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The Coolships Have Landed

Belgian-style spontaneous fermentation has finally made its way to the U.S. So how do the first "American lambics" stack up?


Yeast is everywhere. Taking refuge in wall and rafters, on the skins of hanging fruit, and even floating along the breeze, it’s an omnipresent and essential element of any location’s native ecosystem. For centuries, beer relied on this. Left out in the open or stored in a vessel that held the previous batch, fermentation was a process uniquely tied to the environment of the brewer. As science moved forward, however, the invisible yeast cell was discovered and reliable, controllable lab-cultured organisms took over the brewing world.

But, in one small corner of Belgium, this spontaneous fermentation technique persisted. With its intense sourness and layered complexity, the style known as lambic is one of the most prized and desired exports of its native land. And until recently, that native land was the only place where it was made. The risky, time-consuming nature of the brewing process has kept it at home in Belgium’s Pajottenland for much of history. Now, with a perfect storm of adventurous brewers, a changing public palate, and an intense focus on locality hovering over the beer world, the processes used in lambic brewing have found their way across the Atlantic and into the repertoire of today’s most cutting-edge beer producers.

The iconic vessel of the lambic process is the coolship. A large shallow pan usually made of copper, the coolship does exactly what you would expect: it cools things. After the unfermented beer, called wort, is mashed and boiled, it must be chilled down to a more hospitable temperature (generally 60°-75˚F, depending on the strain) so the yeast can begin its alcohol-producing duties. These days, this task is usually performed by a heat exchanger, but before the advent of refrigeration, every brewery had a coolship to get the job done. The hot wort would be pumped up to the coolship on the roof or in the rafters and left overnight, exposed to the wild microorganisms in the night air.

If done carefully, in a moderate climate, the beer can be cooled to just above the required temperature without introducing the sour notes these critters can produce. In the cold wintertime, however, these microorganisms flourish in the chilled wort. Lambic, not coincidentally, is only brewed in the winter. The indigenous microflora of the local air that fall into the cooling wort graciously consume the feast of sugars surrounding them, producing alcohol and multiplying. This naturally occurring yeast is all that’s required to fully ferment the beer; no lab-grown cultured yeast is ever added, hence the name “spontaneous fermentation”. These wild yeasts and bacteria contribute layers of intensely tart, musty, and funky flavors that shine over the simple barley malt, wheat, and aged hops recipe used to make traditional lambic.

Brewers at Allagash pour hot wort into their coolship to chill

Brewers at Allagash pour hot wort into their coolship to chill

After its night in the coolship, the beer is pumped into oak or chestnut barrels where it will finish fermenting and age for upwards of three years. The unblended old lambic is intensely sour, and is usually blended with younger lambic to make gueuze, or conditioned on any number of different fruits to create fruit lambics like kriek and framboise. The final product is worth the years of waiting. The tartness and funk from the wild yeast is mellowed by subtle woody notes and, in the case of fruit lambics, perfectly balanced by the fruit’s natural sweetness. This rustic and intricate flavor profile has become a premier inspiration for many the young and ambitious craft brewers of the current generation. But as much as they would love to recreate these sublime ales, infecting something with wild yeast, putting it in barrels for three years, and crossing your fingers isn’t exactly the most financially advisable business move.

“We’ve calculated that we’ve already spent around $75,000 on our spontaneous program, which is still in its infancy. We don’t even hope to release spontaneously fermented beer until 2016, and it could take much longer,” says Jeffrey Stuffings, one of the founders of Jester King, Austin’s experimental farmhouse brewery. Jester King is one of several young yeast-driven breweries who have begun to experiment with spontaneous fermentation and lambic-inspired brewing. The roadblocks don’t just stop with money and time. Barrels take up space in the brewery that could be used to make other beers with shorter production schedules. Plus, in many parts of the country, including steamy Austin, lambic-style brewing can only occur for a few short months each year.

Sonoma, California’s sour stalwarts Russian River Brewing were one of the first breweries to take the plunge and experiment with spontaneous fermentation outside of Belgium in 2006. The result was the release of Beatification, the first major American lambic-inspired beer, two years later. This highly sought-after, sporadically-released beer is made from a blend of Russian River’s lambic-style base beer, respectfully titled “Sonambic,” a portmanteau of Sonoma and lambic. Brewers are careful to call their spontaneous fermentation projects “lambic-inspired,” rather than claiming them as actual lambic. The name, which originates from the Pajottenland town of Lambeek, carries an unofficial sort of geographic exclusivity, somewhat like those in highly-regarded wine producing regions of France and Italy, thanks to the unique qualities of the local yeast. For Sonambic, the wild yeast of Russian River’s barrel room was originally attracted to the cooling wort in a jerry-rigged open mash tun, a trick used by several of today’s spontaneous fermenters. These days Russian River has upgraded to a traditional coolship.

Allagash Brewing's coolship shed

Allagash Brewing’s coolship shed

Around the same time that Beatification was being released, across the country in Portland, Maine, Allagash Brewing Company was building a small shed outside of their brewery to use specifically as a coolship room. A few years later they released Coolship Resurgam, a spot-on homage to the prized gueuze of the Pajottenland. Dry and tart, this elaborate beer is earthy with subtle hints of oak and a massively herbal nose. Allagash also produces a framboise-style raspberry conditioned ale called Coolship Red, a Halloween-themed pumpkin lambic-style beer called Ghoulschip, and an incredible tribute to the kriek style called Coolship Cerise. This pink-hued ale, conditioned on cherries, possesses delicate cherry-skin notes behind layers of cedar and must.

