Coffee Processing Method
Double Fermentation
Double fermentation runs two distinct microbial phases — commonly an anaerobic whole-cherry stage followed by a second aerobic or submerged ferment after pulping. Each stage contributes different acids and aromatics, letting the processor layer complexity the way a brewer layers yeast additions.
The technique took hold in Colombia's experimental mills, where producers pair it with precise thermal control. Cups typically show stacked fruit registers — bright citrus over deep berry — and unusually long finishes, which is why double-fermented micro-lots command auction-level premiums.
How the double fermentation works
- Stage one: whole-cherry fermentation (often sealed/anaerobic), 24–48 hours
- Pulping
- Stage two: mucilage fermentation in tanks or under water, 24–72 hours
- Washing and grading
- Slow drying with tight moisture targets
Double Fermentation at a glance
| Flavor impact | Layered acidity and stacked fruit notes with long finishes; more aromatic lift than single-stage ferments. |
|---|---|
| Key risks | Compounding risk across two stages; sanitation lapses in stage one ruin stage two. |
| Water use | Moderate to high depending on stage-two style. |
| Drying time | 10–18 days. |
Origins known for double fermentation
Double Fermentation — frequently asked questions
Is double fermentation the same as Kenya's double soak?
No. The Kenyan double soak adds a clean-water rest after fermentation is complete. Double fermentation runs two active microbial stages — a fundamentally more interventionist technique.
Why would a producer choose two ferments over one long one?
Different microbial communities dominate cherry-on versus pulped fermentation. Splitting stages lets the producer capture both aromatic families and reset conditions between them, giving more control than one long uninterrupted ferment.
How can a buyer verify a double fermentation claim?
Ask for the process log: stage timings, temperatures, and whether stage one was sealed. Credible experimental mills document every batch; the absence of records is a red flag for marketing-driven labels.
Volcana Coffee produces washed, natural, and honey-processed lots on the Bolaven Plateau, Laos, with controlled fermentation and SGS-verified quality. Ask for our current processing menu and cupping samples.
Request a SampleOther processing methods
Washed Process
Clean, articulate cups with bright acidity and clear varietal character.
Natural Process
Heavy body, intense berry and tropical fruit, lower perceived acidity, wine-like sweetness. Signature profile of Ethiopian and Brazilian naturals..
Honey Process
Rounder body and more sweetness than washed, cleaner than natural.
Anaerobic Fermentation
Amplified sweetness and exotic notes — cinnamon, red wine, tropical punch.