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Kveik: A Saccharomyces Superstar

Photo by Getty Images/Roxiller

There’s a new contender on the brewing scene — and, no, it’s not a style of beer. It’s a yeast. Kveik (rhymes with “bike”), is an ancient Norwegian yeast that’s making a comeback in the modern brewing world, thanks to a dedicated beer enthusiast and generations of tradition.

Kveik (a word used in some Norwegian dialects to mean “homegrown yeast”) is actually a whole family of yeast strains, rather than a single strain. Until recently, most homebrewers and commercial brewers only had access to a few different yeasts, primarily English, Belgian, German, and American strains. Norwegian strains weren’t even on the radar. We can thank Norwegian blogger and author Lars Marius Garshol for changing that.

Garshol’s blog, appropriately titled “Larsblog,” is a beacon for beer geeks like myself. It’s full of anecdotal, technical, and scientific information on farmhouse ales and yeast styles found throughout Scandinavia and the Baltics. Garshol, who has a professional background in semantic technologies, has gone to great lengths to document and analyze data pertaining to the farmhouse ales and yeasts he’s researched in his travels. In the time since his “discovery” of kveik, the yeast has become an international superstar.

A Viking-Worthy Voyage

Like myself and other beer historians studying the brewing history of Scandinavia, Garshol’s first introduction to kveik was in the book Brewing and Beer Traditions in Norway by Odd Nordland. He was taken aback when he first read about the ancient yeast. “My thinking then was that it sounded almost too good to be true,” Garshol says. “Could this yeast really have survived like this for so long? And what could a yeast like that be like?” This initial thought started him on a journey worthy of a Viking saga, which led to revelation after revelation in his quest to learn more about the ancient yeast. 

Photo by Jereme Zimmerman

The first step on his journey was a visit with Sigmund Gjernes, a farmhouse brewer in Vestbygda, a Norwegian village located outside of the municipality of Voss. Gjernes claimed to brew with a kveik culture (now called “Voss kveik”) that had been passed down through his family for generations. Not knowing what to expect, Garshol told me he was blown away just seeing the yeast. “Looking at that jar, it was obvious that this stuff was real,” Garshol says. “And it amazed me that keeping your own yeast like this could be so simple.”

Author Jereme Zimmerman and Finnish beer writer Mika Laitinen visited The Ale Apothecary in Bend, Oregon, to brew traditional Finnish sahti using Voss kveik. Head brewer Paul Arney stirs the beer wort. Photo by Mika Laitinen

With permission from Gjernes, Garshol took two samples of the kveik: one for himself and one for the National Collection of Yeast Cultures in Norwich, U.K., where it would be analyzed, frozen, and preserved. After waiting patiently for the results, Garshol learned that Gjernes’ sample contained three related strains of yeast, all in the Saccharomyces cerevisiae, or brewer’s yeast, species. It also contained no other bacteria, which is impressive for a farmhouse yeast. (Farmhouse ales, such as sahti and gotlandsdricka, which are traditionally fermented with bread yeast, often contain souring bacteria.) What makes this even more impressive is that the yeast had been passed down through multiple generations, with no laboratory influence or modern sanitation practices. In Garshol’s discussions with farmhouse brewers, he learned that if a batch of ale turned out sour, the kveik would be tossed so as to keep the yeast pure. Also, it’s worth noting that kveik is taken from freshly brewed batches of ale. Because of the alcohol present, bacteria and yeast other than S. cerevisiae are outcompeted, provided it’s a good, strong fermentation.

When Garshol left the farmhouse in Vestbygda, he was convinced that was a big deal, and was determined to do his part to get the rest of the brewing world to pay attention. And pay attention it did. Kveik can now be purchased from many homebrewing stores and websites, and has been used by breweries the world over for everything from Nordic-inspired ales to American IPAs.

 Brewing with Kveik

Much of how kveik functions may seem counterintuitive to modern brewers. For one, it tends to work well when severely underpitched, which would strain most yeasts and result in off flavors. Not only does kveik thrive at levels that would stress normal yeasts, but it also produces stronger flavors at lower pitching rates. According to Garshol, about 1 teaspoon of slurry per 25 liters (6.6 gallons) of well-aerated wort is all you need.

Photo by Mika Laitinen

 Kveik, particularly Voss kveik, prefers uncharacteristically high temperatures throughout the fermentation process. Garshol has a detailed table on his website with the preferred temperatures of various kveik cultures, ranging from 68 degrees Fahrenheit to 104 degrees. Voss kveik sits at the higher end of the temperature range. It should be pitched and maintained at no lower than 90 degrees, with a preference for closer to 100 degrees. Keep the wort at as high a temperature as possible throughout fermentation, which can be achieved by placing it in a warm area and wrapping the fermentation vessel in towels or blankets. It should be noted that these tips will work well for most kveiks, but data on the particulars for each individual kveik strain is still being studied.

