Coffee Harvesting and Drying
High quality, select coffee is usually harvested by hand over the course of several weeks or months because not all of the fruit ripen simultaneously. Some countries produce so much coffee that they have found it economically advantageous to machine-harvest all of the fruit at the same time and discard the unripe berries. Irrespective of the harvesting method, green and overripe coffee cherries, leaves, and twigs inevitably end up mixed with the perfectly ripe cherries and must be separated during coffee processing.
Overripe and undeveloped coffee cherries, sticks and leaves float in water. Ripe coffee cherries are dense and sink. Therefore, the first step in coffee production consists of separating the "floaters" from the "sinkers." Depending on the environment and atmospheric conditions, local traditions, and economics, the processing that follows the harvest varies significantly. The oldest and most traditional dry method usually involves spreading the intact cherries out on a large patio or roadside and leaving them in the sun to dry in the hot air. The prolonged contact between the seed and the fruit pulp contributes significantly to the distinctive tastes of some desirable coffees (some fine Brazils, Ethiopian Harrar, and Yemen). However, in other regions of the world, this method is considered inferior--often in places where the environment would not allow for this production method anyway.
Worldwide, the predominant processing method, the wet method, takes various forms. This process involves removing the skin, and then the pulp of the fruit is removed by either washing it away immediately with water and special mechanized pulp scrubbers, or more slowly over the course of 10-14 days via enzymatic treatments in large fermenting tanks. Each processing method contributes significantly to the taste characteristics associated with a specifc farm's or region's coffee. The beans are washed and dried, any dry parchment skin surrounding the bean is removed, and some varieties of beans are subjected to polishing. At this stage the raw green coffee beans are ready for export.
Interestingly, there are several well-known coffee origins with long-standing processing methods that manipulate the coffee flavors in other ways. These include allowing the beans to suffer the drying and wetting of two or more monsoon seasons, and the infamous Indonesian Kopi Luwak coffee whereby the coffee bean gathers "flavor" during its journey through the gastrointestinal system of a weasel-like animal known as a civet.