Calling coffee lovers everywhere! At some point, I'm sure you've wondered about coffee processing. That intricate journey that transforms the humble coffee cherry into a delicious, rich, dark and aromatic brew.
Calling coffee lovers everywhere! At some point, I’m sure you’ve wondered about coffee processing. That intricate journey that transforms the humble coffee cherry into a delicious, rich, dark and aromatic brew.
Thing is, processing coffee isn’t a one-size-fits-all affair. Different growing regions worldwide use different processing methods for reasons I’ll reveal later in this guide.
Join me as I spill the beans (pun fully intended) on the processes that makes every cup of coffee a flavor adventure. Each processing method is as varied and unique as the various beans themselves.
What Is Coffee Processing?
Growing coffee is no walk in the park. Many Coffee Belt countries are in the developing world. Right off the bat, farmers face many challenges, including irregular rains, cultivation costs, pests and diseases. Thus, they put tons of effort and resources into ensuring a quality harvest.
But even more challenging is coffee processing. While a farmer may put their best foot forward in growing and harvesting coffee, it’ll all amount to nothing if they process coffee incorrectly.
Why is this the case? The answer lies in poorly processed coffees. A poor process negatively impacts the aroma, flavor and quality of the final cup. In short, choosing the right processing method leads to higher-quality coffee beans.
Ultimately, it protects a coffee harvest’s value and enhances profitability.
So, with that said, what is coffee processing exactly?
Processing coffee involves a series of techniques that transform harvested coffee cherries into green coffee beans. These techniques involve removing the coffee cherry’s skin, pulp, mucilage and parchment to reveal the beans inside.
These beans then go through a series of washing, fermentation or drying processes that produce ready-to-sell (or roast) green coffee beans.
Coffee Processing: The 3 Most Popular Methods
Coffee grows in many different regions around the world. It makes sense that the processing methods that prepare it for the market also differ.
Which processing method a producer chooses for their Arabica or Robusta coffee depends on various local factors.
Environmental and climatic conditions, time availability, costs and access to resources are some of the most important factors determining processing methods.
As do the characteristics and different flavors a producer wants in the resulting coffee.
However, most ripe cherries go through one of three common coffee processing methods. Each of these main processing methods heavily influences the beans’ final flavor, acidity and finish.
Let’s get right into it!
Washed Process Coffee
The washed process (wet processing) involves removing the outer layer of the ripe coffee fruit (coffee cherry), followed by washing and drying the coffee seeds within. This wet method uses a machine called a de-pulper to remove the cherry’s skin and pulp.
A fermentation process follows de-pulping. Coffee beans soak in large fresh water tanks for 18-24 hours. This removes the thin layers of sticky, sugary membrane surrounding the beans (mucilage).
Next, to stop the fermentation process, wet-processed coffee is thoroughly rinsed. Farmers pass the beans through concrete gravity channels to remove low-grade beans, which float to the top. Gone, too, during this process are any traces of fruit remnants from the coffee cherry.
Farmers then spread the beans on raised beds, sun-drying them for an average of 8-15 days until they achieve a 10-12 percent moisture content. As the coffee dries, it’s hand-turned regularly to prevent fermentation spoiling or mold contamination.
Most Kenyan, Tanzanian Peaberry and Rwandan producers favor this processing method. Still, although the washed method is efficient, it can be dreadfully wasteful.
Washed methods also have the disadvantage of being super expensive. They need a lot of water to be effective and a significant infrastructure investment in the construction of washing stations.
Unfortunately, these washing stations may harm the environment. The wet process generates lots of effluent and solid waste. However, introducing intentional recycling efforts at these coffee processing stations could help cut pollution.
Washed coffees have a clean and crisp flavor profile. They are also higher in acidity than natural processed coffee. Unlike natural coffees, the washed process removes sugars in the fruit flesh and mucilage, causing the final cup’s brightness to shine.
Natural Process Coffee
Natural processing or dry processing involves drying the whole fruit – skin, pulp, beans and all. Farmers place the cherries on concrete patios, drying tables or raised beds for 3-6 weeks until they reach 10-12 percent humidity.
