Common methods for drying
1.Natural sun exposure
1.1This is the oldest treatment method in existence. This method is still used in places such as Ethiopia and Brazil.After the fruits are picked, they begin the sun drying process without any treatment. It can be dried with a mechanical dryer, or it can be spread in the yard, on a drying table, a tarp, or on the ground and dried in the sun. The drying process usually lasts about 4 weeks. The natural sun method can retain the fruity aroma of the coffee fruit. When tasting this coffee, you will find that the coffee is rich in fruity aroma and has a brighter taste. After drying, people use a special machine to remove the outer shell.
This process is called “Dry Milling”.
Steps of washing method:
1.Select beans; 2. Separation of the core and flesh; 3. Fermentation; 4. Washing with water; 5. Drying.
The ripe coffee fruits are picked and quickly transported to the processing station, which can be a small shed or a larger processing facility. After preliminary washing and sorting by running water, the coffee berries enter the beater. This is the process that separate the coffee beans from its fruits. Afterwards, it flows into the fermenter, where a series of enzyme-catalyzed reactions occurs, and then, the coffee beans are dried in a larger or more advanced large-scale mechanical dryer. Generally, this method highlights the acidity of coffee and its refreshing qualities.
3.Semi-water washing method
This method is extremely common in Brazil. Picking the ripe coffee berries and spread them in the sun for a few days in order to realize partial drying. Afterwards, using a small amount of water to sort and beat them to facilitate the beating process. This is similar to the water washing method, but without the fermentation step. Beating removes all fruit layers, including peel, pulp, thin skin and silver skin, but leaves clean green coffee beans. Afterwards, spreading the coffee beans under the sun or place them in a mechanical dryer for realizing complete drying. Unfortunately, as the coffee is not fermented, the taste tends to be flat. Therefore, growers will not use the semi-water washing method for super high-quality coffee beans. Most green bean purchasing companies rarely purchase coffee beans processed by the semi-washed method.
4.Honey processing method
Almost all production areas in Costa Rica adopt honey processing method, and this method is also widely spread throughout Central America. As the surface mucosa of coffee beans is extremely slimy and has a very high sugar content, people usually call it “honey.” In the honey processing process, some or all of the “honey” will remain in the coffee when it has been dried. After the coffee berries are picked, graded and peeled off, they are placed on a drying bed for drying. Due to the short drying time of the mucous membrane, the coffee beans are hardly fermented during the drying process. The acidity of the coffee beans processed by this treatment method is slightly higher than that of the natural washing method, but it is much lower than that of the natural washing method and the natural sun exposure method.So far, the four types of processing methods for green coffee beans that are often encountered has been introduced completely. We can see that the course of its evolution is also a process of gradual improvement: the original method is the traditional sun treatment method, the second is the water washing method, the third is the semi-water washing method (also called the half sun method), and the last one is the honey treatment method.
In fact, there are still many other ways to process green coffee beans. For example, the processing method used in Kenya, an important producer of specialty coffee, is called the double fermentation washing method. In some countries, red wine processing methods and even cola processing methods have been adopted as well.