Fox River's Barrel-Aged Sour Program

A slightly different version of this article appears in the November 4 edition of the Oshkosh Herald.

A sour beer can be a tough sell. For the casual beer drinker, the mere idea of sour beer can be off-putting. But that's a rather recent bias. Prior to the 19th century and the rise of industrial lager brewing, tart and sour flavors in beer were not only common, they were sought after and appreciated. Drew Roth isn't thinking he's going to undo a couple of centuries worth of received ideas about flavor. He's just trying to offer an alternative for those interested in exploring the breadth of what a traditional beer can be.

Roth is the brewmaster at Fox River Brewing and earlier this year he launched what is now the most extensive barrel-aged, sour-beer program Oshkosh has seen. To date, Fox River has released three beers in its "Foxxine" series of small-batch sours. Roth had been hoping to work something like this into the Fox River line-up since becoming the brewmaster there last year. He spotted an opportunity after the COVID-19 pandemic struck.

Drew Roth of Fox River Brewing.

"We hit the shutdown period and had this fully fermented batch of beer in the tank that we didn't think we were going to need," Roth says. "And we had these empty wine and bourbon barrels sitting idle that had outlived their use for non-sours. So the thought was, we've got these barrels, and I've got these sour cultures I know work, so instead of just dumping the beer, let's put it in the barrels. Worst-case scenario, we dump out the barrels."

The beer that went into those 59-gallon, oak barrels just happened to be ideal for Roth's purpose. "The original batch was the base beer for our Red Bobber," he says. "There's a sizable amount of wheat in there, which those mixed cultures love, and the hops are low enough not to inhibit the growth of the culture."

Roth has been working up his various sour cultures since his homebrewing days. They're a mix of wild yeast and bacteria that have the ability to re-ferment beer that has already undergone primary fermentation. The "bugs", as brewers sometimes call them, tend to work slowly and perform best in warmer temperatures. "We kicked the barrels out to a secondary storage facility where we filled them and inoculated them with the sour culture," Roth says. "They sat out there in a non-temperature controlled environment. During the summer I'm sure it was up to 90 degrees in there. That beer soured very quickly."

Some four months after the barrels had been filled, Foxxine #1 was released on September 17. It was the first mixed-culture beer Fox River had ever produced. Roth had made the most of the bad situation the pandemic had handed him. A beer on the verge of being flushed had been re-made into a tart, dry ale with notes of pineapple, vanilla, and oak similar to those found in barrel-aged Chardonnay.

That degree of flavor complexity is what differentiates Fox River's barrel-aged from the more commonly found and quickly produced "kettle sours" many craft brewers now offer. The latter beers tend to lean heavily on fruit juices, sugars, and other flavorings to quell the blunt acidity "quick souring" produces. Or as Roth says, "By adding anything to it to make it not sour anymore." Roth isn't opposed to using fruit in his sours, but he'd rather employ it as an accent rather than making it the main feature. For Foxxine #2, he used black currant to highlight the jammy, dark-fruit flavors produced from a separate sour culture working in tandem with the barrel aging.

"I don't foresee these super fruity, super sweet sours lasting too much longer," Roth says. "It just seems like every year or two we rediscover a beer that has already existed." He's hopeful that the barrel-aged sours he's making will get to see their time come again. In the meantime, Roth continues to build-up his barrelage. "I have eight barrels going right now,” he says. “The ninth one will be added soon and that's about as far I want to carry it for now."

"The goal is to keep bringing them out. I want to get to the point where we have a barrel-aged sour on at all times. It's going to be an ongoing project. I want to concentrate on the flavors we develop from the mixed cultures and the barrels and eventually get into blending beers from the different barrels to achieve specific flavor profiles. I love making them. As long as people keep drinking them I'll keep making them."

A Deeper Dive

The section above was written with the Oshkosh Herald's readers in mind. In those articles, I generally try to avoid going off the deep end into pure geekdom. But not here. When I interviewed Drew for this piece we went into the weeds about the mixed cultures he's using. Here are a few snippets from that conversation.  

At the moment, he's working with three separate mixed cultures. He also has a fourth culture that he's currently working up and hopes to introduce into the program in the not-too-distant future.

For Foxxine 1 he used what he's calling his American Sour Culture. This culture is a blend of lactic bacteria, pediococcus bacteria, and Brettanomyces yeast. Drew says it imparts "A citrusy, lactic tang from the lactic and pedio, with a hint of fruity funk from the Brett on the back end. The brett character in it is really subdued, a little more on the fruit than the funk." I had this beer on a couple of different occasions and each time I got a lot of pineapple out of it.

His second culture was used in Foxxine 2. He calls it his lambic culture. This one began from a small batch culture from The Yeast Bay. "It's got a ridiculous blend of different bacteria and yeast," he says. "It's one they don't do for commercial brewers. I propped it up as part of my homebrewed sour program originally." To me, this one came across as more citrusy; with some stone fruit, which lined up nicely with the black currant he used in the beer.

"The third culture is one that I refer to as our Flanders culture," Drew says. "We've got that one going now. I'll eventually transition that into brown, Oud Bruin style beers. With that one, you get more of an acetic character and then a different funk out of the brett."

Finally, there's a fourth culture that he's still developing. "I've got that one going at home," he says. "It was a wild yeast propagation from fermenting wine naturally, so the yeast and bacteria originate from red grapes. I added that into fresh-pressed apple juice this fall, so it will also have the cultures from the apple juice. For that one, I have a red wine barrel that we did a stout in. We'll see what happens."

That unpredictability is part of what makes these beers exciting. You never know exactly what you're going to get until you get it.