Removes skin and pulp, ferments the mucilage off the beans, then dries. The most common process and often linked to the highest quality.
Washed processing removes the skin and pulp by pulping, ferments the thin mucilage layer off the beans, washes them and dries them to 10-12% moisture. Fermentation commonly runs about 12 to 36 hours and has to be watched, or the coffee turns sour. Underwater fermentation is said to emphasize acidity and aroma and suppress some astringency, compared with dry fermentation. It is the most common of the three main processes and often produces the highest quality, but conventional wet processing is water-hungry, at 20 to 100 cubic metres per tonne of green coffee.
How it worksPulping removes the skin and pulp. The thin mucilage layer on the beans is then removed, usually by fermentation, and the washed beans are dried to 10-12% moisture.
Step by step
- 01
Cherry is pulped to remove the skin and pulp.
- 02
The mucilage is fermented off the beans, usually taking roughly 12 to 36 hours.
- 03
The beans are washed.
- 04
They are dried to 10-12% moisture.
Timing · Fermentation roughly 12 to 36 hours, depending on temperature, mucilage thickness and enzyme concentration
History
Described as the most common of the three main processes and as often producing the highest quality.
Field notes
- i
Conventional wet processing may use 20 to 100 cubic metres of water per tonne of green coffee.
- ii
Millers often judge the fermentation end point by touch: the parchment loses its slimy coating and feels gritty.
Our notes on Washed are still being checked against their sources, so for now this page shows only the facts we can stand behind.
What can go wrong
- Fermentation has to be watched closely, or the coffee turns sour.
- Conventional wet processing may use 20 to 100 cubic metres of water per tonne of green coffee.
- It produces large volumes of pulp, mucilage and wastewater (the source cites 40 to 45 cubic metres of wastewater).
In the cup, according to guides
- AcidityMoreUnderwater fermentation is said to emphasize acidity and aroma and suppress some astringency, compared with dry fermentation.
At the same stage
Sources · 2 Every sentence here was checked against a source we read. Taste notes are what guides describe, not promises about your bag. Last revised 2026-09-30.
- Coffee processing · Wikimedia Foundation
- Interaction and Metabolic Function of Microbiota during the Washed Processing of Coffea arabica · PMC / NCBI (journal article)