In the 21st century a wealth of brewing tips, techniques, and recipes are accessible to anyone with access to the internet. Bohemian pilsner malts, New Zealand hops, Belgian yeast strains are available to brewers from Texas to Tokyo. Water chemistry can be bent to the brewers will. Geographic differences in beer styles that were once striking have started to fade as globalization marches forward. Is craft brewing destined to the same fate as rock music, a continuous parade of variations on cyclically recurring themes? Just when you think there’s nothing new under the sun along comes a new family of ale yeast called kveik that might just be a game changer.

Kveik, pronounced with a long i sound something like k’wike, is the word farmhouse brewers in Western Norway use to describe their yeast. Most of us first heard about kveik through the blogging of Norwegian Lars Marius Garshol. His blog, Larsblog, which dates back to 2005, has over time has evolved to be a fascinating series of reports on farmhouse brewing traditions in Northern Europe. Searching through the archives of Larsblog the first mention of kveik appears to be a post entitled “Kveik: Norwegian Farmhouse Yeast” from November 2013. Prior to that one would have to assume few people outside of Norway were aware of this amazing strain of yeast [1]. The first time he encountered kveik in person was documented in a post from June 2014 entitled “Brewing with Kveik” when he traveled to Western Norway, near Voss, to brew with Sigmund Gjernes. A quote from that story captures the excitement Lars felt on his first encounter with Kveik:

I stood there for a long time, staring at the jar in fascination, taking pictures and just watching. I’d never seen anything like it. Sigmund had his own strain of yeast living in the fridge, like a prehistoric domesticated animal, unknown to science. A separate tribe of living creatures descending out of nobody knows what distant past.

Starting from samples Lars collected and sent to yeast banks and labs, kveik became commercially available through labs like Omega and The Yeast Bay in early 2016. My first taste of kveik’s handiwork was a beer brewed at Seventh Son Brewing here in Columbus in the summer of 2017.

There are hundreds of yeast strains commercially available to homebrewers and even more to professional brewers, so what makes kveik unique? Simply put it can ferment at crazy high temperatures (roughly 70−100 °F/21−38 °C) without producing detectable levels of phenols or throwing off a lot of harsh fusels. I attended a workshop at Buckeye BrewCraft back in January, where Mark Schwarz co-founder of Omega Yeast Labs, told the story of fermenting an 11% abv imperial stout with the Hornindal strain of kveik. After pitching the yeast at 88 °F and letting it free rise, the beer finished primary fermentation after 3 days and was ready to drink in 8 days, with minimal fusels! A high gravity imperial stout would normally be fermenting for a couple of weeks, and then conditioning for month or more before being ready to drink. Some strains of saison yeast can ferment at high temperatures, Dupont famously runs their fermentation at temperatures approaching 100 °F, but it also produces a very distinctive mix of phenols and esters that are unmistakably characteristic of a saison. Good luck selling an imperial stout fermented with saison yeast.

Omega’s HotHead Ale (OYL-057) strain of kveik is advertised to give a consistently clean fermentation profile at fermentation temperatures ranging from 72 to 98 °F. The other strains might get a little fruitier at the high temperatures, but still make pleasant beer at blood warm temperatures. So, if you are a homebrewer with no temperature control and no basement who wants to brew in July, enter kveik and problem solved. Same goes if you are a small-scale craft brewer without jacketed fermenters in Brazil or Miami. Even breweries who have temperature control, as most commercial breweries do, could stand to reap substantial energy and cost savings if they don’t have to control the temperature of their beer in the dog days of summer. On top of that you have the prospect of reducing fermentation time. That’s an appealing prospect for a brewery with limited fermentation capacity that’s struggling to keep up with demand. It’s no wonder that only five years since Lars’ first encounter kveik it has spread across the globe faster than a zebra mussel.

Map of Norway showing the locations where Lars Marius Garshol has found traditional brewers using kveik. Image taken from reference [2].

What science tells us about kveik

Since Lars first encounter with kveik in 2014 he has collected samples from dozens of farmhouse brewers in Norway and sent them to various yeast labs for storage, propagation and analysis. Much of this analysis is presented in a paper by Preiss, Tyrawa, Krogerus, Garshol and van der Merwe published in the September 2018 issue of Frontiers in Microbiology [2]. Their testing revealed that what the farmhouse brewers call kveik is actually a mixture of different strains [3], all closely related types of Saccharomyces Cerevisiae – ordinary top fermenting beer/bread yeast (plus a little lactic acid bateria thrown in for good measure). Despite that seemingly normal genetic classification the research shows that kveik is far from ordinary.

