Some of the joys you get to experience when working closely together with talented and inspiring farmers are the projects developed in addition to the main production.
For the past 5 years, Akmel Nuri and I have tried to boost everything we love about his coffee; the rich sweetness that is build up by an interesting acidity, combined with the beautifully intense fruity aromas. And now, we have fruitful results.
Before I introduce you to what an Anaerobic fermentation is, let's go through the steps of traditional Naturals from Ethiopia.
The Fundamentals of Fermentation
For the past 6 years, you’ve been able to taste the full-bodied Natural coffee by Akmel Nuri with an almost syrupy sweetness to it. Part of this coffee’s rich taste comes from the fermentation it undergoes as a Natural coffee. For several years we have wished to create a new and fermented coffee, which has resulted in several tests at Akmel Nuri’s farm.
Visiting Akmel Nuri last year, we were excited to continue with our fermentation tests. The goal is to go even further with fermented coffee and to achieve an intense coffee with a fuller taste beaming with sweetness and acidity.
Natural coffee is known as a sweeter coffee, as this processing method gives taste from the pulp to the seed. Fruity sugars that develop in the coffee seed, will be expressed and caramelized when roasted.
At Akmel Nuri’s farm, coffee cherries are handpicked in his coffee forest. Immediately after picking the cherries, they are sorted on the nearby raised beds. Here, they will dry for 11-13 days. During this time, spontaneous and uncontrolled fermentation processes will happen. Depending on the country and the processing method, the control of the fermentation process will vary as well as the outcome of the taste. In Ethiopia for instance, their Naturals are known for the fruity aromas that develop in the process.
After drying the cherries to the optimum level, the look of the cherry changes from red and glistening to dark and wrinkly. It is now time to remove the dried fruit pulp from the seed, and the green beans are ready to be shipped to our roastery in Copenhagen.
Contrary to the traditional procedure in Natural processing in Ethiopia, we have predominantly used an anaerobic method to process this coffee, involving sealed barrels as a supplement to the airy, raised beds.
In the middle of the beforementioned storage house, we have placed six tall barrels filled to the brim with no more than 3 tons of coffee cherries in total.
Before being placed in the barrels for fermentation, the red, ripe fruit has dried for a few hours to one day on drying tables and sorted. After 10 days of fermentation under a closed lid, they are dried on the drying tables under the sun for 12 days.
Our fermentation test is mainly anaerobic. Instead of using the raised beds for drying the cherries, we have used barrels with sealed lids. In the barrels, the cherries are fermenting in its own fruit juices. Using the method with a closed lid, the carbon dioxide or CO2 is not able to escape, and will eventually build up pressure. What we believe has happened is an anaerobic fermentation, where the oxygen more or less will be forced out. Without oxygen present in the barrels, CO2 will presumably allow the sweet and fruity flavours of the natural coffee juices to be absorbed by the parchment surrounding the seed.
The result is an intense coffee with a great richness. The sweetness and acidity both give that extra boost to the coffee, complimenting the pleasant, fruity aromas of strawberry and papaya.