Lactic Fermentation

Lactic fermentation is a variation of anaerobic fermentation in which conditions are intentionally tuned to promote Lactic Acid Bacteria (LAB) activity — the same bacteria involved in producing yogurt, cheese, and sauerkraut.

The method developed alongside anaerobic fermentation in the second decade of the 21st century, when producers in Colombia and Costa Rica began controlling environmental conditions — temperature, pH, sugar concentration — to promote or suppress specific microbial groups.

Process: depulped beans go into anaerobic fermentation tanks, sometimes with a LAB-promoting additive (whey, liquid from previous fermentations, or commercial culture). Temperature stays between 20-30°C, pH drops gradually as LAB produces lactic acid. This lasts 24-96 hours.

Final profile: cups with very pronounced yogurt and sour-milk notes, deep sweetness, creamy body, rounded-saline acidity (not bright like washed). The coffee takes on a 'lactic' character that fans describe as a soft, full envelope.

Quality is relatively stable (more so than 'wild' anaerobic) because the method is targeted. That said, it's more technical — requiring pH and microbial monitoring — and inexperienced producers can get unfit results.