Coffee Cultivation and Processing

Characteristics of the Coffee Plant

Coffee grows in tropical and subtropical climates, predominantly between the Tropics of Cancer and Capricorn, at altitudes ranging from sea level to 6,000 feet. Although technically an evergreen shrub, the coffee plant is generally referred to as a tree because it grows to more than 20 feet in height if not pruned.

The coffee tree carries white blossoms scented like jasmine. The delicate blossoms last only about three days, and six to nine months later the tree's fruit, called cherries, appears. The cherries begin as berries, which ripen from green to yellow to red. Ripe red cherries have several layers: the outer red skin, a sweet pulp, a membrane called parchment, a thin membrane called silver skin, and two coffee seeds (beans) that have a round or oval shape and are flat on one side. Nature occasionally provides only one bean per cherry instead of two; this single bean, smaller and more rounded than a normal bean, is referred to as a peaberry. With arabica coffee, peaberries normally occur about 10 percent of the time.

Principal Species

Although many species of coffee exist in the wild, only two are traded commercially: Coffea arabica and Coffea canephora (commonly referred to as robusta). Few visible botanical features distinguish the two, although robusta trees have larger leaves with a more corrugated appearance. Also, arabica cherries are oblong, while those of robusta are rounded. Of the two species, arabica coffee is the more delicate and flavorful. It grows at altitudes of 2,000 to 6,000 feet above sea level, predominantly in Central America, South America, and eastern Africa. Although arabica beans represent 75 percent of the world's coffee production, only about 10 percent of them qualify as the specialty coffees sold by gourmet retailers.

Generally, arabica coffees offer a balanced aroma and a sweet, acidic taste. They also command a higher price on the coffee market because of increased production costs. Robusta coffee, which represents about 25 percent of the world's production, grows in wet valley lands and humid tropical forests at altitudes between sea level and 2,000 feel It was discovered in the late lS00s, growing wild in the Congo. Produced predominantly in' West Africa and Indonesia, robusta coffees have twice the caffeine content of arabicas, are more disease resistant, and have a stronger flavor and heavier. body. Although seldom found in gourmet stores, robusta beans are often used in the processing of instant coffees and popular commercial blends.

Bigger Beans

Several countries grow a strain of Arabica coffee known as “Maragogype." Named after the southeastern Brazilian town of Maragogipe. where it was discovered, this botanical mutation tends to grow well at lower altitudes. Although maragogype coffee has different flavor characteristics depending on the country where it is grown, one common characteristic is the large size of the coffee beans. Arabica coffee thrives in tropical and subtropical climates, at altitudes of 2,000 to 6,000 feet above sea level. Cultivation Practices like most fruit-bearing trees, coffee trees cannot tolerate sudden temperature changes. The 25 million acres worldwide devoted to cultivating coffee offer the ideal growing conditions: temperatures that range from 68' to 75' F; shade for protection from higher temperatures and excessive sunlight; well-drained, rich soil; and 60 to 8O inches of annual rainfall.

Coffee trees typically yield good crops for approximately 25 years. When older, unproductive, or damaged trees require replacement, coffee growers use either vegetative or seedling propagation. The first method, which is more expensive, involves either grafting the root of the desired variety onto a seedling or rooting cuttings taken from the desired plant. Vegetative propagation s most often used with Robusta trees, whose seeds can cross-pollinate with other plants and therefore differ genetically from the parent plant. Seedling propagation is used for virtually all Arabica trees, which are self-pollinating and therefore produce seeds identical to the parent plant. This method, usually easier and faster than vegetative propagation, involves planting the carefully selected seeds in nursery beds or small containers.

Once leaves begin to emerge, the seedlings are shaded from the direct sun and tended in the nursery for six to 18 months. When they reach a height of 18 to 24 inches, the young plants are transplanted to the field and planted 10 to 12 feet apart The average coffee plantation contains 1,200 trees per acre, although the ratio changes depending on growing conditions and the type of coffee planted. In some countries the farmers plant fruit trees, such· as banana and coconut, between the coffee trees. The fruit trees not only provide shade and mulch for the coffee trees but also generate additional income for the farmer.

Special Care for Coffee

In addition to ideal climatic conditions, coffee trees require special care. Plantation management usually consists of pruning, weed control, fertilization, and-in some areas-irrigation. Pruning to a height of six or seven feet helps maximize production by concentrating the tree's strength on the important fruit-bearing parts. Restricting the height and width of the trees also makes ·harvesting easier. Compared to robusta, arabica branches require more pruning because they tend to die back from the tip, turning the leaves yellow. Pruning usually occurs right after harvesting ends, before the flowers and buds signifying the next crop appear.

