Does bread yeast exist?

<< 2020-05-04 16:15 >>

Norwegian baking yeast. Oslo, Norway

The title makes it sound like I've lost my mind, because of course bread yeast exists. You've all seen it sitting on supermarket shelves. But I've started to wonder whether what's sold as bread yeast really is a separate kind of yeast, or whether they're just brewer's yeasts that have changed profession.

As I started looking more carefully at farmhouse brewing I started finding that a surprising fraction of today's farmhouse brewers use baking yeast to ferment their beer. And they get really good beer out of these yeasts. Here's a quick list of places where I know farmhouse brewers use baking yeast:

• In Stjørdal, Norway many use Idun Blå.
• On Gotland, Sweden they typically use Kronjäst.
• In Finland the sahti brewers usually use Suomen Hiiva.
• In Estonia the koduõlu brewers usually use one of two brands of bread yeast (one of those is Suomen Hiiva under a different product name).
• In Latvia Ugis Pucens used the local bread yeast.
• In Lithuania some farmhouse brewers use baking yeast.
• In Russia, Dmitriy Zhezlov's farmhouse ale fermented with baking yeast was better than the one with brewer's yeast. Marina Ivanovna also used baking yeast.

Given all the prejudice against baking yeast, that's quite a list of brewers in different locations all finding that baking yeast works well in beer.

Starter from Latvian baking yeast, Aizpute, Latvia

And it's not only me who thinks baking yeast can make good beer. Kristoffer Krogerus did a scientific evaluation of Suomen Hiiva and found it to be "perfectly usable for beer fermentations". Brulosophy also did a recent experiment with baking yeast and although people could tell the difference, 1 in 3 preferred the version with baking yeast.

So a lot of different bread yeasts really do produce good beer. Why?

Well, where does bread yeast come from, anyway?

Norwegian Ethnographic Research's 1952 questionnaire on farmhouse brewing has a question on what yeast people in the countryside used for baking. Pretty much everyone who answers that question says the same thing: they used the brewing yeast.

This may sound odd, but if you consider a farm in the time before it was possible to buy yeast this actually makes a lot of sense. Brewing produces more yeast than you need for brewing, so there would be a surplus of brewing yeast. And whatever yeast you put into your bread or cake goes into the oven and is killed. Brewing produces yeast, while baking consumes it.

The other Finnish bread yeast. Hartola, Finland

The farm would in fact not have a whole lot of other alternatives. They could use wild yeast. They could maintain a sourdough culture. Or they could use their brewing yeast. It seems they overwhelmingly did the latter. At least in Norway. Many of the Swedish and Danish answers say the same thing, so it seems it was no different there. Based on another sources this seems to also apply to Finland[2].

What's interesting is that in the cities the situation was basically the same. Many places the bakeries got their yeast from the breweries, for example in Vienna. In Copenhagen there was even a law saying breweries were required to give the bakeries yeast for free[6]. One Danish questionnaire answer even says if you had a lot of (farmhouse brewing) yeast you could sell it to the baker[1].

All of this is very suggestive, but none of it proves that the baking yeast sold by yeast companies today comes from brewing.

But where could it come from? Well, it could be brewing yeast, or sourdough yeast, or distiller's yeast. But distillation has not really been around for very long. It was only in the 1400s that distillation took off in Europe, and in the Nordic countries it only started growing significant two centuries later. Very likely most distillers started off using brewers yeast.

(Interestingly, a recent study of the use of sourdough yeast for brewing found that those might also work, and that conceivably some sourdough yeasts might also have a brewing background[3].)

Dmitriy Zhezlov making yeast starter with baking yeast. Shitovo, Russia

The Gallone et al 2016 paper [4] includes a lot of data on the yeasts they studied, including their ability to ferment maltose and maltotriose. And what do you know: of the four bread yeasts analyzed, all four have good utilization of both these sugars, which hints strongly at brewing domestication. Three of those bread yeasts were Belgian, the origin of the last is given as "unknown".

