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The yeast has been tamed + oldest Dutch beer recipe

You know you are a bit of a beer nerd if you read a good Dutch article and decide to translate it into English. My goal was to share it with my brewing group, but now that I have put in the effort in I thought I would share it on here. First of all, here is a link to the original article: link

My translation takes some liberties with the source material, and I cut out some parts that I feel lack relevance for non-Dutch/Belgian readers. If you are looking for a word for word translation, this is not it. My contribution to this article is the translation. All credits should go to the author of the original article; Marco Daane. Thank you for writing this great piece.

The discussion is on the history of yeast cultivation – but it throws in a really ancient Dutch recipe to boot. It shortly mentions the style Koyt on which I have written an earlier background and recipe. I hope you enjoy.

Taming the yeast

Using wild yeasts must be something that is tremendously difficult and challenging. It makes you feel a bit like you are brewing and fermenting in the old days; a time when cooling equipment, stainless steel vessels and process control did not exist.

The Brettanomyces festival raises a question every year, a question that without using a time machine might never be answered exactly: when did brewers tame yeast?

For a long, very long time brewers relied on ‘wild yeasts’ exclusively. They trusted nature with their concoctions made out of grain and herbs. In the atmosphere and wooden interior of a brewery there are all sorts of microbes and bacteria that can infect and taint the brewer’s wort. Lambic brewers even welcome the little critters.

But at one point in time brewers realised that they could ‘harvest’ the wild yeast. The yeast will show itself after a while, forming a thick fluffy blanket on top of the wort. The same must be true for brewing in the old days as this is a classic biochemical phenomenon. Perhaps the brewers initially considered the ‘foam’ as waste, and they removed and exposed of it. But there must have been a moment when this was no longer the case, and that they realised that they could keep and reuse the substance. This meant that they no longer were reliant on nature, but control fermentation by using harvested yeast.

The question remains, when was this moment? That is the biggest mystery of yeast. As an homage to the Brettanomyces festival and modern day yeast wranglers I decided to dive into vague descriptions and written sources. I think this is the least I can do, as I unfortunately can’t attend the festival this year. A happy coincidence of my quest is that I found what I think is the oldest Dutch beer recipe.

Godly Saliva

It is often assumed that brewers started to fathom and use yeast in the 16th century. The reason; in 1516 the German Reinheitsgebot was instated. This purity law would impose Bavarian brewers to brew beers using strictly grain (malt), hops and water. Yeast was nowhere to be found in the description of the Reinheitsgebot. The most common explanation of this omission is that people did not know of yeast yet.

But perhaps this is not how we should interpret the omission. Was there was another reason to not add yeast to the Reinheitsgebot? During the celebration of 500 years Reinheitsgebot Jeff Alworth raised this point on All About Beer ( He referred to conversations with Matthias Trum, master brewer at Schlenkerla in Bamberg and he published it earlier in The Beer Bible (2015). Trum is very knowledgeable on local brewing history and thinks that he knows why yeast was initially omitted from the Reinheitsgebot.

In the middle ages there was a profession called ‘hefener’ (roughly translates to yeaster), which implies that there were people that knew yeasts well. The Reinheitsgebot mentions ingredients does it not? Yeast is added to the beer, and during fermentation you are able to be take away more yeast than you originally put in. You can harvest the yeast to use it to ferment a next batch of beer. And that was exactly what the hefener did. You would start with a small amount of yeast and ended up with a multitude.

To conclude: when the Reinheitsgebot was instated they knew exactly what yeast was and how to use it. But how long has that been the case? In the middle ages sounds vague. In any case, for Bamberg the phenomenon dates back to at least 1489. The operator of Schenkerla brewery was known as a hef[e]ner. Chances are that this was not a new profession.

The idea that brewers knew about yeast is also illustrated by another source, in this example an old Nordic Hálfs saga. This god story (comparable to that of the old Greek stories) was handed down in an Icelandic manuscript that is dated from around 1450, roughly the same period. The saga tells of a brewing competition. Alrek, a Norwegoam king, is burdened with two wives, Signy and Geirhild, and that situation is unsustainable. He announced that he will be with the wife that brews the best beer. Geirhild is aided in her brewing by the character Hood – who turns out to be the god Odin in disguise. Hood spit on the yeast, and Geirhild’s beer turns out to be outstanding. She had won Alrek’s heart for ever more.

The godly saliva is of course nothing more than a nice story, but it does contain a relevant element of historical brewing information. Norwegian brewers in the 15th century knew about yeast and spoke of it. Odin’s actions reflect the idea that yeast was a crucial part of getting good beer, and the idea that there were quality differences between yeasts.

Yeast market

This idea about quality of yeast is also reflected in French laws which date back way before this – all the way back to 1268! Frederick W. Salem referred to it in 1880’s Beer. Its History and Its Economic Value as a National Beverage based on some 18th century French encyclopaedic works. Under the reign of King Louie IX, known for his love for reformation, a brewers’ law was instated in 1268 that was really similar to the Reinheitsgebot. It stated: Beer will be made of no other substance than good malt, hop that is kept properly and is cleaned well, and will not mixed with buckwheat, rye-grass or other. Yeast is mentioned, but just like the Reinheitsgebot it is not mentioned under ingredients of the beer. They did have separate rules for it:

Brewers’ yeast can’t be sold in the streets, but will always be sold in brew houses. It can be sold to bakers and confectioners, but no one else. Brewer’s yeast that is taken by foreigners will have to be judged by a jury before it can be offered for sale.

