Decaffeination 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. Tea may also be decaffeinated, usually by using processes analogous to the direct method or the CO process, as described above. The process of 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
Black tea tea is a blend of two or more black teas of the leaves and buds of "Camellia sinensis" that contain at least 30 percent water-soluble extractive, with 4 to 7 percent ash. Unblended black tea contains at least 25 percent water-soluble extractive, with 4 to 7 percent ash. Packaging of black tea is based on the packaging guidelines from the country of origin. Generally, unblended black teas are named after the region in which they are produced. Often, different regions are known for producing teas with characteristic flavors. Black tea is often blended and mixed with various other plants in