Decaffeinated Coffee

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About
Decaffeinated coffee was invented in Germany around 1908. It’s made by soaking green coffee beans with water to dissolve the caffeine, extracting the caffeine from the beans with a solvent (methylene chloride, ethyl acetate), and steaming the beans to evaporate off any remaining solvent. In the “Swiss” or “water” process, water is the only solvent used, the caffeine removed from the water by charcoal filters, and the other water-solubles are then added back to the beans. Some of the organic solvents used in other processes have been suspected of being health hazards even in the tiny traces left in the beans (around 1 part per million). The commonest, methylene chloride, is now thought to be safe. More recently, highly pressurized (“supercritical”) and nontoxic carbon dioxide has been used. Where ordinary brewed coffee may contain 60–180 milligrams caffeine per cup, decaffeinated coffee will contain 2–5 mg.