Want to learn more about coffee processing methods? You're in the right place.
We've gathered information on four methods of processing coffee berries.
The best part?
You will learn how each of these methods determines the flavor of a cup of coffee.
Let's dive in.
Why Process Coffee Beans?
Coffee cherries must be properly processed to produce quality coffee beans. Processing is done immediately after harvest.
There are four main coffee processing methods: natural (dry), washed (wet), wet-hulled, and honey. We'll look at each method in more detail below.
There are also subtypes of these four methods, but most are experimental.
Before we describe processing methods, it will be useful to know the structure of the coffee berry.
Coffee cherries have layers that sit on top of the coffee beans. Processing methods remove these layers and leave only the coffee beans.
Natural Processing Method
This is the most ancient way of processing coffee. It's traditionally used for large-scale coffee production due to its low cost.
Green coffee cherries are dried in the sun on brick patios or African beds. African beds are special tables with mesh.
The coffee beans remain inside the berry until the outer skin (layer 1) is completely dry. During this process, the pulp and pectin layers are gradually removed.
After that, only the parchment (layer 4) remains. This is also eventually removed.
The berry can take several weeks to dry. During this time, the coffee beans absorb all the sugars from the pulp. This gives the beans a very rich set of chemical compounds.
When beans are processed with the natural method, the brewed coffee turns out sweeter in aroma and richer in taste.
When done correctly—and the beans are regularly turned—natural processing can give coffee a unique taste with hints of strawberry, mango, and blueberry in the aftertaste.
The brewed coffee will have an unusual flavor profile and a distinctly sweet taste. But, for each variety, these descriptors can be expressed in different ways.
This process is easy to use over a large area and is ideal for countries with limited water resources. Natural coffee processing is mainly used in Brazil and in Ethiopia and other African countries.
Washed Processing Method
Washed processing, also called wet processing, is one of the cleanest methods.
Before the coffee berries are put in water, their outer skin is removed.
The coffee beans are then placed in water to naturally ferment. This removes any remaining layers that surround the bean.
Bacteria, yeast, and other microorganisms destroy the pulp (layer 2) and pectin (layer 3).
After that, the beans are washed again and then dried.
The beans are dried for about 10-22 days, during which they are regularly turned over. This slow drying is optimal for balanced coffee.
The washed process is used in water-rich countries such as those in Central and South America.
This method is believed to best reveal the true character of coffee varieties, which is why most specialty coffees are processed this way. It is also known for giving coffee beans characteristic light aromas.
Wet-Hulled Processing Method
This method is similar to washed processing. As with the washed method, the coffee berry is stripped of its outer skin (layer 1) and then placed in water for fermentation.
The difference from the washed processing method is that the coffee berries are not rinsed again. In this case, the pulp (layer 2) and pectin (layer 3) remain on the bean.
The berries are then washed to remove layers 2 and 3, which have both turned into a pulpy substance. The berries are then dried until they reach a certain low moisture content approved by the farmer.
Only then can the berries be sent to hulling, a peeling process in which the parchment (layer 4) is removed.
The wet-hulled method is mainly used in Indonesian countries where water is abundant but not of the best quality.
When processed in this manner, coffee beans tend to contain darker, almost earthy notes.
Honey Processing Method
This method first removes the pulp from the coffee cherry. The pulp can be removed in whole or in part. The pectin layer remains.
Then the coffee berries are dried, during which time the fermentation process also takes place. The pectin layer is eaten by bacteria and takes on a honey color and viscous texture, giving the processing method its name.
This method was invented by Brazilians but has been adopted by many farmers around the world.
This process can also be divided into subtypes depending on the amount of pulp removed. Each is named based on the percentage of pulp left on the berry before drying.
Yellow honey is the first subtype. With this method, 25-50% of the pulp remains on the berry. The coffee cherries are turned over every hour to ensure even drying.
The second subtype is red honey. 50-75% of the pulp remains on the berries and they're turned several times a day.
Black honey is the third subtype. 75-100% of the pulp remains on the berries and they are turned over only once a day.
With the honey processing method, coffee producers save money and resources, as with the natural method, but the processing time is quite quick, as with the wet method. As a result, the coffee will have a denser body than washed coffee but a cleaner and fresher taste than naturally processed coffee.
How Do Producers Decide Which Process to Use?
Each of these methods can be used to make a great cup of coffee.
But they are used in different areas based on weather, farmer and processer skill, and more variables.
Most often, the processing method is chosen to match weather conditions.
If the climate is dry and hot, then coffee beans can be processed naturally. This method is also used because of its low cost or where water is limited, for example in Ethiopia and Yemen.
The rest of the processing methods are used more often in humid climates. They allow the beans to dry faster and thus prevent spoilage of the crop.