How is coffee decaffeinated?
There are different ways of removing caffeine from coffee:
- Water extraction: At the beginning solvents like dichloromethane or ethyl acetate were used because they dissolve selectively the caffeine. But because of their toxicity nowadays water is used instead. Hot water extracts both flavor ingredients and caffeine from green coffee beans. Then the extract is passed through activated charcoal and most of the caffeine is removed. Finally, soaking the original beans in the decaffeinated extract restores most of their flavor.
- Supercritical fluid CO2 extraction: Supercritical fluids have both gaslike and liquidlike properties, they fill the container like a gas but can dissolve substances like a liquid. In the caffeine extraction process, this fluid is forced through green coffee beans, it penetrates deep into the beans and dissolves most of the caffeine present. For more information about supercritical fluids click here.
- Genetic engineering: Some researchers are investigating ways to inactivate the gene that codes for caffeine synthasa, the enzyme which catalyzes the caffeine synthesis. Then coffee plants unable to produce caffeine could be grown. You can find some news about this topic here.