A coffee bean's journey from farm to your cup involves many steps. There's more to making coffee than just growing coffee trees and roasting and grinding beans.
One very important step in the journey is the coffee processing. Various coffee processing methods can be used to arrive at the same goal: a dry green coffee bean ready for roasting.
While most coffee-producing countries still use the four more traditional coffee processing methods (washed, natural, wet-hulled, and honey process), more modern methods are also on the rise.
The processing method influences the coffee's flavor, aroma, and body. There's a noticeable difference between natural coffees, washed coffees, and coffees processed via wet hulling.
In this article, we introduce each coffee processing method to help you understand what happens to a coffee bean after ripe cherries are picked from coffee trees and before it turns into a cup of tasty brewed coffee.
What Are The Different Coffee Processing Methods?
Wet Process Coffee (Washed Process)
The wet process, or washed process, is a method that removes the skin and fruit flesh of coffee cherries before the actual bean is dried. This happens via “pulping” of the coffee cherries, which is a mechanical process.
After pulping, only some of the sweet, sticky layer around the bean remains. This is called "mucilage". The mucilage breaks down during fermentation, and sugars are absorbed into the bean.
After fermentation, the beans are washed. This removes the remaining mucilage completely. Depending on the country's climate, the processed beans are sun-dried in thin layers or mechanically dried (or a mix of both).
The wet process (washed process) produces wet-processed coffees with a bright acidity and a clean, crisp taste.
Dry Process Coffee (Natural Processed Coffee)
Dry processed coffees, also known as natural processed coffees, is quite different: During the natural process, the beans remain inside the fruit flesh and skin while they dry.
Dry processed beans are evenly laid out on drying beds, a raised bed, or patios to dry in the sun naturally. They are turned regularly to avoid uneven drying. During the natural process, beans absorb the flavors from the fruit as they shrivel.
Once the natural process coffee cherry is dried, the dry coffee cherries are hulled. This means the outer layers (fruit flesh and skin) are removed to unearth the precious bean.
Natural coffees usually have a fuller body, syrupy sweetness, a fruity acidity and fruity undertones. Natural processed coffees are a popular choice in regions with consistent sunlight and limited access to water. While not everyone loves natural processed coffee, you should try it at least once.
Pulped Natural Processing (Honey Process)
Costa Rica is the country that made honey-processed coffee famous (also known as pulped natural process). This method is a hybrid of wet and dry methods.
Like in the washed method, the honey-processed coffee fruits are put through a pulping machine, but much more mucilage is left on the bean - on purpose. The coffee seeds are dried on raised beds or drying tables with the mucilage still intact. Like during the dry processing method, this allows the absorbtion of the sweetness from the mucilage (but not the flavors from the whole fruit).
After the beans have been allowed to dry naturally, they are washed.
How much mucilage is left on the beans can vary from white honey (least mucilage) over yellow honey (the medium one) to red honey (more mucilage). Honey-processed coffees tend to have a lovely, subtle sweetness, enhanced body, and balanced acidity.
A special version is the black honey coffee, where ALL of the mucilage remains on the bean. This produces flavors of increased complexity compared to washed methods.
Semi-Washed Processing (Wet-Hulled / Giling Basah)
Semi-washed, or wet-hulled processing, is mainly used in regions with a humid climate and lots of rainfall. After all, drying coffee is difficult if it always rains! It's a bit different from the wet processing method even though the names both include "wet"!
During the semi-washed method, the outer skin and pulp are removed from the beans before allowing them to partially dry.
The beans are then hulled while still moist. This gives beans a distinct, bluish-green appearance instead of the green you're used to from other processing methods. Brewed coffees from this method are usually heavy-bodied with low acidity and earthy or spicy notes. It is commonly found in Indonesian coffees like Sumatra. In Indonesia, the process called hulling is known as Giling Basah.
New(ish) Coffee Processing Methods
Anaerobic
The anaerobic processing method involves oxygen deprivation during fermentation. Whole or de-pulped coffee cherries are put into a sealed, oxygen-free environment. After the coffee beans ferment, the cherries are pulped (if they hadn't been pulped before), and the coffee beans are washed. This removes any remaining mucilage.
After that, they are dried on drying beds or patios.
This method creates some rather unique and complex flavors popular in the specialty coffee market - but not everyone's cup of coffee. These coffees have a vibrant acidity, intense fruitiness, and a rich, syrupy body. It's a popular method for coffee beans that tend to be a bit bland when processed another way.
Carbonic Maceration
Carbonic maceration is a technique borrowed from winemaking and is gaining popularity in coffee processing. It's important to note that carbonic maceration is a specific type of anaerobic coffee processing, but not all anaerobic coffees follow the carbonic maceration approach. For this method, the coffee fruit is always left intact during the fermentation. The pulping and washing happen after fermentation.
Carbon dioxide is used to control the fermentation process. This results in very different flavor profiles depending on variables like pressure and duration. These coffees can include a bright acidity, floral notes, and a clean, crisp finish.
Wine Yeast Fermentation Coffee
Wine yeast fermentation is another experimental process heavily influenced by wine fermentation.
This is a DRY anaerobic method. The coffee seeds are extracted from the coffee cherry before being put into airtight tanks (or barrels). Coffee producers carefully add different types of fruit pulp and wine yeast to the tank to produce wild and exotic flavors over hours or days. The process is still fairly new, so there's a lot of experimenting going on. Yeast-fermented coffees often include fruity, floral, or wine-like notes - but there's a wild variety of options out there, so it's impossible to narrow the flavors down.
What Happens After Coffee Is Processed?
After the beans have been processed via different processing techniques, the next steps are the same, with only minor differences depending on the country.
Milling The Coffee Beans
After processing, coffee beans undergo milling. During milling, any remaining layers of parchment, husk, or mucilage are removed to fully “undress” the green coffee beans.
Grading Coffee
Coffee grading is classifying beans based on size, quality, and defects. Depending on the country and region, grading systems vary and can be intricate.
Generally, beans are put into different grade categories, like AA, A, or Specialty.
Specialty coffees, often the highest grade, represent the finest beans with unique flavors and characteristics.
Exporting The Green Beans
Once milled and graded, the green coffee beans are ready for export. They will be sent to coffee roasters worldwide. Of course, the beans will then continue their journey. They will be roasted, ground, and brewed.
Final Thoughts
A coffee bean's journey starts inside a cherry and ends in the final cup. Now you know the basics of various processing methods like natural processing, honey processing, wet-hulled coffee, and washed coffee.
Unfortunately, you will only rarely see this information about the processing method on the bags of coffee you buy from stores. If you love a certain coffee and would love to know whether the wet method or the dry process has been used so you can find similar coffees, you can try contacting the producer and ask them if they can share this information with you.
A good roaster will always be able to tell you - and will be happy to share the info about processing techniques.
