THE PROCESS IN MOTION

Direct solvent: the solvent bathes the bean, the evaporator takes the caffeine back from it

The name comes from this: methylene chloride or ethyl acetate, between 40 and 70 °C, bathes the bean itself, eight to twelve passes. Follow the solvent: it leaves loaded with caffeine for the evaporator, which keeps the caffeine, and returns clean to its tank. Start the scene or choose a step.

▶ Play the process01Moisten the green bean02The solvent bathes the bean, eight to twelve times03The evaporator keeps the caffeine04Drive off the solvent, then dry05The rest goes off in roasting

Moisten the green bean

The green bean is first moistened in baths, until its water content has risen by at least 30%, or simply steamed to open its pores and break the salt that holds the caffeine.

Read the stages without animation

1. Moisten the green beanThe green bean is first moistened in baths, until its water content has risen by at least 30%, or simply steamed to open its pores and break the salt that holds the caffeine.
2. The solvent bathes the bean, eight to twelve timesMethylene chloride or ethyl acetate, heated between 40 and 70 °C, bathes the bean itself in repeated cycles, eight to twelve passes. That is the meaning of the word direct: the solvent touches the bean, with no intermediary. It stops when the regulatory threshold is reached, not before.
3. The evaporator keeps the caffeineThe loaded solvent goes to the evaporator. It boils there, the caffeine stays at the bottom, and the solvent leaves clean for its tank, ready for the next pass. This is the station the other processes lack, and it is where the caffeine resold to the pharmaceutical and beverage industries comes from.
4. Drive off the solvent, then dryCleaning comes next, in three stages. Steaming drives off the solvent, then drying brings the bean back to its original moisture.
5. The rest goes off in roastingRoasting volatilizes what remained: dichloromethane boils at 40 °C, and the bean exceeds 200 °C on the probe during the last minutes of roasting. The residue is capped, 10 ppm in the United States, 2 mg/kg in roasted coffee in Europe, and actual measurements often fall around 1 ppm.

To remember: The solvent touches the bean itself: it is the cheapest and fastest process, and its residue is counted in ppm.

In history: The process was born in Bremen in 1905; it has used methylene chloride or ethyl acetate since the 1970s and 1980s.

Read the full article and its sources ↓

Direct solvent, called the “European method” or “traditional” on labels (Bremen, 1905; methylene chloride or ethyl acetate since the 1970s and 1980s). The name comes from this: the solvent touches the bean itself, with no intermediary.

The green bean is first moistened in baths, until its water content has risen by at least 30%, or simply steamed to open its pores. The solvent, heated between 40 and 70 °C, then bathes it in repeated cycles, eight to twelve passes. It stops when the regulatory threshold is reached, not before.

The loaded solvent does not go down the drain: it passes into an evaporator, where it is distilled to be used again, and the caffeine stays at the bottom, concentrated. A Procter & Gamble patent, filed in 1982 for ethyl acetate, describes this station in so many words. This caffeine is not lost: in both solvent variants, it is recovered and sold to makers of medicines and carbonated drinks.

Cleaning comes next, in three stages. Steaming drives off the solvent, drying brings the bean back to its original moisture, and roasting volatilizes the rest. The temperatures are more than enough: dichloromethane boils at 40 °C, and the bean exceeds 200 °C on the probe during the last minutes of roasting.

Advantages: it is the cheapest, the fastest, and it remains selective for caffeine. Juries often judge its cup the closest to the original coffee, among the solvent processes.

Drawbacks: a measurable residue, an image that has become difficult, and worker exposure, which is the real reason for the American ban of 2024. The residue is capped on both sides of the Atlantic: FDA limit of 10 ppm, European limit of 2 mg/kg in roasted coffee under directive 2009/32/EC. Actual measurements often fall around 1 ppm. Craft roasters rarely use it.

professional training document, Caféine et procédés de décaféination, p. 2; Wikipedia, Decaffeination, accessed on 09/07/2026; Coffee Review, solvent method; directive 2009/32/EC, annex I; US patent 4,474,821 (Morrison and Phillips, Procter & Gamble, filed December 27, 1982, issued October 2, 1984), for the evaporator; Kenneth Davids, Fun without the Buzz: Decaffeination Processes and Issues, Coffee Review, 07/16/2002, for the resold caffeine

THE PROCESS IN MOTION

Indirect solvent: the solvent circulates in a closed loop

Same chemistry as the direct solvent, but look at the loop of the treatment tank: it never leaves its tank. The solvent will never see the bean. Start the scene or choose a step.

