Knowing when it is done: the Fermaestro
How do you know when to wash off the mucilage?
Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.
Cenicafé, the Colombian coffee research center, developed a perforated truncated cone: it is filled with fermenting coffee and plunged into the tank, where it follows the same lot.
Read the stages without animation
- Plunge the coneCenicafé, the Colombian coffee research center, developed a perforated truncated cone: it is filled with fermenting coffee and plunged into the tank, where it follows the same lot.
- Watch the beans pack closerAs long as the mucilage coats the beans, it keeps them apart. As it is broken down, the beans pack closer and the level drops in the cone.
- Read the mark, washWhen the level reaches the mark, the washing point has been reached. Without the instrument, the fermentations observed in the field ran up to 72 hours; with the Fermaestro, they stay between 11 and 20 hours: the coffee had been fermenting three to six times longer than necessary.
- What the trials sayThe device is given as accurate in 97.1% of trials, the associated coffee scoring 81.6 points on average. A follow-up published in 2023 tests mucilage degraded to 25, 50 and 75%, and deliberate over-fermentations of 2 to 8 hours beyond the washing point.
To remember: The instrument tracks a physical change in the lot, the settling of the beans; it does not directly measure cup quality.
In history: Cenicafé developed this tool for lack of a marker to stop the fermentation.
Read the full article and its sources ↓
Cenicafé, the Colombian coffee research center, developed a perforated truncated cone that is filled with fermenting coffee and plunged into the tank: as long as the mucilage coats the beans it keeps them apart; as it is broken down, the beans pack closer and the level drops; when it reaches a mark, the washing point has been reached.
Without the instrument, the fermentations observed in the field ran up to 72 hours; with the Fermaestro they stay between 11 and 20 hours. The device is given as accurate in 97.1% of trials, the associated coffee scoring 81.6 points on average. These numbers do not describe a productivity gain but fermentations that had lasted three to six times longer than necessary, because nobody could say when to stop.
| Fermaestro, Cenicafé | Value |
|---|---|
| Fermentation without control | up to 72 h |
| With the cone | 11 to 20 h |
| Accuracy | 97.1% of trials |
| Average score | 81.6 points |
A follow-up published in 2023 tests mucilage degradations of 25, 50 and 75% and deliberate over-fermentations of 2, 4, 6 and 8 hours beyond the washing point.
Peñuela-Martínez, Pabón and Sanz-Uribe, Avances Técnicos Cenicafé no. 431 (2013) and no. 554 (2023), read in secondary summaries; Cenicafé, Fermentation 9(11):976 (2023)