Norway is a land of myths and legends. Its overdeepened valleys are flanked by the towering, petrified remains of warring troll clans, caught mid-battle by the cresting dawn and turned to stone. A monstrous sea beast terrorises its coastline. There are tales of tribal gods and undead superhumans who can swim through solid rock.

And some of Norway’s creatures, though they may be microscopic, are becoming no less legendary – at least in brewing circles. After clinging to survival for centuries in isolated, mountainous farmsteads, a family of brewing yeast – unique to Western Norway and known collectively as kveik – is enjoying a startling renaissance. Enraptured by its muse, modern craft brewing is breathlessly writing new chapters for a story that had so almost reached an end.

In the last few months alone, leading lights of the UK craft scene including Northern Monk, Duration, Gipsy Hill and North Brew have released beers brewed with kveik strains. They’re a regular feature on Loka Polly’s production schedule, and Manchester’s Beer Nouveau has been experimenting with them since 2017. In July, Yeastie Boys switched its house yeast to kveik. In homebrewing, too, kveik has found devoted converts – on Facebook, groups with thousands of members all over the world share tips and brew day logs, or swap ziploc baggies of dried kveik as though trading rare baseball cards.

Martin Warren, founder of Norfolk’s Poppyland, was the first UK brewer to use kveik in a commercial beer. Back in 2014, Warren had read in a then obscure beer blog – part travelogue, part chronicle of scientific discovery – about some of its unique properties. Kveik could be pitched at crazy high temperatures, went off like a rocket and fermented out in a couple of days. It could be stored, dried, on clean linen or a knurled fist of wood for decades. And – depending on the strain – it threw out ester profiles ranging from milky caramel to crushed citrus zest and Christmas spice.

Poppyland had built a reputation for brewing esoteric and edgy beers. Warren – now retired – handed the reins to new owners in 2019, but started his 300-litre nano brewery in 2012 after years spent hacking homebrew kits with different yeasts, hops and souring bacteria. He turned to traditional European styles for inspiration and in 2015 found himself sat open-mouthed on a train carriage as Norway’s Bergensbanen railway hosted the unfolding geological spectacle of the Scandinavian Mountains.

Warren was heading to the Voss region in search of a Norwegian farmhouse beer called vossaøl, a rich, plummy amber ale made with an infusion of juniper tips, and boiled over an open fire for up to six hours. His voyage followed in the footsteps of Oslo-based software engineer and beer historian Lars Marius Garshol, whose name, blog and books have become synonymous with kveik’s resurrection story. A year earlier, on a road trip which would prove life-changing, Garshol had brewed vossaøl with farmer Sigmund Gjernes, rediscovering in the course of their brew day the kveik culture known now as ‘Sigmund’s Voss’, and catalysing six years of enthralled research.

“I couldn’t get it together to meet up and have a beer with Sigmund,” Warren recalls. “But he very kindly arranged to have a large Coke bottle of his vossaøl to be dropped at my hostel, with a note saying: ‘promise you will drink it all up at once.’ Bearing in mind this was eight or nine per cent, it was quite a tall order – but I did as I was told!”

After an evening on the vossaøl courtesy of another farmhouse brewer, John Nornes, Warren returned to the UK with a pot of his host’s kveik, and used it to brew Poppyland’s ‘Norwegian Farmhouse Ale’, with spruce tips from a garden centre Christmas tree standing in for juniper.

Meanwhile, Garshol was busy cataloguing western Norway’s farmhouse yeasts in what has grown into a database of 64 known kveik. In truth, most are mixed cultures containing several strains of saccharomyces cerevisiae, or brewer’s yeast. Some, including Hornindal and Ebbegarden, bring an added, souring lick of lactobacillus bacteria.

No one can say for sure how long they’ve been around, but Norway’s farmhouse brewing traditions date back to the early 1600s, and kveik would have been passed down from generation to generation, as well as swapped with neighbouring farmsteads. Although the yeast cultures differ from farm to farm, many share defining traits: they survive dry storage well, withstand higher gravity beers, and ferment quickly at temperatures in the mid-to-high thirties, without contributing ‘hot’ fusel alcohols or phenolic off flavours.

Is this an evolutionary nudge, I ask Garshol, caused by a farmhouse brewing tradition of pitching yeast into warm wort?

“What seems to be showing up in scientific research is that wild yeast also has this high temperature tolerance,” he counters. “And the original form of brewing was farmhouse. So it seems like it’s the other way around – that commercial cultures have adapted to the strange way of brewing in modern commercial breweries. It’s not a proven thing, but that’s what it looks like.”

After centuries spent bending yeast to the demands of the modern brewhouse, brewers are now spotting potentially revolutionary boons in using kveik. In fruity pales and IPAs, a strain like Sigmund’s Voss takes a beer with a juice factor of 10 and ramps it up to a Spinal Tap 11. Rapid fermentation with a short lag reduces infection risk and frees up vessels for another batch. High pitch temperatures saves on energy usually used for cooling. Similarly, strains such as Omega Yeast’s Lutra Kveik and Bootleg’s Oslo Kveik produce crisp, clean lagers without the need for chilled fermentation.

America’s Omega Yeast Labs was quick to cotton on to kveik’s commercial appeal by becoming the first lab to offer kveik to professional and home brewers in 2015 (HotHead Kveik — #3 Stranda). Escarpment Yeast Lab, with their microbiologist Richard Preiss, has been instrumental in terms of scientific research, and gene-mapping the kveik family tree. They were followed by the likes of White Labs, Lallemand and Maniacal.

Samples of all of Garshol’s discoveries – and more – are stored at the National Collection of Yeast Cultures (NCYC) in Norwich, ironically a little over 20 miles from Martin Warren in Cromer. For £168 and an annual licence fee of £150, labs can buy a culture, propagate and sell it, or isolate and blend individual strains into their own creations.

Philip Woodnut, from Ireland’s WHC, currently stocks six kveik and plans to add another four or five to the stable.

“Customers who’ve been ordering the same yeast month in, month out, for years are suddenly switching to kveik,” he says. “Brewers used to the New England-style yeasts like London 3 or London Fog are ordering Ebbegarden kveik instead. It has the same tropical fruit profile, but ferments a lot faster and you can get high gravity worts done really quickly. It’s great for double and triple IPAs.”