▶ Play the process01Soak the bean in almost boiling water02The water leaves, the bean stays03The solvent works on the water, without leaving it04The water gives its solubles back to the bean

Soak the bean in almost boiling water

The bean soaks for several hours in water close to boiling. It is the water that touches the bean, and it becomes charged with caffeine and solubles, that is, with the flavor compounds.

Read the stages without animation

1. Soak the bean in almost boiling waterThe bean soaks for several hours in water close to boiling. It is the water that touches the bean, and it becomes charged with caffeine and solubles, that is, with the flavor compounds.
2. The water leaves, the bean staysThe charged water is transferred to a second tank. The bean itself does not move.
3. The solvent works on the water, without leaving itThe solvent picks up the caffeine from the water, then is separated from it. Its loop stays closed on its tank: it never touches the bean. The chemistry is the same as in the direct process.
4. The water gives its solubles back to the beanThe water returns to the bean, which reabsorbs its solubles; the same bath is used from lot to lot until equilibrium is reached. The oils and flavor compounds stay with the bean and the residues are lower, but the process is longer and requires more water and energy.

To remember: The solvent works on the water, never on the bean: that is the whole difference from the direct process, not its chemistry.

In history: A variant developed after the war.

Read the full article and its sources ↓

Indirect solvent (variant developed after the war, same chemistry). The bean soaks for several hours in water close to boiling, which becomes charged with caffeine and solubles; the water is transferred, treated with the solvent, which picks up the caffeine, separated from the solvent, then returned to the bean so that it reabsorbs its solubles; the solvent never touches the bean. The same bath is used from lot to lot until equilibrium is reached. Advantage: the oils and flavor compounds stay with the bean, lower residues. Drawback: longer, more water and energy, and the same solvent on the label.

Coffee Review, Decaffeinated coffee: solvent method; Wikipedia, Decaffeination, accessed on 09/07/2026

THE PROCESS IN MOTION

Swiss Water Process: one tank, one carbon column, nothing else

No evaporator, no pump, no second solvent. The water is not used to wash the bean, it is used to take nothing else from it: from the fourth stage on, a single dot of color passes through the pipe that leaves the tank, the caffeine. Start the scene or choose a step.

▶ Play the process01Making the water comes first02Clean and pre-soak the bean03A bath saturated with everything but caffeine04Caffeine alone migrates05The carbon traps it, the bath returns

Making the water comes first

A first lot of green beans soaks in hot water, which takes from it its solubles and its caffeine. Those beans are thrown away. The water passes over carbon so that its caffeine is removed: what remains is a green coffee extract, saturated with everything except caffeine.

Read the stages without animation

1. Making the water comes firstA first lot of green beans soaks in hot water, which takes from it its solubles and its caffeine. Those beans are thrown away. The water passes over carbon so that its caffeine is removed: what remains is a green coffee extract, saturated with everything except caffeine.
2. Clean and pre-soak the beanThe real lot arrives. The bean is cleaned, stripped of its silverskin, then pre-soaked to swell.
3. A bath saturated with everything but caffeineIt is bathed in a green coffee extract, the GCE of the labels: a water already saturated with all the solubles of coffee, except caffeine. Here the water is the solvent, and it touches the bean; the process uses no other.
4. Caffeine alone migratesA soluble already present in quantity in the water has no reason to leave the bean, since the two media are at equilibrium. Caffeine, on the other hand, is missing from the water: it alone migrates to the extract, by diffusion, while the other compounds stay in place.
5. The carbon traps it, the bath returnsThe extract passes over activated carbon filters that trap the caffeine, then returns to the bath. The cycle lasts eight to ten hours and removes 99.9% of the caffeine. The classic criticism: the bean loses some of its aroma precursors in the first baths.

