As a homebrewer, I used to make saisons in the summer. I don’t have a temperature-controlled fermentation chamber, but saison yeast performs very well under fermentation temperatures as high as 35°C, so it worked for me. How times have changed! Now I can make a good clean ale at similar temperatures using the “new” miracle yeasts known as kveik.
Kveik is much more temperature- and alcohol-tolerant than typical brewers’ yeasts. It will be quite happy with temperatures as high as 37°C while happily tackling brews with the potential for up to 16% alcohol by volume (ABV). The icing on the cake (or the head on the pint) is that your beer will finish fermenting in half the time.
As with regular ale yeasts, different strains can contribute different flavours. Some are fruity and citrussy, while one contributes stone fruit and pineapple. In my experience, these flavours are subdued and the finished beers are quite clean when fermented at normal ale temperatures (16 to 24°C). The yeast character becomes more noticeable when fermented at higher temperature.
You may need to leave more head space in your fermenter and use a blow-off tube instead of an airlock, as the yeast is very active and completes the job so quickly. Activity can be visible within a few hours of pitching. I have seen many photos from homebrewers documenting the mess this yeast can make. You have been warned.
Dave Henry from Full Barrel Homebrew Club has been experimenting with kveik for almost three years. These are his top five tips:
- Pitching rate is important. To get complete attenuation and yeast character, you should pitch much less yeast than regular saccharomyces yeasts. Pitching too much can lead to a stalled ferment (usually at a specific gravity of 1.020) and a lack of the fruity characteristics these yeasts are known for. Most homebrew packs have far too much yeast for a 20-litre batch. I normally make a one-litre starter and then pitch 2 teaspoons into 44 litres.
- Temperature matters. Word of mouth says these yeasts work best at 40°C, but it depends on the strain. Most work best at 32-35°C for fermentation temperature. That means pitching at 28-30°C and letting the brew rise to the mid-30s on its own. I’ve also had success with certain strains fermenting at lager temps, as low as 10-12°C. Temperatures above 40°C can cause most strains to shut down and take a nap.
- Oxygen matters. Adding pure oxygen is the best practice with all yeast. Kveik ferments are at their healthiest with close to double the oxygen other saccharomyces yeasts require. I oxygenate for 60 seconds before pitching and then for another 60 seconds during the following day.
- Yeast nutrients matter. Kveik yeasts need twice as much nutrients as other saccharomyces yeasts. Double whatever you normally use or add the regular amount twice, once in the kettle and again during high krausen.
- Gravity matters. Kveik is domesticated to ferment high-gravity worts. Traditional Norwegian farmhouse beers are usually 7% ABV and higher. Most kveik strains can easily handle a 15% ABV beer. Consequently, they’re not all that fond of fermenting lower-alcohol beers and attenuation becomes inconsistent. The first four tips above become extremely important as the starting gravity of your wort drops below 1.060, especially the pitching rate.
Dave added that kveik is a regional Norwegian dialect word for yeast. It’s not a beer style. You didn’t brew a “Kveik”, you fermented a beer with kveik yeast. And using kveik doesn’t make your beer a Norwegian or Norwegian-style beer. It’s not a Norwegian IPA, it’s an IPA fermented with kveik. That’s very important terminology. These farmers have passed these remarkable yeasts strains down through many generations, and each family’s yeast is unique to them. We’re lucky they’ve allowed us to use them. There are a lot of different strains, so don’t get stuck just using one. Have fun experimenting.
Dave also shared this blog where he first learned of kveik and was able to obtain vials of cultures.
Now that you know more about kveik, go pick some up and make some beer!
Main Image: Lars Gahol/Twitter