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.
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Asked by: Carmen Winstead, High Wycombe
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