To remember: The bath already contains everything except caffeine: equilibrium holds the flavor in the bean, the carbon holds the caffeine.

In history: Technique conceived in Switzerland in 1933, marketed by Coffex S.A. in 1980, introduced in North America in 1988, in Burnaby.

Read the full article and its sources ↓

With water, Swiss Water Process (technique conceived in Switzerland in 1933, marketed by Coffex S.A. in 1980, introduced in North America in 1988 by the Swiss Water Decaffeinated Coffee Company of Burnaby, British Columbia).

The bean is cleaned, stripped of its silverskin, then pre-soaked to swell. It is then bathed in a “green coffee extract,” the GCE of the labels: a water already saturated with all the solubles of coffee, except caffeine.

This extract has to be made first. A first lot of green beans soaks in hot water, which takes from it both its caffeine and its flavor compounds; this starter lot is thrown away. The water, stripped of its caffeine on activated carbon, becomes the extract that will serve for all the following lots.

The whole trick lies in this “except.” A soluble already present in quantity in the water has no reason to leave the bean, since the two media are at equilibrium. Caffeine, on the other hand, is missing from the water. It alone therefore migrates to the extract, by diffusion, while the other compounds stay in place. The extract then passes over activated carbon filters that trap the caffeine, then returns to the bath.

The cycle lasts eight to ten hours and removes 99.9% of the caffeine. The training document describes the same osmosis principle in ten successive baths, each removing half of the remaining caffeine, down to 0.01-0.02%.

Advantages: no solvent, possible organic and kosher certification, and a marketing argument that has become the strongest on the market.

Drawbacks: the bean loses some of its aroma precursors in the first baths, the cost is higher, and industrial capacity is concentrated at two Canadian sites. Aroma loss is the classic criticism of the process. The “Mountain Water” of Mexico, developed by Sanroke, claims to correct it by filtering the caffeine out of the water before reusing it.

Wikipedia, Decaffeination, accessed on 09/07/2026; Swiss Water, Our coffee decaffeination process, swisswater.com, accessed on 09/07/2026; professional training document, Caféine et procédés de décaféination, p. 3; Kenneth Davids, Fun without the Buzz: Decaffeination Processes and Issues, Coffee Review, 07/16/2002, for the discarded first lot

THE PROCESS IN MOTION

Supercritical CO₂: a pump, and the same gas in two states

The station the others lack is the pump. Above 31 °C and 73.8 bar, carbon dioxide penetrates like a gas and dissolves like a liquid: follow its color. Start the scene or choose a step.

▶ Play the process01CO₂ in the chamber, and nothing else02The pump passes the critical point03The same gas, and this time it carries off04Wash the gas, then send it back

CO₂ in the chamber, and nothing else

The green bean, moistened with steam, is placed in a chamber where the CO₂ circulates. The moistening is done beforehand: there is no steam in the chamber. As long as it remains a gas, the CO₂ penetrates the bean, but it does not dissolve like a liquid.

Read the stages without animation

1. CO₂ in the chamber, and nothing elseThe green bean, moistened with steam, is placed in a chamber where the CO₂ circulates. The moistening is done beforehand: there is no steam in the chamber. As long as it remains a gas, the CO₂ penetrates the bean, but it does not dissolve like a liquid.
2. The pump passes the critical pointAbove 31 °C and 73.8 bar, carbon dioxide stops being plainly gas or plainly liquid: it becomes a supercritical fluid, which penetrates like a gas and dissolves like a liquid. Published settings vary by source; converted to bar and rounded, they range from 120 to 180 bar and 40 to 80 °C in the earlier patent cited by Zosel's American patent, which claims 120 to 250 bar and 40 to 100 °C, to 162 bar and 70 °C according to the Institute, and up to 300 bar and 65 °C elsewhere.
3. The same gas, and this time it carries offThe fluid becomes selectively loaded with caffeine: the aromas and chlorogenic acids stay in the bean. It carries the caffeine to a second tank.
4. Wash the gas, then send it backIt is washed with water or over carbon: the caffeine stays there, and is sold to the pharmaceutical and beverage industries. The gas is recirculated, so that the same charge serves lot after lot. The investment is heavy, and reserves the process for large volumes.

