The Best Brewer's Yeast Is Made in the Back of a Copenhagen Pub


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The Best Brewer's Yeast Is Made in the Back of a Copenhagen Pub

At WarPigs, a craft beer pub in Copenhagen's meatpacking district, brewers are using a "yeast machine" to expand the flavor possibilities of one of beer's most overlooked ingredients.
April 28, 2015, 4:00pm

Vanilla, weasel shit, yuzu, hemp, Margherita pizza. Beer ingredients are an abundance of eccentricity, but any decent pint needs quality yeast. At WarPigs, a brew pub recently opened in Copenhagen by local craft beer darling Mikkeller and 3 Floyds from Indiana, yeast is treated so seriously that they now have an in-house lab to develop their fungi.

WarPigs is based in Copenhagen's meatpacking district, where butchers in white coats mingle with Danish trendies on cargo bikes. One side of the huge white-tiled brew pub smells of authentic Texas-style barbecue, cooked on a giant beast of a smoker, while the other is engulfed in hoppy fumes from the brewery. In one of the back rooms, laboratory kit is lined up on the tables: a centrifuge, an autoclave for sterilizing bottles, a spectrophotometer to analyze color, a microscope, and a water bath. Next to that is the main attraction: a large steel apparatus with more tubes, pipes, valves, and levers than a sci-fi spaceship. Troels Prahl, the 32-year-old Danish microbiologist who heads up the lab, calls this "the yeast machine."


Kyle Wolak, head brewer at Warpigs. Photo by Theis Mortensen.

The production facility at WarPigs is the first European outpost of White Labs in San Diego, an industry leader that has pioneered a propagation technique whereby brewer's yeast is packaged in the same recyclable material where it is cultivated, thus avoiding any transfers during the process. The yeast machine at WarPigs is the prototype that Troels brought from San Diego, where he worked as head of research and development at White Labs. He relished the prospect of working on a smaller scale in Copenhagen, side by side with brewers and chefs. "Here, it's about more than just making yeast," said Troels. "One of the brewers might pop in and ask if we have something that can ferment lactose—and then we have to solve that. It's really experimental. This is where we get to play."


Photo by Theis Mortensen.

Troels and White Labs are currently working with a Belgian genetics group to sequence the DNA of more than 220 commercially used yeast strains to further explore its flavor impact on taste. ("If it wasn't big enough to begin with, there are years of geeking out over that stuff.") Another experiment is vandregær—"wandering yeast"—made with spontaneously fermented apples from an orchard on the Danish island of Lilleø. The strains were isolated years ago in collaboration with a Danish winemaker, but they have now been revitalized with beer in mind. The idea is to let a series of Danish microbreweries pass down the culture to see how characteristics develop and affect flavor. Troels originally spent hundreds of hours in the lab selecting and purifying the yeast and described the result as "phenolic, pretty estery, almost wit-like."

Kyle Wolak, the American head brewer at WarPigs whom 3 Floyds had brought with them from Indiana, was eager to try his hand at the wandering yeast and expand the collaborations. "I can't speak for all brewers, but many take yeast for granted," said Kyle. "You buy it, put it in the tank, and it does the work. Normally, people wouldn't put too much thought into it."


Photo by the author.

Troels acknowledged this was a common response from some brewers, but he also saw a burgeoning appetite for understanding of how yeast contributes to the final product. "Compared with winemakers, for example, brewers are rock stars when it comes to understanding yeast and reusing it. The wine folks use it once a year during harvest. Brewers use it every day because they keep this culture alive. If Kyle wants to make something funky, we can do it. We could go outside, right now, into the parking lot and isolate some yeast. There is a pretty awesome synergy on the experimental side, not just the lab analysis."

Kyle, 25, from Indiana, started out as a dishwasher at 3 Floyds' brewpub before graduating to brewer and his secondment in Denmark. What he needed this afternoon wasn't carpark yeast but an old English strain to make a batch of Big Drunk Baby, a 9-percent ABV double IPA. "In the States you are not allowed to use the word 'drunk' in beer names, so we thought we'd have some fun here in Denmark," Kyle said. "After a few Big Drunk Babies, you could definitely turn into one."


Photo by the author.

He stood on the steps of a stainless steel platform, peeking through the porthole into one of the brewing tanks, where 400 kilos of Danish two-row barley was mashing. His grey band T-shirt carried the name of Indiana shoe-gazers Cloakroom; the configuration of the water in the tank was also a US import. "Denmark's water is pretty hard," said Wolak, "and it's not the best for brewing." Instead, he runs the water through a "reverse-osmosis treatment centre," which filters it and strips away the minerals. "We then reintroduce minerals so we get the exact level of hardness we want to brew with. We go by a sample of the water I used at 3 Floyds, which was from Lake Michigan. It's awesome for brewing."


Photo by the author.

In the small office Kyle shares with assistant brewer Lan-Xin Foo, clipboards with beer recipes hang from meat hooks next to a calendar with pictures of dogs. There is also a chart, produced by White Labs, that matches yeast strains with beer types. The old English yeast, originally used for making real ale, was an obvious candidate for the double IPA. "There are different esters in different yeasts," said Kyle. "Most ale yeasts are very crisp and light—unlike something such as hefeweizen, where it adds a strong banana-like flavor. For a good ale yeast, you don't want it to be too much in your face."


Photo by Theis Mortensen.

The Big Drunk Baby turned out to be a pleasantly aromatic and hoppy beer that seemed destined for Texas rub and fatty brisket. "The beers we brew pair really well with the barbecue food," said Kyle. "Nothing is more refreshing with spicy meat than a cold beer.

"That's not rocket science. That's just … life."