Skip to content
Decaf Atlas

Solvent process · Germany

CO₂ process

Caffeine dissolved out under pressure by carbon dioxide above its critical point. The most selective process and the best for body and mouthfeel — and the most expensive to run, which is why you see so little of it.

Also sold as: CO2 · carbon dioxide process · supercritical CO2 · liquid CO2 · subcritical CO2. Same process.

Solvent
Carbon dioxide
Caffeine removed
97–99%
Trademarked name
No — generic
Where it runs
CR3, Germany · Coffein Compagnie, Germany · Demus, Italy · Descamex, MX

What the label claims

Claims seen on real bags and roaster copy, and how each one holds up

  • “Supercritical CO₂”

    No evidence either way

    Not all commercial CO₂ decaf is supercritical. CR3's process is documented as subcritical liquid CO₂ at around 23 °C and 70–80 bar. If a bag names the plant and the state, check they match.

  • “Chemical free”

    Misleading

    CO₂ is regulated as an extraction solvent under the same directive as ethyl acetate. It leaves no residue, which is the meaningful claim — but it is not outside solvent regulation the way the water processes are.

  • “Organic compatible”

    Holds up

    Leaves no residue, so organic certification is retained.

Steamed beans go into a high-pressure vessel and CO₂ is pumped in above its critical point — 31.1 °C and 73.8 bar — typically running at 200 to 300 bar. In that state CO₂ diffuses through the bean like a gas but dissolves caffeine like a liquid, and it is highly selective: it barely touches the larger, less volatile flavour precursors, sugars and lipids.

Caffeine is stripped out of the CO₂ by a pressure drop or carbon filtration, and the CO₂ is recycled. The method was invented by Kurt Zosel at the Max Planck Institute für Kohlenforschung and patented in 1970.

Supercritical is not always the right word

CR3’s process in Bremen is documented as subcritical liquid CO₂ at around 23 °C and 70–80 bar rather than supercritical. Both work; they are not the same thing, and it is worth getting right if you name the plant on a bag.

Why you see so little of it

The real constraint on CO₂ is capital and energy cost, not flavour. High-pressure vessels are expensive to build and expensive to run. Germany is the best place in Europe to actually taste it, with two plants in the country.

Residual note

CR3's variant gets below 0.08% residual caffeine.

On the solvent

Listed alongside ethyl acetate in Annex I Part I of Directive 2009/32/EC. Leaves no residue and is organic-compatible.

In the cup

Best in class for body, lipids and mouthfeel. Reported to fare less well on very bright light roasts, where Swiss Water gives more vivid acidity.

Stated as a tendency, not a rule. No published head-to-head sensory comparison of the processes exists, so this is trade consensus plus tasting — and the green coffee and roast matter more than the process.

Questions

How does CO₂ decaffeination work?
Steamed beans go into a high-pressure vessel and CO₂ is pumped in above its critical point — 31.1 °C and 73.8 bar — typically at 200 to 300 bar. In that state CO₂ diffuses through the bean like a gas but dissolves caffeine like a liquid, and it barely touches the larger flavour precursors, sugars and lipids.
Who invented CO₂ decaffeination?
Kurt Zosel at the Max Planck Institute für Kohlenforschung, patented in 1970.
Why is CO₂ decaf rare?
Capital and energy cost, not flavour. High-pressure vessels are expensive to build and run, so fewer plants exist and less coffee goes through them.

Sources

  • Coffee decaffeination processes

    Industry · Max-Planck-Institut für Kohlenforschung, 1970

    Does not say Not all commercial "CO₂ decaf" is supercritical. CR3's process is documented as subcritical liquid CO₂ at around 23 °C and 70–80 bar — a real distinction if you are naming the process on a bag.

  • Directive 2009/32/EC on extraction solvents used in foodstuffs

    Regulation · European Parliament and Council, 2009

    Does not say It does not certify any process. Swiss Water and Mountain Water fall outside it entirely because they use no extraction solvent — that is an exemption, not an endorsement.

Who sells CO₂ decaf