Research · 11 sources
What I am basing this on
Every factual claim on this site traces back to something on this page — studies, EU regulation, and the plants' own process sheets. Each one lists what it found, and what it tends to get misread as saying.
Peer-reviewed research 03
Published and reviewed. The strongest claims on this site rest here.
The only widely cited direct measurement of caffeine in retail decaf. Ten outlets were sampled; decaffeinated brewed coffee measured 0–13.9 mg per 16 oz serving, and decaf espresso 3.0–15.8 mg per shot. It establishes that decaf is low-caffeine rather than caffeine-free, and that the variation between outlets is large enough to matter to anyone counting.
McCusker et al. 2006 · Journal of Analytical Toxicology 30(8):611, 2006 · Paywalled
The paper describing naturally caffeine-deficient arabica plants found in an Ethiopian germplasm collection in Brazil. The origin of the idea that a coffee plant could be decaf without processing.
Silvarolla et al. 2004 · Nature 429:826, 2004 · Paywalled
The measurement behind the Laurina caffeine figure. Establishes roughly 0.6% caffeine by dry weight against about 1.2% for standard arabica.
Baumann et al. 1998 · Phytochemistry 49(6), 1998 · Paywalled
Regulation 03
What the law actually requires — usually looser than the marketing implies.
The FDA's consumer guidance on caffeine. Gives 2–15 mg per 8 fl oz cup of decaf against 113–247 mg for a 12 fl oz regular coffee, and cites 400 mg a day as the level not generally associated with negative effects in healthy adults.
FDA · US Food and Drug Administration, 2024
The regulation that governs which solvents may be used to decaffeinate coffee sold in the EU, and at what residue levels. It is the document that decides whether "chemical free" on a bag means anything.
Directive 2009/32/EC · European Parliament and Council, 2009
Sets what may legally be sold as decaffeinated in the EU. The threshold is looser than most people assume, which is the single most useful thing to know when comparing a legal claim against a supplier claim.
Directive 1999/4/EC · European Parliament and Council, 1999
Industry and supplier sources 04
Suppliers and plants describing their own processes. Accurate about what they claim; not independent verification that the claim is met.
The plant's own description of the Mountain Water Process. Notable mainly for contradicting the figure that roasters print on Mountain Water bags.
Descamex · Descamex, 2026
The company's own description of its process and its caffeine guarantee. The primary source for the widely repeated 99.9% figure, and worth reading as what it is: a supplier guarantee about a proprietary process.
Swiss Water · Swiss Water Decaffeinated Coffee Inc., 2026
An importer's process sheet for sugarcane ethyl acetate decaffeination. The primary source for the 97% minimum removal figure and the 10 ppm residual ethyl acetate maximum.
Cafe Imports · Cafe Imports, 2023
The institutional record of supercritical CO₂ decaffeination, invented by Kurt Zosel and patented in 1970. Establishes the mechanism and the physical conditions the process depends on.
Max Planck Gesellschaft · Max-Planck-Institut für Kohlenforschung, 1970
Trade press 01
Useful, widely read, and not evidence. Cited where it is the only thing available, and labelled as such.
The only controlled look at how decaffeinated green behaves differently in the roaster and the grinder. Its finding runs directly against the standard shop-floor advice, which is why it matters.
Al-Shemmeri · Independent research write-up, 2023