There are many different ways to process coffee once the cherries have been harvested. But to understand this particular processing method, one must understand the coffee cherry.
Just like any fruit, coffee cherries contain a few different parts:
• Skin/Pulp – a cherry-like outer skin or flesh; this layer is removed soon after harvesting unless using a Natural or Dried-in-the-fruit process; in the coffee industry, this is considered by-product and is typically disposed of after being depulped.
• Mucilage – a sticky substance that surrounds the coffee seeds; also referred to as “honey” due to its sugary, sticky consistency; many fruits contain a mucilage.
• Parchment – cellulose layer that protects the coffee beans that takes on the appearance of parchment paper once dried.
• Silver Skin – a thin silvery layer that coats the coffee bean; also know as “chaff,” which becomes something akin to a flake during roasting, and is thus shed from the bean. Sometimes the chaff does not detach from the bean altogether during the roasting process, and can end up in the final coffee product.
• Bean/Seed – the innermost part of the fruit; this is the part of the cherry that remains after roasting.
3 Main Processing Methods
There are three primary processing methods used in the coffee industry. The difference between the methods is the layers that are removed before drying occurs.
• Washed Process – water and fermentation is used to remove the skin/pulp and mucilage; also known as Fully Washed. This is the most common form of processing for Arabica coffee around the world. A high-tech pressure washing machine process called Pulped Natural is used to avoid the fermentation step.
• Natural or Dried-in-the-Fruit Process – the coffee cherry is dried naturally, therefore none of the layers are removed.
• Honey Process – skin/pulp is removed with some or all of the Mucilage (i.e. Honey), remains. This process falls somewhere part way between Dry (Natural) and Wet (Washed) Processes.
Let’s break it down even more, and expand on the details of each process.
Washed (Wet) Process
Using the Washed method, the skin is removed from the coffee cherry using a machine called a depulper. The beans are then added to a fermentation tank to break down the sugars in the mucilage, essentially washing it away. The fermentation process can take as low as 12 hours on up to 6 days, depending on the method. The coffee can be rinsed several times over a course of days in some cases, which is called the Kenyan method. As soon as the sticky mucilage is no longer present, dramatically large amounts of water is used to wash off the excess mucilage. The Wet Processing method was developed in the 19th century, but the increasing amounts of water required for this method makes it detrimental to the environment. The coffee industry is working towards newer ways to decrease and even recycle the water that is used for this method. Fermentation greatly affects the taste of coffee. If it is over-fermented the resulting taste of the coffee will be sour.
Pulped Natural Process
Similar to Washed Process, the Pulped Natural Process uses a power washing mechanism to remove the mucilage from the coffee bean, which eliminates the need for fermentation. Significantly less water is used in this method than the Washed Process, earning it another term: Semi-Dry. There is such a low risk of over- or under-fermentation since no actual formation takes place, which contributes too much consistency of coffee that is processed with the Pulped Natural method. Despite the intricacies involved in fermentation, this is what contributes to some of the more significant flavor notes amongst specialty coffee. Many Brazilian and some Colombian coffee farmers use this process.
Natural or Dried-in-the-Fruit Process
This is the oldest and most common processing method, as there is very little effort or waste of resources involved. Simply put, the coffee cherry is picked from the plant then dried. Ethiopia and Brazil along with many other dry climates around the world still use this traditional method. What makes this method beneficial is it can be carried out in places where water is scarce. While simple in theory, this method is also a very delicate and complex process; it takes up to 4 weeks to occur, and the prevention of off-putting flavor absorption and mold is difficult, though not impossible, to maintain. However, using the drying method can retain some of the original fruit flavors of the beans. The next time you taste an Ethiopian or other Natural Processed coffee, take note of the fruity or berry-like flavor notes.
As briefly noted above, mucilage is commonly referred to as “honey” because of its sugary and sticky consistency. The Honey Process consists of drying the coffee bean where some of the mucilage, i.e. honey, remains surrounding the parchment of the seed. After the coffee cherries are picked, sorted, and depulped, they are moved to drying beds or patios for the final step of the process. Since some fermentation occurs while waiting for the remaining mucilage to dry, Honey Processed coffees may exhibit slightly more acidity than Pulped Natural Processed coffees, but with quite a bit less than Natural/Dried and Washed Processed coffees. Honey Processed coffees are becoming increasingly notable in El Salvador and Costa Rica.
Stages of Honey Process
Coffee farmers have instituted their own rating system on the degree of honey processing amongst their harvests. There is a 40% to 100% grading scale, which signifies how much of the mucilage, or honey, remains on the bean – typically 40%, 60%, 80%, or 100% is designated. This isn’t an officially recognized system, as it mainly just helps the farmer to determine their own personal honey-grading system, recognizing their efforts to remove the sticky substance surrounding the coffee bean.
Along with the honey percentage rating system instigated by coffee farmers, many farmers have assigned colors to the coffee that has been Honey Processed, particularly in Costa Rica. The color designations are Yellow, Red, and Black, which signify the quantity of light that is exposed to the coffee during the drying portion of the process.
• Yellow Honey receives the most amount of light during the Honey Process. The coffee with this color designation takes the least time to dry (about a week), since more light equals more heat.
• Red Honey is in the middle of the color spectrum, taking two to three weeks to dry, with overcast or shade conditions. To reduce the risk of too much exposure to light, farmers will commonly cover the coffee on the drying beds.
• Black Honey receives the least exposure to light and can take at least two weeks, if not longer, to dry. This is also the most expensive of Honey Processed coffees as it is the most labor-intensive.
The next time you visit your favorite café you may notice your coffee tasting just a little bit richer allowing more appreciation for the seed to cup journey since you’ll have a little more inside knowledge about the processing methods than the average Joe.Coffee, from farm to cup, harvest, honey process, origin, sustainability