WTF Is Mixed-Fermentation Beer? Crooked Run Breaks It Down.

The experts at the Virginia brewery explain the nuances and offer recommendations

May 2, 2023 6:51 am
A mixed-fermentation beer from Crooked Run being poured from a glass vessel into a bottle
It sounds overly scientific, but you've probably had some mixed-ferm beers before.
Courtesy of Crooked Run

If you’ve been hanging out in hipster bars of late, you’re probably no stranger to the term “mixed fermentation.” But while it may sound overly scientific for those just looking for a beer, this phrase is truly just another evocation of the trend towards more natural methods — and what’s more, you may have already tried some of these beers without even knowing it.

At its core, mixed fermentation in beer-making refers to the use of both yeast and bacteria — specifically, a mix of brewer’s yeast, wild yeast and/or multiple kinds of lactic acid bacteria. Perhaps the best-known mixed ferm beers, at least stateside, are sours, but the category also encompasses anything from saisons to lambics to grisettes. 

In Leesburg, Virginia, the team at Crooked Run Fermentation has been experimenting with these types of beers since opening in 2013, releasing them under their sub-brand, Native Culture.

“We try to bridge the gap as much as possible between clean beer, mixed-fermentation beer and even wine or cider,” Head Brewer Mckinnen Leonard tells InsideHook, noting that the trend has really only taken off in the last five years or so.

“It was definitely an uphill battle, getting people to understand it,” adds co-founder Jake Endres. “But we’ve built, over the years, a group of people who really enjoy these beers and understand what they are.”

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If it’s taken so long for people to jump on-board the mixed-ferm bandwagon, it’s perhaps because the varied category defies clear definition, especially when it comes to the flavors drinkers can expect: sour or funky, sweet or savory, lactic or hoppy. And not every mixed-ferm drink is going to be every drinker’s cup of tea.

“If you’re trying to get into gueuzes and traditional lambics, there’s a note on that that’s very kind of blue cheese-y and funky,” says Leonard. “And if you don’t like that, it’s going to be a huge turnoff.”

Endres adds that seeing as some of the early American mixed-ferm beers were “extremely sour,” the entire category could seem like an acquired taste. But luckily, there’s a mixed ferm for everyone, from the delicate, nuanced grisettes and saisons to fruit-forward plays on Berliner Weisses. And since the space is ripe for exploration and experimentation, even the nerdiest of beer drinkers are sure to find their bliss.

Leonard is currently at work on a barleywine brewed in a coolship, a traditionally Flemish style of open fermentor that sees wort cooled in the open air, so that airborne yeasts and bacteria present in the brewery can inoculate and spontaneously ferment it.

People looking over white substance in a machine
A coolship is a traditionally Flemish style of open fermentor that sees wort cooled in the open air.
Courtesy of Crooked Run

“It is a roll of the dice regarding how they come out sometimes,” says Endres. “But we’ve had very good results with it.”

The barleywine specifically is fairly unique, with 13% alcohol and some Madeira notes that come from being aged in barrels formerly home to the Portuguese fortified wine.

“It’s got tons of notes of like…buckwheat honey,” says Leonard. “It’s like an after-dinner drink.”

The resulting beer will also stand out in that it won’t be carbonated, something that the team notes might make it a hard sell. But Endres isn’t worried.

“I saw another brewery just recently did — not a mixed-fermentation barleywine, but a still stout,” he says. “And they basically were like, we don’t care if people think this is stupid, we think it’s better this way, so we’re releasing it. And I kind of like that attitude.”

Leonard agrees, noting that while some of the beer will indeed be carbonated and sold on draft, the nerdiest of beer lovers would do well to snag a bottle from the 10 or 20 cases he plans to market still.

“The people who get it, get it,” he says, “and the people who don’t don’t have to buy it. That’s kind of what it is.”

Whether that sounds right up your alley or you’d rather dip your toe into shallower waters of mixed-ferm beer, here are some these brewers are championing right now. Make your picks and then go pick some up at their 3,200-square-foot Union Market shop

The One for Lager Drinkers

ML: “If we’re talking someone who is a lager drinker, and they’re not super into kind of the funky stuff or even the fruity stuff, we offer a bunch of different saisons and grisettes: a really easy-drinking, highly-carbonated beverage that’s just clean and just delicious.” Try the Native Culture Canary Grisette.

The One for Wine Lovers Who Think They Don’t Like Beer

ML: “We have one that’s a wine-beer hybrid that comes in at like 8%. We actually do a 100% Chambourcin wine, and as soon as we’re done fermenting that, we take a blend of a golden sour and a saison and put it right onto the pomace, so you have a lot of that Chambourcin fruit leather, you get a little bit of acidity from the two-year-old golden, the saison really kind of balances that out, and then that little bit of sugar that’s leftover kind of brings up that ABV. So if you are a wine drinker, you’re not missing the ABV so much, and you get the characteristics from the actual grape. But the acidity is kind of right on point; you have enough funk to keep it interesting and fun.”

The One Who Loves Sours

ML: “We have a coolshipped citrus beer called Picturesque, and in the coolship we laid down a small bit of honey, and then hit it with all sorts of citrus – grapefruit, lemon, lime, several different types of oranges. And then knocked the beer out and set it overnight on those citrus fruits with the honey.”

Slices of fruit sitting in liquid.
Picturesque is made with all sorts of citrus.
Courtesy of Crooked Run

The One Who Finds Sours Way Too Puckery

ML: “Lente. When you bottle-condition it with a lot of hops, it gives this really tropical fruity, almost New England hazy IPA vibe, but it is a coolshipped beer. So you’re left with kind of this cross between something super hop-forward with a little bit of acidity to kind of make it really crisp and refreshing. That one’s honestly one of my favorite beers, so if you’re an IPA drinker, I would steer you in that kind of direction.”

The One to Pair With Dinner

JE: “There are some kind of unorthodox ones that work really well. I think that any of our fruity golden sours, particularly with darker fruit, goes great with barbecue. It really just complements the barbecue sauce and smokiness really well.” Try the Native Culture Persica Sour with Virginia peaches.

The True Champagne of Beer

ML: “A gueuze or some of our lambics are slightly funky, and they’re super carbonated. I honestly treat those kind of like Champagne. I love a gueuze with a blue cheese or something salty, or like oysters, caviar, that kind of vibe.”


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