at started up quickly, and finished speedily would be optimally selected for.
Rather harder to explain is the alcohol tolerance of kveik strains. According to Preiss, “in terms of alcohol production from the wort, some were pretty efficient, but there was a big range of attenuation, from 66 per cent to 95 per cent, and in alcohol production, from 4.4 per cent to 6.4 per cent.” However, when Escarpment tested for how much alcohol kveik strains could cope with, “we were pretty stunned. We tested eight kveik yeasts for ethanol tolerance, and they were all growing in up to 12 per cent alcohol, which is not normal: conventional ale yeasts exhibit a spectrum, some that are not very good at surviving in high alcohol and some that do survive. It’s very rare to screen eight strains and find all of them growing like that. We found that even if we went up to 16 per cent alcohol, a third of the kveik strains will still grow, which is pretty remarkable.
“We also looked at the flocculation and we found that two thirds were very flocculent, many very, very flocculent. But even in one kveik sample there might be a huge variability in the flocculence between the different yeasts in the strain. Some are not very flocculent at all, some are dropping crystal clear in ten minutes. It’s again interesting to see that kind of variability in a single yeast community.
“We also tested the flavours they produce, using gas chromatography. We picked up a few pretty consistently with the kveik strains, fatty acid esters such as ethyl caproate, giving pineapple flavours, ethyl caprylate, giving pineapple, waxy and cognac flavours, ethyl decanoate, which is red apple, phenethyl acetate, which is floral and honey. Only two of the strains were phenolic, meaning [the rest] were likely picked at some point by humans because they were not phenol-producing, making for a taste that is very typical of ale yeasts, clean but with some fruitiness as well. The isobutenol, or fusel, levels were only around 50 per cent of US-05 [a common American homebrew yeast]. We also tasted citrus in a lot of the kveiks, we tasted rum and caramel flavours and we tasted almost mushroomy flavours as well. We’re still not sure what all those favour compounds are, and we may very well find that there are some unique ones made by kveik that are not made by other yeasts.”
Another thing Escarpment noticed, Preiss says, is that there seems to be two main groups of kveiks, looking at their genomes, which correspond, for the most part to the geography of the region where kveik is found: one group, including Hornindal, to the north of the Jostedal glacier, the largest glacier in Europe, and the Sognefjord, Norway’s largest and deepest fjord, and the other group, including Voss, to the south of those two important geographical barriers. “It suggests that though they may have had a common ancestor, they evolved separately because of the geographic isolation of the regions they are now mostly found. The glaciers and the fjords in Norway create barriers which made it hard for people to move around in the past. We don’t often see these kind of geographic links in the genetics of yeast cultures.” Garshol points out that the divide also matches a split between brewing processes: to the north, almost entirely raw ales, with the wort unboiled; to the south, most brewers boiling their wort. (For a proper discussion see Garshol’s own blog here)
The unanswered question at the moment is where kveik strains fit on the yeast family tree. A study released in 2016 by the Flanders Institute for Biotechnology and the University of Leuven in Belgium found that all commercial beer yeasts come in two strains, Beer One, which dates from the late 1500s or early 1600s and Beer Two, dating from the 1650s or so. So far Preiss and his team at Escarpment have only been able to make a rough fingerprint of the kveik strains they have, “which is not very high-resolution, but it’s typically accurate and it can give us an indication of the genetic relatedness of different yeasts. So what we found when we took this approach 