Four methods, one goal: the caffeine must come out of the bean, everything else should stay in. How well this succeeds determines the taste, the price, and whether measurable solvent residues end up in the cup. We spoke with decaffeinator CR3 in Bremen, reviewed patents and limit values, and found an error that appears in almost every article on the topic.
Decaffeination is always done on raw coffee, never on roasted. Four extraction agents are in use: dichloromethane, ethyl acetate, water, and CO₂. The difference between them lies in selectivity, not in marketing names. And decaffeinated doesn't mean caffeine-free: a decaffeinated espresso contains 3 to 15.8 milligrams of caffeine.
What all methods have in common during production
Decaffeination is always done on raw coffee, that is, the green bean before roasting. There is no industrial process that decaffeinates roasted coffee.
Meike Holtmann works at ANKA, the research and innovation subsidiary of CR3, on exactly these processes. She describes four steps that are the same for all methods:
The difference between methods lies in the second step, and there in three variables: temperature, pressure, and time. Holtmann calls it "the operating mode of the entire process".
Selectivity means: how targeted an extraction agent goes after caffeine and leaves everything else alone. A less selective agent also pulls out fats, acids, and aroma compounds. This is the real reason why some decafs taste flat.
Dichloromethane: nine hours and the best price-to-performance ratio
Dichloromethane, or DCM or methylene chloride, is the most common method worldwide. The reason is simple: it works better than anything else. Holtmann calls DCM "the most efficient extraction agent for caffeine".
Pressure, temperature, and target value according to the original patent by Procter & Gamble from 1971. There, beans are pre-moistened to 41 to 50 weight percent water, with a solvent-to-bean ratio of 3:1 to 5:1.
Short process time means low energy consumption, and that directly affects the price. Holtmann: "The price-to-performance ratio works out."
What surprises many: DCM is not the most aggressive, but rather a gentler agent.
"It's relatively selective for caffeine as well. Not many co-extracts come out."
If you put in good green coffee quality, you retain plenty of aroma. Only we haven't yet tasted a specialty coffee decaffeinated using the DCM method. That's probably also because it's a chemical process and market acceptance is limited.
In the indirect DCM process, the solvent never touches the bean. The coffee is soaked in hot water, the caffeine goes into the water, and only this water is treated with DCM. Afterward, the aroma compounds return to the bean with the water. We found no documented figures for temperatures and times of this variant.
How much dichloromethane remains in the coffee? 34 products tested
A working group tested 2024 34 commercially available decaffeinated roasted coffees from EU retail, using headspace-GC-MS. The results:
| Measurement | Value |
|---|---|
| Range in roasted coffee | 5.7 to 816.6 µg/kg |
| Mean value | 127 µg/kg (0.127 mg/kg) |
| Median | 59.5 µg/kg (0.060 mg/kg) |
| Legal maximum EU | 2 mg/kg (2,000 µg/kg) |
| Legal maximum USA | 10 mg/kg (10 ppm) |
| Transfer to beverage, filter coffee | Median 26.8 percent |
| Transfer to beverage, French press | Median 43.1 percent |
Fabian, Süße-Herrmann, McGaffin & Hielscher (2024), Proceedings 109(1), 33. Limit values: EU Directive 2009/32/EG Annex Part II, 21 CFR 173.255.
Three things are now clear. First: DCM is detectable in finished coffee, the statement "nothing remains after roasting" is too sweeping. Second: the highest measured single value is about 41 percent of the limit, the median about three percent. Third, a quarter to slightly more than two-fifths of the residue ends up in the cup, and the French press transfers significantly more than the paper filter.
Holtmann says about the residues: "The prescribed maximum amounts are undercut by a hundredfold." The median of the study is about a factor of 34, the mean about 16. That order of magnitude fits, but individual values vary considerably.
Pure caffeine at Descamex, Córdoba, Mexico
Why the topic is stirring up interest right now, once again
Since 2017, the International Agency for Research on Cancer (IARC) has listed dichloromethane in Group 2A, meaning "probably carcinogenic to humans". In the USA, since November 2023, an application from several environmental and health organizations seeks to remove methylene chloride from food approval. The FDA reopened the comment period on May 28, 2026, and closed it on June 29, 2026; no decision has been made to date. In the EU, we found no comparable initiative.
Ethyl acetate, the sugarcane process
Ethyl acetate goes by two names. The technical one is ethyl acetate, the prettier one Sugarcane Process. Both refer to the same molecule.
"Industrially it's used in synthetic form. But it's also present in traces naturally in sugarcane, in sugar beets, or also in fruit, and can also be produced from natural components. And that's why it carries this name Sugarcane Processing."