Photo by Jereme Zimmerman

Most kveik cultures have a high alcohol tolerance (about 13 to 16 percent), as they’re generally used to ferment high-gravity ales. While kveik is best used for beers with a high percentage of alcohol by volume, it can be pitched in low-gravity worts if provided additional nutrients. Fermentation of high-gravity worts tends to happen very quickly, as soon as an hour or two after pitching. For lower-gravity worts, as well as cider and mead, fermentation can be much slower. You can speed things up by adding yeast nutrient to emulate the nutrient-rich worts kveik is accustomed to.

Another fascinating aspect of kveik is that each culture imparts its own unique flavor profile. Some, such as Voss kveik, impart a citrusy, almost tropical flavor. For this reason, it can be advantageous to minimize the impact of other ingredients and allow the kveik to shine.

Keeping Tradition Alive

If you want to carry on the tradition of saving your own kveik for future brews, there are a couple of ways to do so. The best time to gather yeast to preserve is within a couple of hours of active fermentation. Because kveik cultures are often a mixture of strains, Garshol recommends harvesting the yeast exactly as the original owner did (either from the top or the bottom) so as not to disturb the balance, which could change the kveik.

Photo by Jereme Zimmerman

Some brewers simply keep kveik slurry in a jar in the fridge, while others dehydrate it. To dehydrate kveik, pour off the liquid until you have a thick sludge, smear the sludge on a piece of baking parchment set on top of paper towels on a baking sheet, and put the whole thing in an oven. Set the oven to blow hot air at 86 degrees, with the door slightly ajar. Once the yeast dries into a hard crust, crumple the parchment and drop the yeast chips into a zip-close bag. Store the chips in a freezer, where they can last 20 years or more. When you’re ready to reuse the yeast, create a starter by sprinkling 1 to 2 grams (about 1/2 tablespoon) dried chips into 1 cup of fresh wort (per 5 gallons), and give the yeast an hour or two to wake before pitching the starter.

Some purists feel that using this ancient yeast to brew anything other than traditional Norwegian farmhouse brews defeats the purpose of maintaining it. However, many commercial brewers and homebrewers use it for various beer styles because of its reliability, high temperature tolerance, and rapid fermentation. According to Garshol, the original owners of these yeast strains aren’t too concerned with how they’re used; they’re just pleased that the humble yeast they’ve been keeping alive for generations is now being spread across the globe.

Looking Ahead

Despite the extensive research Garshol has done, including poring over countless ethnographic documents, there’s still a great deal of nuance that must be considered when discussing kveik. Serious studies of, and experiments with, the many different types of kveik are still in their infancy, as it was virtually unknown to the rest of the world until recently. In email discussions with Garshol and Mika Laitinen, a fellow brewing enthusiast and author of the book Viking Age Brew, we noted that a number of kveik’s brewing aspects are highly variable, given the many varieties of this unique yeast. The good news, though, is that as long as brewers stick to some fairly broad parameters, kveik is a forgiving and versatile yeast for all manner of brews.

An old yeast log from the Voss Folk Museum in Voss, Norway, which was used to collect yeast from a fermenter. Photo by Mika Laitinen

To learn more about kveik and the use of other “alternative” yeast strains, look up Milk the Funk, which is both a website with an extensive wiki and a Facebook forum. Launched in 2013, it’s become a highly reputable go-to source for those interested in alternative yeast and bacteria fermentation, with many discussions being devoted to kveik. And, of course, be sure to check out Larsblog for more information from the reigning king of kveik.

Yeast Scream

There’s a special trick Norwegian farmhouse brewers use to ensure strong fermentation and strong beer: They scream at their beer wort as loudly as possible. Yes, you read that correctly. This technique is known as the gjærkauk, or “yeast scream.” There are even contests held to see who can scream the loudest.

While screaming at yeast may seem superstitious, many brewers swear that it works. And it’s fun, so why not? The theory is that the scream scares off supernatural creatures that might spoil the beer. While modern brewers may scoff at this notion, the existence of supernatural spirits was a real concern for people in the past. With no scientific knowledge of why things happened, many people believed fermentation to be a magical process governed by unseen forces. They told stories of supernatural creatures and how to best interact with them to guarantee the desired outcome would come to fruition. If you scream loudly at your yeast and the result is positive, why not keep doing it?

This type of practice isn’t exclusive to Norway, either. Many other cultural brewing traditions involve some sort of ritual to ensure a successful fermentation. Finnish brewers have a yeast-waking “spell” that involves loudly chanting the mantra “The moon has risen! The sun has risen! When will you rise?!”


Jereme Zimmerman is a traditional brewing revivalist, homesteader, and speaker at nationwide natural living events, including the Mother Earth News Fairs. He lives in Kentucky with his wife and daughters.

Published on May 19, 2020

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