Organic Yeast, an organic ingredient  or non-organic aid?

Claus Christensen is the founder of Munkebo Brewery, but Claus also holds a PhD in health science from the University of Copenhagen, and is a specialist in cell biology, protein chemistry and molecular biology. Thus, Claus has taken a special interest in the yeast aspect of brewing from an early stage of his brewing career, prompting him to isolate and propagate natural yeasts from the environment and use them in his commercial brewing. In order to drive this ‘side-project’ further, Claus in 2017 established a separate company, CooLAB™, with his colleague Pia Winther Bargholz in order to commercialize their capacity to isolate and propagate unique yeast strains for use in brewing or other fermentation-based products. 

We at the SBR are very happy to have convinced Pia and Claus to reveal some of the fascinating aspects of the work they are doing in CooLAB. As a start of and an introduction to hopefully many interesting articles from Pia and Claus onwards, we hereby bring you an article with some highly relevant questions and deliberations about the legal status of yeast in general and organic yeast in particular in brewing.

Picture of a yeast isolated from a honey bee. Used in Munkebo Weissbier, Folkvang

The role of organic yeast in brewing

Yeast is an important part of brewing. It helps preserve the beer through the lowering of pH the fermentation implies, it contributes to the aroma, flavor and taste of the fermented product, and, very importantly, it produces the ethanol and warmth of wine and beer. Beer or wine cannot be made without yeast and the contribution from different unique types of yeast strains has a direct impact on the final result of the fermented beverage, not only as an essential technical aid in the process, but also in the total experience of taste when drinking as well as in the visual appearance. 

Legally, the general definition of yeast is very simplified and does not provide the whole picture of its role in the final product.  We have the impression that organic producers in the brewing industry wish to use organic yeasts in their production. But this product has previously not been available on the market and therefore naturally not a present thought in mind when selecting raw materials for organic production.

CooLABTM is producing organic yeast for brewing and was certified in 2018 as a 100% organic laboratory, isolating natural yeasts and producing organic brewing yeasts with the Danish Ø label. (The ‘Ø’ stands for ‘økologisk’, which is the Danish word for ‘organic’.) 

We find that there is a conflict in the way we define yeast. By defining it in the law only as a technical aid, it does not push us to do more for the environment as organic producers. 

The definition of when we as organic producers should choose an organic raw material is clear. But when it comes to yeast, the legislation defines yeast only as a technical aid.  Where does yeast actually belong when it is providing much more to the final beverage? As merely a technical aid, or as a raw material, like malt and hops?

Yeast is the master in fermentation

Brewmasters, winemakers and distillers around the world have since the beginning of brewing mixed water with barley or grapes with yeast to start the fermentation.

From the malts come aroma, sweetness and thereby the body of the beer. Hops give the bitterness and its unique aroma. Hops help conserve the beer and prolong the life. Yeasts provide the fermentation of sugars, and in the process convert these into CO2 and alcohol, and yeasts also produce, as so-called secondary metabolites, their own unique characteristics and aromas such as spices or fruity esters, for instance in a weissbier, a fruity wine or an aromatic whiskey.

Yeast is a natural transformer

Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. Yeasts are very common in our environment, and are often found in or near sugar-rich materials such as the surface of fruits and berries. Since Saccharomyces cerevisiae (the yeast species predominantly used in most alcoholic fermentations of beer, cider, wine, etc.) is not airborne, it requires assistance to move to a new feeding ground. 

Research suggests that yeasts have developed the ability of mimicking the aromatic esters of fruits to attract fruit flies to move yeast around to new living habitats. This is one of the yeast traits brewmasters benefit greatly from in brewing. For instance, in a hefeweiss beer, in which the intense aroma of banana actually comes from fruity esters produced by the yeast. 

Alcohol is the most significant outcome of the yeast’s ability to rapidly convert sugars to ethanol under both anaerobic and aerobic conditions. It is speculated that yeast developed this ability in order to expand potential growth also to environments where air was less accessible, and the anaerobic metabolic pathway – the glycolysis – gave the yeast its capacity to degrade sugar to ethanol. In return, this greatly strengthened yeast in its competition for nutrients with bacteria and other member of the fungus kingdom, under anaerobic conditions.

