Methylene Chloride Decaffeination Methylene chloride decaffeination is a process by which the molecules of caffeine bond to molecules of methylene chloride. Caffeine is removed either directly, by soaking the tea in methylene chloride, or indirectly, by soaking the water (used to remove the caffeine) in methylene chloride and then returning the water to the tea for reabsorption of flavors and oils. Because methylene chloride is widely believed to be unfit for human consumption, a legal limit of 5 parts per million is placed on residual traces in the tea and the U.S. bans all imports using methylene chloride.
Ethyl Acetate Decaffeination Tea processed using ethyl acetate is often referred to as “naturally decaffeinated” because ethyl acetate is a chemical found naturally in tea. Caffeine is extracted in the same way as with methylene chloride processing, but using ethyl acetate as the solvent. However, ethyl acetate is very difficult to remove after the decaffeination process, and is sometimes described as leaving a chemical taste.
Carbon Dioxide (CO2) Decaffeination Carbon dioxide (CO2) decaffeinated tea is essentially “pressure cooked” with this naturally occurring gas. At high pressures and high temperatures, carbon dioxide reaches a supercritical state. The CO2 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 best retains the flavor of the tea.
Water Decaffeination Caffeine extraction with water is used primarily for coffee decaffeination, although a small amount of tea products are decaffeinated using this method. After the caffeine is removed from the tea by soaking the tea in hot water for a period of time, the solution is passed through a carbon filter for caffeine removal. The water is then returned to the tea for reabsorption of flavors and oils. This process is sometimes described as “watering down” the flavor of the tea.