The three methods of decaffeinating coffee are the water processing method, the direct solvent method and supercritical carbon dioxide decaffeinating method. All three methods moisten the coffee beans so that the caffeine can be withdrawn, and all three decaffeinate the coffee at temperatures ranging from 160 to 210 degrees Fahrenheit.
The water processing method is a natural way of removing caffeine from coffee beans without the use of chemicals. The beans are placed in a vessel with caffeine-reduced green coffee, and the oils within the green coffee extract the caffeine from the beans. The beans are then rinsed and dried. The water processing method removes 94 to 96 percent of the caffeine.
The direct solvent method uses coffee oil or ethyl acetate to remove the caffeine. These solvents are circulated through a container of moistened coffee beans, and then the beans are washed and steamed to remove the caffeine. These solvents remove 96 to 97 percent of the caffeine.
The supercritical carbon dioxide method uses carbon dioxide as the solvent that is circulated around the moistened coffee beans. Carbon dioxide has natural properties that enhance its effectiveness as a solvent and is naturally abundant. It is a popular and effective method of decaffeinating coffee beans. It removes between 96 and 98 percent of the caffeine.