To remember: The pump makes the process: beyond the critical point, the same gas starts to dissolve, and it takes the caffeine.

In history: Kurt Zosel, Max Planck Institute for Coal Research, in Mülheim: observation in 1967, patent in 1970, industrial use in Bremen on the former Kaffee HAG site.

Read the full article and its sources ↓

With supercritical CO₂ (Kurt Zosel, Max Planck Institute for Coal Research, Mülheim; observation in 1967, patent filed in 1970, US patent 4,247,570 in 1981; used industrially in Bremen on the former Kaffee HAG site, which passed to Kraft).

Above 31 °C and 73.8 bar, carbon dioxide stops being plainly gas or plainly liquid. It becomes a supercritical fluid, that is, a state that combines both behaviors: it penetrates the bean like a gas and dissolves like a liquid. That is exactly what is asked of a decaffeination solvent, and it is worth going up to such pressures.

The green bean, moistened with steam, is placed in a chamber where the CO₂ circulates. Published settings vary by source; converted to bar and rounded, they range from 120 to 180 bar and 40 to 80 °C in the earlier patent cited by Zosel's American patent, which claims 120 to 250 bar and 40 to 100 °C, to 162 bar and 70 °C according to the Institute, and up to 300 bar and 65 °C according to the Wikipedia encyclopedia, which does not name the plant. The training document, for its part, gives 30.6 °C, a very high pressure, a gas washed with water then sent through again, and beans that “recover their components.”

The CO₂ becomes selectively loaded with caffeine. It is washed with water or over carbon in a second tank, then recirculated, so that the same charge of gas serves lot after lot. The recovered caffeine is sold to the pharmaceutical and beverage industries.

What remains in the bean has been measured. In a Japanese trial published in 2022, supercritical CO₂ treatment makes the caffeine fall and the trigonelline drop a little, but leaves the chlorogenic acids roughly intact, chlorogenic acid and its two isomers, cryptochlorogenic and neochlorogenic.

Advantages: a natural, non-toxic solvent, entirely eliminated, very selective, aromas preserved, and a continuous process.

Drawbacks: the investment is heavy, since high-pressure chambers are needed, which reserves the process for large volumes. These volumes exist: the Max Planck Institute estimates that the process today treats 100,000 tonnes of raw material a year, coffee and tea included.

Max-Planck-Gesellschaft, Coffee decaffeination processes, mpg.de, accessed on 09/07/2026; US patent 4,247,570 (Zosel, filed May 19, 1977, issued January 27, 1981; claims and reference to Austrian patent 290,962); professional training document, Caféine et procédés de décaféination, p. 3; Wikipedia, Decaffeination, accessed on 10/22/2026, for the roughly 300 bar and 65 °C; Honda, Takezaki, Tanaka, Fukaya and Goto, Journal of Oleo Science, 71(10), p. 1541-1550, 2022, DOI 10.5650/jos.ess22194, for the chlorogenic acids

THE PROCESS IN MOTION

Ethyl acetate (sugarcane process): the solvent comes from the neighboring field

Called “EA” or “sugarcane.” Chemically, it is a direct process: the acetate touches the bean. What changes is the sugarcane station, where the solvent comes from. Start the scene or choose a step.

▶ Play the process01The solvent comes from the field02Steam, then swell in hot water03Acetate baths until saturation04Drive off the solvent, dry under vacuum

The solvent comes from the field

The ethyl acetate used here is produced by fermentation of sugarcane, in Palmira. The solvent therefore comes from the neighboring field, and that is where the nickname “sugarcane” comes from.

Read the stages without animation

1. The solvent comes from the fieldThe ethyl acetate used here is produced by fermentation of sugarcane, in Palmira. The solvent therefore comes from the neighboring field, and that is where the nickname “sugarcane” comes from.
2. Steam, then swell in hot waterThe green bean is steamed at low pressure to remove its silverskin, then moistened with hot water until it swells. This swelling begins the hydrolysis of the caffeine-chlorogenate complex, that is, the breaking by water of the salt that holds the caffeine.
3. Acetate baths until saturationThe bean soaks in ethyl acetate baths, renewed until saturation. The solvent touches the bean itself, and leaves loaded with caffeine.
4. Drive off the solvent, dry under vacuumLow-pressure steam drives off the solvent, and vacuum drying brings the moisture back to 10 to 12%. Residual caffeine falls below 0.1% and the acetate below 20 ppm, the European limit being 20 mg/kg.