Technically, ethyl acetate behaves similarly to DCM, with one difference: "It's not quite as selective for caffeine as dichloromethane. So process times are slightly longer." At Descafecol in Manizales, the decaffeination facility in Colombia, the solvent cycles run for about eight hours according to the process diagram, after a half hour of steaming.
Cycles and steaming time according to Descafecol's process diagram, Manizales. The 20 ppm residue specification is a voluntary statement from Descafecol; Cafe Imports states a maximum of 10 ppm in their process diagram.
The legal situation is the real difference. Unlike dichloromethane, there is no numerical EU maximum value for ethyl acetate. It's listed in Part I of the Annex to Directive 2009/32/EG, that is, among the solvents permitted for all purposes under good manufacturing practice.
The most interesting set of numbers for this method comes from a 1999 review and shows what decaffeination costs:
| Condition | Duration | Caffeine removed | Loss of soluble solids |
|---|---|---|---|
| Room temperature, 27 degrees | 8 h | 37 to 39 % | 9 to 10 % |
| Room temperature, 27 degrees | 14 h | 42 to 44 % | 14 to 15 % |
| With hot water circulation | 8 h | 62 to 64 % | 34 to 36 % |
| With hot water circulation | 16 h | 78 to 80 % | 40 to 42 % |
Ramalakshmi & Raghavan (1999), Critical Reviews in Food Science and Nutrition 39(5), Table 5. Laboratory conditions, not industrial parameters.
The water methods: why water alone doesn't work
The most obvious idea is also the wrong one. If you put coffee beans in hot water, caffeine dissolves, but so does everything else. You end up with a cup of coffee and a tasteless bean.
The water methods solve this with a trick. Holtmann: "The coffee bean is extracted with hot water or with hot caffeine-free green coffee extract." This extract is saturated with all soluble coffee components, just without caffeine. From the bean, essentially only caffeine can therefore migrate out; everything else stays in because the solution is already full of it.
The caffeine-laden extract then flows over adsorber filters. "From these adsorber filters comes out a caffeine-free but aroma-rich extract." The cycle begins again.
"We've found that the filters we use there also have lower affinity for co-extracts, which has a very positive effect on the aroma of the decaffeinated coffee because we have fewer losses there."
Two suppliers carry the water methods in their names. Swiss Water in Delta, British Columbia, works with green coffee extract and charcoal filters. Descamex in Córdoba, Veracruz, calls its method Mountain Water Process.
Values from a 1980 patent for the water method with adsorption. Swiss Water and Descamex do not publish their own process data.
"99.9 % caffeine-free", well, sort of
Neither Swiss Water nor Descamex publishes temperatures, pressures, process times, or a decaffeination level. The widespread claim "99.9 percent caffeine-free" for the Swiss Water Process could not be traced to any primary source; it comes from a teaching document that itself refers to a blog. We therefore don't cite it as a fact.
The coffee we started with comes from such a method. Our Sueño from Mexico is decaffeinated with water at Descamex, the coffee comes from Rancho San Felipe.
Supercritical CO₂: from 31 degrees and 73.8 bar
Carbon dioxide is known as a gas and as dry ice. Above roughly 31 degrees and 73.8 bar, it becomes something else: supercritical. It then has the density of a liquid and the diffusion behavior of a gas, and in this state it dissolves caffeine.
Kurt Zosel invented this in Oberhausen; the patent was filed on February 5, 1970. It specifies 40 to 80 degrees, 120 to 180 atmospheres, a water content of the beans of 15 to 30 percent, 5 to 15 hours of decaffeination, and residual caffeine below 0.01 percent. The core of the patent is a subtlety: only the moisture makes the supercritical CO₂ a medium that can take up caffeine.
At today's industrial scale, the values are higher. Holtmann mentions "extremely high pressures, 250 to 300 bar, and high temperatures of 60 to 80 degrees". A 2017 life cycle assessment study documents a facility with 250 bar and 90 degrees, five hours steaming, then 11.5 hours extraction for Arabica and 22 hours for Robusta, with 97 percent caffeine removal.
According to the Max Planck Society, supercritical CO₂ processes worldwide handle approximately 100,000 tons of green coffee per year. That's about one percent of the global harvest.
Subcritical CO₂: liquid at 70 bar, seven days process time
If you lower the pressure and temperature below the critical point, you get liquid CO₂. It's slower and more expensive, and precisely for that reason interesting, especially sensorially.
CR3 calls this method Carbonic Natural. Holtmann describes it this way: "The CO₂ is in a liquid state there and flows through the pretreated beans and is incredibly selective." After extraction, pressure is released, pressure drops from 70 bar to atmospheric pressure, and the caffeine precipitates from the CO₂. It's absorbed in a water stream, and the caffeine-free CO₂ goes back into the next batch.