Unlike saison, hefeweizen, brettanomyces, and wild yeasts, kveik strains do not produce appreciable levels of phenols, molecules that add somewhat divisive flavors ranging from clove and black pepper to smoky and medicinal. Kveik strains also do not produce isoamyl acetate, the banana flavor molecule so prevalent in German hefeweizen, above threshold levels. Production of other fruity esters when fermented at 30 °C/86 °F were higher than WLP001 California Ale Yeast and WLP002 English Ale Yeast, but lower than WLP570 Belgian Golden Ale Yeast. They were roughly comparable to WLP029 German/Kölsch Ale Yeast. Looking at the table below the thing that really jumps out at me is the low levels of isobutanol, a fusel alcohol molecule that will add harsh, solvent-like flavors to the beer. The all of the kveik strains produced around 1 ppm isobutanol, less than half that of three of the four control strains, and only one-quarter of the levels produced by English Ale yeast (WLP-002). This explains in part why Norwegian brewers start drinking/serving their beer 2-4 days after pitching the yeast.

Nineteen of the twenty-four strains of kveik tested were able to undergo healthy fermentations at 40 °C/104 °F, while of the commercial yeasts only WLP570 (Belgian Golden Ale) could ferment at those temperatures [4]. There are limits though, even the kveik strains died when the temperature was raised to 45 °C/113 °F. With one exception the attenuation levels ranged from 75 to 95%, which implies the ability to ferment maltotriose, a sugar that’s common in wort but generally uncommon in nature. The alcohol tolerance ranged from 13 to 16% abv, and at least half of the kveik strains tested were highly flocculent, comparable to English Ale Yeast (WLP-002).

Several of these characteristics—lack of phenol production, high alcohol tolerance, the ability to ferment maltotriose—are suggestive of domesticated brewers yeast, yet others are not, most notably the heat tolerance. As Lars explains in a post from last fall, “Where Kveik Comes From” based on this research they speculate that kveik was formed centuries ago when early European brewing yeast mated with an unknown wild yeast [5]. If this hypothesis turns out to be correct the origins of kveik would be similar to lager yeast, which is thought to have originated when brewers yeast mated with a cold tolerant wild yeast. Some of the characteristics of kveik, like the alcohol tolerance and flocculation are likely due to the beers Norwegian brewers made (higher abv beers) and how they harvested and stored their yeast.

Kveik strains

The kveik strains from Omega Yeast Labs are the most readily available in Ohio. Omega offers three varieties of kveik:

HotHead Ale Yeast (OYL-057) – Seems to be a fairly clean yeast, touted for offering almost identical esters at fermentation temperatures ranging from 74 to 94 °F. Medium-high flocculation.

Voss Kveik (OYL-061) – This is a single strain isolated from Sigmund Gjernes yeast, the first kveik Lars encountered in the wild. It is said to produce orange-citrus flavors. Mark Schwarz suggested it would be a good choice for wit biers. Medium flocculation.

Hornindal Kveik (OYL-091) – This is said to be a mixed culture, that originates from the yeast used by Terje Raftevold who lives near Hornindal, a city in the western fjords 300 km north of Voss. It is the most alcohol tolerant (up to 16%) of the commercial strains and appears to have the most characterful flavor profile. Omega describes it as possessing a tropical flavor and complex aroma that can present itself as stone fruit, pineapple, and dried fruit leather, all of which complement fruit-forward hops. Highly flocculent.

Reports from the Field

To get a better sense of how kveik is being used in a craft brewing setting, I reached out to several brewers and asked if they could share their experiences with this wonder yeast. The virtual panel includes Colin Vent brewer at Seventh Son, the brewery where I first tasted a beer brewed with kveik back in 2017; Sean White of Little Fish in Athens, Ohio’s premier farmhouse brewery (in my opinion); Trevor Luther of Grove City Brewing who currently has two kveik beers on tap, including a Norwegian Raw Ale; Dan Shaffer of Land Grant whose recent use of kveik to brew a lager caught my attention; Joshua Martinez of Pretentious Barrel House, who experimented with kveik as the house yeast for the primary fermentation step of making barrel-aged sours. The panel is rounded out by one respondent from across the pond, my friend Nick Smith from Steam Machine Brewing in Newton Aycliffe, England. To finish up today’s post we’ll get a sense of their experiences with and impressions of kveik. Look for a follow up post where we look at unconventional uses of kveik and break out a crystal ball in attempt to predict where the kveik craze might lead us.

