Farm Process
The coffee is mechanically de-pulped, removing the cherry.
Next, it is fermented in a tank for an average of 18-24 hours. This process helps detach the mucilage (the fleshy interior of the coffee fruit) from the bean, which is then washed thoroughly with water.
Small producers usually dry the beans in the sun — a slower and more careful approach to processing, which helps preserve quality. Beans can also be dried mechanically in silos.
The coffee is mechanically de-pulped, removing the cherry.
Instead of being left to ferment in a tank, the coffee goes directly to drying. Fermentation is more aggressive when it occurs during the drying process — resulting in a final cup with notes of ripe fruit.
The coffee cherries are dried directly, without de-pulping or washing.
Fermentation occurs during drying, but is even more intense than in honeys.
Natural processing can result in very complex, sweet cups. This method of fermentation boosts the production of acetic acid, as well as some fatty acids that produce notes of ripe fruit or fruit wines.
Methods of Drying
Most small coffee growers in Colombia and around the world dry their coffee in the sun. In countries like Colombia, farmers use structures with plastic roofs, called parabolic beds, to protect the beans from rain during the drying process. Farmers in drier regions, like Central America, typically dry their beans on concrete patios in open air.
Sun drying promotes quality, as the beans dry at lower temperatures and with pauses at night. This allows the bean to contract in a slow and controlled manner, losing around 50% of its size from wet to dry. If contraction occurs too rapidly, the cell walls of the bean can be broken and its aromatic components lost, affecting the quality of the end product.
Mechanical silos are another popular method of drying coffee, used primarily by medium and large producers.
Although there are several methods of silo drying, they all work based on the same principle: the silo is filled with hot air, drying out the beans’ moisture. Silos usually run between 45-60 degrees Celsius, and can dry coffee in less than 36 hours.
Although they will never be quite as beneficial as natural heat from the sun, silos can successfully dry beans without damaging them, provided that a low temperature is maintained. However, most silos are operated at scorchingly high temperatures, damaging the structure of the beans, which contract and lose moisture too rapidly.
SUN DRYING
SILO DRYING