Another benefit from yeast is the natural ability to work in low range of pH. The shape of the yeast’s proteins and the efficiency of enzymes are directly affected by the level of pH inside and outside the yeast. Every protein is made up with a unique composition of amino acids, and the sum of this gives a protein its optimal shape and function, like enzymes that accelerate chemical reactions.

In the case of the enzymes which break the bonds in starch to produce simpler sugars like maltose, glucose, etc. have adapted to acidic conditions, just like yeast in fermentation.

This is also one of the benefits when yeast works in brewing, that the low pH in the finished beer – and the pH drop seen during primary fermentation – is a healthy sign that the yeast is thriving, and this also keeps most bacteria from infecting the beer and making the beer unsuitable to sell. Harmful bacteria can’t grow under  the acidic conditions created by the yeast during beer and wine fermentations. Also, the low pH is one of several factors that help prolong the shelf life of beer. In case of lambic beer, yeast and specific bacteria such as lactobacillus are also adapted to a lower pH environment to give the acidic taste loved by many. 

Brewing yeast may come from East Asia

A new article published in the international journal of science, ‘Nature’, describes the work by scientists in France who wanted to look very closely into the variations within the genome of Saccharomyces cerevisiae in order to study what knowledge about the history and proliferation of the species could be deducted from these variations. For this purpose, they set out to find 1,000 different Saccharomyces cerevisiae yeasts. 

The work of these French scientists is similar to when human DNA was collected from all around the world and the studies of the data suggested that the current Homo Sapiens species arose in East Africa. As time passed, humans migrated throughout Africa, where a smaller group went into Asia, Europe, Australia, America and farther out eventually to every corner of our planet. 

This data can be summarized into a conclusion that a small number of humans left Africa with their ‘part’ of human genes, and passed these on, showing a relatively limited diversity, to their descendants. The larger group of Homo Sapiens at that time, having, due to the larger number of individuals, a more diverse collective set of genes, remained in Africa. Analyzing these data also showed that the older a population is, the more diverse a set of collective genes they have. In this way, scientists can, through detailed and complicated analysis of collective genome variations, find out where a species arose.

Yeast strains from termite mounds, tree bark, the infected nail of a 4-year-old Australian girl, oil-contaminated asphalt, fermenting acorn meal in North Korea, horse dung, fruit flies, human blood, seawater or a rotting banana, etc., were collected and analyzed. The French scientists sum up their work finding that gene diversity of Saccharomyces cerevisiae is largest in East Asia, suggesting this may be the birthplace of our beloved yeast.

Red clover improves organic ecosystems

Organic production starts with ecologically sustainable agriculture. Organic farming is an agricultural system that is fully consistent with sustainable growing starting in the farmer’s fields. In this organic production, the management uses very little chemical fertilizer, no pesticides (or other industrial synthetic products) or genetically modified organisms (GMOs). 

The farmers need to produce their own fertilizer, for instance from plants such as red clover, to improve growth in the farmers’ ecosystems. Red clover produces on average 70-150 pounds per acre of nitrogen. This amount of nitrogen can be used to support growth of plants, but even the best of organic farmers will not achieve the same high harvest yield as a conventional farmer. Only around 50% can be expected from the same acreage, making organically grown hops and barley more expensive. 

A 5% rule for raw materials in organic production 

In certified organic production of beer in Denmark, brewers have to verify and back trace all organic raw materials used in production. At all times, we need to know how much organic hops, organic barley or organic sugar we have in stock and prove we have bought it from an authorized supplier/organic farmer with an approved active organic license. This involves keeping a complete record of which materials have been used in which products. We need to prove we can trace all batches of barley and hops used through all steps of the process through to the finished product. Organic production is very time-consuming because of the elaborate requirements for documentation, thus making organic production a bit more expensive compared to conventional.

Malt, hops, sugar, all need to be organic for a certified organic beer. However there is a 5% rule for raw materials for farmed products, so if you can’t find an organic version of your favorite hops, you can use a non-organic hop if it represents 5% or less of the total hop bill. 

Lactic acid is allowed since it is made from barley and can be organic, but inorganic technical aids such as phosphoric acid are not allowed in organic production.

Since yeast is characterized as a technical aid, it is not formally and legally a part of the organic raw materials, so brewers can use whatever they can find of non-organic yeast in their organic production.  

