What makes coffee taste how it does? The answer is almost always, “It’s complicated.”
There are countless variables that impact the characteristics a coffee bean expresses: The coffee plant’s botanical genetics are at play, as well as the terroir where it’s planted, the ripeness of the picked coffee cherry, the roasting style and quality, and, of course, the final brewing.
We happen to think that post-harvest processing is one of the biggest determining factors of a coffee’s profile and characteristics. Of course, as with everything else in coffee, not only the methodologies but also the terms and results will vary from place to place—even from farm to farm between neighbors.
Coffee is processed differently throughout the world, sometimes due to tradition, or as the result of experimentation and intentional design. Producers globally explore and tweak their processing methods every day: The results can be astounding or appalling, such is the nature of experimentation.
There are several major categories of coffee processing that are generally recognized in the coffee industry. These are called by different terms depending on what country you are in or what language you are speaking, but the basic elements and steps are generally similar or at least recognizable.
Additionally, we tend to interchangeably use the terms “fermentation” and “processing,” just like we swap the terms “altitude” and “elevation.” They are related, but they are not equivalent: There is fermentation happening during processing, but not all processing is fermentation. Below, we briefly describe and explain not only the bullet points of the processing methods themselves but also touch briefly on the role that fermentation plays in each.
Washed Process (aka Wet Process)
Fruit Removal: Typically depulped (skin removed) or demucilaged (skin and pulp removed) within 24 hours of harvest Fermentation: Depulped coffees are typically held in “fermentation tanks” for 12–72 hours; demucilaged coffees are not commonly held in tanks but moved to drying surfaces or equipment. Fermentation may occur from the moment of harvest until the seeds reach an inhospitable moisture content for them (11% moisture) Drying Time: On average, 18–36 hours mechanically; 7–15 days on patios, raised beds, or in parabolic dryers Profile: Clean, articulate flavors; caramel or sugary sweetness; a wide spectrum of fruit acidity depending on other factors; capable of bright, crisp notes
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, moisture, acids, etc); the seeds typically become inhospitable to microorganisms when they reach 11% moisture Drying Time: Up to 30 days on average, 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
Fruit Removal: Fruit skin is removed within 24 hours of harvest; all or some of the mucilage is left to dry on the seeds Fermentation: Occurs throughout the drying process (until seeds reach a moisture content of 11%) Drying Time: 18–25 days on average Profile: Can express some fruity/pulpy/jammy flavors or stewed-fruit-like characteristics; caramel or burnt-sugar sweetness; nuttiness
Coffees of any process (Washed, Natural, Honey, etc) can also be processed for decaffeination. The decaffeination itself takes place after the coffee has been harvested, processed, and had its parchment layer removed; most of the time, coffees need to be sent to specific facilities to be decaffeinated, rather than having the caffeine removed at the mill level. At present, there is no such thing as a genetically decaffeinated coffee, which means that decaf coffee needs to be created by physically removing the caffeine from green coffee seeds. Most of today’s decaf processing methods are sophisticated and thorough and can remove 99 percent of the caffeine naturally present in coffee.