Our bodies respond to the negative influence of free radicals by utilising defensive antioxidant molecules present in our systems to detoxify or counter-attack their harmful effects. Scientists encourage us to improve our health by increasing the level of antioxidants in our bodies. One way to achieve this is by drinking several cups of tea a day.
Tea buds and leaves are plucked from Camellia sinensis contain a specific group of antioxidant compounds known as flavonoids. The flavonoids in tea are composed of two groups of substances - flavonols and flavanols. The tea flavanol group contains substances known as catechins - tea's most important antioxidant defence against free radicals.
The fact that green tea undergoes less internal change from fresh leaf means that it contains the largest quantity of impact catechins. Green tea catechins consist of four antioxidant compounds - EC (epicatechin), ECG (epicatechin gallate), EGC (epigallocatechin), and EGCG (epigallocatechin gallate). This last compound is the most abundant in green tea and the most bioactive of the group. These compounds also contribute the light-yellow to golden-green colour of brewed green tea and the fresh, clean, vegetal 'green jade' flavours that connoisseurs seek in early spring-plucked green tea.
Despite the recent attention paid to the healthy nature of green tea and white tea, all classes of tea contain polyphenols. The differing methods of leaf manufacture for black, green, oolong, scented and white teas also results in the formation of different polyphenols within the leaves of each class of tea. For black tea, after leaf-withering and during the leaf-rolling stages of manufacture, polyphenol oxidase enzymes that are present in the fresh leaf interact to cause the catechin to oxidise. These oxidised catechins link together to form a tannins known as theaflavins, antioxidant substances that contribute to the characteristic orange-red colour and flavour of the black tea. These substances combine with caffeine to influence astringency.
Theaflavins consist of several fractions - theaflavin, theaflavin 3 gallate, and theaflavin 3,3 digallate. During this process other catechin compounds oxidise into thearubigens, additional derived tannins formed in tea during oxidisation. The method and conditions of oxidised tea manufacture affects the proportion of antioxidant in the tea and thus corresponding flavour, character and astringency. The longer the tea is oxidised and the darker the colour , the more thearubigens it contains. Both theaflavins and thearubigens contribute the orange-red and red-brown colour that defines the appearance of oxidised tea.
White tea is generally more aligned with green tea and pu erh tea more closely follows black tea. Oolong, a semi-oxidised tea, contain the reverse antioxidant proportions of black tea; it has a higher concentration of theaflavins and a lower concentration of thearubigens.
Some researchers however, believe that the activation of tea enzymes during the manufacture of black tea may result in the formation of antioxidant compounds that are more powerful in preventing some dies than those contains in green tea.
Regardless of which type of tea you prefer, drink yourself healthy!