To ensure the roaster has the coffee bean at its best moment for roasting, coffee goes through different processes after its harvest. These processes are crucial to achieving the best flavor and aroma in the final cup.
Next, I will provide all the necessary information to understand the different processing methods and how they affect your coffee experience.
Methods for processing raw coffee
There are two main methods for processing raw coffee: natural and washed.
The choice of processing method can greatly impact the final coffee’s flavor and quality. While natural processing tends to produce a more complex and earthy flavor, washed processing generally produces a cleaner and brighter coffee with a pronounced acidity.
Producers and roasters should choose the processing method that best suits their goals and preferences.
The natural or dry processing method
In the natural method, the beans are spread out in the sun to dry completely with the pulp still attached.
Once the pulp is dry, it is removed by machines, and then the beans are sorted manually.
This method is more common in regions with low humidity.
This method gives a distinctive and complex flavor. Leaving the pulp to dry with the beans allows the sugars to migrate into the bean’s interior, accentuating its sweetness and producing a cup of sweeter, smoother, richer, richer, and fuller-bodied coffee.
The washed or wet processing method
This washed method is suggested for Arabica coffee beans as it is more balanced, aromatic, and has a pleasant acidity.
This method is most commonly used in countries with high humidity, as the wet process helps to prevent unwanted fermentation and the formation of fungi in the beans.
➡️ For this method, the berries must be harvested manually, as only ripe, defect-free berries are picked at their peak to be processed.
- The berries are immersed in tanks of water and separated by density. This process allows mature berries to settle at the bottom while dry and damaged ones float to the surface to be removed.
- Then, mechanical pulping is performed using a pulping machine. When the coffee is introduced, disks with holes rotate at high speed, causing the pulp to detach from the coffee bean and pass through the holes.
- Once pulping is complete, the coffee beans are moved to a fermentation tank. There, they are submerged in water for a specified time to remove the pulp residue and eliminate the sugars from the coffee.
- They are then washed to remove any remaining residue before being dried.
- Finally, the coffee beans are sun-dried. It is crucial to note that if this drying phase is not carried out correctly, it can cause excessive fermentation in the beans, which could generate unpleasant notes of mold, rot, or even alcohol in the final cup of coffee.
The semi-washed method
This method is a combination of natural and washed coffee processing. It involves manual and selective harvesting similar to the washed method but also includes berry selection and pulping, as in the natural method.
The main difference is that the beans are washed with pressurized water before being dried in the sun. As a final result, a clean and smooth cup of coffee with good acidity, body, and prominent sweetness is obtained.
The semi-dry or honey method
The pulp is partially removed in the semi-dry or “honey” method, and a small amount is left to dry with the beans. The coffee pulp acquires a gelatinous texture, resulting in a sweeter and more complex flavor than the natural method but less acidic than the washed method.
Finally, the beans are pulped with a layer of pulp left on them. This allows sugars to migrate to the bean, making the final cup sweet and intensely aromatic, similar to the natural method.
Depending on the amount of pulp left on the beans, they are classified as Black if it is 100%, Red if it is 75%, Yellow if it is 50%, and finally, Golden or White if it is between 25% and 10%.
The drying is done naturally with the sun, but it requires time. The risk of overfermentation is high, so the technique requires experienced manipulation by growers.
The Wet Hulled or Wet Processed method
Here, manual harvesting of the berries is also required, followed by pulping. Then, the parchment beans (without the pulp) undergo rapid fermentation and are washed. They are then naturally dried with the sun, but only up to 50%.
Before the total drying is complete, and even when the bean is still wet at around 25/30%, the last thin layer (parchment) is removed, and the final drying process is completed after this step.
Conclusion
The quality of a cup of coffee does not only derive from the distinction between Arabica and Robusta. The effort and care that the farmer puts into each step, from selecting the coffee, cultivation, and expression of the plant’s intrinsic qualities, to harvesting methods and processing, make the difference.
However, if the roaster does not work with the same care after these processes, it can ruin everything during roasting.