The climatic conditions under which coffee thrives also provide the perfect breeding ground for weeds. Heavy weeds can reduce a tree's yield by more than 20 percent, so manual or mechanical weed removal becomes necessary- workers either slash the weeds with a hoe or knife, or they drive a tractor pulling a large rake between the rows of trees. Coffee trees produce for so many years that they deplete the nutrients in the soil. To even ut and increase yields, many farmers apply chemical fertilizers (usually nitrogen and potassium) or organic fertilizers (cattle manure, mulch made from dried grass and leaves, and coffee pulp). Although the majority of the world's coffee depends solely on natural rainfall, coffee growers may turn to irrigation to even out crop yields from one year to another or to save a crop from the effects of a drought. Only Arabica coffee is irrigated, either by overhead sprinklers that produce "artificial rain" or by an underground sprinkler system that delivers water to the area right underneath each tree.

Natural Enemies

Climatic changes, ranging from a drought or severe frost to an earthquake or hurricane, can devastate a coffee-growing region and have long-term effects. For example, a frost that struck Brazil in July of 1975 sent world coffee prices soaring and Brazilian coffee growers scrambling to plant new trees: which need up to five years to mature and bear fruit. Like other agricultural products, coffee is also susceptible to insect infestation and disease. One fungus, Coffee Berry Disease (CBD), affects ripening cherries with black spots. The berries become brown and brittle, and the beans inside them decay. First detected in Kenya in 1922, CBD affects only arabica coffee and requires repeated applications of fungicide; even when treated, the fungus can reduce a crop's yield by 80 percent. It's not uncommon for fragrant white blossoms, green berries, and ripe red cherries to appear together on the same branch.

Coffee Leaf Rust (Hemileia vastatrix), another devastating fungus, affects plant leaves with powdery-looking orange spots. The leaves drop off, so heavily infected trees may become completely defoliated and die. This disease, discovered in Ceylon in 1869, spread rapidly around the world and now affects trees in Central and South American countries. Leaf rust occurs during rainy periods and actually affects the future crop more than the current one. Affected trees must be treated with copper-based fungicides. In an effort to develop varieties of coffee more resistant to disease, most growing countries operate research stations and experiment with various methods of plantation management.

Harvesting

Provided a coffee seedling does not meet with climatic disturbances or disease, three to five years will pass before it begins to produce a crop. Generally, the growing area's rainfall and temperature determine the number of annual harvests and the method of harvesting used. Regions with one distinct rainy season, such as Brazil, usually produce one crop and one harvest per year. Regions with two distinct wet seasons; such as Costa Rica, usually have two flowerings and two harvests per year. In regions with rainfall well-distributed throughout the year, flowers, immature; berries, and ripe cherries can appear concurrently on a coffee branch.

A Bit of Bourbon

A small island played a large role in coffee's journey around the world. the island, now named Reunion, was originally a French colony known as Bourbon. Its location in the southwest Indian Ocean, Just east of the Malagasy Republic, provided a perfect environment for cultivating seedlings taken from Louis XIV's coffee tree in Paris. Cultivation became so important that the colonial government issued two decrees in 1723-one required every plantation to grow 200 more coffee trees, and the other prescribed the death penalty for anyone who destroyed a coffee tree. Although the island's coffee production peaked in 1825, when sugar cane became the choice crop, Bourbon seedlings found their way across the oceans to South and Central American countries. These seedlings gave rise to a strain of Arabica coffee-appropriately known as Bourbon-that missionaries took to countries such as Brazil, Colombia, Peru, EI Salvador, Kenya, and Mexico.

The latter situation requires a harvesting method known as selective picking: Workers walk between rows of trees with baskets or bags around their waists, leaving both hands free to pick the ripe cherries. The workers must return to the trees more than once because all the cherries do not ripen at the same time. In this labor-intensive method, an experienced picker can harvest about 200 pounds of cherries daily, the equivalent of approximately 40 pounds of roasted coffee. Strip picking is used in areas with distinct seasonality, where cherries generally ripen at the same time. Cherries are allowed to dry on the branches. One rapid movement strips the dried cherries from the branch, onto a cloth spread beneath the tree. Any leaves or twigs that fall with the cherries are sifted or winnowed out. The mechanical harvesting method relies on a machine to agitate the trees and knock the ripe cherries onto a conveyor belt. Although it offers a lower labor cost, this method has limited application because it requires relatively level terrain and long, even rows of trees. Harvesting high-quality Arabica coffees is very labor intensive because only the ripest cherries are selected and handpicked. Each coffee tree annually yields the equivalent of 1 to 1.5 pounds of roasted coffee.

Green Coffee Processing

Once the harvest concludes, processing must take place to remove the coffee beans inside each cherry. Two processing methods exist: the wet (washed) method, used primarily for arabicas, and the dry unwashed) method used primarily for robustas. The processing method helps determine the ultimate flavor of the brewed coffee. For example, wet-processed coffees tend to have a cleaner flavor, while dry-processed coffees often exhibit a heavier body. In the wet method of processing coffee, a machine breaks away the cherries' outer skin removing most of the pulp and exposing the parchment-covered beans. To remove the sticky coating called mucilage, the beans are placed in large tanks of water to ferment for about 24 hours and then are thoroughly washed. The clean beans dry in the sun for two or three days or are dried by machine. In the last step, a hulling (milling) machine removes, some of the parchment and silver skin to expose the green beans. Wet-processed coffees usually range in color from blue/green to gray/green. They tend to command higher prices because of the additional labor and equipment involved in the process.

