Coffee processing methods

Anna Kerwick @ 2019-08-26 16:00:57 +1000

After the coffee cherries have been harvested, they are processed by one of three methods.

Local farmers will decide which processing method to use based on cost, equipment, access to water, climate and tradition.

The quality of the processing used is vital in meeting international standards and grading specifications which play a part in determining flavour and price.

Defective cherries (from insect damage or being under/overripe) are sorted from the harvest by being placed in channels of flowing water.

The defective cherries float to the surface and are removed. Once they are clean and sorted for ripeness, the farmer then processes the coffee using one of three methods:

Natural (dry) process
The natural (also known as dry) process method is a traditional method of processing; it uses less water and little machinery, but does require spells of dry weather and lower humidity to be effective.

Whole, ripe cherries are positioned on large concrete patios or raised beds (i.e. woven matting suspended on poles at waist height) to sun dry.

Once dry, the skin, pulp and parchment are removed using a hulling machine.

Pulp natural (honey) process
A compromise between wet and dry, pulp natural coffees are known for their sweetness. Cherries are first de-pulped – the outer layer of skin is removed, leaving a thin layer of sugary mucilage coating the parchment.

They are then allowed to sun-dry on parchment on patios or raised beds. In the sun, the exposed mucilage develops as a candy-like coating on the parchment, and the sugars create sweetness within the bean.

The Indonesian pulp natural method is slightly different, in that the beans are partially washed, rather than mechanically de-pulped. Before packing, the beans are hulled to remove this shell.

Wet (washed) process
The most complex and expensive method, fully washed coffee requires access to large volumes of water and a range of sophisticated equipment.

Typically this process creates a clean, crisp and acidic coffee.

The washed method involves completely removing all the outer layers of the cherry down to the parchment in three steps prior to drying, using machinery, natural fermentation and water.