Finding Success with Sours

Effectively working with mixed-culture fermentation and barrel aging can be a tricky, time-intensive business. Three of the industry’s best offer their insights.

Tom Wilmes Apr 27, 2016 - 11 min read

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Like many makers of wild and sour ales, Jester King Founder Jeffrey Stuffings adopts a philosophical attitude when it comes to time and space. Namely, if allowed ample time and appropriate space, wild yeast and bacteria can coalesce to create a multitude of interesting and unexpected flavors and aromas in a beer. But of course, the results aren’t entirely predictable, and the timeline is never linear.

“Everything takes a backseat to our microorganisms,” says Stuffings, who notes that his beers typically require anywhere from four months to a year of fermentation time before release.

“Our most expensive ingredient is time,” he says. “To paraphrase Jean Van Roy of Cantillon: ‘I’m not a brewmaster. I’m simply a companion of the beer.’”

That’s a common refrain among the top makers of wild and sour beers. Provide the best possible environment for a mixed-culture or spontaneously fermented beer to begin its existence and then leave it alone to mature at its own pace and by its own design, all the while keeping close tabs on its progress and listening to what it might like to be.


It’s best not to make too many promises or set too many expectations when it comes to mixed-fermentation projects. Even if you are using techniques such as blending to create a more harmonious finished beer or replicate a previous release, a beer’s expression often varies wildly from one vintage to the next and even in the same beer as it changes over time. This can be a vexing dilemma for those bent on creating large-scale programs with consistent, repeatable results and widespread distribution.

But artisans who’ve built their entire operation or large chunks of it around mixed-culture fermentation—including Jester King, The Rare Barrel in Berkeley, California, and The Bruery and it’s new Bruery Terreux project in Anaheim, California—relish the creative experimentation, serendipitous discovery, and expressive character that arise when working with living organisms in beer.

So how do you set yourself up for success? Here are a few hallmarks of a sound mixed-fermentation and barrel-aging program.

It’s in the Goldilocks zone

Managing a mixed-culture fermentation and barrel-aging program takes a tremendous amount of time, space, equipment, and labor. You also need an adequate number of knowledgeable professionals to brew and inoculate the base beers as well as shepherd the beer through its maturation process and keep sensory notes and other readings on each barrel, not to mention space to house all of the barrels.

“Based on all those hurdles, I think it’s virtually impossible to scale this style of fermentation into something that’s really big—like tens of thousands of barrels a year,” Stuffings says. “I’ve seen some very large barrel programs and giant mixed-culture fermentation programs, but even within these very big programs we’re still talking a relatively small sales volume.”


The trick is to be large enough to experiment with multiple batches at once and have enough beer to work with and stay focused, yet not so large that beer languishes in barrels and the program becomes overwhelming.

Patrick Rue, founder of The Bruery, is currently making these calculations with regard to his cellar program, which includes the new Bruery Terreux, a distinct brand created to focus on farmhouse-style ales fermented with wild yeasts and oak-aged sour ales.

The Bruery currently has about 3,500 oak barrels, which represent about half of its production, says Rue, who estimates that total production will grow from roughly 10,000 barrels in 2015 to almost 15,000 in 2016.

“We’re still trying to figure out our sweet spot with the cellar program. If we doubled in size, I feel like we’d have some problems,” Rue says. “We taste and do analytics on every single barrel—just 1 barrel in 100 thrown into a brite tank can ruin the whole thing.

“When you look at family wineries, the estate is what it is. If it’s 50 acres, that’s the amount of wine they can make without purchasing more land or grapes from elsewhere, and I think that’s awesome. Let that restraint be what it is.”


It’s run like a small winery

As Rue alludes to above, many successful mixed-fermentation and cellar programs view their business model as more akin to a family winery than that of a production brewery. The beers are often tied to the land and native ingredients in some way, produced in limited quantities through barrel aging, and distributed primarily through on-premise retail or across a very limited regional footprint.

Although Stuffings expects Jester King to produce about 2,000 barrels this year, he’s as not concerned about volume growth as he is in developing his farmhouse-style brewery on the outskirts of Austin into a destination that celebrates all things fermentation.

