Dried kveik from Stein Langlo

So. You've gotten hold of a kveik, and now you're wondering: how do I make best use of this thing? You're right to ask, because many people have found when they try it that it doesn't live up to the hype. They pitch it like a normal yeast, and the result doesn't seem that special. That's because this isn't normal yeast, and you have to treat it differently to get the most out of it. Here are some simple guidelines based on what I've been able to figure out so far.

The first thing to realize is that kveik is a type of yeast, not a specific strain. The kveiks are actually quite different from each other, even though there are clear family resemblances. And, there is a difference between kveik (the farmhouse yeasts from western Norway) and farmhouse yeast in general (from Lithuania, Russia, and Latvia). All the kveiks are related to each other, but not to the other yeasts. Whether the others are related to each other we don't know yet.

Our knowledge of the other farmhouse yeasts is not as good as for the kveiks, but we can summarize their properties roughly as follows:

Property Kveik Other farmhouse yeast Alcohol tolerance 13-16% Variable? Phenolic No Mostly yes? Attenuation 75-85% Good Flocculation Excellent Good Can be dried Yes No Temperature Up to 43C High Fast fermenter Yes! Mostly yes? Aroma Tropical fruit Variable, but aromatic?

The table below lists some of the flavours, to give you a clearer picture of the differences. The yeasts in this table are the ones that have been used the most. Of the non-kveiks #16 Simonaitis has become a favourite with many homebrewers.

No Name Kveik? Aroma #1 Sigmund Yes Spicy orange #2 Rivenes Yes Spicy orange #3 Stranda Yes Earthy banana and melon #4 Muri No Sulphur, rubber, fruit #5 Hornindal Yes Milky caramel, tropical fruit #8 Saure Yes Funky #9 Ebbegarden Yes Mango and pineapple #16 Simonaitis No Phenolic, fruity

The farmhouse yeast cultures you can buy are usually a single strain only, while the original cultures always have a number of different strains. The originals sometimes have bacteria as well. The commercial cultures that contain more than one strain are (at the time of writing) those from Escarpment Labs and Mainiacal. It's also possible to buy mixed cultures from NCYC.

Propagating kveik at home

There are two main ways that people use kveik. One is to recreate the original styles, or at least make a beer where kveik is one of the key taste elements. In this case, beware of using lots of craft-style hops: the hops will completely dominate the beer and the yeast profile will drown. The other way is to make a normal beer (porter, IPA, etc), but use kveik because you don't have to worry (too much) about temperature control, and because you get a drinkable beer much more quickly. Either way is fine, but you may want to treat the yeast differently.

These yeasts ferment very quickly. If you're pitching healthy yeast (even in dried form) it's not unusual to see lots of activity within 30 minutes, and within a few hours there should be visible life. A completed fermentation within 36 hours is perfectly normal. However, they're also fast in another way: the beer will be drinkable right away. Remember, the custom is to have oppskåke after 48-72 hours. Letting the beer mature for some days or a week usually improves the flavour, but you don't need the maturation times that are common with normal yeast.

Terje Raftevold's kveik, 31 minutes after pitching dried flakes

The key to really bringing out the yeast character is to underpitch. Kveik thrives with being pitched at levels that would be dangerously low for normal yeast, and produces more flavour that way. A good rule of thumb is a teaspoon of slurry for 25 liters of wort. If you do this take care to ensure there is some oxygen in the wort. Old-style splashing by pouring the (cooled) wort from waist height is enough.

Also, for best results you should try to follow the pitch temperatures in the kveik table for your specific yeast. And not just the pitch temperature. Try to prevent the beer from cooling off too much by placing it somewhere warm and wrapping it in clothes or blankets, so that the temperature stays high during fermentation. The kveiks generally have very wide temperature tolerance, but some are more picky than others.

Kveik has very high alcohol tolerance (typically 13-16%), probably because it's used to fermenting very high gravity beers. That also means kveik seems to have lost the ability to produce some of the nutrients it needs on its own. It's used to having lots of it available at all times. So fermentation on low-gravity worts can be quite slow and give low attenuation. The same goes for fermenting cider and mead. Putting in lots of yeast nutrient helps.

Terje Raftevold harvesting kveik after 40 hours

One of the nice things about kveik is that you can safely harvest and reuse it. When you do, you need to remember that this is a mixed culture (unless you're using the commercial ones). The culture is not evenly mixed: some strains have many more cells than other strains, and if you disturb this balance you may change the kveik. The best thing is to harvest exactly like the original owner, which means at the same time (hours after pitching), and from the same place (top or bottom). The table has the details where we know them.

It's not just to preserve the mix that you want to harvest the yeast early. In general, yeast grows faster than bacteria, so the longer you wait, the more time the bacteria get to grow. To keep the level of bacteria down it's good to harvest early. Especially if you intend to be doing this over and over and over again. Another reason is that if you're harvesting from the top you don't want to be too late; if you wait too long the yeast can sink.

If you want to bottle the beer, be aware that some of the kveiks flocculate so hard that they literally stick to the bottom. If there's no yeast left in suspension you won't get any carbonation. So you may want to add another yeast to get the carbonation.

The simplest way to keep the kveik is to just put it in some kind of jar in the refridgerator. Usually they will keep for a year or more like this. If you do this, beware of pressure. If there is enough wort left and enough sugar in the wort the kveiks are perfectly capable of blowing up the whole thing. Some of these yeasts seem to keep fermenting even in the fridge. That said, I've kept 10-20 small glass jars in my fridge for 3-4 years now with no accidents.

Kveik slurry, ready to be dried

The safest way to keep the kveiks is to dry them. A simple way to do that is to first decant as much liquid as possible, then smear the slurry on baking parchment with some paper towels underneath. Set your oven to 30C blowing hot air, and leave the door slightly ajar. The yeast will dry into a hard crust, and by crumpling the parchment you can drop the chips into a ziploc bag. Then you can put them in the freezer where it will keep for 20 years at least. If using the oven feels too risky 3-4 days in a clean room will also work.

48 hours later (no oven used, just placed in the cellar)

Note that it's only the kveiks that can be dried. They're used to it and have absolutely no problem with it at all. But the other farmhouse yeasts can't handle it. If you want to keep the others for a long time the trick is to mix the culture with 15-25% glycerol and then put it in the freezer in liquid form. Glycerol works as an anti-freeze when mixed with water, so you may find that it doesn't freeze, but you will still get a preservative effect, and while the yeast may not survive 20 years it should survive some years.

72 hours

This is what I've picked up so far. If anyone has anything to add from their own experience, please don't hesitate to post comments below.