Photo by peretzpup/Flickr CC
The future of American craft beer sits in a shed on the industrial outskirts of Portland, Maine. Built by the Allagash Brewing Company in 2007, the shed holds the country's first commercial "koelschip," a shallow, 15-barrel steel pan used to cool down beer wort--and expose the beer to naturally occurring yeasts that float in through the shed's open stained-glass windows. The results, which are still aging in the brewery's warehouse and could be ready for drinking early next year, will be the first American lambic produced according to the traditional methods used in Belgium, where wild-yeast fermentation is considered a national treasure.
Allagash is among the leading American breweries dedicated to Belgian beer styles--whites, dubbels, and tripels, for the most part. But like Lost Abbey and Russian River (among many others), Allagash has recently been experimenting with wild yeasts, primarily Brettanomyces to produce funky, tart beers similar to Belgian lambics. But whereas most of the great lambics, like those from Cantillon, are made with truly wild yeasts, American "bretts" are isolated in a lab before being let loose on a wort.
To anyone versed in conventional beer-making, the koelschip process is an exercise in madness.
Wild yeast, like unwanted bacteria, is usually the bane of brewers. It has rendered many a homebrew putrid and undrinkable. But a few years ago, Allagash got lucky. An infected batch turned out to be not only drinkable, but delicious. Jason Perkins, the master brewer, had a lab isolate the yeast strain and used it to make Interlude, a well-regarded limited-edition release. With that experience in mind, he and Allagash owner Rob Tod decided to go all the way, and build a koelschip of their own.
To anyone versed in conventional beer-making, the koelschip process is an exercise in madness. After boiling the wort and adding a dose of aged hops, the steaming liquid is pumped into the koelschip and left overnight, with the windows open. Wild yeasts and bacteria float in on wind gusts or drop down from the ceiling, which is made of untreated wood boards to give them a hospitable waiting area. The next day the wort is pumped back into a fermentation tank for a year, then into French oak barrels for even more aging.
Photo by cliff1066/Flickr CC
This is no job for the impatient. Natural fermentation can take a few weeks to get started, and it can last for months or even years. And Allagash only uses the koelschip in the fall and spring, when the Maine climate is closest to that of the Zenne Valley, home to the best of the Belgian lambics; during the summer the air is full of unfriendly bacteria, while the temperature is too high to let the wort cool sufficiently.
Such a complete reliance on the whims of Mother Nature is risky--not only does each batch vary significantly, but each barrel will show subtle differences from the last. And there's yet another step in the process: mixing. Allagash is one of the few breweries to blend their barrels. Most breweries strive for such consistency that blending batches is pointless. But Perkins and his team, like master distillers making Scotch--or Belgian lambic brewers--have been mixing and matching different barrels for several years. It's not strictly necessary when using lab-isolated bretts, but with truly wild yeasts, it's an absolute requirement to achieve commercial consistency.
Allagash won't say when it will release its first lambic, or what sort of substyle it will be--though one employee said they're leaning toward making a gueuze, a blend of young and aged lambics. Whatever does roll out their doors, it will be a milestone in American brewing, and further proof that American brewers are as sophisticated and talented as their Old World compatriots.