Sucafina's Coffee Processing Poster

See below for more information

Coffee processing is one way that producers can differentiate themselves, and we've seen incredible innovations in recent years. We at Sucafina celebrate this individuality and the expression of ingenuity we are witnessing across the industry. As new methods and techniques appear across different cultures, they are given names and expressed through local understandings. Again, this individualization and expression is to be celebrated as coffee takes on the characteristics of its unique origins.

As a global coffee industry, we are confronted with a unique opportunity to break out of the traditional “washed and dry” processing terminology that has prevailed since the conception of the washed process in the 1800s. We have assembled the above visual portrayal of green coffee processing as our attempt not to box in coffee processing but rather create a common framework and understanding for conversation and communication. As we seek to learn from each other and exchange information, creating a common framework helps this process.

Our Green Coffee Processing Poster been a delight and joy to work on this project and visually represent the unique and special journey coffee takes from the tree to its green coffee state.

This poster is, of course, incomplete. There is no way to constrict the beauty and complexity of coffee processing with all its nuances, expressions of creativity, and more to one single poster. What we have attempted to do is provide some clarity behind how we can understand the process coffee takes and the important steps along the process. This is why we have focused our interpretation on the key activities that can occur during the process: pulping, mucilage removal, washing, soaking, drying, hulling, and sorting. Several others have proposed this type of organization, most notably Joel Shuler in his “Shuler’s Classification,” and we have expanded on this.

Before we begin breaking down the actual terms and nomenclature used, we need to look at these actions individually. 

Harvesting and Growing. This is the first step in the journey and is often overlooked. The cultivation of a coffee tree and harvesting of the coffee fruit set the stage for the quality journey this coffee takes. Shade grown vs full sun; selection of coffee varieties, sloped or flat terrain; soil management practices; and so much more all play a role in the resulting quality. Until the coffee fruit jumps off the tree itself and walks to a local washing station, the importance of harvesting and the laborious work performed by millions of people across the globe cannot be understated. Various harvesting techniques and methods create the conditions for the state of the raw material sold to coffee washing stations or processed in their own backyards.

Pulping. Defined as the mechanical removal of the skin (or exocarp) and pulp (outer mesocarp/mucilage) of the coffee fruit exposing the mucilage and the seed(s) inside. Though the technologies have improved in recent years, the design of the machinery goes back to the early 1900s and has not really seen too significant of a change since then. Whether a drum or disc pulper, this action does a few things:

• Reduces the layers or barriers for drying
• Initiates chemical processes inside the seed linked to germination, which we are learning is significant in contribution to flavor development
• Exposes the mucilage, which requires attention to minimize defect development
• Creates by-products that require management

After pulping, we are left with coffee that has the parchment layer intact with mucilage remaining on the surface. As by-products, we have coffee skin (cascara!) and mucilage that comes off during the pulping process.

Mucilage Removal is the next phase we find in coffee processing. Now, often this step is called “fermentation.” But really, that’s not the best descriptor for what we are attempting to achieve. You see, the mucilage creates a situation that requires our attention. We can either leave the mucilage intact and begin the drying stage OR we can choose to remove the mucilage via mechanical or biological means. Mechanical demucilagers utilize friction and/or pressurized water to forcibly wash the mucilage free from the parchment. The Biological process leverages the activity of microbes during fermentation to loosen the mucilage so it can be washed free. This action of fermentation also has the opportunity to develop flavor characteristics in the cup (sometimes good…sometimes not!). There are many variations on this that include the use of water, no water, use of selected microbes, and more. Each of these have the potential to bring different nuances to the cup as well as different risks.

Washing follows mucilage removal (or loosening) to ensure that all mucilage is washed free before drying. This can occur inside a single tank or can be done through channels. The benefit of channels gives the processor the added benefit of separation through density – thus why they are often called density channels. We are beginning to see some innovative processors use mechanical means for washing in an attempt to reduce labor costs, time, infrastructure space, and more.

In many East African origins, Soaking follows washing. This step of submerging washed parchment coffee in water for an extended period of time can have varying effects on the final cup. The soluble compounds in the seed have the opportunity to dissolve into the water which could be a positive or a negative. Unfortunately, often the decision to “soak or not soak” is one imparted to from external sources rather than a decision as part of a cupping and assessment exercise. There are circumstances where soaking is used effectively to create beautiful coffees and other instances where quality characteristics are lost.

After this, we begin the Drying process. In my opinion, this is one of the most undervalued and overlooked part of green coffee processing. Fermentation is sexy and seems to get all the airtime, but effective, controlled, and consistent drying, I argue, can impact just as much the resulting flavor as fermentation does. Compared to other grain products, coffee is harvested at a relatively high moisture content and requires controlled drying to ensure stability in storage and minimization of mold/fungus development. During the drying stage, the cellular structure of the seed can also be damaged which initiates lipid oxidation and aging characteristics.

There are two main methods to drying: mechanical and solar. Each of these have their benefits and disadvantages. Both of them can produce exquisite coffees, but they must be utilized with a high-quality focus to obtain better results.

Storage: After parchment coffee has been dried to a 10-12% moisture content, it is bagged and transported to the dry mill. This is where the process of hulling and sorting occurs to prepare coffee for export or sale domestically to roasters. Hulling removes the parchment layer and exposes the coffee seed to the external environment. This is why high-quality packaging in hermetically sealed bags is so important to maintain freshness and minimize the impact of defect development. After hulling, sorting occurs to remove defects based on size, density, and color. This is where we have various grades and distinctions that develop across production countries. Through the use of machinery and/or manual sorting, the coffee is packaged and ready to find its way to roasters across the world.

These steps represent the core principles behind understanding the various green coffee processing nomenclatures. Not only does this provide a clear and organized method based on the anatomy of the coffee fruit and actions where a transformation or change occurs in the process, but it also helps us to understand how these steps are impacting the coffee.

Check out our Coffee Processing Primer to learn in more detail.