Trust the (coffee) process.

You may not realise but coffee is a small cherry that normally house two coffee seeds (the beans). There is no major commercial use for the coffee cherry so producers must choose how to remove it from the desired seeds. This process can dramatically impact the flavour and character of the resulting coffee. Each producing region has its unique processing styles but as a general rule, there are three main processes used to make specialty arabica coffee — washed, natural and honey. 

Washed 

Fruit Removal: Typically within 24 hours of harvest with a mechanical de-pulper or de-mucilager.

Fermentation: De-pulped coffees can be held in fermentation tanks for 12–72 hours; de-mucilaged coffees are not usually held in tanks but moved to drying surfaces or equipment.

Drying Time: 18–36 hours mechanically; 7–15 days on patios, raised beds, or in parabolic dryers.

Profile: Clean, articulate flavours; caramel or sugary sweetness; wide spectrum of fruit acidity depending on other factors; capable of bright, crisp notes.

The quickest, and arguably, most efficient of the post-harvest processing methods is often called the Washed or Wet process, though it doesn’t always require water. It’s the primary method for preparing specialty-quality coffee in most of Africa, Central and South America (except Brazil), and select parts of the Asia-Pacific growing region.

The exact method producers will use varies depending on the place, tradition, climate and access to fresh water, but ‘washed’ typically means the coffee fruit has been removed from the coffee seed as quickly and cleanly as possible.

Fermentation begins the moment microorganisms such as yeast and bacteria begin metabolising sugars - fructose and sucrose - in and around the coffee seeds. This could occur as early as the time of picking, when the fruit and stem are separated and a small hole is typically created in the coffee cherry. Fermentation can take place in Washed coffees as long as there is either fruit material (mucilage) and/or a certain amount of water (11 percent moisture or greater) available as a fuel source.

In the coffee industry we describe the length of fermentation as the period in which coffee is piled in tanks or held underwater, with the goal of either accelerating or retarding the ability and access that microorganisms have to the fruit material. Open or dry fermentation are used to describe coffees that are de-pulped (have their skin removed) and placed in open-air tanks or buckets and allowed to sit in their mucilage, typically for 24 hours or less though occasionally for as long as 72 hours. ‘Underwater’ or ‘wet’ fermentation can take longer, depending on the climate, water quality, and activated populations of microorganisms.

Natural 

Fruit Removal: This is done after drying, and before being packed for export.

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, water, acids).

Drying Time: This process can take up to thirty days, weather permitting

Profile: Noticeably fruity or “boozy” flavours; can also have strong nutty and/or chocolate characteristics, and typically has a heavier or syrupy body.

Natural or ‘dry’ process coffees are the opposite to washed, the fruit is picked when ripe and allowed to dry completely around the seed before being husked or hulled off. Historically hulling was done by hand with a mortar-and-pestle, today it’s largely done by machine. Natural process coffees are most commonly found in Ethiopia, Yemen, Brazil, and Costa Rica, though producers around the world are also experimenting with this methodology. Zukuka Bora Coffee Company has recently been experimenting with the first naturally processed specialty Arabica to come out of Uganda, with exciting results. 

Fermentation occurs during the processing, from the moment the coffee is picked — possibly earlier. Local or intentional populations of yeast and bacteria will enter the fruit and begin to metabolise the sugars and acids inside the coffee fruit, a process that can continue until the coffee is dried. While the coffee itself is not held in fermentation tanks, its fermentation process is altered and can be dictated by things like temperature, exposure to sun or shade, depth of the drying bed and rotation of the coffee during drying.

Drying natural coffees is a considerably longer and riskier process than Washed coffee. Naturals take up more space, require more attention and labour, and are at a higher risk of spoilage or ‘over-fermentation’, as the fruit material that’s intact provides a long-term and concentrated fuel source for yeast and bacteria to metabolise. Natural processing is the oldest technique for preparing coffee, and in ancient times – as well as some cultures today – the fruit was allowed to dry completely while still on the branch and harvested only when needed. Modern Natural coffees are harvested ripe and intentionally dried, typically on patios, raised beds, or drying tables.

Honey

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, with the skin of the cherry removed to produce similar characteristics to Natural processed coffee.

Drying Time: Drying is anywhere from 18–25 days, and has less risk of spoilage than the Natural process.

Profile: Can express some fruity/boozy/jammy flavours or stewed-fruit-like characteristics; caramel or burnt-sugar sweetness; nuttiness.

Honey processing has emerged relatively recently as a processing style favoured by specialty coffee producers across the globe, and no, no actual honey is involved! This process is identical to the traditionally Brazilian method of processing coffee known as Pulped Natural. 

The skin of the coffee cherry is removed, and the seed allowed to dry with some or all of its sticky fruit mucilage intact. This process retains some of the desirable characteristics of a full Natural coffee (heavy body, sweet fruitiness with lower acidity, deep chocolate notes) while speeding up the drying process, and reducing some of the risk of spoilage, mould, and other defects that can occur with Natural processing.

Honey process varies greatly, depending on the amount of mucilage removed from seed. Yellow Honey removes the highest amount of mucilage leading to milder characteristics, Red Honey sits in the middle, and Black Honey leaves the majority of the mucilage intact leading to a character closest to a fully Natural coffee. 

The most obvious benefit to the Honey process over full Naturals is the speed and efficiency of the drying process and the control over various flavour characteristics. But the exposed fruit material can also create more risk for the producers, as it requires more work to prevent taints from developing. 

Often these coffees may also have an uneven or inconsistent appearance in their green forms, which can be unappealing for roasters who are used to the more uniform Washed coffee.

Commonfolk would like to thank Cafe Imports for collaborating on this article. Cafe Imports are one of the world’s premier specialty coffee importers; they share Commonfolk’s passion for great coffee through education and example. For more head to www.cafeimports.com