The skins, which are very acidic, are composted and used as a soil supplement. The beans are fermented in water for 12 to 18 hours to remove a jelly-like membrane called the mucilage. Some other countries use a dry fermentation process that is cheaper, but that can result in a more sour or off-flavored coffee, Royal Kona says. Next, the water is drained off and the beans are emptied onto a screen where they're washed with a water mist, then placed on a large concrete slab under a greenhouse canopy to dry. Coffee needs to be dried quickly to keep it from spoiling, so rakes are used to create furrows that aid drainage.
Coffee is raked and turned every half hour throughout the day to promote drying.
If the weather doesn't cooperate, a mechanical drying process in a rotating drum is used. Then the beans head to the green mill, where they're stored in a silo, and then sent to a huller, where the dried outer skin is removed. Next, they go into the catador, a machine that removes chips, skin pieces and debris. No. 1, prime, Hawaii No. 3 and unclassified. Only prime and above can become Kona coffee.