Q: How is caffeine removed from coffee?A:...

Q: How is caffeine removed from coffee?

A: Caffeine is a bitter alkaloid that makes up about 1% by weight of high-quality arabica coffee beans and about 2% of cheaper, more bitter robusta beans.

For 70 years, coffee makers used methylene chloride, an organic solvent that dissolved caffeine but few of the other components of the coffee bean. In the early 1980s, however, scientists concluded that methylene chloride may be carcinogenic and manufacturers switched to other solvents. Although ethyl acetate is used in some cases, the most common solvent now is supercritical carbon dioxide, a pressurized form of the inert material that is intermediate between a gas and a liquid. Heated to 200 degrees and compressed under pressure of 250 atmospheres, it dissolves caffeine and leaves no residue.