Coffee and Carbonic Maceration Process
We learn and steal a lot from the wine world. Coffee grows and is processed likewise wine, as both come from a fruit. We learned that a mix of variables needs to be at their highest to produce the most out of the cherries such as altitude, soil and climate. That’s what is called terroir. But not also this has a huge impact when producing outstanding coffee. Just after the handpicking phase, we have mastered a new way of processing coffee.
Recently over the past several years, we also learned that we can increase the complexity of a coffee with some new, experimental process which is called carbonic maceration.
The carbonic maceration process comes from France where it has become famous especially in the Beaujolais wine region in where the carbonic maceration comes from. It was first brought to the coffee stage in 2015 by Sasa Sestic during his winning World Barista performance in Seattle, USA.
What is exactly the carbonic maceration process?
Just after being washed, coffee is introduced in a sealed tank for a certain number of hours that can vary from a few hours to up to 3 days. Carbonic maceration just does the job itself but there are a few things to keep monitored if we want to achieve an extraordinary result such as:
- Temperature: as Sasa Sestic says, the temperature plays a big role as we can choose to enhance acidity by fermenting at a lower temperature (4-8°C) or to enhance sweetness by fermenting at a higher temperature (18-20°C);
- Duration of the fermentation: fermenting for more than 3 days can be done only at lower temperature and with the addition of Carbon Dioxide. Sasa says that “the reason why I have decided to flush carbon dioxide is because, without oxygen, we slow down the breaking down of sugars from the mucilage dramatically. The pH also drops at a lot slower pace, which means we encourage less alcohol acidity. Carbon dioxide helps me to extend fermentation by up to 3 days at 22°C, and even longer at lower temperatures, without getting dryness and a vinegar taste – which is normally the case with three days of dry fermentation.”
This enables to produce extraordinary coffee by producing unusual flavours, intensifying both the aroma and the flavours, the sugar content so the body in the cup. It’s usually a tastier cup than a natural coffee with tasting note such as red wine, banana, bubblegum and whisk(e)y. The result is an average increase of the cupping score but it’s also a way to become more sustainable both environmentally and economically.
I just remember now, while writing this article, a coffee cupping that I made a couple of months ago. I was surprised by the intensity of a singular cup and I was wondering about the country of origin.
It was the sweetest cup of the cupping with a strong taste of strawberry. I was pretty sure (like many of those present) it was the case of an Ethiopian coffee from the Guji region. Surprisingly, it was a coffee from Honduras and since that time I understand why more and more farmer is trying to change their approach when processing coffee.
Anyway, it’s more than a new way to process coffee: this process should open to new scenarios about the speciality coffee sector throughout the world: just think of how we can improve the percentage of speciality coffee produced by using this fermentation on a large scale bringing a lot of commercial coffee that is now standing between 70 and 80 points on a 100 points scale, to 84 plus and become then speciality.
The consequences would be obvious: more profit for the farmer as speciality coffee is sold at a higher price, less cost for him to make it happen and more money to invest in new technologies, new ways to prevent diseases, investing in education for their children and improving better living condition.
About the Carbonic Maceration Process
The process takes different name depending on the way is fermented: we call it aerobic fermentation when in case of an oxygenated contest, semi-anaerobic when with and without oxygen and anaerobic when without oxygen.
Interesting is that any of these processes have different consequences on the final product as different flavours and aromas are obtained.
However, carbonic maceration in an anaerobic contest is the most used way to ferment coffee. The process is similar to the aerobic one. The only difference is that coffee is fermented entirely with the whole cherry and not pulped. When we see the use of the “word” anaerobic it is usually referred to a sealed environment.
It’s so typically used a tank made of stainless steel which is good for:
- Maintaining a stable temperature;
- Making a cleaner coffee.
During this phase of fermentation, carbon dioxide is released and fermentation within the cellular structure of the cherries begins (this type of fermentation is called intracellular fermentation).
This fermentation happens because of the gravity: the cherries at the top are pushed down and crushed the cherries that are seated at the bottom.
So, just to clarify, the carbonic maceration is not to be considered as a new method to process the coffee but rather, a step that can be included in the washed or natural method. In the washed carbonic maceration the ripe coffee cherries are handpicked, sorted and depulped before introduced in a sealed tank. On the other hand, when in case of a natural carbonic maceration the coffee cherries are placed in sealed tanks and, after being processed, are sundried in African beds up to 20 days.
The hope is that more of these coffees are going to be processed in this way as it’s more sustainable and also replicable as it seems that it’s more a matter of controlling the process than choosing a particular varietal or coffee producing country.
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I am an Italian coffee lover that pushed for the love of this “amazing drug” decided to come to London to study about coffee and its different extraction procedures and tastes.