What is done with the skin and mucilage from the coffee cherry is what determines or defines the processing method.
Natural or dry processing is one of the oldest methods of processing coffees. After the cherries are picked from the tress, they are cleaned and spread out in the sun to dry on cement or raised tables. They’re left in the sun for weeks and are periodically raked and turned to ensure an even drying process and to prevent mildew growth.
Because the coffee is laid out in the sun for weeks, natural processing is only used in regions that have very little rainfall and long periods of sunshine. As the cherries dry, they darken in color and harden. Once they have reach an appropriate dryness — a maximum of 12% moisture — they are sent to a mill where the sun-dried skin, mucilage and hull are removed and the beans are sorted, graded and bagged for shipment.
Coffees that have been processed naturally are often sweeter and have more body and a more complex flavor and aroma profile.