Pressure, temperature, and residual caffeine according to a documented factory visit by Belco. There, 97 to 99 percent of the caffeine is extracted in the liquid CO₂ phase.
Sebastian Gabriel, Marketing and Sales at CR3, once explained it to us this way: CO₂ is "a lazy solvent".
Two points that matter in everyday practice. The CO₂ comes from natural spring carbonation, so the process is bio-certifiable. And: our Apas Decaf from Brazil is decaffeinated this way, as is our Dipilto Decaf from Nicaragua.
The triglyceride method: much claimed, little proven
In many articles there's a fifth method: the beans bathe in hot coffee oil, triglycerides in the oil pull the caffeine out.
We found no primary source for this. No patent, no peer-reviewed study, no manufacturer statement specifies temperature, duration, oil-to-bean ratio, or decaffeination level. We reviewed and ruled out three relevant patents regularly cited in the literature for this purpose, and they actually describe different methods.
The four methods in direct comparison
CO₂ appears twice in the table because it runs in two modes. The extraction agent remains the same.
| Method | Extraction agent | Duration | Pressure / Temperature | Selectivity | Cost |
|---|---|---|---|---|---|
| Dichloromethane (DCM) | Dichloromethane | approx. 9 h | 2–14 bar / 60–99 °C | high | low |
| Ethyl acetate (Sugarcane) | Ethyl acetate | approx. 8 h cycles | not published | medium | low to medium |
| Water (Swiss Water, Mountain Water) | Green coffee extract plus adsorber filter | not published | 50–100 °C (1980 patent) | high, filter-dependent | high |
| CO₂, supercritical | Supercritical CO₂ | 11.5–22 h | 250–300 bar / 60–90 °C | high | high |
| CO₂, subcritical (Carbonic Natural) | Liquid CO₂ | 6–7 days | 70–80 bar / 23 °C | very high | high |
"Not published" means: the value is not published by any manufacturer and not in any primary source.
What "decaffeinated" legally means, and why "EU limit 0.1 percent" is wrong
Precision is crucial: sentences like "in the EU, decaffeinated coffee can contain up to 0.1 percent caffeine" appear on every other page on the topic. They're not quite right.
The EU regulates with Directive 1999/4/EG exclusively coffee extracts, that is, instant coffee. There the limit is 0.3 percent anhydrous caffeine based on dry matter. For roasted coffee, we found no harmonized EU numerical value.
The 0.1 percent comes from national law:
| Jurisdiction | Roasted coffee | Instant coffee | Basis |
|---|---|---|---|
| Germany | max. 1 g caffeine per kg coffee dry matter, i.e., 0.1 % | max. 3 g/kg, i.e., 0.3 % | Coffee Ordinance, § 2 para. 3 |
| Switzerland | max. 0.1 mass percent, based on dry substance | max. 0.3 mass percent | Federal Department of Home Affairs Ordinance on Beverages |
| EU | no harmonized value found | 0.3 % | Directive 1999/4/EG |
Practically, this changes nothing for you as a drinker: in Germany and Switzerland the same value of 0.1 percent applies.
What ends up in the cup
The limit value says nothing about how much caffeine you actually drink. For that, measurements of the beverage are needed.
The reference study is from 2006. Ten filter coffee decafs from nine chains and local cafés ranged from 8.6 to 13.9 mg caffeine per 473 ml. Decaffeinated espresso came in at 3 to 15.8 mg per shot.
For background: green coffee contains roughly one percent caffeine in Arabica and roughly two percent in Canephora. A 2020 study gives ranges of 0.8 to 1.4 percent for Arabica and 1.7 to 4.0 percent for Robusta. Roasting changes this barely, because caffeine is heat-stable.
What this residual caffeine does in your body is a separate question. How long caffeine works, how quickly it's broken down, and when it disrupts sleep, we've written up separately.
Bremen as the caffeine capital
"Decaffeination was invented in Bremen. Many people don't know that. And you can basically say Bremen is still the caffeine decaffeination capital of the world."
Both are true, with a clarification. The patent "Preparation of coffee" was filed on May 4, 1906, and granted on September 1, 1908. It bears three names: Johann Friedrich Meyer Jr., Ludwig Roselius, and Karl Heinrich Wimmer. Roselius is listed almost everywhere as the sole inventor, but he is not.
And the solvent was indeed benzene, literally in the patent: "We have found that benzene (also called benzol) is eminently suitable for this purpose." Kaffee HAG was founded the same year, 1906. The widespread anecdote that Roselius got the idea from a coffee shipment that was damaged by seawater sounds adventurous, but perhaps a bit too adventurous. I haven't found a reliable source for it yet.
