Supercritical Extractions

Nan's Nook : Archives : Misc Teks : Lab/Extraction Info

Question -  how do they decaffeinate coffee?
if there is more than one method please show all.

The older method used was extraction with solvents; however, since it was not possible to totally remove trace residual solvent. This not only affected taste but also raised questions of toxicity of sub-acute levels of the solvents.

Now supercritical fluid extraction is used almost universally. It has been found that substances, for example CO2, under conditions exceeding their critical temperature and pressure, are excellent solvents. The solubility of various substances, such as caffeine, ephedrine, mescaline, dissolves and separates them from dried coffee beans and such.  The neat thing is that the CO2 can be recovered by reducing the temperature and/or pressure. The extracted substances precipitate and the CO2, or whatever fluid is used is recycled.

You can find out details by searching the term "supercritical fractionation" on the Web. I have found to be the most direct search engine to use.

Other solvents such as butane, or propane, may be used alone, or in conjunction with CO2 for some specific supercritical extractions.