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 point, it is referred to as being "stewed" in the UK). When the tea has brewed long enough to suit the drinker's taste, it should be strained before serving. The ISO Standard 3103 defines how to brew tea for tasting. The biggest producers of black tea in the world are: Plain black tea without sweeteners or additives contains caffeine but negligible quantities of calories or nutrients. Some flavored tea with different herbs added may have less than 1 gram of carbohydrates. Black teas from the Camellia sinensis tea plant contain polyphenols known as thearubigins and theaflavins. Meta-analyses of observational studies