The decaf atlas.

Caffeine is water-soluble, so every decaffeination method begins the same way — the bean is opened up with water or steam. The methods differ only in what carries the caffeine away afterwards: more water, a naturally derived solvent, a synthetic solvent, or pressurised carbon dioxide.

Solvent-free means no chemical ever touches the bean: Swiss Water, Mountain Water, supercritical CO₂. Naturally derived solvent means ethyl acetate fermented from sugarcane — a compound that already occurs in ripe fruit and in coffee itself. Synthetic solvent means methylene chloride or petrochemical ethyl acetate, both legal, both tightly limited by residue law, and both increasingly avoided by specialty roasters for reasons that are as much about story as about safety.

If you remember one thing: sugarcane EA and Swiss Water are the two processes that consistently produce decaf worth drinking as specialty coffee. Everything below is the long version.

Green coffee is soaked in hot water, which pulls out caffeine and everything else that makes coffee taste like coffee. That water is passed through proprietary carbon filters sized to catch caffeine molecules and let flavour molecules through. What remains is a caffeine-free, flavour-saturated extract, and the next batch of beans is soaked in that. Because the extract is already full of flavour compounds, only the caffeine has anywhere to go.

No solvent, certifiable organic, and the cleanest reputation in the trade. It is also the most expensive, and the intellectual property sits with one company in Canada.

A Mexican water process built on the same principle — water extraction plus caffeine-selective filtration — but developed independently of Swiss Water and run at Descamex in Veracruz. Water from the glaciers of Pico de Orizaba gives the process its name.

Solvent-free, organic-compatible, and slightly cheaper. In the cup it tends to read a touch rounder and softer than Swiss Water, with a little less acidity.

Colombian sugarcane is fermented into ethyl acetate, the same ester that gives ripe fruit its lift. Steamed beans are washed with it, the EA binds the caffeine, and the beans are steamed again so the solvent evaporates off. It is a solvent process, but the solvent is bio-derived and volatile enough to leave essentially nothing behind.

This is the method that changed specialty decaf. It happens at origin, so the coffee never leaves Colombia to be processed, and it tends to add a distinctive sweetness — cane sugar, red fruit, a slightly syrupy body. Many roasters, ourselves included, consider it the most characterful decaf available.

Push carbon dioxide past roughly 31 °C and 73 atmospheres and it becomes a supercritical fluid: it penetrates like a gas and dissolves like a liquid, and it is remarkably selective for caffeine. The caffeine is then scrubbed out of the CO₂ with water and the gas is recycled. The process was patented by Kurt Zosel at the Max Planck Institute in the 1970s.

No residue, excellent flavour retention, and enormous capital cost. It only makes economic sense at industrial volume, which is why you find it inside large German plants and almost never on a single microlot.

Dichloromethane is soaked directly onto steamed beans, or used to strip caffeine out of a water solution the beans were soaked in first, after which the beans are steamed to purge the solvent. It is the cheapest method and, historically, the one many tasters rated highest for flavour, because DCM is unusually caffeine-selective.

It is also the reason decaf acquired a bad name. Residues in roasted coffee are capped at 10 ppm by the FDA, and roasting temperatures drive off far more than that; the practical residue is vanishingly small. Nevertheless, a petition to withdraw the approval has been under review in the United States, California has restricted DCM more broadly, and the specialty trade has largely moved on. We do not buy it.

Enzymatic and microbial decaffeination — using proteases such as bromelain from pineapple peel, or bacteria that demethylate caffeine — appear regularly in university papers, particularly on Indonesian robusta. They promise a cheap, solvent-free route with excellent aroma retention.

None of it is commercial. If someone sells you 'enzyme decaf' today, ask which plant made it, because as far as we can establish, no such plant exists.

Decaffeination is capital-intensive, so it concentrates. Canada has one plant that matters. Mexico has Veracruz. Colombia has Manizales. Germany has Bremen. Italy has Trieste. Vietnam has two facilities serving the robusta and instant trade. Almost every decaf you have ever drunk came out of that short list.

The index above sets out each facility, its method, and a plain assessment. Where a claim could not be verified from the plant's own materials or credible trade reporting, we say so rather than guess. Several widely repeated 'facts' about decaf plants — a Swiss Coffex line still running in Zurich, an American specialty decaf plant, an enzymatic facility — did not survive checking.

A good decaf bag names the process and the plant. 'Sugarcane EA, Descafecol, Manizales' tells you everything. 'Naturally decaffeinated' tells you nothing at all — it is a marketing phrase with no regulatory meaning, and it is used for both water and EA processes.

Then look for the same things you would want on any specialty coffee: producer, farm, altitude, variety, harvest, roast date. Decaffeination is a step in the chain, not a substitute for the chain. A washed Huila at 1,800 masl that went to Manizales is a specialty coffee; an anonymous blend that went to the same plant is still an anonymous blend.

Finally, buy it fresh and grind it fine. Decaffeinated beans are more porous and more fragile than caffeinated ones — they stale faster, they roast faster, and they need a slightly finer grind to extract properly. Give a decaf the same 16 g to 250 ml at 92 °C you would give anything else, then tighten the grind one notch.

We roast one decaf: Zenafina, a Castillo from Risaralda, Colombia, grown at 1,500 to 1,700 masl, washed and then decaffeinated with sugarcane ethyl acetate in Colombia. It cups 86, it is roasted light like everything else we make, and the process is printed on the bag rather than hidden behind the word 'naturally'.

This atlas exists so you can buy a good decaf from anyone at all — including people who are not us.