Oolong of steeping oolongs in Taiwan and China is called gongfucha. This method uses a small steeping vessel, such as a gaiwan or Yixing clay teapot, with more tea than usual for the amount of water used. Multiple short steeps of 20 seconds to 1 minute are performed; the tea is often served in one- to two-ounce tasting cups. Oolong generally contains caffeine, although the caffeine content in tea will vary based on terroir, when the leaf is plucked, and the production processes. Oolong Oolong (; ) is a traditional semi-oxidized Chinese tea ("Camellia sinensis)" produced through a process including withering
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