Anaerobic fermentation, washed
Also anaerobic washed, sealed-tank fermentation
Anaerobic washed coffee is a washed coffee whose fermentation step is run in a sealed, oxygen-poor vessel rather than an open tank. Without oxygen, yeasts convert sugars to ethanol, carbon dioxide, glycerol and organic acids, and lactic acid bacteria dominate the microbial community, giving more intense fruit and acidity than open fermentation. The method spread from competition circles in the mid-2010s and is now common in Colombia and Central America. It demands tight control of time and temperature.
- Fermentation
- 24–96h
- Drying
- 7–15days
- Water use
- Medium
- Dried to
- 10–12%moisture
- Ripe cherry
- Sort
- Pulp
- Ferment
- Wash
- Dry
- Hull
- Green
Step by step
Compare every method- 01Pulp ripe cherry
- 02Seal the pulped coffee (with or without its own mucilage juice) in tanks or bags that exclude oxygen, often with a one-way valve
- 03Ferment under controlled temperature, typically 24-96 h, monitoring pH and Brix
- 04Wash off the mucilage
- 05Dry parchment to 10-12%
Cup tendencies
intensified fruit, wine-like and lactic notes; anaerobic lots scored higher for mouthfeel and balance in one study
Risk
Off-flavours (solvent, vinegary) from runaway alcoholic or acetic fermentation; requires temperature control and hygiene