Anaerobic Fermentation

Anaerobic fermentation places coffee cherries or pulped beans inside hermetically sealed tanks purged of oxygen. Without oxygen, a distinct microbial community produces high concentrations of lactic acid and other flavor-active metabolites, generating intense profiles: tropical fruits, fermented notes, red wine-like complexity. The technique entered mainstream specialty coffee in the early 2010s and was popularized on the competition circuit. Producers closely monitor tank temperature and pH (typically targeting 4.0–4.5) over 24 to 120 hours to control intensity and avoid spoilage.