Anaerobic Fermentation

Anaerobic fermentation in coffee is relatively new — it entered specialty coffee in the second half of the 2010s, primarily through producers in Costa Rica and Panama. The idea was borrowed directly from the wine industry: fermentation in an oxygen-free environment promotes different bacterial and yeast communities — particularly lactic acid bacteria (LAB) — that produce flavor compounds not found in regular aerobic fermentation.

Process: cherries (usually) or depulped beans are placed in sealed plastic or stainless steel tanks, sometimes with a one-way valve to release CO2 produced during fermentation. The CO2 displaces oxygen and creates an anaerobic environment. Fermentation lasts 12 to 120 hours under controlled temperature.

This methodology produced a wave of new flavor experiences: exotic fruity aromas, whiskey or wine notes, salinity, creamy body, intense aroma. Farms like El Diviso, La Palma & El Tucán, Hacienda San Pedro, and Diego Bermudez (Colombia) became known for their anaerobic approaches.

Advantages: precise fermentation control, unique flavor profiles, opportunity for new experiences. Downside: when done poorly — unstable result, off-flavors, or 'masking' of the true characteristics of variety and terroir. Also tendency toward homogeneity across different origins, reducing the ability to identify origin character.