What does it mean to say that a coffee is “natural,” “washed,” or “semi-washed
process?” All three describe different methods of removing the fruit from
the green coffee beans after harvesting.
Natural process is perhaps the simplest method, but arguably produces some of the most interesting flavors. After harvesting, the whole coffee cherries are laid on elevated drying beds and allowed to raisin in the sun for weeks with the fruit still on the bean. This method is only viable in areas with very predictable dry seasons since an unexpected rainfall could ruin the coffee. Once completely dried, the coffee cherry and a papery layer called parchment are removed together in dry milling or hulling. The Harrar region of Ethiopia is known for manually hulling the coffee beans in what amount to large mortars and pestles. In natural processing, the green beans take on unique spicy and fruity flavors from being left in the cherries for so long. Natural process coffee is not always for everyone, but it can produce a powerfully fruity cup full of blueberry, stone fruit, and chocolate notes.
Most of our coffees use the washed process. The freshly picked cherries are put through a de-pulper that separates the beans from the cherry. The beans still have some sticky mucilage on them after de-pulping, so they are put into holding tanks for 12-72 hours to ferment. The beans have to be carefully attended to and turned to ensure that the mucilage loosens enough to be removed easily, but not so much as to impart any unwanted flavors. The beans are thoroughly washed to remove the mucilage and then laid out on drying patios. The beans still have the parchment layer on them, which has to be removed by dry milling before the coffee is ready for export. Washed coffees tend to be sweet and bright, and they can also be more consistent in quality since there are more opportunities to sort out undesirable beans.
This process is most common in Brazil and Sumatra (and indeed those are currently the only semi-washed coffees we have available). In the semi-washed process, the freshly harvested coffee cherries are put through a de-pulper, but instead of being washed, the beans are laid out immediately on drying patios. The remaining mucilage dries on the beans and is only removed later with the parchment layer. Indonesian coffees are unique in that their parchment is removed much sooner than in other countries. Since the beans are still relatively high in moisture, they go back on the drying patios after milling. Semi-washed coffees tend to be sweet and spicy, with a big body. The Indonesian style adds a layer of smooth, earthiness to the coffee as well.