The World's First: Koji Fermentation in Coffee

In 2018, Elias and Shady Bayter at El Vergel Estate became the first coffee producers in Colombia — and among the first in the world — to apply Koji fermentation to coffee cherries. The innovation emerged from a collaboration between the Bayter brothers, Kaapo Paavolainen of One Day Coffee (Finland), and Christopher Feran, a coffee professional with a deep background in fermentation science. The experiment combined centuries of Asian food science with the microbiological expertise that El Vergel had been developing since they transitioned from avocados to specialty coffee.

Koji — specifically Aspergillus oryzae, the fungus used in Japanese sake, miso, soy sauce, and mirin production — functions differently from the yeasts and bacteria used in conventional coffee fermentation. Rather than producing primarily alcohol or organic acids, koji breaks down starches and polysaccharides through enzymatic activity, producing a range of amino acids including glutamate — the compound responsible for umami. In coffee, this translates to an enhanced body structure and complexity that sits outside the conventional fruit-acid-sweet coffee flavour spectrum.

The Process: Koji Supernatural

1. Koji spores (Aspergillus oryzae strain MSCO-11) are cultivated on steamed rice for 3–4 days at controlled temperature (25–30°C), creating an active koji culture.
2. Pink Bourbon cherries are harvested at peak ripeness, sorted, and transported to the processing facility.
3. Koji spores are distributed over the coffee cherries in trubs or on tarps with controlled oxygen exposure for 3–4 days. Temperature monitored continuously between 25–30°C.
4. Cherries are sun-dried for 10 days, during which koji enzymatic activity continues.
5. Mechanical drying for 2–4 days at no more than 38°C to complete moisture reduction.
6. 20-day stabilisation in GrainPro bags to ensure stability, preserve aromatics, and homogenise moisture content.

Pink Bourbon at El Vergel: The Variety

El Vergel's Pink Bourbon grows at 1,350–1,550 metres — lower than many Huila Pink Bourbon plots — which influences the flavour profile toward more body and less sharp citrus acidity. The Nevado del Ruiz microclimate moderates temperature even at lower altitudes. Pink Bourbon, now confirmed as an Ethiopian landrace (see Blog #7 for the full genetics story), contributes its signature florality, stone fruit sweetness, and silky body to the Koji process. The combination of Pink Bourbon's high sugar content and the Aspergillus oryzae's glutamate production creates a cup unlike any other — the variety's fruitiness meets the koji's structural complexity.

Brew Guide