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Why America Is Falling for Europe’s Most Pain-in-the-Ass Brewing Technique

January 02, 2019

By Miles Liebtag, January 02, 2019

"I literally don’t drink IPAs,” Brian Taylor says. “I don’t drink stouts, porters, any of that. Sour beer is my passion.” Taylor is a veteran of Boulevard Brewing Company and Goose Island Beer Company, where he was instrumental in developing the barrel program that created influential barrel-aged sours such as Lolita and Sofie. In 2015, he co-founded Whiner Beer Company in Chicago with Ria Neri with the sole purpose of producing sours.

"The coolship and spontaneous fermentation program were right there in our business plan from the start,” Taylor says. "I built a 35-barrel coolship out of stainless steel, and built the base of it out of reclaimed wood. There’s a five-acre farm surrounding our brewery, and we built ductwork going from the coolship room to the outside, so when we’re sending wort to the coolship, we turn that fan on and it sucks in fresh farm air, bringing in bacteria and yeast living outside on the plants.”

Not many breweries welcome outside bacteria and wild yeast, since they can cause problems in both the brewhouse and finished beer itself. At most breweries, once a batch of beer is cool enough to pitch yeast and ferment, brewers do everything possible to prevent the introduction of unwanted “bugs." At breweries using coolships, things work differently. 

A coolship (an English approximation of the Flemish “koelschip”) is a wide, shallow, open vessel used in the production of spontaneously fermented ales. Traditionally used in Belgian lambic brewing, coolships have increasingly made appearances in America over the past decade at Allagash, New Glarus, Russian River, Jester King, and The Veil. However, these breweries are few and far between, because spontaneously fermented beers require a big investment in terms of resources and time, as well as put the brewer’s skills, palate, and patience to the test.

Whiner Beer Company

What is spontaneous fermentation? Many American beer drinkers are familiar with sour beer, that is, a beer with higher-than-usual acidity and tartness. There are many different ways to make beer sour, from fermenting with cultures of lactic acid-producing bacteria to adding food grade acids directly to the beer after fermentation. Wild ales—usually meaning beers fermented with organisms other than traditional brewer’s yeast—can be quite sour as well, though not always. The acidity of a spontaneously fermented wild ale, like a lambic or gueuze, is often softer and more complex than in something like a quick-soured Berliner Weisse or gose. Today, the “wild” yeast and bacteria in most American wild ales are actually domesticated, grown in labs and purchased by breweries. The “spontaneous” in spontaneous fermentation refers to beers that have not been fermented primarily with lab-grown or domesticated yeasts, but instead exposed to the open air and inoculated by native bacteria and yeast.

Which is where coolships come in. Historically made of copper, coolships served several functions in breweries of yore, primarily cooling and fermenting. Before refrigeration and modern heat exchangers, beer was cooled by transferring the hot, sugary, unfermented liquid called “wort” into a wide, shallow, open vessel. The greater surface area allowed the hot wort cool more quickly. Nearby windows were opened to allow cooler outside air in, as well as wild bacteria and yeast which inoculated the wort. Over time, breweries using coolships developed something of a microflora zoo, as yeast and bacteria take up residence in porous surfaces, especially wood. Today, breweries such as Little Fish Brewing Co. in Athens, Ohio suspend wooden beams above the coolship, providing a home for the friendly bugs as steam and condensation rises from the cooling wort and drips back into the open vessel below. 

Whiner Beer Company

“In my experience with people trying to make spontaneously fermented beer in this country, it seems like it takes a few years to get their resident bacteria and wild yeast producing good beers,” says Sean White, co-founder and head brewer at Little Fish. White’s long-term ambition is to make beers according to Méthode Traditionnelle, a set of guidelines for American brewers of lambic and gueuze. If followed, the methods theoretically result in a lambic that is as authentic as a spontaneously fermented beer produced outside of Belgium. For now, White is trying to get Little Fish’s coolship program off the ground relatively quickly. “We won’t inoculate our Method Traditionelle beers, but the room has been 'inoculated,' so to speak,” he says, indicating the repurposed wooden beams hanging above the coolship. “This first batch has everything from pitched saison yeast to our foeder culture, bacteria and wild yeast, and some Brett lambicus.” Little Fish’s ultimate aim is to make a 100% Ohio wild ale. “Not just yeast,” White says. "But barley, hops, fruits, spices. Every single beer we make starts with Ohio malt. My goal for the spontaneous fermentation project is to be producing truly all-Ohio beers."

Time is not on his side. Wild ale fermentations can take months or years to finish and are typically rested in used oak wine barrels. It’s a costly, difficult process. "If you’re working out profit per square foot in your brewery, barrel aged sours are one of the least profitable things you can do,” White says.

“In a very real way, the coolship equates to massive debt and products sitting in barrels for years,” Taylor adds. Brewing with it takes more effort and more time, but it’s so worth it to create something a little different in a super crowded market.” All that time and effort also results in a more expensive end product, usually far more expensive than the canned kettle sours that are many drinkers’ entree into the world of sour beers. Just as barrel-aged imperial stouts command a higher price than their unaged counterparts. They are reflective of the time, place, and people who make them. And that’s worth waiting (and paying) for.


Main photo by Jude Goergen

ZX Ventures, a division within AB InBev, is an investor in October
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