Coffee is one of the few fruits grown only for its seeds. But this presents coffee producers with a challenge, as the cherries must be processed– separated from the fruit, dried, and milled — before being exported. But processing is more than an obligatory step after harvesting: the methods the coffee producer uses has an enormous effect on flavor. In fact, many coffee professionals believe processing has a bigger effect on the way your coffee taste than the variety of the plant or the country of origin.
There are four main ways of processing coffee, with perhaps infinite variations within each category. Certain methods tend to be common in different regions, often driven by the local climate and available infrastructure.
Washed Process (Parchment-Dried)
For the specialty coffee world, the washed process (also referred to as parchment-dried) is the most common. With this method the cherries are first depulped by a special machine which range from small (pictured above), to the size of a warehouse. After the cherry is removed the seeds are fermented— often in a tank of water although some regions practice a dry fermentation in small piles— which allows yeast and bacteria to eat the remaining sugar on the outside of the seed. After fermentation the coffee is washed, often in channels, before being dried. Drying might occur on concrete patios, raised beds, or in large metal drums. After drying the coffee must be milled to remove a final, papery layer called parchment that encapsulates the coffee seed.
The washed process is the most consistent, as unripe “floaters” are easily separated. The final product tends to have a cleaner flavor profile and a more lively acidity. Coffee in Colombia, Kenya, and Central America is usually fully washed.
Natural Process (Cherry-Dried)
The natural process is the oldest way of processing coffee and is very common in places with little water, like Western Ethiopia and Yemen or in places where coffee farming happens on a very large scale, like Brazil. In recent years, the natural process has become more popular in places that traditionally fully wash their coffee as a way for farmers to add value to their coffee, thanks to the process’s distinct flavor profile. With the natural process, coffee cherries are dried with the fruit still in tact. This allows more organic material to make its way from the coffee pulp into the seed (as clearly seen on the outside of unroasted natural process coffee.) When done well, the natural process imparts a distinctive fruity flavor to the cup, often reminiscent of blueberries or strawberries. Unfortunately, poor examples taste dirty and over-fermented.
The process is very labor intensive, as the drying cherries need to be constantly raked, but advocates tout its lower environmental impact, as well as its unique flavor profile.
Honey Process (Mucilage-Dried)
The honey process, or mucilage-dried, is a sort of hybrid process. Outside of Brazil, where it’s called pulp-natural, it tends to be uncommon, practiced mostly by coffee producers with a penchant for experimentation. Like a washed coffee, the coffee cherries are depulped, removing the skin and pulp. But varying amounts of the mucilage (sugary, sticky material on the outside of the seed) are allowed to remain. The honey process is a spectrum ranging from “white honey” to “black honey,” with the latter being closer to a natural. The name comes from Spanish word for the mucilage, miel.
Some excellent examples of the honey process have come out of Costa Rica, El Salvador, and Panama in recent years, often exhibiting dark, fermented-fruit flavors, like molasses.
The wet-hulled, or seed-dried, process is most common in Indonesia, and is largely responsible for the earthy flavors often associated with Indonesian coffee. In many ways the process resembles the washed process, with the important distinction that it is milled (or hulled) before the coffee has been allowed to fully dry. The freshly milled coffee seeds dry much faster than coffee still in its parchment, but often at the expense of quality. The result is very divisive amongst coffee drinkers, some of whom love its leathery, forest-floor profile.
There’s no question that processing method has a tremendous impact on the flavor of your coffee. Whether it’s the sparkling-clean acidity of the washed process of the syrupy-sweet flavor of the honey process, start paying attention to how coffee was processed and don’t be suprised if you start associating process with certain flavors in the cup.