Notes of Food Science: Decaffeination of tea by Carbon Dioxide Processing
Decaffeination of tea by Carbon Dioxide Processing
Supercritical Carbon Dioxide is the most widely used solvent for decaffeination of food products. The gas is odorless, tasteless and inert.
In the carbon dioxide decaffeination process the tea leaves are moistened with water and placed under pressure. Then streams of pressurized and heated CO2 are passed through the tea leaves..
The carbon dioxide reaches a “super-critical state” where CO2 becomes almost a liquid solvent, and it attracts the caffeine molecules and removes them from the tea while leaving the tea leaves otherwise intact.
The caffeine is then removed from the CO2 using activated carbon filters, which are then recycled for further use in decaffeination. Finally, the newly-decaffeinated tea leaves are dried.
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.
Supercritical carbon dioxide removes caffeine while leaving the aroma oils, and the leaves do not need to be treated after decaffeination to remove solvent residues.
Labels: carbon dioxide, decaffeination of tea