Coffee Processing Methods
When you purchase specialty coffee at a café or grocery, the labels often indicates the coffee processing methods used to prepare the green coffees. If you are curious about how coffee makes its way from a cherry on a tree to the green commodity that is shipped to coffee roasters around the world, below the methods are briefly explained.
Natural Process, aka dry or unwashed, prepares coffee beans that roast and brew with smooth, heavy-bodied flavors. Dry Process is when newly picked coffee cherries are sorted and dried in the sun. By spreading the cherries evenly over drying beds and raking them regularly each day, farms and mills dry coffee over a period of days or weeks. Some will machine dry the cherries after sun drying them for a few days. The knowledge of the farmers and the mills is key in this process because too much drying will make for a brittle coffee bean and too little will hold excess water content that leads to fungal or bacterial compromising of the crop.
Pulped Natural, aka semi-dry process, wet-hulled or semi-washed, honey processed (primarily used in Costa Rica), creates coffee beans that will brew with heavy body, earthiness and mild acidity. This process is commonly used in Brazil and Indonesia. In this process the cherry fruit is removed with a wet grinding process and a pulping machine. After the grinding, any excess cherry is washed off before the coffee beans are dried. Some mills do not complete the second washing step and dry the beans with some pulp remaining.
Washed, aka wet process, is used to reduce the acidity of a coffee and provide a more balanced cup with quite fruity and lively flavors. Two methods exist for wet process. In one method, cherries are machine scrubbed until they fall from the coffee bean. In the other, the cherry is fermented and that process breaks the pulp down to free the bean. Following fermentation, pulp is washed which separates the bean from the fruit.
For more information about coffee processing methods take a look at the following articles.
From Bean to Cup from Equal Exchange
How Coffee is Processed Around the World from Serious Eats
Natural and Honey Processing from Coffee Review