There’s more to your cup of coffee than meets the eye. Coffee needs to go through a number of processes to convert it from fresh coffee cherries to a cup of coffee. This section outlines the key manufacturing processes that take coffee on the journey from bean to cup.
The coffee tree is a small evergreen of the genus coffea. It has smooth, ovate leaves and clusters of fragrant white flowers that mature into deep red fruits abut ½ inch (1.27 cm) long.
The fruit, which is green when young, turning yellow and then bright red when ready for harvesting, usually contains two seeds – these are the coffee beans.
The coffee plant prefers the cool, moist, frost-free climate found at higher altitudes in the tropics and subtropics. Optimum growing conditions include:
The coffee tree will start to bear fruit three to four years after planting. A coffee tree yields its maximum sometime between its fifth and tenth year and may bear fruit for about 30 years.
A number of processes are involved in converting coffee from the fresh coffee cherries to the green coffee beans which are eventually sold to roasters.
Depending on their resources, growers may be able to carry out some of the processing themselves, before selling the beans. The more they do themselves, the higher the price they can obtain for their crop.
Farmers who do not have the equipment to process their coffee either pay a processor to do it for them, or sell their coffee on to processors.
Coffee is a very labour intensive crop, grown on both large and small plantations. Most coffee is still harvested by hand, although some larger farms now employ mechanical harvesters.
For best quality, only the ripe, red cherries are selectively picked, leaving unripe cherries on the branches to ripen for picking later. This is the most expensive method.
Alternatively, the farmer may judge the time to harvest, and then strip the trees of both ripe and unripe cherries in one go. This is more efficient, but results in lower quality.
After harvesting, the outer layers of the bean are removed to create a stable, dry green coffee bean. Each cherry contains two coffee beans which must be separated from the skin, pulp and paper-like ‘parchment’ that surround them. This can be achieved by dry processing or wet processing, depending on location and local resources.
The ‘dry’ method is the simplest and more economical of the two methods. It is also often the only method available.
Using the dry processing method, the cherries are washed then laid out in the sun to dry for about four weeks. They are raked over regularly and if it starts to rain they are covered over. The cherries are also regularly covered at night to prevent moisture from dew formation.
The cherries become brittle and form a hard outer shell. This is then broken away by hulling machines and the coffee bean remains.
Larger farms may have mechanical dryers which are used instead of, or in addition to, sun-drying, and these can dry the cherries in three or four days.
The wet method requires significant investment and more care.
The cherry pulp is almost immediately removed in a pulping machine. Water is used to wash away the outer layer and to sort the immature from the mature beans.
The wet beans are then allowed to ferment, which removes the slippery outer skin. This outer skin can also be removed by a machine called a demucilager.
The beans are washed a final time. This leaves beans with the papery parchment still on them. They are dried in the sun or in mechanical dryers.
Once dry, the parchment coffee is fed through hulling machines to remove the parchment.
Wet processing produces better quality coffee and is often used in conjunction with selective picking of the cherries.
Raw coffee beans contain plenty of caffeine, protein, acids, water and sugar. The roasting process produces the aromatic oils that give coffee its unique flavour and aroma.
Roasting is a precise skill; insufficient roasting of the coffee beans fails to fully extract the oils, but excess roasting can see them burnt away entirely.
Each coffee has its own characteristics, for example, Santos coffee has a soft smoothness, Kenya coffee has a lively acidity and Costa Rica coffee has a delicate sharpness.
Generally, the longer the roasting, the darker and stronger the coffee.
Roasted coffee can be served black, with milk or with cream, and can be prepared using all types of coffee maker.
After roasting, the beans need to be ground. Ground coffee has a greater surface area than the whole bean, so hot water can get to it more quickly and release the flavours.
However, excessive grinding will cause the oils to evaporate and the coffee to taste bitter and acidic.
Never grind more coffee than you will use for immediate brewing. Once the coffee beans are ground, the flavourful oils are exposed to the damaging air. As these oils dissipate, so will the flavour of your coffee.
Different methods of brewing will require different grind consistencies. It is important to have the correct grind for your coffee maker, because without it your cup of coffee will not have the proper taste. Here is a guide to help you: