Where the Wild Beers Are: More Minnesota brewers are investing in mixed-culture programs

Photo by Kevin Kramer

Ten years ago, locally made wild and spontaneously fermented ales were rarities. Most examples found in liquor stores and in beer bars were imported Belgian lambics and Flemish red and browns ales. Local brewers were so reluctant to introduce wild yeasts and bacteria in their brewhouse for fear of contaminating their non-sour beers that it inspired the name for the then-nomadic brewing operation, Blacklist Artisan Ales. But today, more and more of Minnesota’s breweries are entering into the wild in varied ways.

There are several reasons breweries begin to brew mixed-culture wild ales. For some, like Portage Brewing Company, it’s a way to draw people to the brewery and learn more about what types of wild yeasts exist while potentially creating something with ingredients nobody else has used before (yarrow flower beer, anyone?). For others, like FINNEGANS Brew Co., it’s a way to diversify and upgrade their portfolio. And then, of course, there’s the fact that brewers simply like to make them and see wilds and sours as a way to experiment and learn.

Before diving into the latest developments in Minnesota’s wild and sour beer scene, here are a few useful terms to know.

Sour Beer: Beer that has an acidic character from the use of lactic acid-producing bacteria, such as Lactobacillus and Pediococcus, during fermentation.

Wild Beer: Beer made using yeast and bacteria beyond the typical brewer’s yeast, Saccharomyces cerevisiae. These wild microbes include Brettanomyces (a family of wild yeast strains), Lactobacillus, and Pediococcus. *Note: While all sour beers can be considered wild, not all wild beers are sour.

Mixed-Culture Fermentation: Fermentation that uses a combination of microbes such as Saccharomyces, Brettanomyces, Lactobacillus, and/or Pediococcus. Sour and wild beers are most often the result of mixed-culture fermentation. Brewers can purchase mixed-culture blends from commercial yeast companies or they can cultivate their own “house blends,” most often in wood barrels and foeders, large wooden fermentors (sometimes spelled foudres).

Spontaneous Fermentation: Fermentation driven by ambient yeasts and microbes floating in the air or found on raw ingredients, which inoculate unfermented wort. Belgian lambics, the most famous spontaneously fermented beers that are made with wild yeast found in the Zenne river valley of Belgium, are exposed to the ambient microbes during an overnight cooling period inside large, shallow, open-air vessels called coolships.

Kettle Sour: Beers that get their sour character from a short fermentation inside the brew kettle using Lactobacillus and/or Pediococcus. When the desired sourness is achieved, the beer is boiled to kill the bacteria, cooled, and transferred to fermentors where fermentation is finished using traditional brewers yeast and/or Brettanomyces. Many, but not all, modern sour beers are kettle sours.

Portage Brewing Co.

Jeff Vondenkamp with a wild yeast strain on the original Portage brew floor // Photo by Tj Turner

Jeff Vondenkamp with a wild yeast strain on the original Portage brew floor // Photo by Tj Turner

Abloom is the perfect name for Portage Brewing Company’s series of wild sour beers. Not only is the brewery beginning to blossom again after a fire destroyed their building in January 2019, but the series itself tasks co-owner and head brewer Jeff Vondenkamp with trekking into the woods to find flowers and other plants that are in bloom to utilize the bugs and wild yeast found on them to make the beer.

Vondenkamp and his team harvest whatever foliage is attracting bees or insects at the moment, because “that’s when microbes are at the highest point of density,” Vondenkamp says. “Bugs, as they pollinate, tend to carry a ton of healthy bacteria and yeast that’s good for fermentation. If we time that just right, we land a huge cache of wild [microbes] and the acidification/fermentation time tends to be a lot faster.”

After being chilled, the wort is sprayed over the recently harvested fruits and flowers in a stainless steel vessel to inoculate the liquid with microbes before being transferred to fermentors—a process Portage calls inline inoculation spontaneous fermentation.

