Tea chemistry: your cup’s content
If you are more interested in tea and health, you can have a look, at our article about tea and health.
Tea and caffeine
Caffeine is present in all colours (type) of tea (Camellia sinensis), and is also found in different plants like coffee, guarana, cola nuts, Yerba Mate, etc. As it is a stable molecule, its concentration in all colours (types) of dry tea leaves is similar.
The brewing method will have an influence on the quantity of caffeine in the resulting infusion (brew). Caffeine is highly soluble in water and therefore quickly released during the steeping. If you want to reduce you caffeine intake, you can quickly rinse your tea with hot water before brewing it. Pour water on the leaves and steep for 10-20 seconds, discard water and brew as usual. This rinsing should be enough to discard 80-90 % of the caffeine from the leaves.
Red (black) or oxidized tea releases also tannins after some minutes of steeping. Tannins delays the caffeine absorption. This means that if you brew a red (black) tea for a long time, its tonic effect will decrease. But this is probably not the best way to lower the effects of caffeine because the taste of your tea would suffer as the tannins are the main responsible for astringency.
Even though tea contains more caffeine than coffee, it has a totally different effect on the body. This is explained by the way caffeine molecules are linked to other substances. If you drink a coffee, caffeine is almost instantly in your bloodstream while with tea, caffeine is absorbed much slower because of the links it has with other molecules like phenols. This is why tea has more a tonic effect than a kicking or boosting effect.
Tea and polyphenols
Polyphenols are present in all colours (types) of tea. They give the anti-oxidizing proprieties of tea.
Flavanoids (a group polyphenols) are present in similar proportions in oxidized and non-oxidized teas. What varies is the type of polyphenol present. Non-oxidized teas like green tea contains more catechins (group of simple flavanoids) while in red (black) tea, the oxidation process transforms a part of flavanoids into other groups of polyphenols called theaflavins and thearubigins.
The most famous and most studied of all these molecules for its anti-oxidizing effect is epigallocatechin gallate (EGCG).
Tea and tannins
Tannins are also phenols or polyphenol molecules linked by starch. It gives tea its astringency.
Tea and vitamins
Vitamins A, B and C are mostly present in non oxidized teas (green tea and white tea). Unfortunately, vitamins are fragile and a great part of them are destroyed during the oxidation process. Consequently, oxidized tea (red or black) contains much less vitamins.
Tea and minerals
The main mineral nutrients found in tea are selenium, fluor and zinc.
Fluor is known for its preventing cavities action.
Selenium is thought to prevent cancer and heart attacks.
Zinc is known to fight indigestions and skin infections.
Other components of tea
Carotene is known to reduce cholesterol and blood sugar as well as lowering blood pressure. It would also be useful in case of infection and to prevent food allergies.
Glycosides are known to prevent blood sugar increase and for their anti-diabetic properties like polysaccharides.