- Using the “direct” method, caffeine is removed by directly soaking the materials in methylene chloride.
- Using the “indirect” method, caffeine, which is water soluble, is extracted by soaking the materials in water. Many of the flavors and oils are also extracted during this process, so the solution is treated with methylene chloride and then returned to the material for reabsorption of the flavorings.
Ethyl acetate processed products are referred to as “naturally decaffeinated” because ethyl acetate is a chemical found naturally in many fruits. Caffeine is extracted in the same way as with methylene chloride processing, but ethyl acetate is the solvent.
To decaffeinate using carbon dioxide (CO2), water-softened materials are “pressure cooked” with the gas. At high pressures and high temperatures, carbon dioxide is in a supercritical state, acting as both a gas and a liquid. It becomes a solvent with its small, nonpolar molecules attracting the small caffeine molecules. Since flavor molecules are larger, they remain intact, which is why this process retains the flavor of the material better.
Caffeine extraction with water is used primarily for coffee decaffeination. The process is similar to the “indirect” method used in methylene chloride processing, but no chemicals are used. After the caffeine is leached out of the material by soaking in hot water for a period of time, the solution is then passed through a carbon filter for caffeine removal. The water is then returned to the beans for reabsorption of flavors and oils. In the “Swiss Water Process,” the same method is used, but instead of soaking in water, the beans are soaked in a coffee-flavored solution. This results in the caffeine being extracted without removing the coffee flavors.
Caffeine is not removed completely using any of these methods, but under federal regulations in the United States, caffeine levels must not be above 2.5 percent of the product in order for a product to be labeled “decaffeinated.”