The extended oxidation of black tea increases the concentrations of thearubigins and theaflavins, two types of complex polyphenols ( 2). See reference 5.īlack tea contains much lower concentrations of these catechins than green tea ( 6). *mg = milligram L = liter fl oz = fluid ounce. The active catechins and their respective concentrations in green tea infusions are listed in the table below.Ĭatechin Concentrations of Green Tea Infusions Catechin in Green Tea Infusion The most active and abundant catechin in green tea is epigallocatechin-3-gallate (EGCG). The polyphenols, a large group of plant chemicals that includes the catechins ( 4), are thought to be responsible for the health benefits that have traditionally been attributed to tea, especially green tea. Tea is composed of polyphenols, alkaloids ( caffeine, theophylline, and theobromine), amino acids, carbohydrates, proteins, chlorophyll, volatile organic compounds (chemicals that readily produce vapors and contribute to the odor of tea), fluoride, aluminum, minerals, and trace elements ( 3). So-called herbal teas are not really teas but infusions of boiled water with dried fruits, herbs, and/or flowers. Tea is brewed from dried leaves and buds (either in tea bags or loose), prepared from dry instant tea mixes, or sold as ready-to-drink iced teas. Dry heat or steam can be used to stop the oxidation process, and then the leaves are dried to prepare them for sale. White tea is made from young leaves or growth buds that have undergone minimal oxidation. Oolong tea is made from wilted, bruised, and partially oxidized leaves, creating an intermediate kind of tea. In contrast, green tea is made from unwilted leaves that are not oxidized. Black tea is produced when tea leaves are wilted, bruised, rolled, and fully oxidized. The amount of oxidation and other aspects of processing determine a tea’s type. This oxidation process can be stopped by heating, which inactivates the enzymes.

During oxidation, chemicals in the leaves are broken down by enzymes, resulting in darkening of the leaves and the well-recognized aroma of tea. Shortly after harvesting, tea leaves begin to wilt and oxidize. Tea is made from the leaf of the plant Camellia sinensis. Oolong and white tea are consumed in much lesser amounts around the world ( 2). In the United States, United Kingdom (UK), and Europe, black tea is the most common tea beverage consumed green tea is the most popular tea in Japan and China ( 2). Black tea accounts for about 75 percent of the world’s tea consumption ( 1). Tea is one of the most ancient and popular beverages consumed around the world.

Mg of caffeine in black tea