aka Dry Process, Proceso Natural
The natural process is the original manner in which coffee was processed. The cherries are dried with the beans inside, like drying a grape into a raisin. The beans are dried with all of their layers intact, including the coffee cherry and mucilage.
The fruit of the coffee plant, known as the cherry, is picked once it ripens on the branch. Mature coffee cherries can manifest themselves in red, yellow and orange pigmentation. In some coffee regions, such as southern Ethiopia, coffee cherries are picked at the same point of maturation as washed and semi-washed/honey/pulped natural coffees and brought to dry on patios or raised drying beds. Coffee beans are dried intact with all of their layers in this process including the coffee cherry and mucilage. The coffee cherry and mucilage are composed of sugars and alcohols, which play a role in the sweetness, acidity and overall flavor profile of the coffee. The fruit is a closed environment, which encourages natural fermentation (and sometimes rot) – helping create the final flavor profile. The fruit dries onto the parchment that surrounds the seeds. The coffee beans are left to rest inside the cherry pods before being peeled (hulled) and prepared for shipment. At this stage the cherry is the texture of fruit leather. The result is the dense heavy body and exotic, wild berry flavors that have become synonymous with natural processed coffees. However, the cup profiles of natural processed coffees can be inconsistent, so an intense analysis on the cupping table and in the lab is integral during the selection process.
The word pasa refers to another technique to create natural processed coffee. In this method, the farmer leaves the coffee cherry to ripen and then dry on the branch, rather than picking and then drying the cherry on raised beds.
Naturally processed coffees typically have heavier mouthfeel, lower acidity levels and intense, exotic flavor profiles.