Sprays koji mold spores, as used for sake and miso, onto cherries during fermentation, aiming for more body and refined fruit character.
Koji fermentation sprays Aspergillus oryzae spores, the fungus behind sake and miso, onto cherries during fermentation. Its enzymes convert starches to sugars and produce amino acids, glutamates, esters and aldehydes, which are meant to add mouthfeel and fruity aromatics. It was formalized at El Vergel Estate in Colombia. Trial coffees reportedly showed more body, aftertaste and refined acidity. It remains experimental, unstandardized and costly, seen mainly in competitions.
How it worksSpores of koji (Aspergillus oryzae, the fungus used for sake, miso and other fermented foods) are sprayed onto cherries during fermentation. Its enzymes break starches down to sugars and generate amino acids, glutamates, esters and aldehydes, which feed later fermentation stages and are meant to add mouthfeel and fruity aromatics.
Step by step
- 01
Spray koji spores onto cherries during fermentation.
- 02
Control time and temperature while the koji grows.
- 03
Continue fermentation, then dry as usual.
History
Formalized through work by Kaapo Paavolainen, Christopher Feran and Elias Bayter Montenegro at El Vergel Estate in Colombia. Early attempts applying koji to green beans gave undesirable umami flavors.
Our notes on Koji Fermentation are still being checked against their sources, so for now this page shows only the facts we can stand behind.
What can go wrong
- The process is experimental and not standardized, and researchers are still confirming that koji fermentation is fully safe.
- Koji spores are costly, so the method appears mostly in competition lots.
In the cup, according to guides
- BodyMoreTrial coffees were reported to show more body, more aftertaste and a more refined acidity than conventionally processed samples.
At the same stage
Sources · 1 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. Some details here are less settled than others.
- What is koji fermented coffee? · Perfect Daily Grind