Wet processing, also known as washed processing, is one of the two primary methods used in the coffee industry to remove the fruit from coffee beans and prepare them for roasting. This method is known for producing clean and bright coffee beans with a distinct flavor profile.
Here’s an overview of the wet processing of coffee:
Harvesting: Coffee cherries are typically harvested when they are ripe. This can be done by hand or using mechanical equipment, depending on the location and scale of the coffee farm. Selective picking, where only ripe cherries are harvested, is preferred for higher-quality coffee.
Pulping: The first step in wet processing is pulping, where the outer skin and pulp of the coffee cherry are removed to reveal the coffee beans, which are actually seeds. This is typically done using a pulping machine that separates the cherries into two parts: the beans and the mucilage.
Fermentation: After pulping, the beans are covered in a layer of mucilage, a sticky substance. They are then placed in fermentation tanks for a period of time, usually 12 to 48 hours, depending on factors like temperature and humidity. During fermentation, enzymes break down the mucilage, allowing it to be washed away later.
Washing: Once the fermentation is complete, the beans are thoroughly washed to remove the remaining mucilage. This is often done using water, either in washing channels or with specialized equipment. The washing process is crucial for removing any residues and ensuring the beans are clean.
Drying: After washing, the coffee beans are spread out to dry. This can be done on raised drying beds, patios, or mechanical dryers. Proper drying is essential to reduce moisture content and prevent the growth of molds or undesirable flavors. Drying can take several days and may involve periodic turning of the beans to ensure even drying.
Hulling and sorting: Once the beans are sufficiently dried, they go through a hulling process, where the dry parchment layer (the outer shell) is removed to reveal the green coffee beans. The beans are then sorted to remove any defects or beans that do not meet quality standards.
Export and roasting: The processed green coffee beans are typically bagged and prepared for export to coffee roasters worldwide. At this point, the beans are ready to be roasted. The flavor and aroma of the coffee will develop during the roasting process.
Wet processing is favored in regions with access to ample water resources and where the goal is to produce specialty-grade coffee with distinct flavor profiles. The method is known for its ability to highlight the unique characteristics of coffee beans, allowing for a wide range of flavors and profiles in the final cup of coffee.