Frenemies: Kettle-Soured and Mixed-Culture, Under the Same Roof

We've heard the argument: Single-bacteria sour beers—so-called kettle sours—are detrimental to the success of more traditional, mixed-culture beers. But for Bret Kollman Baker of Cincinnati’s sour-focused Urban Artifact, the two coexist peacefully.

Jamie Bogner Jun 28, 2020 - 9 min read

Frenemies: Kettle-Soured and Mixed-Culture, Under the Same Roof Primary Image

To hear some tell it, traditionally minded mixed-culture beers are an endangered species whose existence has been pushed to the brink by a fast-moving upstart—the quick (or “kettle”) sour. But for Bret Kollman Baker, cofounder of Cincinnati’s Urban Artifact Brewing, the evolutionary competition between the two species is more constructive than destructive.

“There are some brewers who feel that cannibalization is happening and making things more difficult,” he says. “I have the exact opposite opinion. I just think we’re running into a market-cap issue on barrel-aged sours, personally. The lower-price-point, more-approachable, not-challenging product that is pre-boil sours was always going to sell better.”

As one of the largest sour-only breweries in the country, producing about 6,000 barrels per year, Urban Artifact has a unique vantage point—they brew and sell both types. Quick-sour beers make up about 95 percent of that volume, with more traditional wild beers accounting for the rest. That divided approach and their divergent price points create an added burden for the company in how they tell these different stories to beer drinkers.

The Right Descriptors.

For Kollman Baker, the story starts with the right descriptors. He prefers the term “pre-boil sour.”
“‘Kettle sour’ has some negative connotations, depending on who you’re talking to,” he says. “And we also don’t sour in the kettle—we have a dedicated souring stainless-steel vessel that we do everything in and a controlled house-selected Lactobacillus culture; and we’ve put a lot of time, investment, and research into what works best for us. So, the term ‘kettle sour’ just seems cheap to me. I’m not trying to position my product as that.


“We treat our pre-boil sours like a normal craft beer,” he says. “We don’t need to confuse people with terms like pre-boil versus kettle sour, versus all this other stuff. It’s a tart beer with fruit. That’s the message we’re putting forward, and that’s it.”

Urban Artifact also strives to demystify the idea of more acid-forward beer, pushing toward broader availability and lower prices, so that it isn’t just a niche product.

“There’s a huge opportunity for sour beer and products with a lower pH for the general market. You see it in wine—wine’s 3.2 pH, 3.4 pH—and no one considers it sour. So why couldn’t we essentially try to do the same thing with beer? Where it doesn’t need to be the sourest to be drinkable and something that people want? You make it more approachable by making the pH a little more moderate. We thought there was real potential to grow the substyle, and ultimately, it wasn’t going to be barrel-aged sours that did it. The price point is just never going to allow for it. There’s also a steep learning curve for the consumer because it’s funky beer, and there are a lot of challenging flavors that you have to get accustomed to.”

Pre-boil sour beers also provide an avenue for clean, straightforward acidity unburdened by funkier notes provided by Brettanomyces- based cultures. While some drinkers prize it, the funk can be polarizing. For Urban Artifact, the goal with their canned tart and sour beer is to find a larger audience.

“There just isn’t a large percentage of drinkers that you’re going to pull over into the more complex stuff. In the wine world, the majority of wine sold is sweet garbage wine, then you see fewer people move up into dry wines, then eventually you get people into these rare varietals and funkier stuff and maybe, eventually, into natural wine. But the percentage of people who move up these tiers—you’re talking about a logarithmic drop-off. If we have 100 people come in and I convert 100 people into liking fruited sour beers, that’s a win. And if we get 2 percent that move up to our barrel-aged stuff, to me that’s all just gravy.

“For our business, the barrel-aged stuff is never going to be the main driver of our success financially. But for us, it’s about getting to flex our creative muscles when it comes to barrels and funky microbes.”


Cranking up the Fruit Volume

One of the ways the brewery differentiates between categories is in its approach to fruit. For the canned sours to sell at customer-friendly prices, but still express intense fruit character, they have to be strategic. That often means using purée, resulting in a generic fruit impression instead of the more distinct character of using more expensive whole fruit. That they save for their barrel-aged sours.

“On the barrel-aged side, we’re usually getting frozen, fresh fruit,” Kollman Baker says. “Is it blackberries? If so, then great—what kind? Do we want evergreens, or do we want black patents? We have a lot more freedom to get specialized and niche with our fruit choices, and that’s a lot more fun for us. But the economics are there—I can pay $3.50 per pound for fruit and still use it at 5 pounds per gallon and really get a great expression of what’s coming from these unique varietals.

“Most of our barrel-aged stuff is 49 percent fruit wine, 51 percent beer, so there is a stupid level of fruit. We have a pretty unique, dialed-in process for adding different cultures at different times, for when we add fruit, and for how we’re fruiting. We’ve landed on a process that downplays funk, to the chagrin of some, but really highlights the flavor and fruitiness of the fruit itself. It almost gives a sweet impression even though our beers come out bone dry.”

The key to getting that sweet impression in very dry beers is a not-so-secret, secret ingredient: vanilla.

“We don’t have to use a lot,” he says, “just enough to add this perception of sweetness that you can’t necessarily even pick out as vanilla in there. But if you just put in a little bit, which we do in almost all our beers, it gives that little more candy note to the fruit flavor. It’s in almost all our beers, but we’re talking 15 grams per 1,000 gallons. It’s not much at all.”

Education with Unfermented Fruit

It’s grown more popular today for breweries to release beers with un-refermented fruit, leaving that fruit sweetness in the beer to satisfy our desire for sugar. For Urban Artifact, they decided to use this beer style as a way of teaching their customers about the effect of sweetness. Each Saturday, they put a sixtel of sour beer with unfermented fruit on tap for brunch.

“We started doing that because we wanted to use it as an education touchpoint,” Kollman Baker says, “to tell people, ‘Look, this is the only beer we do like this. It doesn’t go in crowlers. You’re not taking any of this home. You can try it, and we’re going to tell you why this beer is so sweet, and why that raspberry beer tastes different from my fermented dry raspberry beer.’ People still like sugar, so they come in and love the beers because they’re one-third unfermented fruit juice. But for us, the educational opportunity was the reason for wanting to do that—to help combat this weird shift toward fruit beers needing to be sweet.”

Kollman Baker has goals for the barrel- aged side of the business that are modest, at best. He doesn’t see it growing, but he does expect to grow the canned sour side.

“I eventually think the barrel-aged stuff is going to be less than 1 percent of our brewery production, if we get to the size we want to be. If it gets big, I’ll be surprised, but not disappointed.”

Photo: Matt Graves/

Jamie Bogner is the Cofounder and Editorial Director of Craft Beer & Brewing Magazine®. Email him at [email protected].