To remember: The acetate touches the bean; what distinguishes this process is where the solvent comes from: fermented sugarcane.

In history: Descafecol, in Manizales, processes most of the specialty decaf of this type; the plant was running at 75% of its capacity in the summer of 2025.

Read the full article and its sources ↓

With ethyl acetate from sugarcane, called “EA” or “sugarcane” (Descafecol, Manizales, Colombia, which processes most of the specialty decaf of this type; the ethyl acetate is produced there by fermentation of sugarcane in Palmira). The solvent therefore comes from the neighboring field, and that is where the nickname “sugarcane” comes from.

The green bean is first steamed at low pressure to remove its silverskin. It is then moistened with hot water until it swells. This swelling is not only a mechanical opening: it begins the hydrolysis of the caffeine-chlorogenate complex, that is, the breaking by water of the salt that holds the caffeine.

The bean then soaks in ethyl acetate baths, renewed until saturation. Low-pressure steam then drives off the solvent, and vacuum drying brings the moisture back to 10-12%. At the end of the chain, residual caffeine falls below 0.1% and ethyl acetate below 20 ppm; directive 2009/32/EC sets no numerical maximum residue for it, it allows it “in compliance with good manufacturing practice,” and the 20 mg/kg threshold in coffee targets two other solvents, methyl acetate and methyl ethyl ketone.

Advantages: a solvent naturally present in fruit, biodegradable and cheap, and a cup often judged fruity and soft. It is this cup profile that made its fortune in specialty coffee.

Drawbacks: the word “natural” here covers an industrial solvent, and ethyl acetate sometimes imprints a note of varnish or fermented fruit on light roasts. Above all, dependence on a single Colombian plant weighs on supply. Descafecol was running at 75% of its capacity in the summer of 2025.

Coffee Intelligence, What's happening with decaf?, 08/26/2025; Interamerican Coffee, Descafecol EA decaf from Cauca; DecafLife, Ethyl-acetate process; directive 2009/32/EC

Old or marginal processes. In 1922, Ukers described a whole graveyard of attempts. All of them run up against the same obstacle: pulling the caffeine off its salt without carrying off the rest of the bean.

• Ammonia and acidsVariants used to free the caffeine from its salt before extracting it.
• Chloroform, petroleum ether, alcohol, acetoneSo many solvents tried in direct extraction.
• Sodium salicylateUnder pressure, followed by steam distillation. Ukers judges the process “ingenious but costly.”
• Hubner processIt let the bean germinate under water at 15 °C before extracting it with water at 50 °C. According to Ukers, a simple aqueous extraction in disguise.
• Triglycerides, 1980sThe bean soaks in coffee water, then in hot coffee oil, whose triglycerides capture the caffeine. It made little headway.

The other route does not touch the bean but the plant: the selection of Laurina and the search for caffeine-free species. It remains anecdotal.

Whatever the process, the target is set by regulation, and the two shores of the Atlantic do not word it the same way. In the United States, the FDA requires at least 97% of the caffeine to be removed, hence an extraction rate. In Europe, what remains is measured: in France, at most 0.1% caffeine for decaffeinated roasted beans, according to decree no. 91-340 of April 3, 1991; throughout the Union, at most 0.3% of the dry matter for instant coffee extract, according to directive 1999/4/EC.

Something always remains, and it can be measured. A 470 mL cup of decaf, analyzed in 2006 by a Florida team, still contained 8.6 to 13.9 mg of caffeine. From one brand to another, the difference ranged from 3 to 32 mg.

Ukers 1922, ch. XVIII; Wikipedia, Decaffeination, accessed on 09/07/2026 (triglyceride process, FDA and EU thresholds, Florida study 2006); decree no. 91-340 of April 3, 1991, annex; directives 1999/4/EC and 2009/32/EC