Capturing Indigenous Yeast Cultures with Antidoot

The yeast wranglers of Kortenaken, Belgium, got better at it over the years.

In the beginning, homebrewers Tom and Wim Jacobs would leave out wort samples in small Erlenmeyer flasks. Typically, they would add local berries or other produce, to see what they could harvest from nature’s own tiny fermentations. Out of 10 samples, maybe one or two would turn out pleasant enough to step up and try in a brew. As they developed experience and a sense for what works, about half of those indigenous yeast samples would succeed.

Those successful experiments survive, in a form, as part of the house mixed culture of Antidoot Wilde Fermenten, which—like the culture—has taken on a life of its own. The Jacobs brothers released their first commercial beer in 2019, and aficionados have been hunting bottles ever since. In 2020, Ratebeer—based on the scores of its users—named Antidoot one of the top three breweries in the world for wild beers, alongside Side Project of St. Louis and Casey Brewing and Blending of Glenwood Springs, Colorado.

For more about Antidoot and its approach to locally rooted mixed-culture fermentation, check out “Metamodern Tastes in Country Beer”—also featuring Eik & Tid of Norway and Kemker Kultuur of Germany—in our February–March 2022 issue. For more tips on capturing local yeast, see Spontaneity: Prospecting for Bugs.

Here, Antidoot brewer Tom Jacobs shares practical advice based on their earlier experiences in gathering the kinds of wild cultures that can ferment tasty beer. [PAYWALL]

Think Cool

Antidoot’s usual approach was to add local produce to the wort and see what happens. What you want is the presence of sugars because wild yeast will inevitably find it and live there, too.

“It’s best, I would say, in winter times,” Jacobs says. “Let’s say, if you just take some fruits in summer, of course you know there are sugars. But it’s too easy, and then you have a lot of bad pioneering yeast, which are dominating, say, the overripe berry.”

Essentially, there are many more microflorae thriving in the summer, and most of them are less desirable than the hardy Saccharomyces strains that can work through the winter. In the summer, Jacobs says, “you also have a lot of bacteria. So if we just would take some overripe blackberries, we would get mold, or just the yeast you don’t want, like maybe Candida, or other interesting stuff.

“But if we would go in winter, where we have some sugars from tree sap or lichen… Or, what always worked were juniper berries because they’re already somehow fermenting on the inside. So, they go from green to black in winter, and you have Saccharomyces living on there.

“So, just think: ‘Where do we find some sugars in winter, in nature?’ And it always worked for us somehow.”

Put Local Produce in Wort

Can you leave out fresh wort to collect local bugs from the air? Sure. Sometimes it works, Jacobs says. But he and his brother usually got better results from adding locally picked or foraged things directly to the wort.

“You can try to do it airborne,” he says. “Or just look for some [things] that you think wild yeast is living in, and put that in fresh wort. It’s a bit easier to take the juniper berries and put it in the wort than the airborne, where you have to be a bit more lucky.”

Take Multiple Samples and Keep Checking on Them

“Let’s say you have 10 samples,” Jacobs says. “Then, of course, you have to follow up on what happens.”

He suggests getting several small Erlenmeyer flasks. Sanitize the flasks, and add fresh wort brewed to a gravity of about 1.050. After you’ve inoculated your samples, cover them loosely with sanitized aluminum foil.

“And you keep shaking it a lot, just to get fermentation going,” he says. “You aerate it in the first days, and then you have to follow up. If you have what you think is a successful fermentation, then you can start measuring the density. So you started with 1.050—we’ll see what happens. And if you think, ‘Oh, this is alcoholic fermentation that’s going on,’ you can step it up. You add every day a bit of fresh wort to it, to keep it going.”

For at least a month, it’s a bit like look, but don’t touch—except instead it’s smell, but don’t taste.

“It’s very important not to drink it in the first days because you don’t know what you’re getting,” Jacobs says. “We’ve always just worked with smelling. If it’s nasty smells, we normally just dump it directly. But then, you will find a few with a good smell. We only used to really drink from it—or just taste it—after a month of keeping it going, and [when] you know that the alcohol is above 4 percent [ABV], just to stay safe. Normally, after a month and above 4 percent, there are no risks involved.

“With your nose you can detect a lot of things.”

Be Patient, and Work with Your Environment

Jacobs says they eventually were able to have a roughly 50 percent success rate with their samples. “But that means you need to have a kind of intuition for what will work,” he says. “In the beginning, it might just be one or two. It’s very hard; there are so many parameters. Let’s say if you do it in Michigan or you do it in Florida, it’s going to be totally different.”

You Can Simplify by Combining

After a while, the Jacobs brothers had a few different cultures that they liked and used in separate beers. Those have long since joined the “Borg” of the mixed house culture.

“It was too complicated,” he says. “We have no laboratory, so it was impossible to keep them separated. So, they all morphed into one culture.”

There is no yeast library for them, either—the Antidoot culture is a living thing that evolves with their products—including beer, cider, and wine—and experience.

“There is no ‘original culture,’” Jacobs says. “We have nothing in the freezer. There’s no pure version we can go back to, or something like that. Everything has evolved through the years. It evolves also through cider. And all the beer is coolshipped.

“So, it’s somehow constantly evolving, but at the same time we find that it’s pretty stable.”