Indirect Method
In the indirect method, beans are first soaked in hot water for several hours, in essence making a strong pot of coffee. Then the beans are removed and either dichloromethane or ethyl acetate is used to extract the caffeine from the water. As in other methods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. An equilibrium is reached after several cycles, wherein the water and the beans have a similar composition except for the caffeine. After this point, the caffeine is the only material removed from the beans, so no coffee strength or other flavorings are lost. Because water is used in the initial phase of this process, sometimes indirect method decaffeination is referred to as "water-processed" even though chemicals are used.
Read more about this topic: Decaffeination
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