During this process, the drying cherry ferments. The mucilage and sugars in the dried fruit flesh stick to the beans. As a result, dry-processed coffees are intense and sweet compared to wet-processed coffees.
One criticism of the dry process is possible inconsistencies in flavor that can lower cup quality. That said, drying only ripe cherries and ensuring regular hand-turning prevents this defect. Once the cherries are sufficiently sun-dried, a de-pulper machine separates the dried fruit flesh from the coffee beans.
Native to Ethiopia, this coffee processing method is more sustainable and affordable than the wet process. There’s a reduced need for ground water to separate the bean from its cherry, which is perfect for more arid regions. This process also requires less machinery, infrastructure and labor and is, thus, more profitable.
Processing coffee using dry processing techniques means that the beans ferment in the coffee cherry for longer. As a result, the natural sugars develop in and around the coffee bean, infusing dry-processed coffees with lots of sweetness.
Natural-processed coffees are full-bodied with complex fruity flavor profiles. They also display lower acidity than washed coffee, along with complex berry-like notes in the final cup.
An even sweeter version of natural-processed coffee is wine-processed coffee. Farmers leave the cherries to over-ripen on coffee trees (like wine grapes) before they process coffee naturally. This imparts the cherries with a higher sugar content, resulting in a “cooked fruit” flavor that comes through in the brewed coffee.
On your next shopping trip, look out for these dry-processed coffees and give them a try! Hawaii Kona, Colombia Finca Las Flores and Ethiopian Sidamo are excellent examples.
Honey Process Coffee
Honey or pulped-natural processing originated in Costa Rica. It’s a unique coffee processing technique combining washed and dry methods. As you’d imagine, combining the two processes is quite demanding and less common than the above methods.
The coffee cherries are de-pulped during honey processing to reveal the inner coffee beans. Next (this is where this method differs from the washed process), the coffee beans dry on raised beds or concrete slabs. Farmers keep the mucilage (the “honey” in this process) on the beans as they dry.
The honey process can take 6-8 days to ensure the beans reach 11 percent humidity. Constant turning prevents them from spoiling and destructive mold contamination.
Honey-processed coffee has a unique complexity of flavor and beautifully balanced acidity. The natural process produces coffee beans with varying intensity.
This intensity will depend on how much sunlight the beans get and the total drying time. Black honey coffee results from a slower development time and a more prolonged exposure to high humidity. Less humidity and shorter drying times result in red honey- and yellow honey-processed coffees.
As we’ve seen, honey processing incorporates elements of the dry and washed method. Because of this, the resulting coffees have an incredible complexity and depth of flavor.
Honey-processed coffee is full-bodied and sweet thanks to its mucilage. Due to de-pulping, this coffee also displays a clean, crisp flavor profile like washed coffees, but with a mellow acidity.
Costa Rica and other Central American countries primarily process coffee this way. Some gems to look out for in the market include Costa Rica Las Lajas Black and Red Honeys and Guatemala Santa Felisa Honey.
Other Coffee Processing Methods
The coffee industry is constantly evolving. Innovative coffee growers have been experimenting with brand-new processing techniques for years. Seriously, the innovation is endless! Fermenting coffee in low oxygen conditions or with citrus fruits to impart unique flavors are some of the more intriguing methods.
Science-based coffee processing methods are also on the rise.
One such method is puffing as an alternative to coffee roasting. It uses heat and pressure to cause physico-chemical changes in the green coffee bean. As a result, these coffees’ antioxidant capacity and extract yields are high.
These novel processes result in rare and exotic flavor profiles that are hard to replicate.
Today, I’ll examine three new processing methods currently making waves in the industry.
Anaerobic Fermentation
Anaerobic fermentation is a new coffee processing technique, adopted in Brazil from French winemakers. Coffee beans ferment in oxygen-free tanks for up to 100 hours, developing a unique winey flavor profile.
To begin, coffee farmers put whole fruit or de-pulped coffee cherries with their mucilage through this processing technique. Once fermentation is complete, they put the beans through one of three drying processes. This yields anaerobic washed, natural (dry-processed) or honey (in-mucilage) coffees.
