Quick answer: how is decaf coffee made?
Decaf coffee is made by taking caffeine out of green, unroasted coffee beans, then roasting them like any other coffee. The caffeine comes out with a solvent (methylene chloride or ethyl acetate), with water alone, or with carbon dioxide under high pressure. In the United States the FDA requires at least 97% of the caffeine to be removed, according to Wikipedia.
| Fact | Figure | Source |
|---|---|---|
| When caffeine is removed | Before roasting, from green beans | NCA |
| U.S. standard | At least 97% of caffeine removed | Wikipedia (FDA) |
| European Union standard | 99.9% caffeine-free by mass | Wikipedia |
| Caffeine in an 8 oz cup | About 2 to 15 mg in decaf, against 95 mg in regular coffee | NCA |
| Swiss Water processing time | 8 to 10 hours to reach the residual caffeine target | Wikipedia |
The basic steps
The National Coffee Association describes the most common approach, which it calls the European Method, in five steps:
- The green beans are steamed.
- They are rinsed with a liquid solvent that bonds to the caffeine and carries it out.
- The caffeine-laden solution is drained off.
- The caffeine is extracted from that solution for other uses.
- The beans are dried, then roasted.
The solvent is either methylene chloride (Wikipedia uses the chemical name dichloromethane) or ethyl acetate. Oregon roasters who use ethyl acetate label their decaf sugarcane process or EA.
The water and CO2 methods swap the solvent for something else but keep the same shape: work on green coffee, pull the caffeine, dry, roast. Every method starts with green coffee.
The methods side by side
| Method | What pulls the caffeine | What to know |
|---|---|---|
| Methylene chloride (direct solvent) | Dichloromethane | One of the solvents that replaced benzene, per Wikipedia |
| Ethyl acetate (sugarcane, EA) | Ethyl acetate | Labeled sugarcane process or EA by Oregon roasters |
| Swiss Water | Water only, no organic solvents | Developed in Switzerland in 1933, commercialized in 1980, introduced from Burnaby, British Columbia, in 1988 |
| Mountain Water | Water | Named by several roasters; we found no independent source for the details, so we say no more |
| Supercritical CO2 | Carbon dioxide at 300 atmospheres and 65 °C (149 °F) | At those conditions CO2 behaves partly like a gas and partly like a liquid |
Our glossary has a short entry for each: Swiss Water Process and sugarcane process are the two you will see most on specialty bags.
Where decaf came from
The first commercially successful decaffeination process came from the German merchant Ludwig Roselius and his co-workers in 1903, after a shipment of beans soaked in seawater turned out to have lost caffeine, according to Wikipedia. It was patented in 1906. It steamed the beans with acids or bases and used benzene to remove the caffeine. Solvents such as dichloromethane and ethyl acetate replaced benzene later.
The water-only route came later. A method developed in Switzerland in 1933 was commercialized by Coffex S.A. in 1980 and introduced by The Swiss Water Decaffeinated Coffee Company of Burnaby, British Columbia, in 1988.
How much caffeine is left in decaf
A little, and it varies. The NCA puts a cup of decaf at about 2 to 15 mg of caffeine per 8 ounces, against 95 mg for regular coffee. Wikipedia cites a 2006 study that found decaf drinks held 1 to 2% of the original caffeine as a rule, but sometimes as much as 20%, and one study measured 8.6 to 13.9 mg in a 473 ml cup. Another survey of popular decaf brands found 3 to 32 mg.
So decaf is low caffeine, not zero caffeine. If you need none at all, ask your doctor, not a coffee label.
What Oregon roasters use
Seven Oregon roasters we list name a decaf method on their own pages, as checked on 2026-09-27. Case Study sells a Mountain Water Process decaf from Mexico, and Roseline describes its decaf subscription as mountain water processed. Sterling and Dapper & Wise both sell a sugarcane process decaf from Colombia. Lone Pine in Bend lists its Decaf Colombia as Rainbow EA process. Noble in Ashland and Water Avenue in Portland call their decafs water processed without naming a brand.
None of them named Swiss Water when we checked. Several more, from Coava to Sisters Coffee, sell a decaf without stating the method at all. The decaf itself gets the same care as the rest of the menu: Sterling roasts its sugarcane decaf a touch longer than its light roasts for a more traditional cup.
Buying decaf from an Oregon roaster keeps the money with a Portland, Hillsboro, Bend or Ashland business. Our decaf subscription sends a 12 oz bag of decaf from a different independent Oregon roaster each box, at the same $16.99 a bag as everything else. More on why local roasters matter.
Decaf questions
Is decaf coffee made with chemicals?
Some is and some is not. The European Method uses a solvent, methylene chloride or ethyl acetate. The Swiss Water Process uses water only, and the CO2 method uses carbon dioxide.
Does decaf have any caffeine?
Yes, a little. The NCA puts it at about 2 to 15 mg per 8 ounce cup, against 95 mg in regular coffee.
Is decaf roasted differently?
It is roasted after decaffeination like any green coffee, and some roasters adjust the roast. Sterling in Portland roasts its sugarcane decaf a little longer than its light roasts.
How do I know which method a decaf used?
Read the bag or the roaster's product page. Seven of the Oregon roasters we list name the method; the rest do not, so ask at the counter.
Sources
- Wikipedia: Decaffeination (Roselius, solvents, Swiss Water dates and hours, CO2 conditions, U.S. and EU standards, residual caffeine studies)
- National Coffee Association, About Coffee: Decaf coffee (green beans, the European Method, caffeine per cup, the FDA risk finding)
- Oregon roaster decaf methods: each roaster's own pages, checked 2026-09-27.