Coffee Production and Trade

Coffee processing

Dry processing

Winnowing coffee cherries - Brazil

Dry processing is simpler and requires less machinery than wet processing, and is the oldest method for processing coffee.

Essentially, the whole cherry is dried to allow separation of the bean from the exocarp and mesocarp. There are some local variations on how the process is completed, according to the facilities available¹, but there are three basic steps: cleaning, drying and hulling.

Harvested cherries are initially sorted to separate unripe, overripe and damaged cherries, and cleaned to remove soil, twigs and leaves, usually by winnowing using a large sieve. As with wet processing, ripe cherries can also be separated by flotation in washing channels.

Typical small-scale dry cherry huller

The coffee cherries are then sun-dried on drying terraces or on raised drying tables. The cherries are raked to ensure even drying, which can take up to 4 weeks to reach the optimum 12.5% m.c. On larger farms, a few days of sun-drying is sometimes followed by machine-drying.

As mentioned elsewhere, the drying process is the most critical in terms of the quality of the product. Coffee that is not dried sufficiently and quickly will be too wet, and is thus prone to fungal infection and the concomitant risk of OTA development. Coffee that is over dried becomes brittle and will break during hulling, broken beans being considered defects.

Once dried the cherries are either stored in silos before hulling, or sent directly for hulling, grading and bagging/export. The hulling of dried cherries removes the outer layers in one go, leaving the dried green bean behind.

¹ For example, in parts of Indonesia, cherries are frequently 'split' in order to speed up the drying process.