Farmhouse yeast: what do we know?

<< 2021-02-06 20:33 >>

Aldona Udriene watching her beer ferment at the Jovaru Alus brewery in Jovarai, Lithuania.

There's a lot of excitement over kveik at the moment, but kveik is only one kind of farmhouse yeast. The other kinds have so far been very little known, and so I thought it was time to take a little look at the bigger picture.

Having your own yeast

Manufacture and sales of yeast is a relatively recent thing. Contrary to what many think it did not begin with the work of Pasteur or Emil Chr. Hansen, but was an entirely independent development. In Scandinavia it seems to have been in the second half of the 19th century that commercially produced and packaged yeast became available for sale.

Before that, maintaining your own yeast for brewing purposes was completely normal. It was something everyone who brewed did, and just about every household in northern Europe brewed until the last few centuries, so having your own yeast was incredibly common. Having shoes was more common, but not hugely so.

Map of where farmhouse brewers definitely had their own yeast.

This means that even quite late people over huge areas of northern Europe had their own yeast. The dots in the map above shows places where I have documentation showing that in this specific place people really did maintain their own brewing yeast. Of course, people did it in many, many more places, but I just lack the documentation of it.

The people who have their own kveik today are extremely unusual, but only in that their yeast has survived. And the yeast hasn't really survived that long.

But what kind of yeast was it people had?

Farmhouse yeast

People are already used to there being different kinds of yeast, such as brewers' yeast, which has been used to brew beer for so long it has become domesticated and adapted to beer brewing. There's bread yeast, which has been selected for (if not necessarily adapted to) baking bread. And wild yeast, which lives in nature and is adapted to that. But what is farmhouse yeast?

I use that term for yeast that has been used in farmhouse brewing for so long that it has adapted to that specific form of brewing. You might think farmhouse brewing is so similar to modern brewing that this would basically be the same as brewers' yeast, but that's not the case. There are at least three ways I would expect farmhouse yeast to differ from brewers' yeast.

Farmhouse brewers generally fermented very hot, basically at body temperature, and they seem to have done so in all of northern Europe. So just as with kveik, I would expect all farmhouse yeast to be able to ferment at these temperatures without producing off-flavours.

Histogram of pitch temperatures.

The histogram above shows what pitch temperatures were the most common according to the descriptions of farmhouse brewing that I have been able to collect. The higher the bar, the more people who say they pitched their yeast at those temperatures. (For information on how the diagram was produced, see this paper.)

Farmhouse brewers also generally had very short fermentations, again just like with kveik, and so I would expect these yeasts to ferment faster than ordinary yeast, and to produce beer that is immediately drinkable.

Histogram of fermentation times.

As you can see from the histogram above, fermentation times were very short indeed. I should add that "fermentation time" in this diagram is defined as the time from the yeast is pitched until the beer is moved to cask. There usually was a little more fermentation in the cask, but most of the fermentation was done by the time the beer was racked. (More details will be coming in another paper, but that one is still in review.)

It was very common to preserve the yeast between brews by drying it, and so most, although not necessarily all, farmhouse yeast should be able to handle drying. Again just like kveik.

This probably sounds like I think farmhouse yeast all over Europe belonged to the same genetic family as kveik, but we already know that it did not. For one thing, the yeast Aldona Udriene at the Jovaru Alus brewery in Lithuania uses is a hybrid of Saccharomyces cerevisiae and another species, so it's not a kveik. Saison yeast, which definitely fits at least the heat criterion above, belongs to the Beer 2 family, so it's not a close relative of kveik at all.

All over northern Europe people seem to have had farmhouse yeast, behaving much like kveik, but belonging to different genetic groups. And look at that map again: the dots are not yeast cultures. Each dot is a small districts with hundreds or thousands of families with their own yeast culture. The number and diversity of yeast cultures that existed in the countryside of northern Europe until 150 years ago is so immense that by comparison all the commercial beer yeast currently in existence could probably fit into a single one of those dots.

