Green Coffee Bean Processing: Wet Method
The production of green coffee beans involves successive removal of the outermost red skin and the pulp of the coffee berry, followed by removal of the mucilage, parchment covering, and finally the silver skin surrounding the green coffee bean.
There are are two methods currently used to produce green coffee beans; “wet” and the “dry” methods.
However, and alternative nomenclature is often used: “washed” and “natural processing”, respectively, and to avoid a misunderstanding it is often necessary to obtain a definition of the processing used on a given batch of coffee beans.
This is relatively intricate and is best carried out with uniformly ripe coffee berries that are still firm.
To achieve this uniformity the coffee berries are selectively handpicked.
As soon as possible they are sorted further in a water flotation system and sent directly to a pulping machine. Here the berries have the outermost skin and pulp removed and the mucilage layer is exposed.
Removal of mucilage ios brought about in concrete fermentation tanks, where the beans are slurried with water, A fermentation occurs that is mainly due to lactobacilli and yeasts.
Enzymes are produced that dissolve away the mucilage. The beans are washed free from the mucilage and the parchment layer is exposed.
Now the beans are dried in the sun or more usually in mechanical dryers.
Hulling completes the process. The parchment layer and most of the silverskin are removed in a hulling machine. Green coffee beans produced in this way are now ready for storage and shipping.
Green Coffee Bean Processing: Wet Method
