Coffee seeds, commonly referred to as coffee beans, go through the following process at the planting level:
- They are planted in seed beds in large nurseries;
- Seeds on the nurseries that have sprouted are then moved to individual pots;
- From the pots they are planted on large fields.
Shading and sufficient water supplies are important when the seeds are on the nursery beds and in their individual pots. The fields they are transferred to should also be moist for seamless transitions from the pots, which is why coffee is ideally planted during the wet seasons.
In Kenya, the highlands have the perfect conditions for coffee growing. Some of the coffee growing areas in Kenya are:
- Kisii Highlands (Nyamira);
- Ukambani (Machakos & Makueni);
- Central Kenya (Kiambu, Nyeri, Kirinyaga, Murang’a);
- The Great Rift Valley (Nakuru, Nandi, Kipkelion, Trans Nzoia, Baringo);
- Embu, Meru, Mt. Kenya, Aberdare Ranges, Mt. Elgon, Nyanza, Bungoma and Kericho.
Fruits of coffee trees are called ‘coffee cherry’ and they are what are harvested after 3-5 years when the trees have borne fruit. When they ripen, they become bright red in colour.
There are two methods of harvesting coffee- selective picking and strip picking. Selective picking entails picking the ripe cherries only, thus it is done frequently. According to the USA National Coffee Association, this technique is commonly used to harvest high quality Arabica beans. Strip picking entails removing all of a branch’s cherries in one instance. Every year, at least one primary coffee crop should be harvested but some farmers get secondary crops depending on their planting approaches and their harvesting styles.
Harvested coffee cherries are processed as soon as possible to keep from getting spoiled.
The Dry Method
The dry method of processing coffee is very straightforward. The harvested cherries are spread out on large surfaces in the sun and raked and turned from time to time to ensure every cherry is dried. This takes a few days with the cherries being covered at night to shield them from rain. In Kenya, the dry processing method results in ‘Mbuni Coffee’, which is thought of as low quality coffee, especially because the coats of the coffee bean are not removed- the coffee cherries are dried in their post-harvest state/ without any modification.
The Wet Method
The wet method of processing coffee begins with pulping, a technique by which skins and pulps are separated from coffee beans using pulping machines. The skins and pulps are then washed away, to be used as mulch on coffee plantations. Next, the beans are sorted by density by being conveyed through water channels. Heavy beans sink while light beans float.
After being sorted, the coffee beans are fermented in large tanks of water, in which they last 12- 48 hours subject to the environmental conditions of a particular place. In the tank, the layer of muscilage is removed by naturally occurring enzymes, after which the beans are rinsed using washing channels and prepared for drying. At the end of the wet processing method, coffee beans in Kenya are often grouped into ‘Mbuni’, ‘Parchment I’, ‘Parchment II’, ‘Parchment III’ and ‘Lights’.
Beans that were processed by the wet method must be dried before they are milled in order to be ready for storage.
Milling coffee beans entails hulling, grading and sorting. In hulling, parchment layers are removed from the coffee beans. From wet processed coffee the endocarp is removed and from dry processed coffee the whole of the dried husk is removed. This is the process that results in clean/ green coffee.
When grading and sorting, the coffee beans are analyzed more keenly based on their sizes and weights. This is done by a series of machines that separate the beans by size. The machines also remove unwanted materials such as rocks, sticks, nails and other such materials.
The beans are also sorted by colour and in Kenya and many other parts of the world, this is an exercise done by hand. It is thus a long and exhausting process but it provides employment to many people in rural communities. Machines were once used to meticulously sort coffee beans but they are no longer as common because of their delicacy and the high costs of buying and maintaining them.
At the end of the milling process, grades of coffee are the result. The grades of wet processed coffee, in descending order in terms of quality are:
- AA- large bean with with good size formation, that fetches a price higher than the price of any other coffee grade
- AB- a combination of grades A and B, regarded as a representative of other grades in a consignment
- PB- (pea berry) round beans which grow as one bean in a cherry
- C- beans smaller than grade B beans
- T- the smallest and thinnest beans most of which are in form of chips, broken and faulty
- TT- any light beans which are ragged and are blown away from all other grades
- E (elephant beans) the largest of all the beans that has two beans joined together to form the seed in a single cherry
- SB (sorted beans)
- UG (ungraded)
- HE (hulled ears)
Coffee graded as ‘Mbuni’ is that which has not gone through wet processing/ is unwashed. It comprises about 10% of the total crop. It’s grades are as follows:
- MH (Mbuni Heavy)
- ML (Mbuni Light)
Grade info source: Kenya Coffee Magazine 2010, p.7
After KCCE’s coffee, for instance, is processed, the green beans are stored in sacks in its warehouse at the Kenbelt Business Park from where it is exported or sold locally, to both individuals and organizations. KCCE uses the avenue created by the Nairobi Coffee Exchange that takes place weekly to auction its green beans. Different coffee dealers export coffee in different ways.
While it is processed, coffee must repeatedly be tested for quality and taste. Tasting/ cupping is done by a taster/ cupper/ liquorer in a coffee laboratory. The visual quality of the coffee beans is evaluated before they are roasted by a small lab roaster, ground and brewed. As such, coffee labs usually have several samples of coffee beans and ground coffee all around.
After grinding and brewing, the cupper ‘noses’ the coffee for its aroma. In a cup, the coffee is slurped to spray it evenly, inhaled, sipped, weighted in the mouth and then spit out. Tasting also determines the specific types of beans to be blended. After cupping, the liquorers also classify the coffees.
Coffee roasting is a straightforward mechanized process. The machines maintain very high temperatures throughout the process with the beans rotating constantly to keep them from burning. The green beans that are roasted either turn light or dark brown dependent on the levels of roasting required.
The decomposition of the coffee at very high temperatures, also referred to as pyrolysis, is what results in the flavours and the strong coffee aromas. The smell of coffee at the roasting location is too strong for those not accustomed to it. Roasted beans are cooled in large barrels by air or by water, immediately after which the beans are packaged for dispatch to wholesale and retail outlets.
Grinding is the process by which roasted coffee beans are broken down info finer states that can then be used by individuals to prepare their own cups of coffee. Grinding occurs at various levels such that the end results are eight fine or coarse coffees.
After being ground, cups of coffee are brewed using different types of machines meant to prepare different types of coffee. The finer the grind, the more quickly a cup of coffee will be prepared. Coffee drinkers the world over have 2 choices when it comes to brewing- they can have it done for them at offee shops, hotels or restaurants, or they can brew if for themselves at their homes or work places.