Wet vs Dry Processed Coffee Beans

Wet Processing

Wet-processed coffees is a relatively new method of removing the four layers surrounding the coffee bean.  This process results in a coffee that is cleaner, brighter, and fruitier.  Most countries with coffee valued for its perceived acidity, will process their coffee using the wet-process. This method is called wet process because water is the primary means to both moving the coffee through the process and to making the extraction of the seed possible. After picking, the berries are first sorted in a large machine to parse out any of the smaller, less desirable berries.  After sorting and cleaning, the pulp is removed from the cherry. This operation is the key difference between the dry and the wet methods, since in the wet method the pulp of the fruit is separated from the beans before the drying stage. If the pulp does not come off in this step, then it is not completely ripe and is hand sorted out and used in the lesser quality coffee. After the berries have had the pulp removed, they must go through a process of washing and sieving to remove any remaining pulp and skin.

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Fermentation Tank

At this point, all that remains surrounding the two beans is parchment and mucilage. Mucilage, composed of natural sugars and alcohols, plays a crucial role in developing the sweetness, acidity and overall flavor profile in the coffee beans. It is important in the washed process that all mucilage is removed from the bean which leaves only the flavor that developed in the cell structure of the bean prior to processing. To that end, the beans are put into tanks, approximately 3 feet deep with cement walls. Sometimes water is added to the tanks, but often the moisture in the mucilage itself is used to promote the slight fermentation necessary to remove the mucilage from around the parchment covered beans. This process can take anywhere from 6 to 80 hours depending on the climate and composition of the mucilage itself and the tanks must be stirred often. Once the mucilage has dissolved, it is removed completely through thorough and repeated washings. The beans are ready now for the next stage, which is drying.

Dry Processing

The dry process is a simpler, natural method of processing coffee beans. The dry-process is often used in countries where rainfall is scarce and long periods of sunshine are available to dry the coffee properly.  Most coffees from Indonesia, Ethiopia, Brazil, and Yemen are dry-processed. Naturally processed coffees typically have heavier mouth feel, lower acidity levels and intense, exotic flavor profiles. The cherries are dried with the beans inside, like drying a grape into a raisin. The beans are dried with all of their layers intact, including the coffee cherry and mucilage. As the cherries dry, they are raked or turned by hand to ensure even drying. It may take up to 4 weeks before the cherries are dried to the 12.5% maximum moisture content, depending on the weather conditions. Typically, after about 20 days, the berries are dry and resemble dark nuts. The fruit dries onto the parchment that surrounds the seeds. The coffee beans are left to rest inside the cherry pods before being peeled (hulled) and prepared for shipment. At this stage the cherry is the texture of fruit leather. The drying operation is a crucial stage of this process, since it affects the final quality of the green coffee result is the dense heavy body and exotic, wild berry flavors that have become synonymous with natural processed coffees.