After being hand-picked from the rows of shade grown coffee shrubs lining the steep hill sides of a coffee farm, the coffee cherry must undergo a process to remove the beans from the fruit. This is called the processing method and is often found on labels of specialty coffee worldwide. While the idea seems simple, the processing method used has a dramatic impact on the taste, aroma, and quality of your specialty coffee.
In this article, we're going to explore the fascinating world of coffee processing methods. We'll cover three main methods - natural, washed, and honey, as well as venture into some experimental methods that are pushing the boundaries of flavor. Each method is unique, shaping the beans' characteristics and setting the stage for the flavors you experience in your cup.
The coffee bean begins as the pale green seed of a fruit called the coffee cherry. The coffee cherry grows on the Coffea plant, a leafy green shrub (often called a coffee tree) growing as tall as 20 feet high. It takes up to four years before the Coffea plant can bear fruit, at which point rows of coffee cherries grow amongst the large shiny green leaves. The shrubs are often maintained at under half their potential height to allow for the hand picking of the cherries. Once the coffee cherries reach a ripe color of red, they are hand-picked and prepared for processing. Coffee cherries generally contain 2 beans. When a coffee cherry contains a single bean, it is referred to as a peaberry.
Different varieties of coffee plants impart different flavors to these cherries and the beans within them. Other growth factors that contribute to the flavor of the specialty coffee bean include geography, climate, and soil. Taken together, these factors create the coffee’s terroir, or conditions that contribute to a specialty coffee’s aroma and flavor.
Once a specialty coffee is grown and picked, the beans must be removed from the fruit. This is called the processing method. Historically, the processing method was dictated by culture and water accessibility. In dry regions, natural processing was primarily used while in wet regions, washed was most common. This resulted in a high predictability of regional coffee flavors. However, as research, investment, and interest have increased in specialty coffee, processing methods are being used to modulate the flavor and aroma of the beans beyond the traditional terroir, leading to an even greater variety of flavors throughout the world.
Natural processing involves drying the freshly harvested coffee cherries under the sun, with the beans enclosed within the fruit. This method allows the beans to soak up the inherent fruitiness of the cherry, similar to marination. Natural processing can produce specialty coffee with a bold, fruity flavor and a heavier body. It is commonly practiced in countries with abundant sunlight like Ethiopia and Brazil.
Washed processing involves removing the fruity pulp and skin of the cherry before drying the beans. This stripping process results in a specialty coffee flavor that is crisp and bright. Regions with plentiful water resources, such as Colombia and Costa Rica, have historically adopted this method.
Honey or pulped natural processing falls in between natural and washed methods. In this technique, some of the mucilage, a sweet, sticky substance that encases the bean, is retained during the drying process while removing the skin of the cherry. The resulting specialty coffee can feature prominent sweetness and a fuller body.
Over the last several decades, investment and research have greatly shifted the specialty coffee production landscape. Experimental changes to processing methods by adding additional steps have created exciting flavors previously absent from specialty coffee.
Carbonic Maceration is a process borrowed from the wine industry, particularly used in France. In this method, the coffee cherries are put in sealed, oxygen-free tanks and infused with carbon dioxide to prevent the growth of bacteria and promote the production of lactic acid. The coffee is then processed and dried like natural or washed coffees. This method enhances the fermentation process and leads to a unique profile with heightened fruit flavors and amplified acidity.
This innovative processing method involves soaking the coffee cherries in a sugar solution, causing the water inside the cherries to flow out due to osmosis, replaced by the solution itself. The resulting specialty coffee bean can feature intensely sweet and fruity flavors. The sugar solutions used in the osmotic dehydration process can vary greatly, often including fruit juices. These juices impart their flavors on the resulting cup of coffee.
Anaerobic Fermentation is where specialty coffee cherries are deprived of oxygen and allowed to ferment. This is usually accomplished by sealing the coffee cherries in airtight containers and purging them of oxygen with a gas like nitrogen. This creates an oxygen free environment where certain microbes thrive, greatly altering the flavor profile of the specialty coffee. Anaerobic fermentation takes 24 - 48 hours, at which point the coffee is processed and dried like a natural or washed coffee.
When you next visit the grocery store or coffee roastery, look at the packaging and note the processing method used. Also note the flavor profile listed. The flavor profile is the subtle flavors natural and inherent to the specialty coffee bean. Generally, natural coffees host fruitier flavors while washed coffees exhibit brighter, floral flavors. Experimental processing methods will commonly show different or uncommon flavors. As you try different beans, keep track of what you enjoy so you can easily identify similar specialty coffees in the future.
At the end of the day, the best coffee is the one you like the most. Coffee is a subjective experience, one unique to everyone. By tracking the processing methods and flavors present in the specialty coffees you try, you can easily identify the types of coffee you enjoy.
Nathan Jones is the owner of Canyon Coffee Roasters in Lincoln, Nebraska. He has extensive experience (10+ years) in the specialty coffee industry, both as a roasting professional and barista. Nate’s love of coffee, people, and community inspire him to share his knowledge with others with the aim of demystifying the rapidly expanding world of specialty coffee and create meaningful relationships along the way. Nate’s favorite way of drinking coffee is either as a latte or from his Moccamaster, shared with his wife Kate. Nate enjoys spending time with his friends and family when he’s not posted up at the roaster.