“We produce a very low volume, but we sell everything in large-format bottles and do make a good margin on the beer—our average retail ends up being about $12 a bottle and, fortunately, we can sell about 75 percent of our beer right out our front door,” he says. “Being in every market under the sun isn’t something I have much passion for. I like to go to different places and try what’s unique to that place.”

Many smaller sour- and wild-ale programs distribute primarily on-premise, often through exclusive beer societies or clubs such as The Rare Barrel’s Ambassadors of Sour program and The Bruery’s Preservation Society.

“This is a specialized process, and it requires a special way of selling the beer,” says Jay Goodwin, cofounder and head brewer of The Rare Barrel. “Certainly we’ve borrowed a lot from what wineries do. We have different vintages of our beers and the production is variable. We can also make specialized small-batch blends for a group of people who are interested in that and give them other perks like being able to buy our beer online before it’s available to the general public. It’s a great way to connect with the beer drinker who not only supports what we’re doing, but also has a passion for sour beer.”


If a variable can be controlled, it is

Wild and sour programs may be experimental by nature but, like any well-founded experiment, it makes sense to limit the number of variables and set up controls wherever possible.

At The Rare Barrel, for example, Goodwin works with just three base beers—a golden ale, a red ale, and a brown ale—in all of his projects. Primary fermentation takes places in stainless steel, where the beer might ferment for several weeks or as many as several months.

“That’s out of necessity for the experimental part of our operation,” Goodwin says. “We’re trying out new wild yeast strains and bacteria all the time in different combinations, amounts, and timings. To have twenty different base-beer recipes would complicate the experiment beyond our abilities to extrapolate anything from the results.”

More than half all Rare Barrel releases are built around the golden-ale base, he says, which also serves as the starting point for all new projects. The malts bills in the darker beers tend to limit the types and quantities of secondary additions he can use, Goodwin says, while the golden base lets the yeast and bacteria shine through.

“Especially with different strains of Saccharomyces,” he says, “where we want it to take the reins of initial fermentation and see how it affects the beer.”


Stuffings takes a similar approach at Jester King.

“We work with some pretty simple grist and hops bills,” he says, “typically 80 to 85 percent malted barley with some raw wheat and maybe some oats, as well as a blend of fresh and aged hops, along with adjunct ingredients such as fruits, grains, and spices.”

“We tend to start with those common variables, and we’re certainly thinking about how hopping rates impact acidity,” he says. “Time, temperature, and hopping rates are the levers we adjust to make beer where the acidity of all the bacterial components in a mixed-culture fermentation results in organic acids that are drinkable—that are tart, soft, and more lactic-acid focused—versus something that’s harsh, acetic, and, frankly, not very drinkable.”

The beers are ready when they’re ready

“You can make a nice-tasting sour beer at a younger age, but I think the trick to really making a sour beer successful is letting it age further and round out those flavors,” Goodwin says. “With our beers, we find that we get 80 to 90 percent of the way to a finished product fairly quickly, in three months or so, but it’s the next six, nine, twelve months—whatever it’s going to be—where we go from that to 100 percent.”

Brewers at The Rare Barrel sample each barrel every ten days and also take sugar-content readings, as well as pH and temperature readings, to monitor its stability.


“We want to know not only does this beer taste good, but also when it’s ready to package,” Goodwin says. “We’re looking for two months straight of readings that tell us that the taste is not changing and the sugar content is at a low enough level that it’s not continuing to ferment.”

Stuffings notes that re-fermentation in the packaging vessel is also a critical, if often overlooked, consideration.

“In our experience, the bottle-conditioning stage has a huge impact on a beer’s flavor profile,” he says, adding that he typically enjoys a sour beer best between six and eighteen months after bottling. “When we blend, we’re aware that that blend is going to change quite dramatically as the beer continues to ferment in the bottle or in a keg.”

But for all of the time and effort, and especially in spite of all of the mixed-fermentation experiments that just didn’t turn out, Stuffings and his fellow beer shepherds remain dedicated to the craft.

“The scope of what can be done with malts and hops, and certainly culinary-inspired ingredients and adjuncts, can be interesting and great,” Stuffings says. “But combine those with microbes that are diverse and unpredictable in nature, and that can lead to some of the most satisfying and delicious experiences in the beer world.”