Harvesting & Processing
As coffee is often grown in mountainous areas, the ripe coffee cherries are picked in one of two ways:
- Strip Picked – all the cherries are stripped off of the branch at one time, either by machine or by hand such as in Brazil where its landscape is flat.
- Selectively Picked – only the ripe cherries are harvested and they are picked by hand.
- Pickers check the trees every 8 to 10 days and individually pick only the fully ripe cherries.
- Selective picking is primarily used for the finer Arabica beans.
- Coffee trees yield an average of 2 to 4 kilos of cherries
- a good picker can harvest 45 to 90 kilos of coffee cherry per day (9-18 kilos of coffee beans)
After harvesting the next step is to remove the coffee seeds from the ripe fruit and dry them. This can be done in two ways: the dry and the wet methods.
The Dry or ‘Natural’ Method
- It is the oldest, simplest method and requires little machinery.
- involves drying the whole cherry.
- Almost all the Robustas are processed by this method.
- Majority of the Arabica coffee produced in Brazil, Ethiopia, Haiti and Paraguay, India and Ecuador
- The harvested cherries are sorted and cleaned, by hand, to remove unripe, overripe and damaged cherries as well as any dirt, soil, twigs and leaves. Can also be done by floating the cherries in water.
- The coffee cherries are spread out in the sun, either on large concrete or brick patios, or on matting raised to waist height on trestles. If it rains they are covered up.
- As the cherries dry, they are raked or turned by hand to ensure even drying.
- It can take up to 4 weeks to dry the cherries. On larger plantations, machine-drying is sometimes used to speed up the process after the coffee has been pre-dried in the sun for a few days.
- Dried cherries are brittle with a hard outer shell and should have a maximum moisture content of 12.5%.
- The dried cherries are stored in silos and then sent to the mill for hulling, where the outer layers of the dried cherry are removed. The ‘green coffee’ beans are sorted and graded ready for selling.
The Wet Method
- The wet method requires the use of special equipment and the availability of water.
- The ripe cherries are first cleaned.
- They are then pulped by a machine that squeezes the cherries so that the flesh and the skin are separated from the beans. The beans are left with a slippery outer skin (the mucilage) and a parchment covering.
- The beans are further cleaned to remove lingering bits of pulp and put in large tanks; there the mucilage is broken down by natural enzymes and washed away, takes between 24 and 36 hours.
- Then the coffee is thoroughly washed with clean water. At this point, the coffee is approximately 57% moisture.
- To reduce the moisture to a desirable maximum of 12.5%, the parchment coffee is dried either in the sun, in a mechanical dryer, or by a combination of both.
- Sun-drying takes from 8 to 10 days and then
- Just before sale, this coffee is hulled to remove the parchment, and cleaned, screened, sorted and graded.
Effect of Wet v’s Dry Processing on Coffee Taste
|WET PROCESSED||DRY PROCESSED|
||· A slight wildness
· A little extra tartness
· An unevenness
· A little randomness to the taste
· If the coffee cherries aren’t dried fast enough there will be a slight rottenness to the coffee.
· In poor grade coffees, there’s also a slight chance of dirt granules or rocks.
· Selection by hand