People have been thinking of kveik as an extreme outlier yeast with incredibly unusual behaviour, but this raises the question of whether perhaps it's actually the other way around. Is it modern brewers' yeast that's unusual?

Bread yeast generally also seems to ferment fast and tolerate high temperatures. Is that because it originally was farmhouse yeast? Or because that's how yeast normally behaves and brewers' yeast is unusual? Nobody really knows yet.

Keeping the concepts straight

Richard Preiss introduced the term "landrace yeast" to mean domesticated yeasts which have never been purified in a lab into single cultures. All the kveiks and other farmhouse yeasts we have collected so far are landrace yeasts. But there are also landrace yeasts that are not farmhouse yeasts, even though they are becoming very rare. The Harvey's brewery in the UK has a yeast culture that has never been purified. It's just been repitched over and over since they first received it some time in the 1960s. So that's also a landrace yeast.

Venn diagram of yeast concepts.

Above you see a diagram of the concepts, with some specific yeast strains and cultures placed where they belong as examples.

What have we found?

Famously, we found kveik, which is by now well known, and which turns out to be related to modern brewing yeasts. Kveik is a separate family of yeasts, genetically defined as a sub-branch of the family tree of brewing yeasts. However, there is a whole list of different farmhouse yeast types, of which kveik is just one. All of these groups are currently being researched, so for the time being we know less about them than we do about kveik.

The first group to be found was the Baltic farmhouse yeasts, which exist in both Lithuania and Latvia. At the moment we know of 8 from Lithuania and 2 from Latvia. There's at least two different kinds of yeast in the area, genetically speaking, and quite possibly more. They are warm-fermenting, fast-fermenting, and at least some can be dried, but a major difference with kveik is that many of them are phenolic, although not all. Some of them are very fruity, just as with kveik, and the famous Jovaru Alus yeast is diastatic (STA+).

Rimma Ivanovna packing up the yeast samples I am about to bring home. Ishlei, Chuvash Republic, Russia.

I've written before about the two yeasts I collected from Chuvashia in Russia. A single visit to one village, called Kshaushi, was enough to get me two different cultures. I was able to return to Chuvashia briefly in February 2020 and collected another culture just a few kilometers from Kshaushi. People say that most families in Chuvashia who have an old grandma are still brewing. From Russian news reports I can find online it's clear that there are many of them. So there could potentially be a huge number of yeasts still alive in this area. The difficulty is collecting them.

We don't know anything like enough about the Chuvashian yeasts yet. They are definitely heat-tolerant, and seem to be phenolic, but there could be many types of farmhouse yeast in Chuvashia for all we know.

But there is actually more farmhouse yeast in Norway besides kveik. I wrote about gong in Ål, upper Hallingdal, in eastern Norway. That blog post is about visiting Sverre Skrindo, but his neighbour Bjarne Halvorsgard also has gong. And there are a few more brewers in the village with their own yeast. There could be more in the area without me knowing yet.

These yeasts are significant because they are from eastern Norway, a region separated from western Norway by a major mountain chain. So there was reason to assume these yeasts might be different from kveik genetically, and so they are. But they are related to kveik. (More on this when the paper(s) come out.)

More recently, we discovered there are a group of brewers in Tinn county in upper Telemark, who still brew, and use a yeast they call berm. For now, I'm calling this group of yeasts "berm", but we don't know yet if it really is a separate group the way kveik is, or whether these yeasts actually are kveik, or perhaps the same as gong.

The farmhouse yeast registry has some checkboxes above the map where you can filter the registry by group to make it easier to navigate this. (I wrote a paper for MBAA TQ with more details on this registry.)

Rolf Tore Djønne (outside frame right) giving me a sample of #60 Djønno. Ulvik, Hardanger, Norway.

Outside of Europe

In order to remain sane I have restricted the scope of my research to Europe, but there are also living farmhouse brewing traditions in South America, Africa, and Asia. And in many of these places the farmhouse yeasts are still alive.

