COFFEE WASHING PROCESS

Washed Dry Ferment

In the washed-dry-ferment method, the processing steps are highly identical to the washed-wet-ferment, apart from how the beans are fermented. Firstly, ripped cherries are harvested and submerged into water to remove impurities and immature fruits as well as ensuring consistent ripe level across the fruits.

The cherries then run through the depulpers - machines that squeeze the cherries, to extract the beans from the rest of its body. The beans will be placed in a dry tank to allow the dry-fermentation process to take place. The beans will simply ferment in its own juice where microorganisms interact with enzymes.

After dry-fermentation, the beans will be washed in order to remove loose mucilage and any other impurities. Thereafter, it will be ready to be dried through brick patios, raised beds or through mechanical drying. To ensure even and consistent drying, the beans will be turned regularly. What is left on the coffee beans then, will be a thin layer of skin known as the parchment skin; this skin will be removed through the last step which is also known as hulling.

Although dry-fermented coffee beans produce similar cup-quality to wet-fermented coffee, dry-fermented coffee tends to be more complex and sweeter, brighter and drier in taste.



Washed Dry Ferment
Pick Ripe Cherries
In the picking stage, the level of ripeness and elevation of fresh fruits (cherries) are critical. Red and purple-red cherries produce the best flavours, while under-ripe (green) and over-ripe cherries produce astringent tastes which deteriorate the overall cup-quality. Often, red-cherries grown at higher altitudes are highly demanded as it produces better flavours due to better maturity and higher sugar content.
Submerge in Water
Submerging is a process of removing impurities from the harvest. Through the fluidity and gravity of water, the immature fruits, floaters, withered beans, sticks and leaves are removed. When the fresh cherries are submerged in water, the pulp which carries microorganisms will hasten the fermentation process.
Depulp
After Cherries are harvested, they have to be depulped within 24 hours or else the cherries may produce an overly fruity or rotten flavour that can ruin the coffee’s cup-quality. Depulping is the process of separating the coffee seeds from the outer layer of flesh from the fruit and it usually happens at the farm or a centralized depulping station.
Ferment
During fermentation, microorganisms in mucilage will react with sugar to degrade, leading to fermentation. This is an essential stage of coffee processing as this is when microorganisms interact with enzymes and amazing flavours are developed. The coffee fragrance changes from fresh fruits to berry-like, transforming into tropical fruits and rich red wine - the ideal state of natural fermentation.
Remove Mucilage
After the cherries are depulped, what remains are coffee beans covered in a thin and sweet (sugary) layer known as the mucilage. There are two ways of removing the mucilage: 1. Fermentation. 2. Mechanical separation. Through fermentation, the beans are poured into a clean tank where its natural bacteria and enzymes react to break down the mucilage layer. On the other hand, removing mucilage through machines is easier, however it disallows the producers in having the flexibility to influence the coffee flavour.
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