Motivations for using kveik

To begin with I asked each brewer what motivated them to start using kveik. Perhaps not surprisingly just about everyone was motivated largely by a desire to try something new.

Colin Vent: I’m always trying new things here, kveik is part of that.

Sean White: Our motivation was just to try a fun new thing, and this yeast is very interesting. We’ve used the Kveik strain so far only in collaborations with Willoughby Brewing, Fifth Hammer & Yonkers Brewing, and Market Garden. That’s part of the fun of collaborations for me, to get adventurous and not necessarily know how something is going to turn out.

Trevor Luther: I had Norwegian in my family history and wanted to brew something traditional.

Joshua Martinez: I started using kveik because I could ferment it warm in a mixed fermentation with bacteria, and the high temperatures would speed up the acidification process. I stopped using it when I discontinued mixed primary fermentation. Because of the sporadic brew schedule we had, I needed a yeast that would be able to sit in the fridge for 2 weeks and still be viable. Which is why I switched over to a lager strain.

Nick Smith: How could we resist using a yeast strain that seems to have been forgotten to the brewing world, except by isolated Norwegian farmers; a yeast that seems to re-write the way brewing yeast should be used?

Dan Shaffer: There has been a lot of activity recently on the Milk the Funk Facebook group/wiki regarding kveik strains and their capabilities. With their ability to ferment at extremely high temperatures (85 to 100+ °F), I think it naturally brought up the question of what happens when you ferment at more traditional temps (65-70 °F). Members of the group started experimenting, but the first one I saw that really peaked my interest was a kveik fermented helles.

What does kveik really taste like?

The flavor and aroma profiles given by the yeast manufacturers are all well and good, but part of their job is marketing. I wanted to get a reality check on the kveik profile, so I asked each brewer to tell me what strain(s) he had used and to describe the flavors and aromas kveik imparts to the beer?

Sean White: The beers we have made have been pretty “freestyle”, definitely not traditional kveik brews. They have always included some botanicals such as juniper branches, citrus zest, chamomile, lemon verbena, etc. We have used the Hothead strain as well as the Hornindal strain, both from Omega. As we have not brewed an unspiced beer with kveik yeast, it’s difficult to say exactly what flavors and aromas the yeast imparts. I personally think it’s a very clean, somewhat fruit/estery yeast, but I have found the claims of tropical fruit or citrus esters to be a little over-sold. It’s just really clean, in my experience. It doesn’t produce phenols and it apparently does not produce fusel alcohols, even in hot, high gravity fermentations. Compared to the saison strains we use extensively, kveik doesn’t have nearly the fruity profile, or the phenolics, for better or for worse. It also doesn’t super-attenuate like most saison yeasts do. I don’ think kveik yeast makes a great saison, but that makes it more applicable to other clean beer styles, like IPA’s or whatever else.

Colin Vent: We started out just using the Voss as its description suggested a little more character than HotHead. Those were the first two strains released. Then we switched to the Hornindal, and actually now we’re fermenting with a blend of all three. All of the sour barrels at Antiques on High have kveik in them also. As for the flavor profile that’s hard to say. We’ve done so many one-off beers with it, or beers with a high amount of dry hopping, but we haven’t tried putting it into a very neutral beer or doing a side-by-side with the house strain.

Nick Smith: We initially purchased a tiny homebrew-vial from an Irish supplier called ‘Wicklow County Hops’, although based on the supplier’s descriptions, we believe it is the same as Omega’s cleaned up Hornindal. The Hornindal has provided a great sensory experience, with bready, cake-like character akin to freshly baked pudding goods, it can also add stone fruit aromas found in traditional English ales, and borders on the tropical pineapple that we’ve seen from New England yeasts. It’s been a very positive experience so far.