As for the world capital: the Coffein Compagnie in Bremen, according to its own statements, processes around 120,000 tons of green coffee annually across five facilities and calls itself the world market leader. Additionally, CR3 is also located in Bremen. There is no independent global capacity ranking because Descamex, Descafecol, Demus, and Swiss Water don't publish their capacities.
Which method makes the best coffee?
Stacey Linden from Swiss Water told me something to this effect in a conversation for the main article:
The decaffeination process leaves a sensory footprint, more or less depending on the method. We find it interesting whether this sensory change is a flaw, or whether it can add a new quality.
Fast and cheap methods like DCM, in our view, leave a soy-like character. Water methods can leave a malty taste in flatter coffees. Ethyl acetate can increase acidity, while the subcritical CO₂ method can slightly mute the coffee.
If you know that as an importer or roaster, you then select the right green coffee for the right method, and this way a new, sensorily interesting product can emerge.
Decaffeination as quality improvement of poor green coffee?
We asked Meike Holtmann whether it's true that poor qualities used to be decaffeinated primarily. Her answer: "I don't perceive that here on our premises these days. A large portion of the coffees we sell here as green coffee have good, sometimes even very good sensory quality." The low qualities, called "bird feed or muesli coffees" affectionately in-house, are extremely rare.
Her observation about the effect is interesting: "With impure qualities, you sometimes actually perceive it as an improvement of the coffee." Less so with good qualities. So the process smooths things out, which helps poor green coffee and costs good coffee something.
Anyone wanting to judge decaf needs to know both: the green coffee quality and the method used. More on taste, faster aging, and why decaf extracts differently is in the main article on decaffeinated coffee.
For further listening
Conclusion
Four methods, and none is categorically the best. Dichloromethane is fast, cheap, and more selective than its reputation suggests, but leaves measurable residues and is under regulatory scrutiny. Ethyl acetate is similarly fast, somewhat less selective, and regulated more loosely legally. The water methods avoid solvents entirely but publish hardly any process data. CO₂ in its subcritical mode is the slowest and most expensive method and, according to CR3, the most selective.
You'll find our decaffeinated coffees in the decaf collection, each with the method indicated.
Sources
Conversations
Meike Holtmann, Research and Innovation, ANKA (research and innovation subsidiary of CR3), Bremen.
Sebastian Gabriel, Marketing and Sales, CR3 Kaffeeveredelung, Bremen.
Stacey Linden, Swiss Water, Delta, British Columbia.
Studies and reviews
Fabian, Süße-Herrmann, McGaffin & Hielscher (2024): Dichloromethane residues in decaffeinated roasted coffees, Proceedings 109(1), 33.
Ramalakshmi & Raghavan (1999): Critical Reviews in Food Science and Nutrition 39(5), Table 5.
McCusker, Fuehrlein, Goldberger, Gold & Cone (2006): Caffeine Content of Decaffeinated Coffee, Journal of Analytical Toxicology 30(8), 611–613.
Gaibor, Morales & Carrillo (2020): Determination of Caffeine Content in Robusta Roasted Coffee (Coffea canephora) by RP-UHPLC-PDA, Asian Journal of Crop Science 12(2), 90–96.
De Marco, Riemma & Iannone (2017): Supercritical Carbon Dioxide Decaffeination Process, a Life Cycle Assessment Study, Chemical Engineering Transactions 57, 1699–1704.
Patents
Meyer Jr., Roselius & Wimmer: "Preparation of coffee", filed May 4, 1906, granted September 1, 1908.
Zosel: Process for decaffeination with supercritical CO₂, filed February 5, 1970.
Procter & Gamble: Decaffeination with dichloromethane, 1971.
Water method with adsorption, 1980.
Law
Coffee Ordinance, § 2 para. 3 (Germany).
Directive 2009/32/EG on extraction solvents, Annex Part I and Part II.
Directive 1999/4/EG on coffee extracts.
Federal Department of Home Affairs Ordinance on Beverages (Switzerland).
Ordinance on technical regulations for food products, VTVV, Annex 1 (Switzerland).
21 CFR 173.255 (USA).
Additional information
IARC Monographs: Classification of dichloromethane in Group 2A, 2017.
FDA, Proceeding to delist methylene chloride from food approval, ongoing since November 2023.
Max Planck Society, statements on the supercritical CO₂ method.
Process diagrams from Descafecol (Manizales) and Cafe Imports.
Documented factory visit by Belco at CR3.
Coffein Compagnie, Bremen, own statements on processing volume.
