Anaerobic Processing
Anaerobic coffee processing ferments coffee cherries or depulped beans in sealed, oxygen-free tanks (often under CO2 pressure or vacuum) for 24-72+ hours. Without oxygen, lactic acid bacteria dominate instead of acetic acid bacteria, producing a distinct fermentation signature: tropical fruit, liqueur-like sweetness, hibiscus, winey notes. Anaerobic naturals and anaerobic washed are the two main subtypes. First popularized by Diego Bermudez (Colombia) and Carlos Caballero (Panama) around 2015.
Background & Context
Traitement anaérobique (anaerobic processing in English) refers to the coffee processing method in which cherries or depulped seeds are fermented in sealed, oxygen-free containers — typically stainless steel tanks or food-grade plastic barrels — to produce distinct flavour profiles unavailable through conventional aerobic fermentation. In French specialty coffee vocabulary, "traitement anaérobique" or "fermentation anaérobique" designates lots processed under controlled oxygen exclusion. The anaerobic environment shifts microbial metabolism toward lactic acid and acetic acid production rather than aerobic respiration, generating distinctive tropical fruit, wine-like, and fermentation-forward flavour compounds — passionfruit, pineapple, hibiscus, kefir, wine notes — that characterise speciality lots processed this way. Colombian, Costa Rican, and Ethiopian producers have led the commercial development of anaerobic processing since approximately 2015.
Practical Use
For French-speaking buyers and café professionals evaluating anaerobic lots, the key assessment criteria are: fermentation control documentation (pH monitoring, temperature records), whether the process is "anaérobique naturel" (whole cherry sealed) or "anaérobique lavé" (depulped before sealing, producing a cleaner ferment), and the duration of fermentation (24–72 hours is typical; longer durations risk over-fermentation off-notes). Anaerobic coffees require specific brewing calibration: their elevated volatile compound load means that too-high extraction temperature (above 94°C) or too-fine a grind can amplify alcohol or nail-polish notes. For espresso, ristretto-style yields (1:1.5–1:2) concentrate sweetness; longer yields risk destabilising the fermented aromatic structure.
Related Terms
Related terms: Anaerobic fermentation, Carbonic maceration, Honey process, Natural process, Washed process.