|The Coffee Process|
Arabica coffee tree leaves are broad, shiny, and shaped like an arrow or spearhead. They are three to six inches long and line up in pairs on either side of a central stem. The flowers are small, white, star-shaped blossoms and are borne in clusters at the base of the leaves and produce an exquisite, slightly pungent scent.
In six or seven months, the coffee cherries have matured; they are oval, about the size of your little finger. Most varieties turn bright red when ripe; a few varieties ripen to a golden yellow. Inside the skin and pulp are nestled two coffee beans with their flat sides together. Each tree can produce between one and twelve pounds of coffee per year, depending on soil, climate, and other factors.
How the fruit is removed from the coffee and how it is dried is extraordinarily important to how it finally tastes. If the fruit removal and drying, collectively called processing, is done carefully, the coffee will taste clean and free of distracting off-tastes. Furthermore, the various processing methods -- dry, wet, and semi-dry -- influence the cup character of coffee in fascinating and complex ways.
The Dry Method: The coffee fruit is simply picked and put out into the sun to dry. It is spread in a thin layer and raked regularly to maintain even temperatures from top to bottom. Drying takes anywhere from ten days to three weeks, and, on larger farms, occasionally may be accelerated by putting the coffee into mechanical driers. The hard, shriveled fruit husk is later stripped off the beans by machine.
The Wet Method: The coffee fruit covering the beans is removed before they are dried. In the classic ferment-and-wash version of the wet method, the fruit that covers the beans is taken off gingerly, layer by layer. First the outer skin is gently slipped off the beans by machine, a step called pulping. The beans then are allowed to sit in tanks while natural enzymes and bacteria loosen the sticky residue by literally beginning to digest it. This step is called fermentation. If water is added to the fermentation tanks it is called wet fermentation; if no water is added and the beans simply sit in their own juice it is called dry fermentation.
After the fermentation step the coffee is gently washed and then dried, either by the sun on open terraces, where the thin layer of beans is periodically raked by workers, or in large mechanical driers, or in a combination of the two. This leaves a thin skin covering the bean, called the parchment. The parchment is thoroughly dry, crumbly and easily removed. The final steps in coffee processing involve removing the last layers of dry skin and remaining fruit residue from the now dry coffee, and cleaning and sorting it. These steps are often called dry milling to distinguish them from the steps that take place before drying, which collectively are called wet milling.
Removal of dried fruit residue: The first step in dry milling is removing what is left of the fruit from the bean, whether simply the crumbly parchment skin in the case of wet-processed coffee, the parchment skin and dried mucilage in the case of semi-dry-processed coffee, or the entire dry, leathery fruit covering in the case of dry-processed coffee.
Coffee Sorting & Grading
Sorting - Size and Density: The coffee goes through a battery of machines that sort the coffee by density of bean and by bean size, all the while removing sticks, rocks, nails, and miscellaneous debris that may have become mixed with the coffee during drying. First machines blow the beans into the air; those that fall into bins closest to the air source are heaviest and biggest; the lightest (and likely defective) beans plus chaff are blown in the farthest bin. Other machines shake the beans through a series of sieves, sorting them by size. Finally, an ingenious machine called a gravity separator shakes the sized beans on a tilted table, so that the heaviest, densest and best vibrate to one side of the pulsating table, and the lightest to the other.
Sorting - Colour: With most high-quality coffees colour sorting is done in the simplest possible way -- by hand. Teams of workers, often the wives of the men who work the fields, deftly pick discoloured and other defective beans from the sound beans.
The last step in coffee's complex, labor-intensive trip to market is grading, the procedure whereby agricultural products are categorized to facilitate communication between buyer and seller. Approaches differ from country to country, but there are four main grading criteria: how big the bean is, where and at what altitude it was grown, how it was prepared and picked, and how good it tastes, or its cup quality.
The key to the success of the current mode of coffee making is the roasting process, to which we owe the delicately flavoured oils that speak to the palate as eloquently as caffeine does to the nervous system.
Much of what happens to the bean in roasting is interesting, but irrelevant. The bean loses a good deal of its moisture, for instance, which means it weighs less after roasting than before. It loses some protein, about 10 to 15 percent of its caffeine, and traces of other chemicals. Sugars are caramelized, which contributes colour, some body, and sweetness, complexity, and flavour to the cup.
Roasting is simple in theory: The beans must be heated, kept moving so they do not burn or roast unevenly, and cooled, or quenched, when the right moment has come to stop the roasting.
Before the bean is terminally burned, the moment of truth arrives for the roast master. Roasting must be stopped at precisely the right moment to obtain the degree of roast and associated flavour desired. The beans cannot be allowed to cool of their own accord or they may over roast. When delivered to the roaster in burlap sacks, the coffee bean ranges in color from light brown to whitish green to a lovely bluish, emerald green. The beans are always stored in their raw, or green, state. (All above information provided by "The Coffee Review")