We have talked about how to taste and talk about coffee. We’ve talked about coffee’s regional profiles. The third topic in our series on coffee flavor profiles is processing methods. The way that a coffee is processed can have just as much impact on the coffee’s flavor profile as its growing region. Some processing methods, when they are common, or specific to a particular growing region, even help to define the terroir of the coffee.
Before we start, it may be helpful to talk a little bit about coffee’s anatomy. First of all, coffee is not a bean. It is the seed of a fruit (often referred to as a “cherry”) that grows on a short, bushy tree. The cherry has a thick skin covering a thin layer of sticky fruit that we refer to as “mucilage." The mucilage generally covers two seeds that you would recognize as coffee beans - they fit together with the flat parts touching, like a brain. They also have a protective hull that remains intact until the final stages of processing. We call this the “parchment.”
With those terms in our arsenal, we can begin to talk about how coffee is processed after the cherries have been harvested, and how different methods affect flavor. There are three primary ways to process coffee - most other methods can be considered variations.
The most common type of processing in the world of specialty coffee is known as the “washed” process. This process is practiced all over the world, and when done well, is regarded as the most invisible processing method, allowing the coffee seeds’ inherent traits to be present in the cup. Using this method, very little flavor is imparted to the coffee by the processing itself.
The washed process begins with the coffee cherry, which is sent through a pulping machine as soon after picking as possible. The pulping machine removes the skin, exposing the fruit underneath. The seeds are then soaked in water and fermented anywhere from a few hours to a few days, depending on the climate, in order to dissolve the mucilage. After fermentation, the coffee is rinsed again to remove any residual fruit, dried on patios or in raised beds to a moisture level of between 10 - 12%, and then hulled to remove the parchment.
Coffees that have been washed have a higher acidity than coffees produced using other methods, and are often lighter in body. While they may have fruit notes in their profile, they lack the heavy, “fruity” flavors of fermentation that are commonly created with the Natural and Pulped-Natural processing methods.
The "natural" process is the O.G. coffee processing method, originating in Ethiopia with the coffee itself. This method has remained popular in dry areas with plenty of sunlight, and inconsistent access to clean water. It is considered to be less reliable than the washed process, and its unpredictable and uncontrolled fermentation can lead to both exciting surprises and horrific mistakes.
The natural process is very low-tech. With this method, the coffee cherries are simply picked and laid out to dry on patios, raised beds, or mats. Once the fruit is completely dry, it is simply hulled away (and sometimes made into a tasty tea called “cascara”), leaving only the seed. While this method requires very little equipment, and does not produce the water waste of the washed process, it does require very specific environmental conditions and strict attention. If either criteria is missing, results can be at best unpredictable, and at worst disgusting.
Because the coffee is dried in the cherry, its flavor is heavily influenced by the fruit itself - adding another dimension to the coffee’s terroir. Acidity in natural coffees is generally lower than that of washed coffees, and body is often heavier. When the process is executed well, the coffee bursts with fruit flavors, including blueberry, strawberry, raspberry, and melon. When the process is executed poorly (usually the result of excess moisture), the coffee can taste sour, rancid, sweaty, or rotten.
Somewhere in between the washed process and the natural process lies the “pulped-natural” process, sometimes poetically referred to as the “honey” process. While this method has always been popular in Brazil, honeys are experiencing a bit of a renaissance as specialty producers experiment with the different ways in which processing can create unique and interesting flavor profiles.
This process begins like the washed process - the coffee is sent through a pulping machine to remove the skin, exposing the fruit beneath. Then, rather than soaking in fermentation tanks, the coffee is laid out to dry as in the natural process, with the mucilage still clinging to the parchment. The amount of fruit left on can vary - a “yellow honey” leaves very little fruit attached, while a “black honey” leaves a great deal - but the principal remains the same. Once the coffee reaches 10 - 12% moisture, it is hulled normally.
Honey process coffees, predictably, have a flavor profile that lies somewhere between a washed coffee and a natural coffee. They lack both the sparkling acidity of washed coffees and the heavy fruit flavors of natural coffees. When executed well, the result is lightly fruity and well-rounded, with good structure and body. When executed poorly, honey process coffees have some of the same concerns as natural process coffees, and moisture needs to be carefully controlled in order to minimize off-flavors.
REMIX: The Wet-Hulled Process
We told you that there were only three main processing methods. Which is true. Sort of. The “wet-hulled” method is a process that is specific to coffees from Indonesia. While very little of the world’s coffee is processed in this way, wet-hulling has played a large role in defining Indonesia’s specific terroir.
You could think of the wet-hulled process as a variation on the honey process. The coffee cherry is pulped, then dried with the fruit still attached to the parchment. Here’s where it goes off the rails: instead of allowing the coffee to fully dry in the parchment, the coffee is hulled when the moisture content is still quite high - in the neighborhood of 30%. The bare seeds are then laid out again to fully dry on patios or mats. This is done to prevent mold and mildew in Indonesia’s hot, humid environment.
Wet-hulled coffees have some of the same qualities as honeys - with a heavier body and low acidity. As a result of the coffee’s high moisture content when it is hulled, the seeds tend to absorb some of the sensory qualities of the material on which they are dried. This contributes to the earthiness that often defines coffees from Indonesia. It is not uncommon to encounter coffees that taste - quite literally, and often pleasantly - like dirt.
So which process is best? We regard this question as a matter of personal preference, and you will find all four of these methods on our menu. Processing can add another dimension to the experience of a coffee’s terroir, or be employed creatively by farmers and mills to create unique flavor profiles! At Mocha Joe’s, we try to strike a balance between offering coffees that accurately reflect a coffee’s regional profile, and shaking things up with the occasional wildcard.