Continuous Working Horizontal Coffee Washer
Whether coffee is washed or not, it has to be dried; and there is a kind of fermentation that goes on during washing and drying, about which coffee planters have differing ideas, just as tea planters differ over the curing of tea leaves. Careful scientific study is needed to determine how much, if any, effect this fermentation has on the ultimate cup value.
Preparation by the Dry Method
The dry method of preparing the berries is not only the older method, but is considered by some operators as providing a distinct advantage over the wet process, since berries of different degrees of ripeness can be handled at the same time. However, the success of this method is dependent largely on the continuance of clear warm weather over quite a length of time, which can not always be counted on.
In this process the berries are spread in a thin layer on open drying grounds, or barbecues, often having cement or brick surfaces. The berries are turned over several times a day in order to permit the sun and wind thoroughly to dry all portions. The sun-drying process lasts about three weeks; and after the first three days of this period, the berries must be protected from dews and rains by covering them with tarpaulins, or by raking them into heaps under cover. If the berries are not spread out, they heat, and the silver skin sticks to the coffee bean, and frequently discolors it. When thoroughly dry, the berries are stored, unless the husks (outer skin and inner parchment) are to be removed at once. Hot air, steam, and other artificial drying methods take the place of natural sun-drying on some plantations.
In the dry method, the husks are removed either by hand (threshing and pounding in a mortar, on the smaller plantations) or by specially constructed machinery, known as hulling machines.
Cobán Pulper in Tachira, Venezuela