Coffee processed this way is deliciously fruity and fragrant. The long fermentation times – ranging from hours to a week – give the bacteria and yeast enough time to work on the beans. The result is a novel brew with distinct winey notes.
Ethiopia Guji Messina is an excellent example of this coffee. It has bright, crisp, clean notes that set it apart from nearby dry-processed Sidamo and Yirgacheffe coffees. Brazil Ipanema Anaerobic – Premier Cru is another fine example.
Carbonic Maceration
Carbonic maceration is a coffee processing technique much like anaerobic fermentation. It borrows from the French Beaujolais wine industry. Wine fermentation breaks down the grape and its juice. In contrast, coffee fermentation breaks down the seeds (coffee beans).
In this process, whole cherries soak in sealed containers to ferment with the coffee beans inside. Carbon dioxide is then pumped into these containers to create an oxygen-poor environment. These conditions lessen the oxidation of the fruit and seed tissues, making for an intensely flavored coffee.
Variables like fermentation time and temperature affect the final cup. Carbonic maceration coffees show intense and aromatic flavor profiles. They’re also sweet, juicy, winey, chocolaty and fruit-forward. I guess you could call these coffees the “wines of the coffee world.”
Needless to say, producers that choose this method need to be on top of their game. It comes with the risk of producing dry coffees, high in bitterness. Hawaii Kona Geisha and Ethiopia Jabanto are some specialty coffees produced using this method.
Wet Hulling
Wet-hulled or semi-washed coffee processing is unique to the Indonesian island of Sumatra. It’s like the wet processing method but with distinct differences. As with the washed method, a de-pulping machine removes the skin and pulp of coffee cherries to reveal the coffee beans within.
Next, the coffee beans soak in huge plastic water tanks overnight with their mucilage layer still intact. This process preserves moisture in the beans as the mucilage develops into a solid husk that covers the beans as they ferment.
In the morning, farmers remove the husk and the coffee bean’s parchment layer. They then dry the beans on drying tables for only a few hours, achieving a 50 percent moisture level. In contrast, washed and dry coffees dry for weeks to achieve the desired 10-12 percent humidity.
As I mentioned, this coffee processing method is popular in Sumatra, Indonesia. Due to the high humidity, farmers find it challenging to dry coffee beans in open air. This process works well as it requires minimal drying.
When the coffee achieves a 25-35 percent moisture content, the beans pass through a wet mill that removes the parchment to ease air drying. After hulling, the coffee air-dries until it reaches 12 percent humidity.
Wet-hulled Sumatran coffees are one-of-a-kind. These coffees are rich, earthy, chocolaty and nutty, with a unique acidity and sweetness you won’t find anywhere else. In the specialty coffee scene, javaphiles appreciate Sumatran coffee blends for these qualities.
What Happens After Coffee Is Processed? The Final Stretch to Market
After processing, most coffee beans will still have their parchment layer. Coffee producers store these green coffee beans in dry warehouses. The moisture levels in coffee beans are low enough at this point to prevent further fermentation or rotting. Coffee rests in these warehouses for 60-90 days on average.
When the beans are ready for export, coffee producers will run them through adry mill in a process known as dry hulling. This process removes the yellow outer parchment from the coffee beans.
After hulling, green coffee experts grade the coffee bean for size and quality. Warehouse workers then pack these sorted beans in 130-pound (60-kilogram) jute bags to get them ready for transport. The coffee is now ready for export, or sold on to roasteries for coffee roasting.
Coffee processing is a science, an art and an example of human ingenuity all in one. Without these processing techniques (which began as a happy accident with some Ethiopian monks over a millennium ago), we would never have enjoyed this magical brew.
As a coffee lover – industry expert or not – it pays to learn about these various processing methods. Ultimately, this knowledge is asecret weapon in your quest for the perfect cup of joe!
Did some of these coffee processing methods surprise you? I’d love to hear your views in our community section below. You’re welcome to check out our blog on the diverse origins of coffee beans to understand this topic better!
