Working Knowledge; June 1997; Scientific American Magazine; by Katz; 1 Page(s)

Spurred by the belief that excessive coffee drinking had poisoned his father, the German chemist Ludwig Roselius, in about 1900, found a number of compounds that dissolved the natural caffeine in coffee beans without ruining the drink¿s taste. Chloroform and benzene did the job but were toxic, so for 70 years methylene chloride became the solvent of choice.

When it was discovered in the 1980s to be a suspected carcinogen, the chemical was abandoned by all the big U.S. coffee labels. The Food and Drug Administration continues to permit the use of methylene chloride if the residues in the coffee are below 10 parts per million. Processing for specialty decafs still often uses it because it perturbs other flavorings so little.