Coffee Processing Method
Anaerobic Natural
The anaerobic natural combines both intensity levers: whole cherries ferment in sealed oxygen-free tanks, then dry intact as a natural. Fruit compounds developed under pressure in the tank soak into the seed throughout weeks of whole-cherry drying, producing some of the most flavor-dense coffees on the market.
This is the process behind many recent Cup of Excellence winners and the profile many roasters mean by 'funky' done well — controlled boozy fruit, cacao, and spice rather than accidental ferment. Because both stages are slow, output is limited and drying discipline is everything.
How the anaerobic natural works
- Ripe whole cherries sealed in tanks, CO₂ environment
- Anaerobic fermentation 48–96 hours
- Whole-cherry drying on raised beds 3–5 weeks
- Constant turning and night covering
- Rest, then hulling
Anaerobic Natural at a glance
| Flavor impact | Very intense: winey berries, rum, cacao, warm spice; heavy body with unusual aromatic persistence. |
|---|---|
| Key risks | Longest total exposure to mold and over-ferment risk of any common method; requires excellent drying infrastructure. |
| Water use | Minimal. |
| Drying time | 21–35 days whole-cherry drying after fermentation. |
Origins known for anaerobic natural
Anaerobic Natural — frequently asked questions
What does 'funky' mean in anaerobic naturals?
It describes intense ferment-derived fruit — rum-raisin, overripe berry, cacao — that is deliberate and clean. In a well-made lot the funk reads as sweetness and complexity; solvent, vinegar, or rotten notes indicate a defective ferment instead.
Why are anaerobic naturals often small lots?
Tank capacity limits each ferment, and the 3–5 week drying stage occupies bed space ten times longer than washed parchment. The bottleneck is physical infrastructure, which keeps volumes low and prices high.
How should roasters handle anaerobic naturals?
Their dense sugars brown quickly, so most roasters charge lower and extend development slightly to avoid scorching, and cup them against a washed control to calibrate the profile honestly.
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.