ancient anniversary beer, and Sam Adams’ dizzyingly strong Utopias contains brews that are more than two decades old. Dogfish Head’s fondness for wood led the brewery to install a solera program, while Colorado-based Crooked Stave Artisan Beer Project’s solera helps it crank out tart beers like clockwork. Baladin, in Italy’s Piedmont region, utilizes solera methods for its Xyauyù barley wines, and deep in Cambridge Brewing Company’s basement you’ll spot a solera that would be at home in 19th-century Spain.

Time is on Their Side
Unlike winemakers, whose annual vintages display variances, sherry and port producers strive for a consistent profile. Each year’s batch is but one component on a shared continuum of flavor. “I’m amazed when you have a bottle that contains port that’s 20 or 30 years old,” says Patrick Rue, The Bruery’s CEO and founder. “I wanted to see how that could work with craft beer.”

For The Bruery’s first-anniversary ale, Rue designed a brawny, almost tawny port–like old ale fermented with Belgian yeast and partly aged in bourbon barrels. The beer was strong enough to endure and even be enhanced by oxidation, which can make weaker beer taste like cardboard but imparts nutty, sherry-like notes to a strapping ale. To great effect, Italy’s Baladin uses solera’s principles to create its Xyauyù trio of fruity, vinous barley wines, each of which undergo different degrees of oxidation.

Released in 2009, The Bruery’s Papier was a robust mélange of dark fruit, vanilla and oak that became the foundation of Rue’s modified solera. A portion of that batch remained in bourbon barrels, joined by a fraction of the following year’s batch, and so on. As his solera has developed, Rue’s anniversary ale (Bois was the 2013 edition) has also evolved. To create it, a percentage of solera beer is mixed with another version of bourbon barrel–aged old ale, then the solera beer is topped off and allowed to age another year. With each calendar flip, the beer grows mellower, richer and fruitier. Rue savors the symbolism. “As the beer ages, hopefully it reflects the brewery’s maturation and evolving complexity,” he says.

Time’s passage is equally important to Boston Beer founder Jim Koch. Head deep inside the brewery’s Boston facility, past the steaming kettles and shiny fermentation tanks, and you’ll find a heavy wooden door leading to the Sam Adams barrel room. Inside sit casks stacked to the ceiling, a liquid library spanning more than two decades. “We’ve been doing this since George Bush the First was the president,” says Koch. “Each barrel has a unique history that builds on the solera idea of different aging times in different barrels.”

For example, a beer that began in a port pipe might move to a Scotch barrel that previously stored sherry, then that might mingle with beer seasoned in a Madeira cask. A single barrel could contain a blend of brews that are one, five and 15 years old. “We’re creating a growing library of flavors that will continue to age and evolve,”
he says.

Every few years, the blending team selects some of the choicest barrels to create Utopias, Sam Adams’ biannual experiment in creating a very strong beer (close to 30 percent ABV for the 2013 bottling) that’s more akin to Cognac. “Every release will have older barrels than we have ever had,” Koch says of Utopias, which was again released this fall. “It’s going to stretch your definition of what beer can be.”

Bugging Out
For brewers, a healthy colony of bacteria and yeast can be the difference between vinegar and sour-beer bliss. Replicating their results is always difficult, given that the living microbes evolve over time. Pioneering sour brewers speculated that perhaps a solera could create a more consistent sour beer. While the alcohol content of sherry and port, as well as stronger ales, kills most bacteria and yeast if the barrels are filled with a mid-strength ale, the solera is a veritable microbe motel. The bacteria and yeast check in and never check out.
To help colonies thrive, brewers refrain from fully emptying the barrels, adding fresh beer or wort to supply necessary nutrients. Colorado’s trailblazing New Belgium Brewing embraces this practice for numerous beers, including its La Folie sour brown ale.The Wild Beer Co. of Somerset, England, recently embarked on a solera project designed to create a rustic, low-alcohol saison. And St. Louis’ Schlafly tends to an ambitious souring program centered on a single directive. “The whole idea is to keep the bugs alive,” says Schlafly taproom brewer Brennan Greene.

Recently, Schlafly cleaned out its old boiler room—nicknamed the “spoiler room,” due to the bacteria and wild yeast colonizing the beer—and filled it with around 30 wine and bourbon barrels. Portions of the brewery’s earliest sour beers, which date back to 2010, are blended into newer batches, which will hopefully be bottled in two or three years. “We want to keep the infection going,” says Greene.

