Coffee is the seed of a berry from the coffee tree. It grows in a narrow, sub-tropical belt between the Tropic of Cancer and the Tropic of Capricorn. Coffee tree cultivation begins with planting the seeds in well-drained soil, after which they are kept in greenhouses for approximately 9 -18 months, or until they reach a height of up to 18 inches. Then the young coffee plants are transplanted to permanent groves, here it takes an entire year for the plants to grow only 30 centimeters tall; they will reach maturity in approximately 3-4 years.
Coffee trees bear fruit in lines or clusters along their branches. When the fruit ripens, it turns bright red (hence the name coffee cherries) and is ready to be harvested. Coffee beans are actually the seeds of these mature cherries. Most Arabica coffee cherries ripen after 6 – 8 months; Robusta beans take between 9 and 11 months to fully develop. Shade trees are typically grown nearby to protect the coffee trees and developing fruit from the sun.
Though harvest times vary according to geographical zone, there is typically only one harvest a year. North of the Equator, the harvest takes place between September and March. South of the Equator, the main harvest occurs in April or May and may last until August. In countries like Colombia and Kenya, where the line is blurred between the wet and dry seasons, there may be two flowerings a year, thereby allowing a main and secondary crop. Equatorial countries harvest fruit all year round.
The vast majority of coffee is harvested by hand in one of two ways: 1) strip picking or 2) selective picking.
Strip picking means the entire crop is picked in one pass, stripping all the cherries off the branch at one time.
Selective picking means only the ripe cherries are harvested. This involves the pickers making several passes among the coffee trees at intervals of 8-10 days, choosing only the cherries which are at the peak of ripeness. Selective picking is used primarily for Arabica beans because it is labor-intensive, and thus more costly.
During the harvest season, whole families (men, women, and children) join in the work. On an average farm, pickers gather between 100 and 200 pounds of coffee beans. The beans are bundled and shipped from the farm in 100-130 pound bags. Therefore, it takes one picker 3-6 days to fill just one bag!
Processing must begin immediately after the fruit is harvested to prevent the pulp from fermenting. Processing the beans (preparing them for roasting) is done is one of two ways: 1) the dry method or 2) the wet method.
The Dry Method is the traditional, less-expensive method of processing coffee. The ripe cherries are separated from the unripe, overripe, and damaged cherries, usually with the help of a large sieve. The harvested cherries are spread over a sunlit concrete, brick, or matting surface to prevent fermentation. If it rains or the temperature falls, the cherries have to be covered for protection. The cherries are dry after about 7-10 days when the moisture content of each cherry has fallen to 11%. The outer shell becomes dark brown and brittle, and the beans can be heard rattling around inside their husks. The cherries are then stored in large silos where they continue to lose moisture. As moist coffee is prone to deterioration, this is one of the most important stages of coffee production.
The Wet Method requires more care and a greater investment than the dry method, but it causes less damage and helps to preserve the intrinsic qualities of the bean. The primary difference between the two methods is that the wet method utilizes a procedure to remove the pulp from the bean within 12-24 hours of harvesting, instead of allowing the cherries to air dry. The coffee produced by the wet method is usually considered of better quality than that produced by the dry method and consequently brings higher prices.
Using a pulping machine, the freshly harvested beans are separated from the skin and pulp. The pulp is washed away with water, usually to be dried and used as mulch. The beans are then separated by weight as they are conveyed through specially designed water channels, with the lighter beans floating to the top and the heavier, ripe beans sinking to the bottom.
The beans are then stored in water-filled fermentation tanks for 12 – 48 hours, which allows enzymes to naturally detach the slick outer layer (the parenchyma) from the parchment-like covering (the endocarp). Fermentation usually takes place in concrete tanks of varying sizes; when the process is complete, the beans will feel rough and pebbly. The condition of the beans and the climate determines the length of the fermentation process; the lower the altitude, the shorter the fermentation time.
After processing, the beans must be dried to retain about 11% moisture to properly prepare them for storage. The beans, still encased in the endocarp, can either be dried by the sun or by mechanical dryers. If the beans are sun-dried, they are spread on large drying tables or on concrete floors and turned regularly. After 7-15 days, the beans are referred to as parchment coffee and will usually remain in this form until immediately before being exported.
