What is Coffee Processing?

The word “processing” often has a negative connotation in the world of food and beverage as it is often associated with chemicals and unnatural additives. However, coffee processing is a different story. Simply, coffee processing is the way in which the coffee seed (a.k.a. bean) is separated from the fruit and other layers (figure 1).

Figure 1: Sweet Maria’s Cross Section of the Arabica Coffee Cherry, Macro Photo by Thompson Owen.

Types of Processing

The types of processing can vary by growing region. Cultural tradition, water access, and the desire for a specific flavor profile can all be reasons a farmer or producer might choose a specific method; while there are many different methods and many more experiments being done to develop new ones, we will focus on 3 main ones.

Washed (Wet Process) | La Morena

A popular method found throughout the world, washed processing takes a much larger investment in resources and materials from the producers. It is this reason why not all farmers might be able to offer this for their coffees.

Figure 2: Coffee cherries being submerged in a tank as part of the washed process

The Process

Depulping - Once the cherries are picked/harvested and sorted, the fruit is then sent though a machine, often cranked by hand, that removes the “fruit/outer skin” and “mucilage” layers, leaving the “parchment” and “silver skin” layers.

Fermenting - After depulping, seeds are placed in a tank that is filled with water. The coffee is then left to sit anywhere from a few hours to days, depending on the level of fermentation the farmer is trying to achieve. It is here where the naturally occurring microbes from the environment help break down the remaining layers surrounding the seed.

Washing - After the set time, the coffee is then rinsed and washed using more water, sent flowing down different channels, being sorted by density as they go. The denser beans are separated and considered to be more nutrient rich, resulting in a higher grade. This process is mainly done at a centralized station called a wet mill or washing station.

Drying - Once depulped, fermented, and washed, the coffee is set out, usually on massive tarps, to dry in the sun.

Other Steps - While the previous steps are the most common, there are others that can be added depending on what the farmer/producer is trying to achieve. Some producers might send their cherries through a whole flotation step that allows them to separate ripe cherries from unripe cherries. This extra step, while more costly, helps them ensure quality, hopefully yielding a higher cup score and quality. A post-fermentation soak can also be added and is often noted by a “double-washed” or “triple-washed” notation.

Flavor Profile

Washed coffees are often considered to have a “cleaner” taste that allows individuals to taste the unique characteristics of the growing region, terroir (the natural environment, consisting of such elements as topography, climate, or soil), and cherry variety.

Natural (Dry-Process) | Cerrado

Probably one of the earliest and least intensive forms of coffee processing, the natural processing of coffees means that the coffee cherries are picked and left to dry in the sun. The simplicity of this method is the reason behind its accessibility and common use among many smallholder farmers.

The Process

Ripe cherries are picked, sorted, and placed on raised beds, patios, or tarps. The cherries are then left out for days to dry in the sun where they dry up and shrink. It is this process that allows the natural microbes and sugars from the fruit to impact the seed. To prevent spoilage, the cherries are rotated regularly and once dried are taken to a dry mill where the fruit and seed can be separated.

Figure 3: Coffee cherries being dried in the sun.

Flavor Profile

In my experience, it’s the natural coffees that open people’s eyes to what makes specialty coffee different. While not everyone’s cup of tea, the bigger body, fruity notes, and sometimes floral notes can be a huge eyeopener.

Honey (Pulped Natural & Semi-Washed) | La Gionconda

Unfortunately, honey processed coffees aren’t as straightforward as their washed and natural counterparts. The best way to describe them is as a mixed method that carries components of both processes.

Figure 4: Comparison of 3 common processing methods based on the level of material left on the coffee seed, Photo credit Savaya Coffee Market

The Process

There are varying levels of honey processing, and the terminology can differ from producer to producer. In honey processed coffee, parts of the coffee fruit/cherry are left on the seed during the drying phase. Once dry, the fruit is then removed. Names like black honey, red honey, yellow honey, and white honey are used to differentiate the varying levels of fruit left on the seed with black being the most fruit left on the seed and white being the least (figure 4).

Flavor Profile

As one might expect, honey processed coffees carry notes reminiscent of both washed and naturally processed coffees. Depending on the level of honey processed, coffees can taste fruity, clean, and floral, with varying degrees of body.