Because caffeine is soluble, different decaffeination processes have been tested so far to extract it from green coffee:
With carbon dioxide
Green beans are moistened with steam and water until they reach the right moisture content (max 40%). Then the beans are passed through the extractor along with carbon dioxide, which is in a special physical state called "supercritical." This state has the dual property of diffusing like a gas and solubilizing like a liquid. The method does not involve the use of other substances. Extraction takes place "gently" and requires a pressure between 120 and 250 atmospheres. Finally, the beans, separated from the caffeine, are dried. Decaffeination with C02 ensures high extraction selectivity and does not affect the other substances that contribute to coffee quality.
With dichloromethane or ethyl acetate
Again, green beans are preliminarily humidified by steam and then passed into extractors where, through dichloromethane or ethyl acetate, (two organic substances authorized by current European legislation) they are decaffeinated. A subsequent steam treatment removes all residues and finally, through roasting, further traces are evaporated.
It should be noted that both fluids are volatile compounds of which no trace remains in green coffee, let alone in roasted coffee.
English
Italian 
German 
Spanish