Once coffee cherries have been harvested, they must be processed to produce the green coffee beans used for export and roasting. During processing, the outer fruit layers are removed and the sticky mucilage surrounding the bean is broken down or dried away, leaving the green coffee bean inside. Achieving the correct moisture content is essential for preserving quality during storage and transport. There are several common methods used to process coffee.
Wet Method
Also known as the washed method, this is the most widely used processing technique. The harvested cherries are immersed in water, where ripe cherries sink while underdeveloped or defective cherries float and are removed. The cherries are then fermented in water for around 24–36 hours before being washed and dried. This method typically produces clean, bright coffees with balanced acidity and a refined body.
Dry Method
Often referred to as the natural or unwashed method, this approach is commonly used in regions where water is scarce. Whole coffee cherries are cleaned, sorted, and then dried in the sun on patios, raised beds, or rooftops. Drying can take around two weeks, although timings vary depending on climate and local practices. Some farms also use mechanical dryers. Natural processing often creates coffees with heavier body and fruit-forward sweetness.
Semi-Dry Method
Known by several names including pulped natural, semi-washed, and wet hulled, this method sits between washed and natural processing. In Indonesia, it is commonly called Giling Basah, meaning “wet grinding.” The cherries are first depulped to remove the outer skin, after which the beans are partially dried before the remaining layers are removed. This process can produce rich, earthy coffees with distinctive character and body.