Conventional non-organic yeast is made with sugar from corn or leftovers from the beet industry. To increase cell density, chemicals such as magnesium sulfate, calcium sulfate, ammonium sulfate and potassium phosphate are added. These are used as building blocks in cell maintenance and cell division. This is not allowed in organic yeast production. 

Brewmasters brewing organic beer or wine are taking care that all materials are coming from ecologically sustainable agriculture, but one of the most important parts,  the yeast, is considered a ‘technical aid’ and does not need to be organic before the new EU rules for organic production are implemented in January 2021. 

Why is yeast a ‘technical inorganic aid’ when it goes against the very definition of organic production?

We prefer using organic raw materials such as grapes grown without any pesticides, hops cultivated without phosphate used as fertilizer and yeast grown organically. Organic yeast has a considerably lower cell density as it is propagated without addition of chemicals. This limitation also reduces the cell count pr. HL considerably (down to 50% less) during the initial stages of production.

Crystal clear beer, without yeast or unfiltered beer?

Beer has for a very long time in Denmark been seen as a bright, filtered product like a clear lager, easy to drink in large quantities. With the revolution of craft beer, new varieties of different hops and a wider selection of malts are being used to generate new flavors in a large variety of new beer styles like Imperial Stouts or NEIPA. With the organic production of beer and wine winning more percentage in sales each year, an approach to a more sustainable production is slowly getting more attention: organic production is here to stay. But we find it troubling to see a beer label that specifies in writing ‘this beer is 100% organic’ when the yeast used is not important enough to be organic.

Here are some examples of how important yeast is in beer:

Example 1: Unfiltered beers – like a ‘Tuborg Raw’ – that are not filtered, not heat-treated and organic, thus live yeast remains in the final product and contributes to the taste and overall impression. Tuborg also writes on the can, ‘Water, organic barley malt, wheat extract, hops and yeast’. The yeast is thus declared as an ingredient in this organic beer. (Source: 

Example 2: Many classical Belgian beers are often bottle-conditioned with live yeast in the bottle. The same taste and character would not be found in the same beer without the yeast in the bottle, nor could it reach the desired high carbon dioxide level without the live and active yeast.

Example 3: German ‘Hefeweiss-bier’ is a classic German wheat beer style, which emphasizes the importance of the yeast as an important part is the beer, and here contributes significantly to the taste. This beer should not be filtered, and you make sure to include all the yeast when pouring into the glass. So, again, not just a technical aid. The same goes for a Belgian Wit.

A start-up of an organic yeast laboratory

We – CooLABTM – are the team behind one of the first exclusively certified organic yeast producers in the world. An organic yeast laboratory, situated a short distance south of Copenhagen. The team has switched to become a 100% organic laboratory, growing yeast and isolating yeast strains from nature, aimed for brewing. 

Together, the business partners, Pia Winther Bargholz and Claus Christensen, PhD., decided to make all their yeast strains organic and apply for the Danish organic certification, achieving this in 2018. Since then, CooLABTM has managed to get a small organic yeast production up and running.

To turn CooLABTM into a business that can supply organic production in Denmark and other countries, more equipment is needed and a larger investment is necessary. Talking to potential distributors and clients, we find there is a positive interest in using organic yeast to complete their organic beer production. However, when brewers know that the competitors choose not to use organic yeast in order to increase their profit, organic yeast is forfeited.

We think a debate is necessary on a national and preferably EU level about the topic ‘how organic yeast is defined’ according to the legislation, and whether the yeast should formally and legally be treated at least on equal terms with the other essential ingredients in brewing. Considering how important yeast is to both the character of the finished beer as well as to the process by which this is produced.

About the authors


Pia Winther Bargholz, CFO, is educated as a brewer from the Scandinavian School of Brewing in Copenhagen (and formerly was a commercial helicopter pilot). She trained as a brewer at Herslev Brewery, an organic brewery in Denmark. Pia founded her own small brewery, Bryghuset Winther & Bargholz, in 2013.

Claus Christensen, PhD, CEO, has a master’s degree in biology and a PhD in health science from the University of Copenhagen. He’s a specialist in cell biology, protein chemistry and molecular biology. Claus performed military service as a Royal Guard, worked as a farmer, and has been a brewmaster in Denmark and Germany. He founded Munkebo Brewery in 2013 and has isolated several yeast strains from a honey bee, to be used in breweries around the world.