On a chilly night early in April, a batch of unfermented beer cooled in a large trough, called a coolship, outside of Wild Mind Artisan Ales in Windom.
Wild yeasts and bacteria in the air combined with the mixture, called wort, converting its sugars into alcohol and carbon dioxide. Brewery staff let it sit outside for about 12 hours before transferring it into barrels, where it was to ferment for about nine months.
Most breweries cool their unfermented beer in carefully controlled indoor environments. Almost none allow wild yeasts to combine with the wort.
But that’s not always the case at Wild Mind. Twice a year, staff at the 3-year-old brewery cool a few select worts outdoors, a process they said leads to unique and tasty beers.
“You can get really, really great results out of this process,” said Ryan Placzek, Wild Mind’s head brewer. “We’re all really big fans of [making] traditional Belgian brews this way.”
Wild Mind has been using its coolship in the brewing process since it opened in summer 2016. In a May 2017 blog post, the brewery said the coolship method fit within its priority of bringing back “funky, unpredictable beers.”
“We tend to focus on brewing traditional farmhouse-style beers, and the coolship is the epitome of paying homage to old-world brewing techniques,” the post said.
Placzek said Wild Mind can only use the coolship in the late fall or early spring, when temperatures are just chilly enough to avoid spoiling the process. He said the brewery was able to fill 28 barrels of beer using the process this year.
Coolship beers are more acidic than ones cooled via traditional methods, Placzek said. He said the brewery will add fruit or different flavorings to its products later in the process to create different tastes.
The brewery will have one of its coolship beers, a framboise raspberry sour, coming out in the coming weeks, Placzek said. He said he expected it would be for sale by the end of May.
Visit wildmindales.com to learn more.