That’s also the plan at Delaware’s Dogfish Head. Since 1995, the brewery has been at the forefront of wood-aged beers, from the maple syrup–infused Immort Ale to Palo Santo Marron, which matures in 10,000-gallon tanks carved from Paraguayan timber. Solera seemed like a natural progression, says founder and president Sam Calagione, who sees the system as a showcase for wild yeast and bacteria. “Those beers are of a great complexity and are not just wood-forward,” explains Calagione. Previous Dogfish Head solera success stories include Festina Lente, a lambic-inspired sour ale flavored with 400 pounds of Delaware-grown peaches. (Released in 2003, it was one of America’s first bottled wild ales.) Sweet-and-sour Single Barrel Peche Myces was also fermented with Brettanomyces and peaches. And next fall will welcome a solera version of strong, raisin-fueled Raison D’Extra, the first barrel collaboration with a prominent, still-undisclosed California winery.

Popular as it’s become, few brewers have embraced the solera’s possibilities for cultivating Brettanomyces and bacteria quite like Denver’s Chad Yakobson. While studying winemaking, Yakobson was so gripped by Brettanomyces that the yeast became the subject of his master’s thesis, which in turn became the Crooked Stave Artisan Beer Project. Focusing exclusively on wild and tart ales is a trailblazing, if treacherous, endeavor. The yeast is persnickety. Off flavors are common. To minimize the uncertainty, Yakobson has traveled across the U.S., exhaustively tasting beers and picking brewers’ brains. “I’ve pinpointed all the critical processes in sour beer,” he says of his process, a modified solera that he uses to create rustic Belgian saisons.

To fashion the vinous, zesty Surette and tart and floral Vielle (“old”), Yakobson outfitted his barrel-aging room with gigantic oak foeders inoculated with his favorite strains of Brettanomyces. The tanks are loaded with the saisons, and when ready, about two-thirds of the aged beer is drained and replaced with fresh, young beer. (Each foeder is around 70 percent young beer, while the remainder is more than a year old.) The aged beer is then blended with soured saisons pulled from bacteria-filled wine barrels, which are then filled with more aged foeder beer. “It works like a cascading waterfall,” Yakobson says.

To keep his souring bacteria strong, whenever the wine barrels are emptied they’re rinsed and inoculated with cultures from other barrels. “If you practice good housekeeping, then the art is not in getting lucky,” says Yakobson, who has begun applying versions of this technique to other beers, namely the St. Bretta Citrus Wildbier. “I have to be able to mix the art and science. Sometimes the science is just being practical.”

Tending the Nursery
As perfected by sherry producers in the 19th century, tending to a traditional solera—criadera and all—is labor-intensive, a prospect that’s not terribly appealing to most brewers. One day back in 2004, Will Meyers, the brewmaster at Massachusetts’ Cambridge Brewing Company, was chatting on the phone with his winemaker friend Carl Sutton. Talk swung to Sutton’s visits to Spain’s famed sherry-producing Jerez region. Was it possible to apply solera techniques to beer? Meyers’ mission unfolded: to create America’s first true solera-style beer, following every step of the sherry process.

That first year, Meyers crafted a sour beer called Cerise Cassée, which was made with hundreds of pounds of cherries and aged inside five neutral oak wine barrels abounding with Brettanomyces. After a year, 30 percent of each barrel was drained and blended for serving. Cerise Cassée was then re-brewed and used to top off the old barrels and fill five new ones. The solera and nursery were set. The blended offspring was sublime: tart, bubbly and intensely ruby-hued, with flavors of fruit, vanilla and a lingering sour finish. Each (more or less) annual release of around 200 gallons, only available at the brewpub, vanished within weeks.

In 2007, however, Meyers noticed that the beer’s levels of acetic acid were increasing dramatically. Cerise Cassée was growing aggressively sour and harsh. Buildup prevented the barrels from breathing, compromising aerobic activity and leading to off flavors. “The solera is a living, breathing organism and it needs to be fed,” says Solera Brewery’s Kahler.

Though he had beer turn acetic after several years at home, Kahler has thus far avoided that issue with his solera, which fills the basement of the cidery across the street from his brewpub. If his flora progress according to plan, he’ll be able to pull off a portion of beer, blend it, bottle it and replenish every few months. “This is challenging, and as a brewer I like being challenged,” he says.

For Meyers, the challenge was how to clean the barrels, which were stacked like firewood in a cramped basement. “I’d interpreted the idea of ‘levels’ in a solera system literally,” he says. “That’s a problem when you have something go wrong with a barrel in the middle.” In 2009, the barrels were dragged from the basement, cleaned and rearranged. Lesson learned. Today the Cambridge Brewing Company solera project continues to evolve, a living experiment.

Some years, Meyers adds sour cherries directly to barrels, or bacteria and yeast harvested from a favorite beer. Though the solera beers have diverged in flavor, making each blend more challenging, Meyers has no intention of cutting corners or the project’s cord. “I don’t want to compromise my initial intent, even if it means more work,” he says. “Craft beer customers don’t often have the opportunity to consume such an old beer. When you tell them that it’s a blend of beers, they look at you pretty shocked. They didn’t realize beer could be aged like that.”