New developments in coffee processing

Themagic of natural fermentation, or fermentation, has been known to humans since time immemorial. Today, fermentation is making a big comeback in kitchens, both professional and domestic. It is a modern and actually rediscovered technique for processing fruits and vegetables. For our grandmothers, vegetable fermentation, or fermentation, was a familiar and especially common technique. Just think of the typical "sour pickles" or fermented cucumbers. Yes, these too are processed by fermentation.

Modern times encourage healthy eating and fermentation seems to be an excellent technique for processing raw materials, which are then very beneficial for our organism. It is not only cucumbers that are fermented, but also carrots or oatmeal. Fermentation is commonly used in the food industry. For example, in bakeries when making sourdough bread, in breweries, in the processing of tea and, of course, fermentation is an integral part of the wine-making process.

The question then arises as to how it is possible that in the processing of green coffee, which is the world's most traded commodity, fermentation is a novelty and so far mostly an experiment?


When asked "How is green coffee processed?", the most common answer is that there are three ways of processing coffee:

  • natural (dry) method
  • washed method
  • and thehoney (partially washed)method

In the first case, this is the original coffee processing process. The coffee cherries are simply picked and left to dry in a concrete courtyard or better on so-called African beds. After peeling off the dried skins, they are cleaned and distributed to the roasting plant.

The washed method is the process of treating the coffee cherries with water, in which the beans are cleaned and the washed coffee is dried.

The last of the classical methods is the partially washed method, for which the name honey is appropriate. Theskins of the harvested coffee cherries are removed but the flesh is left on. The beans are dried in this natural lubricant and processed as in the natural method.

On further reflection, we realise that in the case of the first and last methods, i.e. dry and honey, a certain natural fermentation takes place. In this case, the process of such fermentation cannot be completely and precisely controlled. It is precisely uncontrolled fermentation that poses a risk to the farmer, which can destroy the crop being processed.


To understand fermentation, let us recall our chemistry lessons. Fermentation, or fermentation, takes place in the presence ofyeast and bacteria. They multiply by breaking down sugars. The sugars then become simpler substances like acids and alcohols. Fermentation depends on a humid environment and just enough sugars. Such a coffee cherry contains both sugars and moisture.

The process of fermentation is therefore directly offered in its processing. Yeasts, fungal micro-organisms, start working after the coffee cherry has been picked. Unwanted and uncontrolled fermentation can manifest itself as mould or spoilage of the coffee flavour. This is the danger of the natural method of processing green coffee and the reason why it is important to rake the drying coffee cherries regularly.


Intentional fermentation can look like letting the harvested crop rest in a container or bag for a period of time. This is aerobic fermentation, i.e. fermentation in the presence of air. One aerobic fermentation technique is the tropical fermentation method, which is practised in the processing of coffee at theEcoagrícola farm in Brazil.


If the coffee cherries are enclosed in a container, or often in a tub filled with water, fermentation takes place without air, i.e. anaerobic fermentation. Controlled fermentation monitors the time, temperature and overall progress of fermentation. This allows a positive fermentation to be achieved, making the flavours in the coffee more varied, brighter and bringing out other subtle flavour nuances that would not otherwise stand out.


The world-renowned barista champion Sasa Sesticis the main innovator and pioneer of improvements in coffee processing . His aim is not only to improve the standard of coffee in the world, but also to improve the living conditions of people working on coffee farms and in processing stations. To this end, he created Project Origin, a company that makes transparent the sale of green coffee from quality farmers. Project Origin focuses on sustainability, farmer community and farmer development. It isSasa Sestic who is the ambassador of carbonic maceration. He "borrowed" this technique from winemakers. It involves fermenting the wine, in this casecoffee cherries, under CO2 pressure. To get a better idea of the process, watch the video that was made for the documentary based on Sas Sestica's book of the same name , The Coffee Man.


These new trends in the processing of green coffee are based on thefarmer'sown experience, who first has to find out how his coffee reacts during fermentation. Controlling the whole process provides valuable information for further improvement of this coffee processing method. Farmersdo not share theinformation gained through long research and experience of failed processing with each other. They are afraid that other coffee plantations will not use this information to their own advantage and that their coffee will not gain themarket position that it has due to the uniqueness of this processing.

It is the low level of awareness that is the main reason whyfermentation is new to coffee processing. The modern civilised world is based on a huge amount of information flowing to us from all sides. However, coffee is often grown in remote areas of underdeveloped countries. It is very difficult for a small farmer whose coffee trees grow hidden in a forest in the interior of Africa to get news and advice on how to achieve a better quality crop. It is by educating farmers that they will improve the quality of their production. This will result in higher profits, which they can reinvest in their business and increase its value. As the business grows, not only the standard of living of the coffee plantation owners increases, but also that of their employees and the local community.