Tea Chemistry

21 11 2008

The chemical structure of tea can be generally divided into two parts – insoluble in water and soluble in water. The insoluble part contributes to the physical structure and appearance of tea and consists of crude fiber, cellulose, proteins, lignin, fats, chlorophyll and other pigments and starches.

The part of tea that we are mostly interested in is the soluble part, which contains all those health benefits that we like so much, but also defines the way tea will taste. This part consists of polyphenols to a large degree (commonly known as catechins also refereed to as tannin), amino acids (theanine), caffeine and minerals. Catechins are a type of antioxidants and can make up about 30% of the dry weight tea. Catechin content is higher in green and white tea, because black tea undergoes the oxidation process which reduces catechin content. Caffeine makes up about 3% of dry weight tea.

 

 

Different concentrations of compounds in tea are responsible for different characteristics in tea:

Polyphenols– astringency and bitterness
Amino Acids – sweetness and flavor
Caffeine– bitterness and briskness

Catechins

It’s because of catechins that tea is listed by research as one of the top foods to be consumed for better health and longer lifespan. There are four main catechin types found in tea EC, ECG, EGC and EGCG of which the last one is most potent.

Amino Acids

The amino acid L-theanine is characteristic only to tea plants and a few kinds of mushrooms. This substance provides the sweetness in tea. Leaves and buds collected early in the season have a higher concentration of theanine and are therefore sweeter in flavor.

Caffeine

Caffeine is a stimulant that affects our central nervous system and gives bitterness to the tea. Young tea leaves amd buds have a higher caffeine amount, but generally a cup a tea can contain 15 – 30mg of this substance.

How it works

Any substance that works in our as an antioxidant gives away an electron – this is the most important characteristic for antioxidants. Electrons like to be in pairs and substances with an uneven number of electrons can cause damage to our body – these are also known as free radicals. When an electron is donated by the antioxidant to the harmful substance is can be ‘calmed down’ and potential damage can be avoided. What also occurs is that the antioxidant after giving away the electron becomes a radical itself and has to be given an elecrton from a different type of antioxidant. The antioxidants work togather as a team and your body needs different kinds of antioxidants from rich sources like naturally grown foods, fruits, vegatables and tea in order to keep a balance.

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One response

24 07 2011
John Shoane

Caffine is actuall an insecticide! A bit like tobacco. Anyway, can you do a review on Oolong tea? It is a semi-fermented tea, very good for the body and digestion.

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