The washed process involves completely removing both the cherry and the mucilage from the outside of the parchment with the use of friction, fermentation and water. The coffee cherry is picked from the branch as soon it is ripes. The ready-to-picked coffee cherries can be found in red, yellow and orange pigmentation.
Once the cherries have been handpicked, are transported to washing stations where they are first weighed and then loaded into a depulping machine. The coffee cherry is then sliced open by a blade. The two beans are pushed out of the cherry, which leaves the beans with mucilage as their outermost layer. Mucilage, composed of natural sugars and alcohols, plays a crucial role in developing the sweetness, acidity and overall flavor profile in the coffee beans. It is important in the washed process that all mucilage is removed from the bean which leaves only the flavor that developed in the cell structure of the bean prior to processing. In the washed process, the mucilage is removed either with fermentation or mechanically.
KENYAN ’72 HOUR’ WASHED PROCESS
Kenya has a particularly complicated processing method for its coffee which accounts for its relative fame for unique, high-quality coffees the world over. It involves two separate fermentation stages and a long soaking stage to produce its coffee.
One of the first steps is to determine the relative density of the coffee beans themselves, which can be done by using specialized McKinnon depulping units. Density is a good indication of good quality and low quality beans, as low quality beans will float in the depulping units while good quality beans will sink. This allows them to be sent through separate channels, with the poorer quality beans to be sent off to be processed separately while the higher quality beans are sent straight to the fermentation tanks.
The primary fermentation begins and lasts for up to 24 hours. Beans are washed of loose mucilage, and then sent back to the fermentation tanks so that they can spend the next 12-24 hours fermenting again. Fermented beans now spend up to six hours being washed, with bacteria, yeast mucilage and other solids being removed during this process. Any beans that float, indicating that they are of lesser quality, will run off and be disposed of. Finally the beans are soaked for up to a full 24 hours underwater. This produces a much more intricate acidity within the bean as amino acids and proteins increase within each bean.
During the pre-drying process, devices called “skin beds” are used, in order to promptly remove the vast amount of moisture that the beans have accumulated through the complex washing and soaking processes outside of fermentation. The beans are laid out in the sun quite thinly, allowing the sun and wind to quickly evaporate moisture. They are left here for another six hours until they are ready to be properly dried. In the final stage, raised drying beds are used, where the coffee is laid out on for approximately 5 to 10 days. The total drying time depends mainly to the weather conditions, such as wind, clouds, sunlight etc.
The difference that the Kenyan method applies here is that it allows all of the coffee to breathe properly as it dries. They use ‘bodegas’ to dry the coffee in cages. In many other locales, drying beans will be allowed to rest in bags, which sometimes cause sweating and will probably result in unusual flavors in the bean.
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