In wet-processed coffee, hulling is used to remove the endocarp, or hull, immediately surrounding the bean. Hulling dry-processed coffee involves removing the entire dried husk (endocarp and mesocarp) of the original beans.
Polishing beans is an optional process in which the silver skin that remains on the bean after hulling is removed in a polishing machine. While polished beans are considered superior to unpolished ones, there is very little difference between the two.
Before being exported, beans are graded by both size and density. Beans are sized by being passed through differently sized screens. They are sorted pneumatically, using an air jet to separate heavier beans from the lighter beans. The next step involves removing defective beans. Usually, over-fermented or unhulled beans are removed by hand as the beans move along on a belt, but electronic sorting is also used occasionally.
Although some countries use different systems to grade their beans, generally six export grades are used. The export grades vary according to different growth factors, the highest grade being SHB (strictly hard bean), or strictly high grown, which means that the beans are produced at a minimum altitude of 4,000 feet above sea level.
Green coffee, as the milled beans are now referred to, is kept and transported in coarse fiber bags made of jute or sisal. The beans are also shipped in bulk using plastic-lined bulk containers. Approximately seven million tons of green coffee are produced each year.
The tasting of coffee is referred to as cupping. During every stage of production, coffee is slurped by an expert to evaluate the quality and characteristics of the brew. Coffee tasting is a difficult and very disciplined process, beginning with the taster (usually called the cupper) assessing the appearance of the beans. The beans are then roasted in a small laboratory roaster and tasted for flavor and aroma. The cupper noses the brew after it has been ground and infused in boiling water. After three minutes, the brew is gently stirred and the cupper breaks the crust by pushing aside the grounds on the surface of the cup and smells it again.
The cupper then slurps a spoonful and lets it swirl around in his/her mouth before spitting it out. This allows the brew to evenly coat the cuppers taste buds and then be briefly weighed on their tongue. This procedure is repeated with each sample in order to determine differing flaws and characteristics, as well as to blend different beans and determine the proper roast style. An expert cupper can sample hundreds of different coffees in a day and still distinguish subtle variations in the brews.
There are four main criteria used to describe coffee:
3) Acidity, and
Strictly speaking, the aroma cannot be separated from acidity and flavor. Nevertheless, certain high, fleeting notes are reflected most clearly before the coffee is actually tasted. There is frequently a subtle floral note to some coffee that is experienced most clearly in the aroma, particularly at the moment the crust is broken in the traditional tasting ritual.
\Describing flavor is difficult in that the term itself is quite subjective. Balance is the characteristic that yields the best flavor: it is the sensation of harmony between the acidity, the body, and the regional nuances. No one overpowers the other; rather, there is a pleasurable complexity to the best-tasting coffees.
: A high acid coffee can be compared to a dry wine. It can leave a sharp sensation at the edges of your tongue. The darker the roast, the lower the acid – but there are some varietal beans which have more natural acid, or “winy-ness”, than others.
: The sensation of heaviness on the tongue describes the full body in a coffee. The body is diminished by adding milk to coffee; therefore, if you prefer your coffee black, you can enjoy those with a light or a medium body.
Roasting green coffee generates the characteristic aroma, flavor, and body of the brown coffee beans that we purchase in stores. The air temperature of most roasters is kept between 450 and 550 degrees Fahrenheit. The beans are kept moving during the entire process to prevent them from burning. When the beans reach a temperature of about 400 degrees Fahrenheit, their color begins to deepen and the coffee oil, or caffeoyl, starts to emerge.
This process, called pyrolysis, is at the heart of roasting. Pyrolysis produces the flavor and aroma of the coffee we drink. The darkness or lightness of a roast determines its flavor development; the darker roasts require longer roast time and have a greater intensity and flavor. After being removed from the roaster, the beans are rapidly cooled using air or water. As freshly roasted beans must reach the consumer as quickly as possible to maintain quality, roasting is performed in the individual importing countries.
The coarseness or fineness of a ground coffee depends on the type of brewing method used. The objective of a proper grind is to get the most flavor from the beans into your cup: generally, the faster the infusion, the finer the grind.