How is caffeine removed from decaffeinated coffee? © Getty Images

How is caffeine removed from decaffeinated coffee?

There are several different ways, but the most common method is to soak the coffee beans in a safe solvent.

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.

Advertisement

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.

Read more:

Asked by: Carmen Winstead, High Wycombe

Advertisement

To submit your questions email us at questions@sciencefocus.com (don’t forget to include your name and location)