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Carbonic Maceration Process

This Week we are roasting an Ethiopia Guji Mesina, Carbonic Maceration Washed process from the well known green bean sourcing company / World Champion Barista, Sasa Sestic's Project Origin. We have roasted a few Carbonic Maceration and few other similar concepts of processing in the past years and most of those turn out to have such great body, sweetness and more intense aroma then the traditional coffee processing.

This Ethiopia Guji Mesina CM Washed lot #809 especially, has a really complex sweetness, floral aroma and tasting notes of white peach and mandarin. What exactly does ‘CM Selections’ mean? CM’ stands for Carbonic Maceration. It is a process that is generally used in winemaking, in which whole grapes are fermented in a carbon dioxide-rich environment prior to being crushed for their juice. We have adopted a method which also utilises carbon dioxide in order to push boundaries of fermentation and development in coffee. So, the CM Selections is our selection of coffees that have been processed using this method.

How is this processing different from normal coffee processing?  The terms that we are accustomed to in the coffee world include natural, washed, honey, semi-washed and so on. These processing techniques use a variety of methods to extract the green beans/seeds from the coffee cherries. The CM process does not replace these methods; rather, it adds another step in processing. For example, the CM Selections coffees are still identified as being natural, washed, etc but as they also do through this maceration process, we need to include that information too. So instead of being just washed, we say that a CM Selections coffee is carbonic macerated (washed).  Coffee cherries are picked perfectly ripe, hand sorted and floated to remove unripe and over-ripe cherries. The washed CM Selection coffees are then pulped, before being placed in temperature and humidity controlled tanks flushed with carbon dioxide (CO2) to remove oxygen from the tank. Natural CM Selections coffees are placed in the tanks and after fermentation, the coffee is dried on African beds for 12-18 days before being stored to rest before dry milling.

What does the carbonic maceration method do to the coffee?  The result of a carbonic maceration process is increased development of flavour profiles. By using a controlled, carbon dioxide-rich environment to ferment the coffees, we can control which yeasts and bacterias are active during fermentation and for how long, and this are able to intensify and further  develop the flavours of the coffee without risk of over-oxidization or alcoholic fermentation, which will ruin the profile of the coffee.

So does carbonic macerated coffee taste better than other coffee? Taste is of course a subjective experience, and what tastes ‘good’ and ‘bad’ depends on what different people like. The CM Selections coffees aren’t ‘better’ than any other coffee; they offer an experience that pushes the boundaries of development, so that the consumer can experience intensity in flavour and aroma.

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