When producing coffee most farms will ferment the coffee beans as apart of their process. Coffee fermentation is just as important as the washing process, they both work together to create a unique and flavorful coffee. The fermentation is a microbial reaction with yeast and bacteria, breaking down sugars from the juices of the coffee cherry, producing acids adding to the complexity of the flavor. There are many methods of coffee fermentation and just about every estate uses a slightly different processes.
The lowest fermentation level will typically be a wash processed bean, this is because the bean has been washed from most of the cherries juices. The beans are depulped (washed) then placed in large tanks to lightly ferment the coffee. Light fermentation is favored because it allows for the natural regional flavor of the bean shine, generally creating clean and vivid flavors.
Mild fermentation levels are typically natural, and honey processed coffees. The bean is partially pulped but the cherry juices are left to coat it, then the coffee is left out in the sun to dry. The mild fermentation process gives the coffee a creamy sweetness. It is a commonly used tactic to add flavor to bland coffee crops. Mildly fermented coffees are the most popular, because of their approachable flavor.
Highly fermented beans will be natural or dry processed coffees. The coffee cherries are picked and immediately laid out on beds to dry and begin fermenting. When performing a high fermentation the coffee cherries should be picked at a similar ripeness, each cherry has a different sugar content, and this allows for a more consistent flavor. A high fermentation gives the coffee intense and complex nuances, similar to a wine.