Instead of brewing styles like lambic-inspired beers, the Portage team crafts what they call hybrid saisons and other spontaneously fermented beers. For example, Vondenkamp has brewed with yarrow, a wildflower that imparts a strong rosemary flavor to beer. They have also brewed a sour Belgian dubbel inoculated with the wild yeast found on yarrow. “[We’re] trying to blow the lid off how most people are doing the mixed fermentations,” Vondenkamp says of the brewery’s future.

Vondenkamp says he can complete a hybrid saison in a month, whereas fermentation time is closer to a year if he wants more oak flavor from a barrel to be noticeable in the beer, or if he’s using fruit.

“Fruit and oak tend to produce some off-flavors such as THP or acetobacter, requiring some extended time to clean up,” he explains. “You also need extended oak time to develop the wood tannins so common in an oak-aged beer. Depending on the freshness of the barrel, this process can be lengthened.

“There’s really nothing off limits that we won’t experiment with [using] yeast,” he continues. “When we come back that will be our bread and butter.”


Birch’s on the Lake and Birch’s Lowertown have been known for sour beer ever since the original brewpub opened three years ago. (The Lowertown location opened late summer 2018.) Up until recently, however, they were all kettle sours. That changed when the brewpub’s wild fermentation program, built on sour beers that have aged in wine barrels, came to fruition last October.

The brewery’s first wild beer release was an oud bruin—a sour beer aged in oak barrels that is defined by notes of slight acidity, caramel, toffee, and dark fruit. In May, Birch’s released Peach Lambic, a “barrel-fermented Belgian sour ale aged for two years before refermenting on peaches.” Both were aged in used wine barrels, the former in red wine barrels with tart Oregon cherries, the latter in white wine barrels.

“Wild fermentation was always something Birch’s wanted to do,” Birch’s head brewer and owner Brennan Greene says. “To have barrel-aged and wild sours is a lot of fun. It’s a lifetime worth of study—that’s why I really like wild sours versus kettle sours. It’s always something different.”

Greene used Roeselare ale blend—a mix of lambic cultures—for the first two releases, which is why he named the peach beer a lambic, even though it wasn’t made in the Zenne River valley of Belgium. “It’s our take, our experimentation,” explains Greene.

Birch’s has more kettle sours and wild sours on the way, including a Flanders red that has been aging in barrels for over two years and a beer fermented with Brettanomyces working its way to completion—just a couple of the varieties currently occupying the brewery’s 36 used wine barrels.

Junkyard Brewing Co.

Junkyard Brewing Co. already has a lot of mixed-culture beers in its repertoire, and it’s about to have a lot more thanks to the recent addition of a 620-gallon French oak foeder to its brewhouse. The foeder fits in with the boundary-pushing brewery’s modus operandi to be creative with the beer it brews.

“Over the years we have done many small experiments with mixed-culture sour beers, usually aging in wine barrels with Brettanomyces and mixed Lactobacillus cultures,” Junkyard co-founder Aaron Juhnke explains. “So, it’s not something new to us, but we haven’t done these types of beers on this big of a scale before.”

The first beer to be made with the new vessel is a Berliner weisse fermented on Lactobacillus and Brett. He says it should be ready to release this summer or fall, depending on how the fermentation goes.

Related Post: Bringing Berliner Back: Jace Marti gives the traditional German beer a second life at The Starkeller

And that’s just the start; Junkyard has big plans for its foeder. Junhke expressed interest in making grisette-style beer down the line. (A grisette is a French or Belgian style of beer that features a low ABV, can contain characteristics akin to a saison or farmhouse beer, is made with wheat, and can have a strong hop presence).

“We’re going to experiment with all the variables, so I wouldn’t expect one thing in particular,” Juhnke says. “We want to do fruited mixed-culture sours, dry-hopped sours, and try out different blends of microorganisms.”


With its Barrel of Life series, FINNEGANS Brew Co. is seeking to prove that it’s more than the malty beers it’s well known for.

“We also want people to know [head brewer] Ryan Mihm and I make bomb-ass stuff,” FINNEGANS’ assistant brewer Logan McLean says. “FINNEGANS is not just an Irish Ale factory anymore. We can produce better, higher quality, fun, funkier things to please everyone’s palate. We want to have a little of everything on tap [and] are trying to do more soured stuff, both kettle souring and in the barrels.”