Yeast in France was sold by brewers, reused by bakers, and even exported abroad (but could not be sold in the streets). This must mean that it was harvested during the fermentation process, was separated and conserved. It might be the oldest evidence of yeast cultivations; and there is a good chance that this cultivation is a good deal older.

Yeast in the Netherlands

To conclude: way before the 16th century yeast was broadly known in North-Western Europe. It was sold in France, used in Norway and harvested in Bavaria. And yes, this practice seems to be common for brewers in the Netherlands as well. The oldest documented evidence (possibly older than that from Bamberg) is a manuscript in Middle Dutch (old version of the Dutch language). It also contains a pretty elaborate description of a beer – most likely the oldest Dutch beer recipe!

The texts in the handwritten document were published in 1894 by W.L. de Vreese in Middle Dutch medicinal recipes and tracts, blessings and magic formulas. It can be found in the University library of Ghent University, and Jori Reynaert has dated the document to about mid-15th century.

Reynaert’s dating makes sense if you look at beer history. The manuscript mentions a recipe for a substance that likens Hamburg beer or Kuit (Koyt). Kuit was ‘invented’ around 1400 in the Northern Netherlands and gained great popularity in the following century.

The recipe is as follows:
To make a good beer you take equal measures barley and white grains; in proportion to the quality of the beer; and if you want to you can add wheat. Grind them with the other grains and put a kettle of water on the fire. Put the flour of the ground grains in the water and stir the pot. Let it boil in to half or two thirds of volume and remove it from the fire. Let it cool off until it is lukewarm (literally blood warm – so I guess around 35 degrees). When it is cooled down you transfer it to a vessel. Take good heef (yeast) and under-yeast and add them together. Take the remains of the boil, mix the heef and under-yeast together and stir well. Put it in the vessel and let it sit to ferment; it will ferment above ‘huut’ and at the third day the beer will be good, ready to drink. Do not forget that you need to add to the remains of the boil a little hop, gale, and broet and to add these in the boil.

That brewers needed to add yeast to the fermentation vessel is obvious. It proofs that no wild fermentation was used. What is more remarkable is that there seem to be two kinds of yeasts. Heef (related to the German Hefe) is defined in the Middle Dutch dictionary as sourdough when it is used for bread and defined as yeast otherwise. The under-yeast is a bit more mysterious. It is extremely unlikely that under-yeast relates to the current bottom fermenting strains of yeast that require low temperatures to ferment. This technique is 400 years older than this manuscript. Even at the originating areas of bottom fermenting yeasts, like Bavaria and Nurnberg, they use terms like warm or cold fermenting. Bottom fermenting as we now know it is a relatively new term. Further along in the text it also says that the yeast rises above and that the beer is drinkable at the third day – all typical for top fermenting yeast. What it does mean is a mystery to the author. Perhaps it’s a combination of sourdough (heef) and beer yeast?

The manuscript contains some other interesting beer facts. Barley in equal measure to white grains (most likely they mean pale oats) to brew good beer. People started to realise how important barley was for good beers, replacing the classic brewing malt oats. In the 15th century the proportion of barley was increasing in Kuit (Koyt) beer, but brew decrees from Haarlem, Zutphen, Amsterdam and Leiden stated that it should not be more than one third of the malt bill. In this recipe barley seems even more important; it suggests that you need to use 50 percent barley to create a good beer.

It seems that this manuscript was never published and as such did not have a big impact on the brewing landscape. The rules for brewing beer were decided by the city it was brewed in. Perhaps these were the notes of a private or home brewer that did not feel tied to his cities colours. Nevertheless; it is a recipe, it is complete and it is ready to use.

The recipe allows to add wheat if you would want to. Wheat was often expensive in this time. Hop and gale were required in the beer. Elsewhere in the text a substance called ‘broet’ is mentioned. There are no entries for ‘broet’ in any old dictionaries so it remains a bit of a mystery what it means.It could mean gruit (a mix of herbs), but using gruit for brewing was on its way out in the first decennia of the 15th century. This recipe does not call for gruit, but still uses gale (part of gruit’s herbs) as a remnant of older brewing practises. It was most likely used for flavouring as the recipe calls for only a little hop.


All these sources make it clear that using yeast (harvesting, reusing, trading, applying) was common practice for brewers in the 15th century. Based on the French brewing laws it was already common practice as early as late 13th century, or early 14th century. Who knows, perhaps earlier sources from German or Dutch speaking areas might be found. These dates are not surprising as the urbanisation of Europe really started to take flight around this time period. Brewing beer became a real craft which was best practised in cities, bound by the rules and limitations of that city. Brewers slowly evolved in their craft, for example when they moved from using gruit to using hop. Somewhere in this evolution they learned to understand the utility of yeast and how to control it. Between 1268 and 1516 there is a period of two and a half centuries– they had plenty of time to do so.

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