I recently wrote about the “wet process” that produces “washed” coffees and if you missed that article you should read it before you take on this one. Coffee processes are named funny. If one coffee is washed, but another isn’t, does that make it unwashed? If one is natural processed, is the other processed unnaturally? Hmmm
So-called “natural” processing (or dry processing) of coffee is probably the original way it was done. To quickly review, wet processing of coffee involves removing the seed (what we call a coffee bean), the parchment layer that surrounds it, and the mucilage (a goopy nutrient layer that surrounds a nourishes the seed) using machinery and water. It also gets fermented to break up the mucilage and remove most, if not all of it, before other steps in the process.
In the dry or natural process, the entire coffee cherry is dried with the seeds/beans inside, so they are picked, sorted and laid out in a variety of ways to dry in the sun and air, like turning grapes into raisins. The mucilage and pulp of the fruit is loaded with nutrients and sugars and as drying takes place, some natural fermentation may happen, too, creating a host of alcohols, aldehydes and other chemicals that produce flavors. The coffee beans absorb a certain amount of these compounds as drying takes place, so when the cherries are eventually hulled and the beans are separated from the rest of the fruit they will retain some of the character they took on.
Natural process coffees tend to have fruity, berry-like profiles (like some of the famous blueberry bombs of Ethiopia) and heavier mouthfeels as a result of the sugars and other compounds absorbed during this process. There are so many variables that their flavors can change a lot from season to season, so the roasters who use natural process coffees have to carefully cup them each and every time to make sure the flavors they want are present in the lots of coffee they are considering buying.