Natural Process (aka Sun-Dried or Dry Processed)
Fruit Removal: After drying
Fermentation: Occurs inside the fruit mucilage surrounding the seed and under the pulp, will take place as long as there is fuel available to the microorganisms (e.g. sugar, water, acids, etc)
Drying Time: Up to 30 days, weather permitting
Profile: Noticeably fruity or “pulpy” flavors, often described as “boozy” or “winey’; can also have strong nutty and/or chocolate characteristics, and typically has a heavier or syrupy body
While Washed coffees have their fruit removed relatively quickly after harvesting, Natural or “Dry” process coffees are something like the opposite, in a manner of speaking: The fruit is instead picked when ripe and allowed to dry completely around the seed before being husked or hulled off. While historically this hulling was done by hand with a kind of mortar-and-pestle setup, today it is largely done by machinery that can be finely calibrated. Natural process coffees are most commonly found in Ethiopia, Yemen, Brazil, and Costa Rica, though producers around the world are also experimenting with this methodology.
As with all coffee preparation, there is fermentation occurring during the processing, from the moment the coffee is picked (or possibly earlier, whenever an access point is created in the fruit). Local or intentional populations of yeast and bacteria will enter the fruit at the access point and begin to metabolize the sugars and acids inside the coffee fruit immediately, a process that can continue until the coffee is dried to the standard of 11%. While the coffee itself is not held in “fermentation tanks,” its fermentation process is altered and can be dictated by things like ambient temperature and exposure to full sun or shade; depth of the drying bed; rotation of the coffee during drying, etc. (Note: At Cafe Imports, we typically avoid describing these coffees as “Sun-Dried” and instead prefer the term “Natural,” since many other coffees are also dried under the sun. We also avoid using the term “Unwashed,” which is common in some parts of the world.)
Drying Natural coffees is considerably longer and the overall process is riskier than for Washed coffee, which hints at some reasons the Washed technique was developed: Naturals take more space on drying surfaces, require more attention and labor (to prevent mold and infestation during drying, for example), and are constantly at potential risk for spoilage or “overfermentation,” as the fruit material that is intact on the seeds provides a longterm and concentrated fuel source for yeast and bacteria to metabolize.
Natural processing is the oldest basic technique for preparing coffee, and in ancient times (as well as currently in some cultures and applications), it’s possible that the coffee fruit was allowed to dry completely while still on the branch, allowing it to be harvested only when needed. Modern Natural coffees are harvested ripe and intentionally dried, typically on patios, raised beds, or drying tables; they cannot be dried in mechanical dryers as Washed coffees can.