Tea is decaffeinated by various methods. Briefly the tea is prewetted and extracted by some organic solvent such as dichloromethane or ethyl acetate. Alternatively, an extraction using supercritical carbon dioxide can be used. Supercritical carbon dioxide is the most widely used solvent for decaffeination of food products. The gas is odorless, tasteless and inert.
When highly pressurized, carbon dioxide assumes a supercritical state and has properties of both a solid and a fluid. At this point, it becomes an efficient solvent for caffeine.
The compressed carbon dioxide is pumped into a chamber with tea. It extracts the caffeine, and the carbon dioxide is separated from the tea and carbon filtered to remove the caffeine.
Carbon dioxide processing leaves no toxic residues. In addition, extraction of the caffeine takes place at room temperature which protects product quality by preventing the breakdown of temperature-sensitive components.
After extraction occurs, the supercritical fluid turns back into a gas, so no solvent residue remains. CO2 decaffeinated teas best retain the original flavors of the teas.
Other advantages of supercritical CO2 as a decaffeination solvent:
*CO2 has suitable critical constant for this application
*CO2 in small amounts is physiological harmless an cause no environmental pollution
*CO2 is cheap, easily available and non flammable
Decaffeination of tea by carbon dioxide supercritical process
