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Coffee Beans: Harvesting and Processing

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A drink made from the roasted ground beans of several species of the genus Coffea, drunk by at least one-third of the world's population. It is a leading tropical commercial crop. The plant is a relatively low evergreen shrub usually associated with tropical rain forests where it thrives as a constituent of the shrubby ground vegetation. The shrub bears round cherries (bright red when ripe), each of which contains two seeds or coffee beans.

Africa is the original home of many of the present-day economic coffee species which were originally found growing wild. The commercial cultivation of coffee started in Arabia Felix (modern Yemen), where one of the most popular species (Coffea arabica) was apparently introduced from the Ethiopian province of Kaffa (Kefa).


Harvesting and Processing

The cherries may be allowed to ripen until they shrivel and begin to dry. They are then shaken off onto large canvasses. However, the higher grades of coffee are selectively picked by hand when the cherries are properly ripe.

Two processes are used for drying and depulping the cherries. The dry process (the older of the two) is common in many producing countries, especially those with adequate water. The fresh cherries are spread up to 2 in deep on a drying floor and are stirred several times a day and covered for protection against rain at night. After 10 to 21 days the dried cherries are milled to extract the coffee beans. When open-air drying conditions are unfavorable, mechanical drying is used.

The wet process differs in that the cherries are soaked in water and then depulped by machine, thereby extracting the beans. The latter are fermented in large tanks for 12 to 16 hours and are then washed and dried. The beans are milled to remove the parchment husk and the silvery covering. The wet-process coffee beans are preferred in world trade.

Coffee beans must be roasted and ground before use. The flavor depends on the ripeness of the berries, the physical environment, the variety of plant and the curing, drying and roasting processes employed. Roasting gives the product its brown color and transforms the natural coffee elements into those responsible for the splendid aromatic qualities which are so pleasant to taste.

There are important differences of type, kind and grade of coffee. The two principal world coffee categories are the Brazils and the milds. The milds, produced in countries other than Brazil, are generally (but not always) superior in quality to the Brazils. Coffees may also be hard or soft.

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