If you’ve ever purchased specialty coffee, you may have noticed that one of the key descriptors stamped on the bag is the processing method the beans went through to get them ready for consumption.
While this process may not seem overly important, it’s actually one of the most significant factors determining the quality and taste of your coffee. Even if everything else in the journey from seed to cup is done perfectly, incorrect or poor processing can destroy the quality of your final brew.
In this article, we explore what coffee processing is, the four main coffee processing methods in use today, and how these methods ultimately affect the taste of your morning cup.
Table of Contents
What Is Coffee Processing?
In its most basic form, coffee processing is the “process” of removing the seed (or coffee bean) from the coffee cherry.
As with all fruit, the coffee cherry has multiple layers:
- Skin: The protective outermost layer of the cherry, often referred to as the exocarp.
- Pulp: The thick, fruity layer just beneath the skin, also known as the mesocarp.
- Mucilage: The sticky, honey-like inner layer of pulp surrounding the bean.
- Parchment: A thin papery layer or hull, also known as the endocarp.
- Silverskin: A very thin, silver-colored protective layer, also known as the epidermis (this comes off during the roasting process and is known as chaff).
- Seed (Bean): The heart of the cherry, typically containing two seeds.
Each of these layers needs to be properly removed in order for the bean to be ready for roasting.
Proper processing is also essential when it comes to preventing spoilage, identifying defects, and developing the bean’s flavor and aroma. The specific method of processing can even have a major impact on the final price of the coffee.
Processing methods often vary from one coffee producing country to another. It’s also not uncommon for them to vary at the individual producer level as well. This variance is often influenced by factors such as climate, water availability, access to equipment and labor, and even the tradition of a producer’s respective growing region.
What Are the Different Coffee Processing Methods?
There are four main coffee processing methods in use today: natural, washed, wet-hulled, and honey. While all four are similar in their goal of removing the bean from the cherry and getting it ready to be roasted, the techniques each use can vary quite significantly.
Also known as the dry process, the natural method is one of the oldest and most traditional ways of processing coffee. This method involves drying the coffee cherry with the seed still inside.
Once picked, the coffee cherries are sorted by hand to remove the ones with defects and those that aren’t fully ripe. At the same time, they’re spread out in thin layers on drying beds to dry in the sun. These beds often consist of either brick patios or raised drying tables, the latter of which allows air to circulate better and leads to more even drying. While drying, the cherries are frequently raked or turned to avoid molding and rot.
The entire drying process can take anywhere from 3 to 6 weeks, depending on a variety of variables. During this time, sugars and mucilage latch onto the seeds, producing a bean with a much sweeter, fruitier flavor.
Once the cherries are fully dry, they’re run through a machine to remove the skin, pulp, and mucilage layers and then are stored and “rested” before being exported to a roaster.
The natural method is predominantly used in regions with limited water resources, such as Ethiopia and parts of Brazil.
The biggest criticism of the natural method revolves around its inconsistency in flavor. This often arises from the uneven drying and fermentation of the cherries, leading to a lack of uniformity in taste from one batch to another.
Additionally, the flavor profile of naturally processed coffees can be overpowering. They’re often characterized by their intense fruitiness, heavy body, and winey flavor. However, when processed correctly, they can produce a fantastic cup!
If you want to learn more about the natural method, check out this video:
Also known as the wet method, the washed method takes an entirely opposite approach to processing the coffee cherries. In this method, the skin, pulp, and mucilage are fully removed before the beans are dried.
After the cherries are picked, they go through a sorting process to identify defects and determine ripeness. This is done by placing the cherries in a tank of water. Those that sink to the bottom are kept, while the ones that float to the surface are skimmed off and discarded.
The cherries are then run through a depulping machine. Afterward, they’re placed in a water tank for 24 to 72 hours to ferment, allowing any remaining mucilage to break down.
After the beans are cleaned, they’re spread out on brick patios or drying tables to dry in the sun. As with the natural method, they’re raked regularly during this phase of the process to avoid any molding and rotting. Once the moisture content reaches roughly 11-12%, they’re then bagged and stored.
The washed method is most common in regions where water is more abundant, such as Colombia and numerous Central American countries.
Washed coffees tend to have a more consistent flavor profile that is cleaner and crisper than natural coffees. They’re often described as being more acidic and having white wine undertones.
While producers often prefer this method because of its ability to reduce defects, the two big knocks against it are that it’s more expensive and environmentally wasteful due to its heavy water usage.
If you want to learn more about the washed method, check out this video:
Also known as Giling Basah, the wet-hulled method is unique to Indonesia, where its high humidity makes traditional drying more challenging.
Like the washed method, coffee cherries are sorted and then mechanically depulped. However, instead of then being washed, they’re moved to a storage tank to ferment. Here, the remaining layer of mucilage begins to dry (but only partially) and forms a thick husk around the bean.
When the moisture content of the beans reaches approximately 30-35%, they’re taken through a hulling process to remove the husk and parchment layer. Once hulled, the beans are laid out to finish drying and then stored.
While the wet-hulled method is faster and more efficient than other coffee processing methods, the coffees it produces aren’t sweet or aromatic. Wet-hulled coffees tend to be less acidic and have a heavier body. They’re also characterized by flavors such as wood, spice, tobacco, and leather.
If you want to learn more about the wet-hulled method, check out this video:
Also referred to as the pulped natural method, the honey method is a unique hybrid of both the natural and washed methods. This method is especially popular in Costa Rica and other Central American countries.
Like the washed method, harvested cherries are placed in a water tank and sorted to identify defects and determine ripeness. They’re then run through a depulping machine. However, during this step, not all of the mucilage, or “honey,” is removed.
Depending on the desired flavor profile the producer is trying to achieve, depulping machines can be set to leave a specific amount of mucilage on the bean. The more mucilage, the sweeter and fruitier the final cup of coffee.
The honey method has evolved to feature several subcategories: black, red, yellow, and white. These categories indicate the amount of honey remaining on the beans, with black honey having the most and white the least.
Once depulped, the beans are laid out on patios or drying tables and dried in the same manner as the other two methods. After they’ve dried, the beans are then stored until they’re ready to be exported.
If done correctly, the honey method can produce a much more balanced cup in that it can offer more fruitiness than a washed coffee but be less wild and overpowering than a natural coffee.
If you want to learn more about the honey method, check out this video:
While there are four main coffee processing methods, and each has its own unique impact on a bean’s final flavor, there isn’t one method that’s better or worse than another. Like with different roast types and brewing methods, which is best ultimately comes down to personal preference.
Whether you’re looking to take your home barista skills to another level or just curious about the exciting world of coffee, make sure you check out our brewing guides and the coffee basics section of our website.
Frequently Asked Questions
A wet mill is simply a facility that’s used to process coffee regardless of the method. It can be as small as an individual farm serving a single producer all the way up to a large industrialized facility for processing massive amounts of coffee. While the name may seem to imply that water is a key component of the facility, that isn’t actually the case. The name is used to distinguish between the initial processing and the later stage when the coffee is hulled and graded.
Generally speaking, the washed method results in a higher price tag compared to the other three coffee processing methods. This is due to the fact that it requires more water, labor, and specialized equipment. On the flip side, the natural method requires significantly fewer resources, thus, is less expensive to produce. The wet-hulled and honey methods typically fall somewhere in between.
No, the processing method does not have a significant impact on the caffeine content of your coffee. The amount of caffeine in a cup of coffee is primarily determined by the bean type and variety, as well as your chosen brewing method and serving size.