Currently there are different methods in which coffee can be processed after harvesting. As you know, coffee fruits must be dried after being harvested and thanks to the type of drying, you will be able to perceive different flavors in the coffee, some types allow the coffee to have more fruity flavors, others to be sweeter or even to be a pleasant, clean and easy to enjoy cup. Many coffees develop exotic and unique flavors thanks to the drying process.
The drying of coffee is a post-harvest handling process during which the quality of the coffee is generally preserved instead of improving it. Washed, natural and honey process coffees should be dried at some stage of the process.
There are two main factors that contribute to the way in which coffee dries: temperature and air flow. This generates, over time, the reduction of humidity within the green coffee.
Throughout the drying process, it is important to keep in mind the temperature limits for each type of processing method; parchment coffees should not be dried at temperatures above 40 °C, while natural coffees should not be dried at temperatures above 45 °C. It is also recommended that the producer maintains the temperature at a constant level during certain periods of the drying phase.
Moisture levels should also be monitored in order to avoid the development of mold on the beans. Moisture levels prior to drying will be between 40% and 50%, and should be reduced to between 11% and 12%.
Natural Drying Process
The method consists of drying the whole cherry after harvesting, without removing the skin or peel. The cherries are then laid out on drying patios or on mats or beds raised off the ground. As the cherries dry, they should be moved so that they all dry equally.
Drying in this type of process generally takes 20 days, although depending on weather conditions, it could take up to four weeks.
In terms of flavor characteristics, coffees processed in this manner tend to have a high body, low acidity and exotic flavors. It is also common to find winey flavors and intense fruit.
In some regions a distinction is made between 3 different types of honey process: yellow, red and black. The main difference is in the flavor, which develops as the drying times and techniques are adjusted.
The yellow honey is the one that dries the fastest, approximately 8 days, and it is in this method that the coffee receives the most sunlight, giving the parchment that covers the coffee bean a light yellow tone by the time it finishes drying.
The red honey takes a little longer to reach the optimum level of humidity, in this method the coffee is dried in the shade or without direct sunlight, and for this reason it obtains its characteristic color.
Black honey takes the longest time to dry. In this method, the coffee is covered with black plastic in beds similar to African beds.
Then, we found some risks of drying coffee in the sun that include lack of control in fermentation, animal contamination, inadequate manual drying and adverse weather conditions. All of these can have a great impact on the quality of the cup.
In contrast, the main advantages that mechanical dryers have over sun drying coffee are the elimination of uncontrollable environmental variables that can affect coffee quality, improved accuracy and minimized delays.
Although drying coffee on raised patio beds may still be a suitable option for many coffee producers, mechanical dryers offer a number of different advantages. Some technologies such as drying control systems provide the producer with greater precision and accuracy throughout the drying process.
Rotary dryers have historically been associated with drying large batches of commercial grade coffee. However, innovations in mechanical drying now mean that they can also be suitable for the production of specialty coffee.