By Steven Luff, published in Health Supplement Retailer magazine August 1999.

There are two types of decaffeination processes used in tea. One is accomplished using ethyl acetate, an organic [chemical] solvent, and the other is with carbon dioxide. With ethyl acetate, the tea is moistened and the solvent is passed through the leaves. As it passes through, the ethyl acetate takes the caffeine with it. Ultimately, the tea is heated to remove [most] of the remaining chemical residues and then is dried. In carbon dioxide decaffeination, moistened tea leaves are put under heat and pressure and treated with carbon dioxide gas. The carbon dioxide mixes with the caffeine, and when it is released to the atomsphere, it takes the caffeine with it.

Both of these options are successful in removing caffeine from tea leaves, but only the carbon dioxide process preserves the majority of the medicinal integrity. EGCG, along with other medicinally significant flavonoids found in tea, is water soluble. Therefore, any decaffeination process involving water will remove these components at the same time it removes the caffeine. Ethyl acetate does this when it bonds with the caffeine. Carbon dioxide, however, does not interfere with the flavonoids.