Processing Coffee

Wet Method

The wet method is employed immediately after harvesting. If a coffee is referred to as "washed", it is wet-processed. The wet method utilizes fresh water throughout the processing. This method requires a constant supply of fresh, clean water and more resources than dry processing.

After the beans are harvested, they are loaded into trucks and transported to a mill. (Small farm owners often pool resources to utilize the expensive machinery of the mills.) The cherries are unloaded into large tanks of water. Sticks, leaves, and lightweight cherries float to the top, while ripe cherries sink to the bottom. The floaters are pulled and spread to dry sun dry on the patios. (Very little coffee is wasted; lesser quality beans are sold for lower prices, and used in cheaper blends or domestic coffees.) The ripe cherries are sent through a de-pulping machine, which strips away the fleshy outer layer. Mechanical graders, which separate beans by weight and size, sort the beans again. Generally, the consistently larger and denser beans are considered to be a higher grade of coffee. (The more consistent the size and density of the bean, the more consistent the roast and flavor will be.) Exporters and Importers refer to these as "A's" and "B's".

Fermentation

The various sorts, or grades, of beans are then fermented in large tanks of water for 12 to 48 hours, during which time natural enzymes break down the outer layer (parenchyma) from the parchment-like covering (endocarp) Fermentation time depends on the altitude where it is performed, some farmers simply grab a handful of beans and determine the time by feel.

Drying

The beans are then dried to retain 11% moisture content. Most farms will use concrete patios and the sun to do this, a process which can take anywhere from 7-15 days. The beans are raked to ensure even drying and have to be protected from moisture. Some modern mills use mechanical driers which expedite the drying process and allow greater control.

Resting

The beans are then rested in silos. This step allows them to stabilize chemically, and moisture content is evenly distributed. Another step to ensure the consistency of the final product.

Hulling

In wet processed coffee, hulling refers to the removal the dried parchment layer immediately surrounding the bean. Hulling dry processed coffee refers to removing the husks or whole dried outer covering of the original cherry.

Polishing

Polishing in not always done, but refers to the removal of any remaining silver skin on the bean. Some claim that polishing gives the end product a cleaner, more refined flavor in the cup.

Grading & Sorting

The beans are then further subjected to a variety of sorting which focuses primarily on size, density and color. Mechanical shakers are used to sort by density, and an electric eye searches for defects: scanning for pits, discolorations, broken edges, and other malformations. There are always defects in every lot, but one single bad bean can ruin a cup of coffee. Finally, high quality coffees are sorted by hand; machines can never compete with a well-trained, discerning human eye.

It is impossible to understate the importance of processing coffee. At any one step, if things are mishandled, even slightly, entire harvests can be ruined. If beans are left too long unraked on a patio, they will begin to mold, producing a grassy, fermented taste in the cup. If dried too quickly, the acidity of the bean will fade greatly and it will taste dull and lifeless. The amount of work that goes into a single cup of coffee is staggering. When you witness the entire process from beginning to end, it is a wonder that a cup of coffee sells for as little as it does.