It was thought until comparatively recently that green tea was the most effective antioxidant-containing tea and that green-tea catechins (the unoxidized polyphenols present in tea leaf) alone were the antioxidants giving tea its health-giving attributes. It is now well known that the theaflavins and thearubugins produced by the condensation of oxidized catechins, during the fermentation stage of black tea manufacture, are equally effective antioxidants (Leung et al 2001).
The catechins present in tea flush and as such in green tea are:
Expressed as a % of dry weight
Epicatechin 1 – 3%
Epicatechin gallate 3 – 6%
Epigallocatechin 3 – 6%
Epigallocatechin gallate 9 -13%
Catechin 1 – 2%
Gallocatechin 3 – 4%
During manufacture of Black Tea these catechins get oxidized & polymerized (condensed), for example :
Epicatechin + Epigallocatechin gallate + Oxygen —> Theaflavin
The paired catechins as they appear in Black Tea are now known to be equally effective antioxidants. The body produces free radicals (FRs) under certain conditions. Carcinogens and radiation from the environment facilitates the formation of FRs. These FRs within the body cause oxidative changes to DNA (the genetic material present in all cells). Changes to DNA carry the risk of cancers. The FRs are inhibited and destroyed by the antioxidants in tea, both green and black tea.
Green and black tea comes from Camellia Sinensis. Green tea is unfermented, steamed immediately after plucking, and retains a lighter colour and flavour. Black tea is allowed to ferment and is then dried, resulting in a darker leaf colour and a more flavour and aroma.