British Coffee Association - Processing
Processing

Processing

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.

Dried coffee beans ready for distributionDry Processing

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.

Wet Processing

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.