Anaerobic processing

A coffee processing method where cherries or pulped beans are fermented inside sealed, oxygen-free tanks before drying. The lack of oxygen changes the way microbes break down sugars, producing experimental flavours that aren't possible with traditional washed or natural processing.

Why it matters — Anaerobic processing has expanded what coffee can taste like. Tropical fruit, cinnamon, rum, candied notes — flavours that didn't exist in mainstream coffee a decade ago — now appear regularly in competition lots.

Good to know

• Light-roasted anaerobics can taste polarising. They reward open-minded tasting and a slightly higher brew temperature.
• Some producers ferment for 24 hours, others for 200+ hours — the longer the ferment, generally the more intense the flavour shift.