Since opening the Crooked Stave Artisan Beer Project in 2010, Chad Yakobson has done things his own way, pushing Colorado's craft-beer scene forward with his brewing technique, his chosen style of beers, his collaborations and his brewery-less taproom.
But his latest innovative leap will actually be a step into the past.
When Yakobson opens his new twenty-barrel pilot brewery in the Source this fall, it will include a coolship, a surprisingly simple piece of equipment that brewers used for hundreds of years -- but which is now rare, even in Belgium, where they were once very popular.
A coolship -- or koelschip in Dutch -- is a huge, shallow pan that beer-makers used to naturally cool down their boiling wort (unfermented beer) overnight before inoculating it with yeast, which can't be added if the wort is too hot.
These rectangular, open-air pans were typically made of copper, and now stainless steel, and could also be used to separate solid ingredients out of the liquid. They were necessary in the days before refrigeration, but could only be used during certain seasons when the weather wasn't too hot or too cold, and in certain climates.
"It's a really interesting vessel," Yakobson says. "Traditionally, it is used to cool wort. It's not the most economical way to do that, but it was the traditional way, and it worked. But coolships can also be used for a lot of other things."
One of those things is to allow naturally-occurring yeasts to spontaneously ferment the wort -- a process that has been famously reinvented by Brewery Cantillon in Brussels, Belgium, which keeps its coolship on the top floor of its brewhouse in a room with open windows (windows that incongruously open onto a gritty urban neighborhood).
Spontaneous fermentation creates "wild" or sour beers -- as do desirable bacteria like lactobacillus, which make their way into the mix -- that take on funky flavors as a result of these yeasts and bacterias, but it only works in regions with an abundance of good yeast and with brewers who can figure out how to repeat their process consistently.
And although Yakobson, who has a master's degree in yeast, specializes in those styles of beers, he doesn't plan to use his coolship for spontaneous fermentation -- at least at first.
Instead, he'll use it to add other ingredients, including hops and spices, and then let them settle out before transferring the liquid to barrels for fermentation. "We will have a protective roof over ours," he explains. "We'll be using ours like a whirlpool would be used, and as a third cooling vessel. It's such an interesting tool."
Several other U.S. breweries also have coolships, including California's Russian River; Hill Farmstead in Vermont; Peekskill in New York, Block 15 in Oregon; Jester King in Texas; and Maine's Allagash Brewing. The Allagash coolship, which was placed inside a fancy shed behind the brewery in 2007, can hold up to fifteen barrels of wort, and the brewery had it built specifically to experiment with spontaneous fermentation, says Allagash spokeswoman Dee Dee Germain.
Made of stainless steel -- and commonly considered to be the nation's first modern coolship -- the piece of equipment looks like "a giant brownie pan."
"We knew it would be a crapshoot and that it probably wouldn't work, but we wanted to try it," Germain says. "We knew the yeast was there, but it is getting the temperature right and being able to repeat it that is the real trick."
And then there's the time. Once Allagash had exposed the wort to the yeast, the brewery poured the liquid from the coolship into stainless steel tanks and then into barrels, where it let the beer ferment for three years before finally bottling it. Now the brewery sells its Coolship series of beers in limited quantities from its taproom only.
Crooked Stave's coolship, which was built by Metalcraft Fabrication in Oregon, arrived by truck in Denver this week, along with the rest of Yakobson's brewing system.
The stainless-steel vessel is about nine feet by ten feet across and eighteen inches high, with good ventilation underneath. It can hold 25,000 liters -- which equates to 21.3 barrels -- of wort, making it larger than Allagash's, and possibly the largest coolship in the U.S.
It was designed by Metalcraft engineer Tom Sage, who researched the proper size and shape so as to allow proper settling to occur. "There are proteins that need to settle out of the wort before you go into fermentation, and if you have a large shallow pool, it doesn't take long for them to drain out," he says. "But getting them spinning does it more safely, because you might want bacteria in there, but not the wrong kind."
Metalcraft has built two other coolships, for Peekskill and Block 15, and Sage hopes to design more of them. "The idea of the coolship went out of fashion a long time ago but it is coming back because of its interesting history," he says.
And in Colorado, Crooked Stave isn't the only brewery planning to experiment with a coolship. Sanitas Brewing in Boulder, which should open later this year, also plans to install one, as does Former Future Brewing, which should open in Denver this year.
"We are going to modify an old dairy tank...it will be a large, open flat fermenter, right against one of the walls of the building, and we're installing windows above it," says Sanitas co-owner Zach Nichols. "We'll start by letting it go and seeing what it in the air around here. Rudi's Organic Bakery is close, so we are convinced that there is yeast in the air. Is it enough to ferment and create the beers we need? We will wait and see."
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