Even if it doesn’t look like it, the drying of the coffee is one of the most important steps in the entire coffee production, because depending on the type of drying, very different beans can be produced.
In this blog you will learn everything you need to know about coffee drying.
The importance of coffee drying
Drying the coffee is an attempt to control the moisture content of the bean, which should be between 12% and 10% to allow the final roast to bring out all the goodness of the bean. In addition, there are two very important reasons for designating bean drying as one of the most important procedures.
- By keeping the moisture content of the bean low, the growth of microorganisms in the coffee can be controlled, thereby extending the bean’s shelf life.
- The microorganisms can multiply easily at humidity levels above 12% and affect the quality of the beans.
- The coffee beans must be dried evenly. Otherwise, this can also affect the quality.
Drying the beans is one of the last jobs done by the coffee growers and it is here that the beans with the best qualities are selected to be packaged and sold.
Types of drying
Many effective methods of drying coffee have been discovered over the years.
The drying process is determined by many factors, from the purchasing power of coffee farmers to their customs. Below is a list of the most commonly used coffee drying methods.
Drying under the sun
This method is the most economical as no equipment or machinery is required, just a flat space on which to lay out the beans.
Many utensils can be used to dry the coffee. With this method of tables, African beds or even with sacks on the ground as in some plantations, a large investment is not necessary to dry the coffee in this way. In Colombia’s villages, coffee is also laid out in front of the house on the street.
How does sun drying work?
The beans should be placed on the tables so that they are not in the shade and the sun hits the beans directly. The tables should have an incline of 1° so that no puddles can form on the tables.
Coffee farmers use special devices that help them determine the temperature and moisture content of the beans.
In the expected conditions, this process can last between 8 and 12 days, depending on the climate of the area; however, in the case of sudden rains, it may last longer than expected.
This method is used for coffee beans with mild aromas, since the bean, in contact with nature, acquires fruity and floral aromas; in some specialty coffee plantations this is the method par excellence.
Sun drying problems
The main problem with drying the coffee using this method is natural, as birds or other animals can contaminate the coffee.
The climate is also a constant factor of uncertainty. Too much rain, too much sun and heat, the climate usually does not allow for reliable drying.
To solve these problems, many coffee farmers dry the coffee in enclosed courtyards, where they cover the roof with a fine mesh that lets sunlight through but doesn’t attract curious animals.
This method requires a high investment as it requires a drying machine, preferably a rotary machine, which ensures the coffee is dried evenly.
Depending on machine characteristics or capacity, the investment can range from $1430 to $4280.
How does machine drying work?
Normally rotary dryers are used. These are large drums into which the appropriate amount of coffee beans is filled.
The drum then rotates and the beans are dried with warm air. This variant allows controlled drying and also protects the beans from environmental influences.
With these machines, the productivity of the plantation is increased and labor costs are reduced.
Machine drying problems
Even if it doesn’t look like it, this method of drying can still cause a lot of problems.
On the other hand, even if labor costs are reduced, input costs increase, as these machines require electricity and some even fuel, which not only increases costs but also pollutes the plantation and the environment.
Drying according to the honey method
Honey coffee has a very long and sometimes complicated cultivation process, but today we will focus on the drying process, which is very similar to drying in the sun, but with many differences.
How does honey coffee drying work?
There are two main methods of drying honey coffee, the most popular being dome drying, where coffee farmers can either purchase special domes or make them themselves from materials such as guadua (a species of bamboo).
Usually inside the domes there are two tiers of African beds in which the honey coffee is placed based on the mucilage content as the drying time may vary depending on the mucilage content of the beans.
The walls of the domes are usually made of plastic or glass to allow sunlight to penetrate. Thanks to the walls of the domes, many problems can be avoided, such as: B. the intrusion of wild animals or environmental pollution.
The temperature in the domes is constantly measured, because in order for the honey coffee to dry as desired, the temperature must not exceed 45°. When the temperature reaches 40°, the domes’ doors and windows are opened to equalize the temperature inside the domes.
The other method of drying honey coffee is in direct sunlight. This method is the same as the one above, except that you have to better control the ambient temperature.
Drying by natural method
The natural drying process begins as soon as the coffee cherries are harvested.
How does natural drying work?
Once the coffee cherries are harvested, they are placed on African beds and left there until completely dried.
That is, the cherries are spread out on the African beds in the same way they were taken from the tree.
The cherries can be left on the African beds for up to 20 days to allow the whole fruit to dry; this is the oldest drying method.
Because the bean is dried along with the cherry, it acquires a very sweet, wine-like aroma, a very pronounced fruit flavor and the acidity of the coffee is almost completely eliminated.
Problems with natural drying
The main problem with this method is the waiting time for the beans to dry, because the normal 20 days can be extended to 40 or 45 days, depending directly on the climate.
When the African beds are outside, wild animals can be a big problem as they might try to eat the coffee.
Drying after the washing process
Drying by washing is a very particular method because the first part of the process is totally different from the others, but the last part of the process repeats a process that we have already seen.
How does drying by washing work?
After harvesting, the coffee cherries are put into a washing machine, i.e. the cherries go into the machine completely without their skins.
These machines require a large amount of water to work and basically, they remove all of the cherry until the bean is completely clean and then move on to the drying process which can be done in the sun or in a machine.
Sun drying requires the coffee beans to remain in the sun for up to 10 days to eliminate any moisture the beans may have absorbed in the washing machine.
This process removes the sugar from the coffee cherry, which allows the coffee to ferment while it sits in the water. This method results in a coffee with very intense fruit aromas and little acidity.
Problems with the washing method of drying
Using these machines to remove all the fruit from the coffee requires many liters of water, which in many cases are not reused.
Without proper supervision, the beans can overferment and damage the crop, and even if bits of cherry remain on the beans after removal from the washer, they can continue to ferment and ruin the bean.
Does the type of drying have an impact on the final taste of the coffee?
The final taste of the coffee is also influenced by the type of drying.
Consequences of poor drying
The most common errors in a drying process are:
- The bean has been exposed to dirty equipment or been in fermentation for a long time.
- The crushed bean was threshed while wet.
- Discolored, the bean has been drying for too long.
- The crystallized bean was exposed to temperatures in excess of 50°.
Most of the time, however, beans with defects are sorted out.
Drying the coffee is a fundamental step for the taste of the coffee because depending on the method used to dry the beans we can get completely different results, from very sweet taste and aroma to very robust aromas with a high acidity.