Tea Basics
There are three types of tea manufactured: green tea, black tea (often labeled as pekoe or orange pekoe), and oolong tea. The difference between them lies in how the leaves are processed. Black tea is by far the most popular, comprising 77% of the world's tea production, and is the result of allowing the leaves to ferment before drying. Oolong tea production involves partial fermentation, while green tea is not fermented at all.
Tea leaves are an abundant source of flavonoids (sometimes called bioflavonoids), a group of compounds with antioxidant properties that lend many plants their color. Of specific interest are the flavonoids catechins and flavonols which prevent the synthesis of peroxides and free radicals, agents that can invade cell membranes and damage genetic material. Certain chemicals found in the molecular structure of these beneficial flavonoids, collectively known as phenolic groups, bind with peroxides and free radicals to annul their ability to cause damage.
The fermentation process activates the oxidation of catechins to convert them into the secondary flavonoids theraflavin and thearubigin, also highly oxidant and responsible for the rich color and flavor of black and oolong teas. Green tea, on the other hand, is manufactured without fermentation and the original catechin structure is preserved. The most significant catechin present in tea, epigallocatechin gallate (EGCG) is much more abundant in green tea, with a single cup yielding from 40 to 90 milligrams.
A New Look at an Old Tradition
For more than two decades, researchers have been trying to understand the role of tea, particularly green tea, in the prevention of certain diseases. In September of last year, scientists from around the world gathered in Washington, DC for the Second International Scientific Symposium on Tea & Human Health to present some promising new findings that suggest the antioxidant qualities of tea may rival that of broccoli, carrots and even vitamin E.
