decaffeination processes that include supercritical CO2, as CO2 does not absorb in the UV-Vis range. A controlled study in 2006 at Florida State University of ten samples of prepared decaffeinated coffee from coffee shops showed that some caffeine remained. Fourteen to twenty cups of such decaffeinated coffee would contain as much caffeine as one cup of regular coffee. The 473 ml (16 ounce) cups of coffee samples contained caffeine in the range of 8.6 mg to 13.9 mg. In another study of popular brands of decaf coffees, the caffeine content varied from 3 mg to 32 mg. In contrast, a 237 ml (8 ounce) cup of regular coffee contains 95–200 mg of caffeine, and a 355 ml (12 ounce) serving of Coca-Cola contains 36 mg. Both of these studies tested the caffeine content of store-brewed coffee, suggesting that the caffeine may be residual from the normal coffee served rather than poorly decaffeinated coffee. Decaffito As of 2009, progress toward growing coffee beans that do not contain caffeine was still continuing. The term "Decaffito" has been coined to describe this type of coffee, and trademarked in Brazil. The prospect for Decaffito-type coffees was shown by the discovery of the naturally caffeine-free Coffea charrieriana variety, reported in 2004. It has a deficient caffeine synthase gene, leading it to accumulate theobromine instead of converting it to caffeine. Either this trait could be bred into other coffee plants by crossing them with C. charrieriana, or an equivalent effect could be achieved by knocking out the gene for caffeine synthase in normal coffee plants. Decaffeinated tea Tea may also be decaffeinated, usually by using processes analogous to the direct method or the CO2 process, as described above. Oxidizing tea leaves to create black tea ("red" in Chinese tea culture) or oolong tea leaves from green leaves does not affect the amount of caffeine in the tea, though tea-plant subspecies (i.e. Camellia sinensis sinensis vs. Camellia sinensis assamica) may differ in natural caffeine content. Younger leaves and buds contain more caffeine by weight than older leaves and stems. Although the CO2 process is favorable because it is convenient, nonexplosive, and nontoxic, a comparison between regular and decaffeinated green teas using supercritical carbon dioxide showed that most volatile, nonpolar compounds (such as linalool and phenylacetaldehyde), green and floral flavor compounds (such as hexanal and (E)-2-hexenal), and some unknown compounds disappeared or decreased after decaffeination. In addition to