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The 10 Steps To Coffee
There are 10 steps through which a coffee bean passes from seed to cup:
1. Harvesting The Beans
- After three to four years, when they reach maturity, coffee trees bear fruit in lines or clusters along the branches of the trees. Referred to as a berry or cherry, this fruit turns red when it is ready to be harvested. Coffee beans are actually the seeds of these ripened cherries. Most arabica cherries ripen after 6-8 months; robusta beans take between 9 and 11 months to ripen. Beneath the cherries' red skin (exocar) is a fleshy pulp (mesocarp), a slimy layer (parenchyma), and a parchment-like covering of the bean (endocarp). Inside these layers are usually two beans, which are covered by a thin membrane or coat. This membrane or seed skin (spermoderm), is referred to in the coffee trade as the "silver skin."
- Harvest times vary according to geographical zone, but typically there is 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, although it may last until August. In countries in which the division between wet and dry seasons is not clearly defined -- like Colombia and Kenya -- there may be two flowerings a year, therefore permitting a main and a secondary crop. Equatorial countries can 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. Selective picking involves making several passes among the coffee trees at intervals of eight to 10 days so that only the fully ripe berries are taken. Selective picking is more expensive and, when used, is used only for arabica beans.
- On an average farm, pickers gather between 100 and 200 pounds of cherries per day. Of this total weight, 20 percent is actually bean (20 to 40 pounds). Coffee beans from the farm are bundled and shipped in 100 to 130 pound bags. Therefore, it takes one picker three to six days to fill one bag.
2. Processing The Beans
Processing the beans, or preparing them for roasting, is done in one of two ways: (1) the dry method, or (2) the wet method.
- The Dry Method
This is the simplest, cheapest and most traditional method of processing coffee. The harvested cherries are spread over a concrete, brick or matting surface, ideally in sunlight, and raked at regular intervals to prevent fermentation. If it rains or if the temperature falls, the cherries have to be covered for protection. After about seven to 10 days, when the moisture content of each cherry will have fallen to about 11 percent, the cherries are dry. The outer shell will have become dark brown and brittle, and the beans can be heard rattling around inside their husk. The dried cherries are then stored in silos, where the beans continue to lose moisture.
- The Wet Method
This method requires greater investment and more care than the dry method, but it causes less damage and helps to preserve the intrinsic qualities of the bean. The main difference between the two methods is that the wet method uses a procedure to remove the pulp from the bean within 12-24 hours of harvesting, instead of allowing the cherries to air dry. Using a pulping machine, the beans are separated from the skin and pulp, which are washed away with water. The lighter, immature beans are separated from the heavier, mature beans through specially designed washing channels or by an Aagaard pre-grader, a system involving shaking the beans through a strainer into a tank of water. Next, the beans are stored in fermentation tanks for 12 to 48 hours, during which time enzymes work to naturally separate the slimy layer (parenchyma) from the parchment-like covering (endocarp). When the process is compete, the endocarp has a "pebbly" feel. Fermentation is usually carried out in concrete tanks, which vary considerably in size. The length of the fermentation process is based on the condition of the beans and the climate's conditions. In regions of low altitude, fermentation time is short. At higher altitude, fermentation can take up to 48 hours.
3. Drying The Beans
- The endocarp must then be dried to retain about 11 percent moisture so the beans can be stored in a stable condition. The endocarp can be dried by the sun or by mechanical dryers. If drying is left to the sun, the beans are spread on concrete floors or on drying tables, and turned regularly. After 7 to 15 days, the beans are known as "parchment coffee," and will ideally remain in this form until immediately before export.
4. Hulling
- In wet processed coffee, hulling is used to remove the hull or dried parchment layer immediately surrounding the bean. Hulling dry processed coffee refers to removing the husks or whole of the dried outer coverings of the original cherries.
5. Polishing
- Polishing beans is an optional process that is not always done. During the polishing process, any silver skin that remains on the beans after hulling is removed in a polishing machine. While polished beans are considered superior to unpolished ones, in reality there is little difference between the two.
6. Grading And Sorting
- Although coffee beans are of a fairly uniform size and proportion, they are graded first by size and then by density (the elephant bean is the exception). Typically the size of beans is expressed on a scale of 10 to 20. The number represents the size of a round hole's diameter in terms of 1/64's of an inch. A number 10 bean would be the approximate size of a hole with a diameter of 10/64 of an inch and a number 15 bean, 15/64 of an inch. Beans are sized by being passed through a screener. Beans are also sorted by using an air jet to separate heavy and light beans (the pneumatic method). Next, over-fermented or unhulled beans are removed. This is usually done by hand as the beans move along on a belt, but other methods include electronic color sorting. Different countries grade their beans according to different systems. In general, however, there are six export grades, the top grade being SHB (strictly hard bean) or strictly high grown, which means that the coffee beans are produced at a minimum altitude 4,000 feet above sea level.
7. Exporting The Beans
- Approximately 7 million tons of "green coffee" (the term used to describe coffee beans before they are roasted) are produced each year. Beans are often kept and transported in coarse fiber bags made of jute or sisal. Beans are also shipped in bulk using bulk containers with plastic liners. The shipments are then sent to warehouses or directly to the roaster.
8. Tasting Coffee
- The tasting of coffee is referred to as "cupping." Cupping coffee is a process by which coffee brew is slurped by an expert for the purpose of evaluating the brew and determining characteristics. The tasting of coffee is a rigorous and disciplined process. The taster (also known as the liquorer) first assesses the green beans for appearance. The green beans are then roasted in a small laboratory roaster and tested for flavor and aroma. After the coffee has been infused in water, the taster "noses" the brew. After three minutes, the brew is lightly stirred and smelled again. The resulting foam is removed and the tasting begins. The cupper takes a spoonful of coffee into his/her mouth and "chews" it around before spitting it out. The procedure is repeated with all of the samples, and notes are made as each brew is sampled.
Following is an example of 10 criteria that may be used to describe and categorize coffee:
Type -- robusta, washed, arabica
Taste -- Strictly soft, harsh
Body -- lacking, too heavy
Acidity -- some, too much at the top
Age -- old to fresh
Defects -- sour, grassy, musty
Cup -- roast, watery, burned, old
Overall assessment -- neutral, spicy, hard
Aroma -- weak to strong
Fullness -- slight to considerable
9. Roasting Coffee
- Roasting is the heat treatment which transforms the green beans into the aromatic brown nuggets that we buy whole or ground. Most roasters use air temperatures of about 550 degrees Fahrenheit. The beans are kept moving during the roasting process to keep them from burning. When the beans reach a temperature of about 400 degrees Fahrenheit, they start to turn a darker brown, and the oils (called coffee essence, coffee oil or caffeol) start to emerge. This process, called pyrolosis, is at the heart of roasting, as it produces the flavor and aroma of the coffee we drink. When the beans are removed from the roaster, they are cooled by air or water. Roasting is performed in the individual importing countries, because roasted beans must reach the consumer quickly to get the full coffee flavor.
10. Grinding Coffee
- The objective of grinding coffee is to get the most flavor from the beans. This is done by infusing the ground beans in hot water. Generally, the faster the infusion, the finer the grind.
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