Countries lacking sufficient water supplies, such as Brazil and Ethiopia, most often use the oldest and simplest method of processing the dry method. In this method, the ripe cherries partially dry while on the tree and then are spread out in the sun on patios. Raked and turned several times a day, the beans dry for another two to three weeks. Finally, the dried beans are put through hulling machines to remove the dried pulp, parchment, and silver skin. Dry processed coffees tend to be greenish to brownish in color. The coffee industry sometimes refers to these coffees as "naturals."

Cream of the Crop

The interchangeable terms European Prep, German Prep, and Cream of the crop refer to specialty coffees that have received extra attention during the processing phase. These beans have been washed carefully for a cleaner flavor, sorted by hand to ensure uniformity of size, and may be polished during the hulling process, all the silver skin is removed to give the green beans a glossy appearance. Generally, European Prep coffees command a premium of at least 10percent over other high-quality Arabica coffees.

Sorting and Grading

After processing, the beans are ready for sorting and grading. Sorting (separating) and grading the coffee beans can be done by hand or by machine. In the first method, workers pick out undesirable beans moving past them on a conveyor belt. Machine methods include scanning the beans with light beams or subjecting the beans to a blast of air, which lifts out the lower density or less desirable beans. Typically, beans are sorted by their size, shape, density (which relates to hardness or softness), or color (which ranges from bluish to brownish). Peaberries, for example, are sorted out from normal-sized beans and graded separately.

Once sorted, coffee is graded for export. The criteria for grading coffee may include altitude of growth in an individual producing area, the age of the beans, and flavor characteristics of the brewed coffee. The number of imperfections, referred to as physical defects, are another means of grading coffee. Physical defects include the number of black beans, broken beans, stones, or small sticks found in a given sample of beans. Each producing country sets its own standards for sorting, grading, and labeling coffee beans. Kenya AA, for example, denotes that country's top grade as determined by the beans size. Costa Rican Strictly Hard Bean describes a coffee grown at a higher altitude than Costa Rican Hard Bean. Some coffees, such as Brazilian Santos or Venezuelan Maracaibo, carry the names of the ports through which they are commonly exported. Others are named for growing regions, such as Harrar and Sidamo (regions in Ethiopia).

Ready for Export

One step remains before green coffee can leave the shores of a coffee growing country: packing in jute, hemp, or sisal bags. The bags, generally weighing 132 pounds (60 kilograms) or 152 pounds (69 kilograms) each, are transported via rail or truck to the port to await shipment. In most cases, the country of origin, method of processing, and grade of bean appear on the bag. Many countries store the bags in ventilated warehouses, which protect the green coffee from absorbing moisture and strong odors. Coffee still in parchment ("in pergamino") stores better because the additional layer lessens the potential damage from excessive heat or moisture. If a coffee in storage is referred to as "new crop," that means the coffee has been harvested during the current crop year. (The crop year varies from country to country and may start in October, January, April, or July.) A "past crop" label means the coffee is not freshly milled, having been harvested during a previous crop year. Generally, past crop coffees offer a small reduction in cost.

Some coffees, such as Sumatran, are deliberately held in storage for a year or more. Generally stored in pergamino, these aged coffees, over time, develop a desirable smoky characteristic because of chemical changes within the beans. Aged coffees command a premium in price, but few are available because of the expense associated with long-term storage. ICO Classification for exporting purposes, the "International Coffee Organization (ICO) developed a classification system that groups coffees according to three main criteria: species (Arabica or Robusta), processing method (wet or dry), and altitude of growth (low, medium, or high grown). The ICO classification system includes these four categories:

• Colombian Milds are Arabica coffees grown at high altitudes (4,000 to 6,000 feet) and processed using the wet method. Grown in Colombia, Kenya, and Tanzania, they represent 15 percent of the world's coffee production. Colombian Milds, typically graded on the size of the beans, have a high level of aromatics and a thick body.
• Other Milds are grown at altitudes of 2,000 to 4,000 feet above sea level-mostly in Mexico, Central America, and South America.
• Milds represent 25 percent of world production. They are graded by altitude, density, size, and number of defects. Other Milds offer coffee drinkers a mild taste, a moderate level of aromatics, and a light body.
• Brazilian and Other Arablcas are usually grown between sea level and 4,000 feet in Brazil, Ethiopia, and two other countries; these coffees represent 35 percent of the world's production. Brazilian and Other Arabicas tend to be graded by the number of imperfections; they possess a winy taste, a moderate level of aromatics, and a smooth body.
• Robustas coffees are grown between sea level and 2,000 feet and processed using the dry method. Produced primarily in Africa and southeastern Asia, they represent 25 percent of the world's production. Robustas, which are usually graded on density, color, and number of defects--have a taste ranging from neutral to strong, pungent aromatics, and heavy body.