The original process, developed by Ludwig Roselius in 1903, used benzene to dissolve the caffeine from the unroasted beans. Benzene is carcinogenic, so it has since been replaced with much safer solvents including dichloromethane and ethyl acetate, which evaporate when the beans are roasted.
High-pressure CO2 is also used by mass-market brands as an alternative to organic solvents. A third system, used primarily in the US and Canada, is the Swiss Water Process. This passes a very strong coffee solution through a carbon filter to remove the caffeine, and then uses this solution to remove the caffeine from unroasted beans by diffusion, without damaging their subtle flavour compounds.
- Why does the clinking sound go down in pitch when I stir sugar into my coffee?
- Why does coffee make me need a poo?
- How long does caffeine take to kick in?
- Why do I feel wiped out after too much caffeine?
Asked by: Carmen Winstead, High Wycombe
To submit your questions email us at firstname.lastname@example.org (don’t forget to include your name and location)