That paper also shows that besides the two big families of brewer's yeast, called Beer 1 and Beer 2, there is another family they called "Mixed", consisting of beer yeast, distiller's yeast, and bread yeast. A later, more extensive, study [5] renames the group to "Beer/baking", because it seems to mostly consist of those two types of yeast. Which really does seem to indicate that there is a strong historic connection between bread yeast and brewers yeast.

In my archive I have scans of a Finnish notebook written by one W. G. Åberg in 1885, and it includes a recipe for pressed baking yeast, the same kind of cube that baking yeast is often distributed as today. The recipe very clearly says to start with beer yeast (though not what kind).

Mika Laitinen kindly summarized a Finnish book on the history of the Finnish yeast industry [2] for me, and says: "The earliest Finnish yeast factories produced both baker’s yeast and spirits. These factories brewed some kind of beer from grain, harvested the yeast, and then distilled the beer. The book doesn’t say what kind of yeast they were using but obviously, it was brewer’s yeast."

As Andreas Krennmair writes, the process for making pressed yeast, the form the first commercial bread yeasts were distributed in, was invented by a brewer, who used brewer's yeast.

Yeast starter from bread yeast. Kudymkar, Russia

So it does seem that what we know as baking yeast today could originally be brewer's yeast. One reason I'm so interested in where these yeasts come from is how they behave. The brewers using these yeasts generally ferment at typical farmhouse brewing temperatures of 30-40C. The baking yeasts also ferment very fast, and seem to have high alcohol tolerance. So these don't seem to be normal commercial beer yeasts. Could it be that some of these yeasts are originally farmhouse yeasts? If so, that might help us fill out the family tree of farmhouse brewing yeasts and get more of a handle on what kind of yeast people were using in the areas where farmhouse yeast no longer exists. It might also help us work out how the various kinds of farmhouse yeast, such as kveik, evolved.

Of course, without direct proof we can't do that. The best way to get it would be to ask the producers directly where they got their yeast from. I have tried to do that, but unfortunately very few of them have answered yet. So one reason I'm writing this is to see if the blog post can help flush out some more answers from these producers. Or more knowledge from somewhere else. Here's a summary of how far I've gotten with the various producers:

The two answers I have gotten, from Norway and Sweden, indicate that these waters may be muddier than they seem. From Idun Industri I got a reply from Inga Breivik where she says that "in the early days of yeast factories it often happened that employees bought bread yeast in grocery stores when they happened to be abroad. They took it back to the lab where it was tested to see how quickly the dough rose, how long it could be stored, and so on." She goes on to explain that if the tests were good enough the factory might decide to switch from its own production strain to one of these foreign acquisitions.

One intriguing thing about the answer from Idun is that those properties she says they were seeking, fast fermentation and ability to be stored for a long time, are exactly the ones that are characteristic of farmhouse yeast. So clearly baking yeast producers would naturally gravitate toward yeasts that are either farmhouse yeasts, or just like them.

Unfortunately, those answers also indicate it may be difficult to unravel this. On the other hand, perhaps the producers still have the originals banked away somewhere? And that answer from Suomen Hiiva sounds promising.

References

[1] NEU 3408, dated 1945, from just a few kilometers outside the town of Frederikssund, Zealand, Denmark.

[2] Hiivan tarina: Suomen leivinhiivateollisuuden vaiheet 1885–1970, Olli Vehviläinen. Suomen hiivatehtaitten myyntiyhdistys, 1970.

[3] Sourdough derived strains of Saccharomyces cerevisiae and their potential for farmhouse ale brewing, Martina Catallo et al, Journal of the Institute of Brewing, 20 February 2020,DOI 10.1002/jib.608.

[4] Domestication and divergence of Saccharomyces cerevisiae beer yeasts, Gallone et al, 2016, Cell 166, 1397–1410.

[5] A polyploid admixed origin of beer yeasts derived from European and Asian wine populations, Fay et al, PLOS Biology, 2019.

[6] Beer And Brewing In Pre-Industrial Denmark, Kristof Glamann, University Press of Southern Denmark, 2005.

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