As roasters we purchase coffee in its green un-roasted form. But by the time it reaches us it has undergone lengthy processing.This processing, both its variations and the care with which it is performed, have a significant effect on the flavor and quality of the coffee.
Coffee – The Plant
Coffee species are members of the Family Rubiaceae, some of its relatives include quinine, ayahuasca (yage), and the plant bedstraw, common in pastures and meadows. While there are over 100 families in the genus Coffea, virtually all coffee that we drink is of the species Coffea arabica. The only other significant coffee in commerce, Coffeea canephora, more commonly known as robusta, seldom appears as higher grade, specialty, coffee.
Coffees from Ethiopia, where coffee still grows wild in forests, and Yemen, where it quite possibly has been grown by smallholders for as long as a thousand years, can rightly be considered heirloom crops. Coffee was established in other places originally through the transportation of a small number of plants from an established coffee growing region. Today there are a profusion of varieties, as can be seen in this wikipedia article.
Growing, Harvesting, and Processing
Coffee undergoes a number of lengthy and demanding processes to get it ready for eventual consumption. Each bean you grind and brew has undoubtedly been handled, sorted and selected several times, by hand, before it reaches you!
Coffee grows on small trees or bushes, rarely exceeding twenty feet in height. Contrary to the common conception, most high quality coffee is not grown on large plantations, but instead on small farms and even to a significant extent by subsistence farmers as a cash crop. The coffee plant has abundant scented flowers which develop into green, then yellow and eventually red cherry-like fruit before harvest. Better grade coffees are usually the result of picking and selecting only ripe fruit.
Processing involves removing the fruit from the seed and sorting and drying the coffee, leaving it in a state that can then be roasted. There two basic ways of doing this;
Natural, or dry process (D.P.), where the beans are spread out in thin layers and dried to the point wherethe fruit can be easily removed from the seed, and
Washed, or wet process, where the fruit is submerged in water for 24 to 48 hours and allowed to ferment, after which the fruit can easily be separated from the seed.
The two methods produce distinct flavor profiles, even when applied to the same coffee, with natural coffees having what are referred to as rustic qualities with generally more subdued and idiosyncratic flavor characteristics and washed coffees being cleaner, with more distinct flower and fruit flavors and more noticeable brightness, or acidity.
Which process a batch (or lot) of coffee undergoes produces perhaps the most distinguishable differences in coffee flavor. A good part of flavor profiles that are commonly associated with region of origin are really attributable to the predominant processing method in a particular region.