At Norsk Kornølfestival last year Martin Thibault did a talk surveying three hotspots for farmhouse yeast, one on each continent. If you're interested I really recommend the talk.

There is a lot of work left to do on this. Just surveying and collecting all the yeast would be a giant undertaking. And there is certainly no lack of work for the microbiologists trying to learn more about what has been collected so far.

The kremlin in Kazan, Russia.

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Johann Renner - 2021-02-07 03:08:07

Thanks Lars! As always, I really enjoy learning more and more about farmhouse brewing with you. I appreciate your effort to save it.

As a side note, I can't see the map and diagrams in my phone (Android, Chrome browser).


Lars Marius Garshol - 2021-02-07 09:19:42

Thanks for warning me, Johan. I forgot to publish the images. They're up there now.

Bryan Betts - 2021-02-07 12:03:47

Berm is clearly cognate with many other West Germanic words for yeast, probably including English 'barm', meaning the foam on fermenting beer.

Lars Marius Garshol - 2021-02-07 12:28:34

@Bryan: Correct. All the British farmhouse brewers whose yeast words I know called their yeast "barm", but that's probably a coincidence.

The same word was used in Swedish (bärma) and Danish (berme).

The map of yeast terms in my book has more detail.

Andrus Viil - 2021-02-08 15:11:06

In common modern Estonian language yeast is called Pärm, so kind of makes sense.

Lars Marius Garshol - 2021-02-08 15:25:23

@Andrus: Yes, it's clearly the same word, from Swedish, Danish, or possibly German.

Mac - 2021-02-08 17:35:10


Lovely article, I have learned a lot.

FYI Your second image has the wrong title. It says "Histogram of pitch temperatures." I believe it should be Histogram of fermentation times" .

Lars Marius Garshol - 2021-02-08 17:48:39

@Mac: That's right. Thanks! Fixed now.

Steve - 2021-02-08 17:49:49

Any thoughts on the word "berm" being etymologically related to the english "barmy", meaning crazy, mad or nonsensical? My inner language nerd was just thinking that back in the day you might store juice, and if that developed barm the juice could be described using existing linguistic constructs as "barmy", then it's just a matter of slang slippage for "barmy" to mean "acting unexpectedly drunk", then generalized to "acting in a crazed and unpredictable manner".

Lars Marius Garshol - 2021-02-08 18:11:39

@Steve: Looks like "barmy" really does come from "barm" in the sense of yeast, and the logic is actually straighforward. Barm derives from "froth", so a barmy person was foaming/frothy in the head. Foaming mad is actually quite descriptive.

Good blog post on it.

Kyle Navis - 2021-02-10 00:31:34

Have you considered using your platform to organize and funds grants that could be made to, say, anthropology graduate students in places like Chuvashia? The conditions of the grant could specify what kinds of data they need to collect, how samples are collected, and guidelines for documenting them, etc. This would greatly amplify the body of knowledge, and you seem uniquely placed to attract the kind of grassroots funding and interest to organize this kind of endeavor.

Lars Marius Garshol - 2021-02-10 07:23:09

@Kyle: I don't have the capacity to take on something like that on top of all the other things I do. If someone else were to organize it I'd be happy to advise them but it's just too much work run something like that.

Lars - 2021-02-10 12:20:23

Great post!

Looking at the map I see that there is a yellow dot right where I live, or at least very close to it. I would love some information on the farmhouse brewing from my area. Do you have a name of the brewery or farm associated with the Luleå area (or the norrbotten region) on your map?


Lars Marius Garshol - 2021-02-10 12:48:31

@Lars: This is all about farmhouse brewing, so no breweries. Just people brewing on the farms for themselves.

The dot near Luleå is EU 7838, a response to the Nordic Museum's questionnaire no 58, written in 1935. It's 15 pages, so I can't reproduce it here, but you can see it if you make an appointment and visit the museum.

It's classic farmhouse brewing: barley (and some rye) self-malted, dried in bastu, very weak beer for the most part, hops, juniper, Myrica gale, and Rhododendron tomentosum.

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