From tree to our cups, there is a lot that happens to the coffee fruits. Coffees that we prepare our drinks from are basically the beans obtained from the bright red (or yellow or green) coffee cherries bunched up together as you may have seen in many pictures. But as to obtain the final beans that could be roasted and grind to brew a perfect cup of coffee there are more than one method.
In fact, there is a chain of various steps, from harvesting to roasting, that need to happen. There is also a bit of variation when it comes to the methods of obtaining beans from the coffee fruits and hence the flavor of beans varies too at the end of each processing method.
The reason behind different types of processing methods depends of factors such as the size of plantation or location of the farm.
The naturally processed coffee is when the coffee cherry is picked and eventually dried when fully ripe. Another way is when the coffee cherry dries up naturally while still attached to the tree and then picked and gathered on the drying patios. Both are natural processing and in either case the fruit as a whole (pulp, parchment or the papery covering around the beans and the beans) are dried. The removal of the outer layers is done only before export. Dried pulp and parchment are removed mechanically and the green beans thus obtained are packed and exported.
Natural drying and processing is a method that is popularly used for almost all Robusta coffee and with most of the Ethiopian and Yemen Arabica. In countries like Ethiopia where there is plenty of sunlight and dry weather natural processing is the dominant method. When the skin and pulp all are allowed to dry around the beans, the beans exhibit the fruity flavor greatly infused in them.
Although natural processing is low-cost and relatively simple process, many growers don’t opt for it. Reason is, usually naturally processed coffee don’t score well in the specialty sector. In order to make sure the farmers receive higher premiums, few countries have even put a ban on natural processing of coffee beans, such as Rwanda and Burundi for example.
What are the farmers persuaded to opt for then? It is called “Washing the Fruit” off of the beans or the seeds. Washed coffee has proved to be more popular lately as compared to the natural processed for multiple reasons. The flavors are said to be more balanced and beans less defected in washed coffee.
Pulping is carried out right away after the cherries have been harvested. Batches of cherries are put into large tanks (depending upon the size of the batch) and the cherries are propelled towards rotating rollers of the pulping machine by water. Skin of the fruit fall to the bottom in the pulping machine and beans come out of the machine from a separate channel.
The slimy beans are then tied in plastic sacks and left alone for a while allowing bacteria to do their work. One or one and a half day is the usual duration farmers let the bean ferment naturally. It is up to the judgment of farmer as when to move the beans (now sticky) to the next stage.
Next comes simple washing. Large tub, pot bucket or pool anything can be used to wash the slime off of the beans. Beans are then laid on drying patios under the sun. Occasionally drying beans are moved about and mixed to make sure all beans dry evenly.
It can take up to 8-12 days for entire drying process depending mainly upon the weather conditions. Farmers usually bite and chew coffee beans to check up on the moisture content remaining in the beans and generally 9-11% moisture is kept retained by the bean. Any more moisture and the bean may rot. Any lesser moisture and the bean gets too dry to go to the roaster.
Once the beans are dried at the optimal level, next step is hulling; the removal of the hull or covering of the bean, carried out mechanically. Beans obtained are “green beans” that will be packed and exported for roasting.