COFFEE WASHING PROCESS

Mechanical

Aquapulp-process or mechanical demucilaging process, is yet another subdivided method of the wet-process method. Ripped cherries are first harvested and submerged in 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 bean from the rest of its body. Thereafter, the depulped beans will be placed in the mechanical demucilager machine to clean the beans by further removing any remaining sticky pulp as well as the mucilage. This method is essentially a faster, short-cut approach in removing the sticky fruit residue (mucilage) as the beans will be scrubbed against the machines instead of having to ferment and wash like the conventional wash-process. Furthermore, due to sustainability reasons, over the years Aquapulp-process has been gradually replacing conventional wet-processing methods.

After removing the mucilage, the beans will be dried through brick patios, raised beds or through a mechanical dryer. 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 the Aquapulp process is more environmentally friendly, there is a trade-off is in the taste of the coffee beans produced. By robbing the beans of the “fermenting and washing” step, it is essentially disallowing the beans to develop its flavours. Hence, this process takes away producer’s ability to influence the coffee flavour greatly.


Mechanical
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.
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.
Dry
Drying is a phase where the quality of the green bean and developed coffee flavours are preserved. Typically, drying takes about 23 days and during this period the water content in the coffee beans are reduced to the appropriate range at around 10-12%. Usually, drying is done with a suitable temperature through using convective hot air
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