What is decaf coffee? How caffeine is removed, and how to grind it

How much caffeine is in decaf?

Usually a few milligrams per cup. The FDA gives 2 to 15 milligrams for an 8-ounce cup, and Swiss Water gives a similar 3 to 15 milligrams.

The rules differ by country. Wikipedia says the European Union requires decaf beans to be 99.9% caffeine-free by mass. The National Coffee Association says decaffeination removes around 97% of the caffeine.

The amount in your cup also depends on how you brew. Swiss Water notes that brew method, strength, time and dose all change the final caffeine.

Can you drink decaf late at night?

For most people, yes, though it is not zero. For most adults, the FDA cites 400 milligrams a day as an amount not generally linked to negative effects. A decaf cup is a small fraction of that.

Decaf varies more than the label suggests. Wikipedia describes a 2006 Florida State University study that found 8.6 to 13.9 milligrams in 16-ounce cups of decaf. By that measure, 14 to 20 cups of decaf held as much caffeine as one regular cup.

If you are very sensitive to caffeine, those few milligrams can still matter. Swiss Water notes that a stronger brew or a bigger dose yields more caffeine, decaf included.

How is caffeine removed from coffee?

There are three main approaches: solvents, water, and pressurized carbon dioxide. All of them work on green beans.

Swiss Water stresses that its own process works without adding any chemical solvents.

The oldest is the solvent method. Wikipedia credits German coffee merchant Ludwig Roselius and his team with the first commercially successful process in 1903, patented in 1906.

His coffee was sold as Kaffee HAG in Europe and later as Sanka in the United States. Early versions used benzene as the solvent, which modern processes have replaced.

Does decaf taste different?

It can, and processors compete on how little flavor they lose. In the Swiss Water process, Wikipedia explains, only the caffeine is drawn out, while the other water-soluble coffee elements are retained in the green beans.

The Swiss Water process was developed in Switzerland in 1933 and reached North America in 1988, according to Wikipedia. Like any coffee, a decaf also tastes best when it is fresh, so check the roast date.

Does decaf need a different grind?

Often a slightly finer one. Swiss Water recommends using a little more coffee than usual, a slightly finer grind, or both, to make up for decaf's different composition.

Perfect Daily Grind explains part of why decaf behaves differently. Decaf beans are lighter and less dense, and the process degrades their cell structure. Swiss Water decaf even starts a few shades darker than regular green coffee, so color is a weaker guide to roast level.

Treat this as a starting point, not a rule. Grind one step finer than your usual setting, brew, and taste.

If the cup is sour or thin, it is under-extracted, so go finer again. If it turns bitter, back off.

Our guide to dialing in pour-over walks through the process.