How is coffee decaffeinated?
Before roasting: green beans are moistened, then caffeine is extracted using water, CO₂, or a solvent. The beans are then dried and roasted normally. About 97–99% of caffeine is removed. Swiss Water and CO₂ methods work without organic solvents.
Why that is
Decaffeination always happens to green coffee—meaning before roasting. A roasted bean would be too brittle and break apart during the process. The basic principle is the same across all methods: caffeine is extracted from the bean without destroying the other flavor compounds.
The basic process:
- Moistening the green coffee — the beans swell and their cellular structure opens up.
- Extracting the caffeine — using a solvent, water, or CO₂.
- Drying the beans — back to their original moisture content.
- Roasting normally — just like any other coffee.
The four common methods:
| Method | Solvent | Caffeine Removal | Flavor |
|---|---|---|---|
| DCM method (direct) | Dichloromethane | 97–99% | Good, very common |
| Ethyl acetate method | Ethyl acetate (from sugarcane) | 97–99% | Good, marketed as "natural" |
| Swiss Water Process | Only water | 99.9% | Very good, chemical-free |
| CO₂ process | Supercritical CO₂ | 97–99% | Very good, chemical-free |
Swiss Water Process is especially popular in the specialty scene because no chemical solvents are used. The caffeine is drawn out through osmotic pressure into "Green Coffee Extract" (caffeine-free, but flavor-saturated water)—the flavors stay in the bean.
CO₂ process uses carbon dioxide under high pressure (over 73 bar and 31 °C). In this "supercritical" state, CO₂ acts like a solvent that selectively extracts caffeine. Expensive, but very gentle.
Are solvent methods dangerous? Residues are subject to legal limits (EU: max. 2 mg/kg dichloromethane in roasted coffee), and roasting at over 200 °C drives off most of any remaining solvent.
In practice at Green Wall Coffee
At Sophienstraße 27, we use decaffeinated coffee from the CO₂ process. If you want a coffee in the afternoon or evening, you can also have it decaf.
You'll find us at Sophienstraße 27 in Berlin-Lichtenberg, Monday to Friday 8am–5pm and Saturday 10am–5pm.
Further reading
Related questions:
- What decaffeination methods are there?
- Does decaf coffee really have no caffeine?
- Does decaf coffee taste different than regular coffee?
Also relevant:
- Does espresso or filter coffee have more caffeine? — Health & Caffeine
- Why Does Coffee Need to Be Roasted? — Roasting & Roast Levels
All questions in this topic: Decaffeinated Coffee