Examples of processes for decaffeinating coffee using organic solvents

1 Examples of processes for decaffeinating coffee using organic solvents 

Although its future may be uncertain, methylene chloride is still in use as a decaffeination solvent, its advantages being its non-combustibility and high volatility. Because of these attributes the solvent can easily be stripped out from the beans with simple equipment entailing low energy and investment costs. A typical example of an extraction process using this solvent is described in US Patent 3671263 [13]. 

Initially (before start-up) the fresh green coffee beans are charged into a series of extraction columns where they are steamed for between 15 minutes and one hour at a temperature of about 230°F (110°C). During this period the moisture content of the beans increases to between 16 and 18 weight %. The beans are then wetted to bring their moisture content to between 40 and 50%. 

Ethyl acetate is also sometimes used as the decaffeination solvent [14]. The process details are similar to those described above for the extraction with methylene chloride. It should be noted, however, that unlike methylene chloride, ethyl acetate is flammable and that, in consequence, the extraction installation has to be designed to be explosion proof. Investment costs are therefore higher than for the methylene chloride process. 

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