Dan Shaffer: We used the Omega Hornindal strain, and fermented it at 70 °F. With so much going on in the beer (hops, honey, spelt), it’s difficult to pin down, but I thought it was pretty clean and crisp.

Trevor Luther: We’ve used the Hornindal, and I love the way it gives a light fruitiness, with a slightly dry finish.

Joshua Martinez: We only used Omega’s HotHead Ale strain. The profile was pretty clean I would equate it to a California Common in ester profile, clean almost hybrid like.

How hot, how fast?

Next I was curious to see what kind of temperatures brewers were using and if the claims of a faster turnaround time were true. Not surprisingly the answer to the second questions is highly dependent on the answer to the first.

Colin Vent: Our fermentation temperature depends on the beer and if there are any other strains included, such as Brett or our house English ale. If it’s straight kveik and we want it fruity we’ll let it rip into the 90s, if we’re going cleaner we’ll hold it in the 70s. Primary fermentation generally takes 4 to 5 days, while the time from pitch to packaging depends on the beer and dry hop schedule. The yeast doesn’t have much influence on that for us.

Trevor Luther: We knockout at 85 °F degrees and I set my temperature control to not let it rise above 110 °F. Primary fermentation lasts 3-4 days and pitch to packaging has been as short as 8 days for us! Visible signs of fermentation (bubbling) have started as soon as 15 minutes after pitching.

Dan Shaffer: As stated above for Helios (lager) we fermented at 70 °F. It was four days for primary, but around two weeks in total. We decided to “step crash” after terminal the same as we do for our normal lagers (-3 degrees every morning and evening until we get to 32 F). For Qingdao and Strata (both hoppy ales) we set the fermentors not to rise above 95 °F. Next time we might just let em rip. Time wise those were three day ferments prior to the dry hop versus 9-10 days for our British hazy yeast strain.

Joshua Martinez: I fermented at 85 °F. Primary fermentation lasted 36-48 hours, over which time the gravity dropped from 12.0-3.0 Plato (1.048 to 1.012 in gravity terms).

Sean White: We have gone up to 85 °F with fermentation temps. We have mainly opted not to go higher just because we don’t want to lose a lot of beer through a violently active high krausen.

Nick Smith: The most recent batch was pitched at 38 °C (100 °F) and has now cooled off to 30 °C (86 °F), after three days of primary fermentation it seems to have finished. We’re also brewing a lager (more on that in the next post) where we pitched at 22 °C (72 °F) before cooling to 15 °C (59 °F). It’s still going after three weeks.

Closing Thoughts

While I don’t expect kveik to sweep away more conventional strains of yeast, the way hops eventually put the gruit makers out of business 500 years ago, it seems obvious that kveik is much more than a passing fad. All of this due largely to the research and writing of Lars Marius Garshol. I don’t think it would be too much hyperbole to suggest his efforts to champion traditional brewing practices and spread the kveik may have had more influence on the beer world than any writer since Michael Jackson.

Look for a follow up post where I ask my virtual panel of brewers to talk about using kveik in less common ways, we’ll discuss brewing raw ales, and go into more detail on using kveik to brew lagers. Finally we’ll get out the crystal ball and try to predict where all this is leading.

Endnotes

[1] In this post Lars mentions that Michael Jackson found brewers using kveik in Voss in 1995, and that a sample was submitted to a British yeast bank in 2009. So, there was some knowledge in the outside world, but I think it’s fair to say only those deep into yeast cultures were aware of its existence.

[2] R. Preiss, C. Tyrawa, K. Krogerus, L. Marius Garshol, G. van der Merwe, “Traditional Norwegian Kveik Are a Genetically Distinct Group of Domesticated Saccharomyces cerevisiae Brewing Yeasts” Front. Microbiol., 12 September 2018.

[3] Using yeast samples taken from 9 different farmhouse brewers they isolated 24 different kveik strains from Norway. They also tested one strain of farmhouse yeast from Lithuania and four control strains WLP001 California Ale Yeast, WLP002 English Ale Yeast, WLP029 German/Kölsch Ale Yeast, and WLP570 Belgian Golden Ale Yeast.

[4] What a beer fermented at 104 °F with Belgian Golden Ale Yeast tastes like was not addressed in the paper.

[5] The brewers yeast may have been an English Ale yeast, or at least that’s what Omega’s Mark Schwarz suggested when I heard him speak.