Methods of coffee decaffeination
Wrote at 12:02 by Stefano Urso in: Coffee Quality,
Since caffeine is soluble, so far have been tested different procedures for extracting it out from green coffee:
With carbon dioxide
The green beans are moistened with steam and water to reach the proper percentage of moisture (max 40%). Then the beans are passed into the extractor with carbon dioxide that occurs in a particular physical state called "supercritical". This state has the dual property to spread like a gas and dissolve like a liquid. This method doesn’t include the use of other substances.
Extraction is "softly" and requires a pressure between 120 and 250 atmospheres. The beans, finally separated from the caffeine, are dried. The decaffeination with C02 method provides high selectivity of extraction and does not affect other coffee substances that contribute to the quality of the coffee.
With dichloromethane or ethyl acetate
Again the green beans are first humidified and then passed through steam ejectors in which, through the dichloromethane or ethyl acetate (two organic substances permitted by current European legislation) are decaffeinated. A subsequent treatment with steam will remove all debris and finally, through the roasting, evaporate the additional tracks. It has to underlined that both fluids are volatile compounds for which no trace remains in the green coffee and even less in roasted coffee.
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