Kveik is the given name for a family of yeasts recently made available to brewers all over the world. Whilst it is a new product for brewers and a new drinking experience for beer lovers, it is in fact a group of yeasts with a long history. Kveik hails from Norway and has been used for generations by small-scale, seasonal farmhouse brewers; think Saison yeasts, but with a snowy alpine backdrop. Kveik yeasts have developed and evolved over generations, but since only a small group of Norweigan farmhouse brewers have been using it, Kveik has flown entirely ‘under the radar’ of the wider brewing world. The word Kveik itself means ‘yeast’ in a Norwegian dialect and is one of a number of words used by Norwegian brewers to describe their special yeast.
What is so special about it? The reason why this yeast is so interesting is that it has a number of unusual and beneficial properties. Firstly, the temperature at which this yeast can ferment is much hotter than normal yeasts. A normal ale yeast will ferment in the high teens or low twenties celsius, whereas Kveik yeast can happily ferment in the mid thirties. If you fermented a normal ale yeast at this temperature, at best you’d create a beer riddled with undesirable characteristics. At worst, the yeast would overheat and you’d be left with an unfermented beer. Not only can you use this yeast at very warm temperatures, but you can also use a lot less than you would with a typical ale yeast. Some brewers are pitching their wort (unfermented beer) with up to a tenth of what they would normally pitch with a typical ale yeast.
These two factors would normally lead to weird results and an undrinkable beer. However, Kveik yeast is actually a more efficient yeast than most other ale yeasts. Typically, once yeast is pitched into wort, there is a period of inactivity known as the ‘lag phase’, that generally lasts around 24 hours. The yeast is active in this period but is doing lots of things other than creating alcohol. So, to a brewer’s eye it seems like nothing is happening. Kveik yeast has a lag phase as short as a couple hours. Once it starts fermenting, Kveik yeast can ferment a batch of beer days quicker than the next fastest yeasts. In fact, once the Kveik yeast has been used in the traditional Norwegian method, it is dried by the fire and stored for up to a year until it is needed for next season’s brewing. This situation is weird, wonderful and previously considered unthinkable by most.
Is there a downside to any of this? Well, not really! When yeasts ferment sugar into alcohol, they produce smells and flavours, some of which stay in the beer right up until the point of it being served and drunk. Some of these flavours and aromas are chemical compounds known as esters and depending on the style of beer, can be desirable. If you drink a cheap mainstream lager, you probably don’t want any ester flavour. However, if you drink a German wheat beer, you are probably hoping for some banana and/or clove flavours and aromas; these are esters produced from wheat beer yeasts. Kveik yeasts also produce esters, but they aren’t produced to an overwhelming degree and generally create light and delicate flavours that complement a wide range of beers. Here at Mammoth Beer, we’ve certainly noted some enjoyable stonefruit/apricot flavours in our Primordial and Sozonozo beers thanks to the Kveik yeast.
Kveik is a weird, obscure family of yeasts discovered after generations of use by Norweigan farmer/brewers. It is incredibly fast, hardy, and produces great beer. What’s not to like?
Big shout out to Lars Garshol, the unofficial godfather of Kveik yeast and a great number of other fermentation oddities. https://www.garshol.priv.no/blog/
