The washed process is widely used across Latin America and parts of East Africa and requires both the cherry and mucilage surrounding the parchment to be removed with the use of friction, fermentation and water.
Once the ripe cherries have been picked, they are delivered to a wet mill where they are loaded into a depulping machine which forces the beans out of the cherry. At this stage, the beans are contained within the pulp of the cherry, also known as the mucilage. This sticky mucilage is composed of natural sugars and alcohols and contributes massively to the sweetness, acidity and overall flavour profile of the coffee.
Once the beans have been pulped, they are put into fermentation tanks for around 12-24 hours dependent on temperature, though farmers are now experimenting with fermentation time to develop different flavour profiles. For example, a longer fermentation means the beans have more time to absorb some of the sugars and can result in a slightly sweeter, ‘funkier’ flavour, though this can be a hard balance to strike as leave it too long and the beans become over-fermented with unpleasant vinegar-like characteristics.
Fermentation results in the mucilage being broken down leaving the beans in their parchment which are then ready to be washed. This can either happen in tanks of clean water or, in East Africa, it is often done in channels. Once the beans have been washed they will feel gritty in your hands which means they are now ready to be dried.
At this stage, the parchment beans are taken to drying tables (raised African beds) or to patios to sit for a period of around 10-22 days where they are gently turned. It is widely accepted that a slower drying time contributes to greater balance and complexity in the cup. Some washed coffees, particularly in Central America, are dried in large ‘guardiolas’ which are mechanical dryers often used if a farm or dry mill has a lack of space. In this instance, the coffee is dried in around 3 days and we have found from experience that this can sometimes reduce the shelf life of the green coffee, allowing aged characteristics to creep in at an earlier stage.
The washed process is arguably our favourite at North Star due to the incredibly bright and clean coffees that it can produce – washed Ethiopian and Kenyan coffees are fantastic examples of the clarity of flavour that can be coaxed out if the coffee is processed correctly.