With Russian River and Allagash proving that true lambic-style spontaneous fermentation can be done outside of Belgium, other breweries have begun to try their hand at the art. In addition to Jester King, sour-beer specialists like Vermont’s Hill Farmstead and Alaska’s Anchorage Brewing Company have experimented with spontaneous fermentation in traditional coolships. Some breweries have opted for a cheaper, more improvisational route. In St. Louis, Side Project Brewing just carried out their first lambic-inspired brew day using a second-hand milk balance tank. Prairie Artisan Ales of Oklahoma got even more creative and strapped their mash tun into the bed of a pickup truck to cool a batch of wort in the open air.

The reason for this recent surge in spontaneous fermentation is multifold. First off, the demand for sour beer has never been higher. As the craft beer craze grows and grows, the palates of an increasingly large number of people have been introduced to the intricate and addictive flavors of beer under the influence of wild yeast and bacteria. Then there’s the nature of the breweries themselves. With the market demand as high as it, brewers don’t have to put all of their time and money into producing the basic IPA, wheat beer, and stout. They know that they can afford to experiment with limited, small-batch styles like massive barrel-aged barleywines and three-year-old blended wild ales.

As our culture continues to demand more and more sustainable, natural, and local products, beers like these can only become more popular. Locavorism has also inspired breweries to take new risks with their ingredient selection. “We use well water, central-Texas-grown barley and wheat, hops aged in burlap bags in the attic of a barn near the brewery, and native microorganisms,” says Jester King’s Stuffings, regarding their spontaneous beer project. Utilizing local grain and water is an obvious first step, but utilizing only the naturally occurring airborne yeast to ferment the beer completes the circle of localization. For Stuffings, it’s all about creating a connection between taste and memory. “What elevates a beer to a special status in our minds is when the flavors and aromas are uniquely tied to a physical location and drinking the beer in some ways transports you back to when you may have visited the brewery in the past. Spontaneous fermentation has the ability to create this sense of place.”

The currently available spontaneously fermented, lambic-inspired ales made outside of Belgium are the ultimate in limited-run, hard-to-find craft beers. Here are three of the most “common” examples and three classics to condition your palate for the upcoming surge of lambic-inspired craft beers.



Beatification, Russian River Brewing Company
Santa Rosa, California. 5.5% alcohol by volume, $18 per 375mL bottle

The original and most-infamous spontaneously fermented ale produced outside of Belgium, the most recent Beatification release drew one of the longest lines in craft beer history. This beer is a blend of several barrels of Sonambic, Russian River’s unblended lambic-style base beer, aged in wine barrels for various timeframes.

Coolship Resurgam, Allagash Brewing Company
Portland, Maine. 6.0% ABV, $15 per 375mL bottle

Tasting Resurgam blind, it would be easy to confuse it with an authentic gueuze. It has all of the telltale must, funk, and tartness of the authentic ales – only the yeast hails from New England. Allagash utilizes their specially designed coolship room to produce their Coolship series, complete with stained glass louvered windows to allow the ambient Portland air to flow in and drop yeast into steamy wort.

Coolship Cerise, Allagash Brewing Company
Portland, Maine. 8.1% ABV, $15 per 375mL bottle

A prime example of craft-brewing’s focus on locally-sourced ingredients, Coolship Cerise utilizes not only airborne yeast and bacteria from Maine, but also locally grown cherries, to referment this take on a traditional Belgian kriek. The Belgian Schaerbeekse cherry is replaced with Balaton and Montmorency, but this beer has the same tannic, tart bite and vibrant pink-hued body of classic examples of the style.

Original Lambic

Oude Gueuze, Hanssens Artisanaal
Dworp, Belgium. 6% ABV, $10 per 375mL bottle

Hanssens has been brewing authentic lambic ales since 1896. Their flagship Oude Gueuze is a blend of old and young lambic beers that have been bottle and matured for at least three years. Packed with intensely acidic lemon juice and spicy pepper flavors, this beer is an excellent and relatively easy-to-find example of classic spontaneous fermentation.

Lou Pepe Framboise, Brasserie Cantillon
Anderlecht, Belgium. 5% ABV, from $25-$65 per 750mL bottle

Brasserie Cantillon has become the cult-favorite of the lambic world and their Lou Pepe Framboise is one of the most coveted and beloved of all beers. Conditioned on raspberries in Bordeaux wine barrels, drinking this beer is like eating berries left in a hay bale in the rafters of a barn for three years. And that’s a very good thing.

Oude Quetsche Tilquin a L’ancienne, Gueuzerie Tilquin
Rebecq-Ronon, Belgium. 6.4% ABV, $16 for a 375mL bottle

A relative newcomer to the lambic scene, Pierre Tilquin specializes in aging and blending the un-fermented wort from other authentic lambic producers to make his own special gueuze. Rather than stick to the classic kriek for his first foray into fruit lambic, he chose to condition this beer on sweet plums giving it a distinctive raw-sugar sweetness that’s perfectly counter-balanced by the tart snap of fresh plums and delicate sourness of his proprietary blend.

Photos courtesy of Allagash Brewing via Flickr (Creative Commons)

Frank is a Biomedical Engineering major at Drexel University with a serious interest in the world of craft beer. When he’s not studying how to engineer solutions to human disease and injury, he can be found visiting breweries and bottle shops expanding his knowledge of brewing techniques, beer styles, and history.


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