Basically, “processing” is anything a producer does to clean the coffee bean from skin and pulp and to dry the bean to the “exporting” moisture level (that is usually 11-12%).
The actual techniques vary greatly, but we can focus on the most common and wide-spreaded, which are: washed, natural and so-called honey.
Washed Process is the most common method in specialty coffee world. Freshly harvested coffee is sorted for ripeness and the skin and mucilage is removed within 24 hours of harvest. The removal of the fruit layers is called depulping. Before the coffee is depulped, the cherries are put in some amount of water for a float test. This test checks to see if there are any cherries that float in the water, which indicates a defect. The floating cherries are usually removed. After that, the cherries go through a depulper, which removes the pulp from the seed.
After depulping, the sticky seeds with the rest of the pulp will usually go into a fermentation tank for 12-36 hours. All coffee processing methods have at least some fermentation, and the washing process makes this step more delicate than other methods. Fermentation will help the mucilage to come off the seeds so that it will be easier to remove when washed.
After fermentation the seeds are submerged in fresh water and agitated. After this, the beans are put onto some plain surface to dry. To ensure even drying, the coffee will be agitated a couple of times per day. After the coffee is dried, it is bagged and ready to be shipped to the roaster.
The flavour profile of washed coffees are usually more “clean” and delicate than the others, with pronounced acidity and elegant texture.
Natural process is the oldest method of processing coffee and is more ecologically friendly, as it does not require water. For this process a farmer leaves the coffee cherry unaffected for the duration of the drying. After the cherries have dried, the pulp is removed. The cherries are picked ripe, which is important since the pulp itself imparts flavor during this process. Just like in the Washed, the cherries are placed on any plain surface for the drying stage, but the best way of drying is via raised beds, which allow the airflow to move around the whole cherry. It can take 3-4 weeks for the cherries to dry and the seeds inside to reach 11% moisture. After the drying process, the coffee goes through a dry mill which removes the dry pulp and skin, and the parchment layer around the seed. After a final sorting, the coffee is bagged in burlap and ready to ship.
The flavour of naturals is usually more “bold” compared to the washed coffees, with rich texture and intense fruity notes.
Honey Process is “in the middle” between the washed and natural processes. Like washed coffee, the fruit skin is removed within 24 hours of harvest. But later on, the mucilage is left on the seed to dry, which reminds the natural process where the fruit juice stays in contact with the seed during the drying process. Like the natural process, honey is also more ecologically friendly than the washed process as water is not required. The seeds can be dried in one of several ways including on a tarp on a patio under full sun or piled in a greenhouse for longer fermentation before being raked to an even layer. The whole process takes place over 3-4 weeks, depending on weather conditions.
Due to different level of mucilage that can be left on the seeds, the flavour profile of honey coffees can vary greatly. But usually they go for a combination of nutty and fruity notes, with balanced sweetness and layered acidity.
New-wave processing methods. Nowadays, more and more farmers that are seeking to improve their coffee quality turn to science and other industries. They implement totally new techniques that differ a lot from what their parents and grandparents did. This gives us, the customers, a new world of flavors in a cup of coffee.
One of these new technologies is so-called anaerobic fermentation. This technique comes from the wine industry, and the main idea is that coffee cherry (or bean) is fermented under non-oxygen conditions. As a result, we can find specific flavors of tropical fruits, champagne and others, that are not so common in coffee and only appear under these special conditions.
Such coffees are for those who seek a new experience in a daily cup of coffee.