The Barrel of Life series has seen five Brett-forward beer releases and six non-wild barreled beer releases since its inception in March 2018. The most recent release is Aronia, the brewery’s first sour ale in the series. Aged in oak barrels with aronia berries, it’s also the first of Mclean’s Barrel of Life debut as a brewer. A mixed-culture Berliner weisse aged on black currants is also resting in oak barrels until it’s ready, which should be in mid-July. “We have a few other beers aging now with souring cultures,” McLean adds. “Sadly, we will not be seeing those until next year.”

Scribbled Lines Brewing Company by Lupulin Brewing Co.

Justin Nathe of Scribbled Lines and Lupulin sampling a golden sour base from the barrel // Photo by Tj Turner

Mixed-culture beer is just hitting tap lines at Lupulin Brewing Co. in Big Lake, Minnesota, but the brewers there have been thinking about adding it to their repertoire since 2016.

“About a dozen of the barrels that we’re blending from have been aging since then,” say head brewer Aaron Zierdt, co-founder Matt Schiller, and brewery quality control Justin Nathe collectively over email.

After doing market research and internal discussion, Lupulin decided to bring their sour beer program to life under a new brand, Scribbled Lines.

“Lupulin Brewing is known mainly for IPAs and other styles,” the trio writes. “In order to better tell the story of what we are doing with our sour barrel program, we found it was better to just have a whole different label.”

Related Post: Lupulin Brewing Company Acquiring South Dakota’s Hydra Beer Company

The name Scribbled Lines is a nod to experimentation and seeking out flavors the team enjoys—“quite similar to a piece of art being sketched. Also, there are no parameters on what we are trying to do, but rather [it is] a series of different beers where we experiment with different techniques and flavors.”

Speaking to that lack of binding, Scribbled Lines will showcase Old World brewing traditions along with new techniques—all except for one. “One thing you will not see is kettle sours,” the team says.

While still in its early days of launching, a few Scribbled Lines beers will find their way to shelves and tap lines soon, including a strawberry whiskey sour that’s nearly ready for packaging and a couple fruited sours following shortly on its heels.

ONE Fermentary & Taproom

Concrete fermentors being produced for ONE Fermentary & Taproom by Sonoma Cast Stone // Photo via Sonoma Cast Stone

True to its name, ONE Fermentary & Taproom aims to be an experimental testing grounds for all methods of fermentation. “We plan to ferment some traditional styles and hope that we can provide a different take on them by fermenting, aging, and lagering them in our concrete fermentor or oak foeders,” head brewer and co-founder Ramsey Louder says. “I’m especially excited about what our Cognac foeder will do to a barleywine, an imperial stout, or a Belgian quad. We hope to collaborate with other breweries to make unique wort [the sugar-rich water that is fermented into bee] that we can transport back to our brewery and split between our virgin oak foeder and concrete fermentor. We can then either pitch the same yeast strains or not, add the same adjuncts or not. The combinations are endless.”

Louder says he’s especially curious about what he can do with the concrete fermentor. “The concrete fermentor is uncharted territory for me, but that’s what makes it exciting. I was able to have cooling coils added to it so I’ll be able to lager a Pilsner in it and see what happens.”

While the brewpub’s aged mixed-culture beers won’t be ready immediately when the brewpub opens in fall 2019, Louder will have kettle-soured Berliner weisse on tap to begin.

“We won’t open with a housemade mixed-culture sour beer on tap, but hope to have a couple ready by next spring. In the meantime, we will put out some kettle sours,” Louder says. “We will offer housemade syrups to go with the Berliner instead of fruiting the entire batch.” (Using syrups is traditionally done with this style of beer in Germany.)

Some of the Berliners and other beers on tap will be made using wort brewed at other breweries outside of ONE as a part of the brewpub’s collaboration series.

The brewery anticipates that wild and/or sour beers will constitute 1 to 5 percent of its yearly production.