How is Coffee Decaffeinated?
Surprise! Decaf is never totally caffeine-free, this chemist explains
By Michael W. Crowder, Professor of Chemistry and Biochemistry, Miami University
For many people, the aroma of freshly brewed coffee is the start of a great day. But caffeine can cause headaches and jitters in others. That’s why many people reach for a decaffeinated cup instead.
I’m a chemistry professor who has taught lectures on why chemicals dissolve in some liquids but not in others. The processes of decaffeination offer great real-life examples of these chemistry concepts. Even the best decaffeination method, however, does not remove all of the caffeine — about 7 milligrams of caffeine usually remain in an 8-ounce cup.
Producers decaffeinating their coffee want to remove the caffeine while retaining all — or at least most — of the other chemical aroma and flavor compounds. Decaffeination has a rich history, and now almost all coffee producers use one of three common methods.
All these methods, which are also used to make decaffeinated tea, start with green, or unroasted, coffee beans that have been premoistened. Using roasted coffee beans would result in a coffee with a very different aroma and taste because the decaffeination steps would remove some flavor and odor…
