Coffee cherries are typically processed in three basic ways:
- Natural processing
- Honey processing
You can read more info in our article
Recently, anaerobic coffee fermentation has come to the fore. It is not a novelty in the field of coffee and in winemaking it is a complete basis.
What is fermentation
Coffee cherry contains sugars and acids. Yeast and bacteria start consuming these sugars and acids and turn them into other acids, CO2, alcohol and other substances. This process continues until they have food or until the environment becomes inhospitable. This process takes place to some extent during each processing method until the coffee is dried to 9-12% moisture.
What is anaerobic fermentation.
We have the same players. Sugars, acids, yeasts and bacteria. But we'll make sure they don't have access to oxygen. Coffee cherries are immersed in tanks filled with water. When the feast begins, the CO2 pressure increases. It is necessary to make sure that it can escape, but at the same time does not let oxygen in. When we ferment without access to air, we create a different taste profile of coffee than when there was oxygen present.
Another means of controlling fermentation comes into play. And that's the temperature. The higher the temperature (within certain limits, of course), the more turbulent the fermentation. Conversely, the colder, the slower until it can possibly stop despite there is still enough food (sugar). Different fermentation rates and even several fermentation phases produce different taste profiles. An example we have very interesting coffee of Diego Samuel Berumudez.
Another wonderful example of anaerobic fermentation is the 96-hour fermentation of Colombian Anserma.