Antioxidants in tea

Tea, a beverage originating from a single species of plant, Camellia sinensis, is widely cultivated around the world in both tropical and subtropical regions.

Tea us a natural source of antioxidants.  The actual concentration of antioxidants in tea varies according to the type of tea and its manufacture.

Some of the research that has been done with tea and its antioxidants have given some proof that it may help to guard against certain types of cancer, weight loss and it may even help protect against the onset of Alzheimer's, along with other diseases.

Antioxidants prevent cell damage due to oxidation by intercepting free radicals and have been credited with reducing the impact of such diseases as macular degeneration.

In addition to this, various research studies appear to indicate that tea may even reduce the relative risk for diabetes as well as improve insulin sensitivity.

From biological point of view, the largest and most important groups of tea leaf components are polyphenols. There are three major polyphenols in teas: catechins, theaflavins and thearubigins. Catechins are major constituents of green tea leaves and are also present in Oolong and black tea, whereas thearubigins and theaflavins are found only in black tea and Oolong teas.

The most important catechins contained in tea leaves are epigallocatechin gallate, epigallocatechin, epicatechin gallate and epicatechin.

Tea catechins lower blood sugar levels by inhibiting the action of amylase, an enzyme that breaks down starches such as carbohydrates and coverts them into glucose.

There is research on tea and its possibility of lowering the incidence of skin cancers plus the ability to aid smokers in recovering and repairing damaged cell structure.

Current evidence would suggest that antioxidants retard deterioration caused by oxidation especially of fats, oils and foods and thus provide a defense mechanisms against the threat posed by unstable free radicals.

The result of epidemiological study stated that one of the health benefits of drinking tea is that it can reduce the risk of esophageal cancer in men and women by up to 60%.

Another wonderful benefit from drinking tea is it is rich in natural fluoride and prevents tooth decay. It is important to avoid using sugar in tea for these benefits to be maximized. Tea catechins prevent growth of bacteria that also cause tooth decay and the formation of plaque.
Antioxidants in tea

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Taste of tea

Besides the aroma, the taste quality is also one of the key criteria used by tea tasters to describe the quality of tea liquor.

Green tea, oolong tea and black tea all have their own distinctive flavors. Its taste is at first bitter and astringent and then sweet.

The balance of astringency, bitterness and brothy taste is important to the characteristic taste of tea; catechins and caffeine are counted as the major contributors to astringency and bitterness.

The major catechins in green tea are EGCg, ECg, EGC, and EC, which are classified as either gallate-type catechins (EGCg and ECg) or non-gallate type catechins (EGC and EC) by the presence of galloyl group on the oxygen atom at the C3 position.

Human perceive the taste of the gallate-type catechins to be more bitter astringent than that of the non-gallate type catechins.

Black tea and green tea are different in flavor due to the fermentation process during production of black tea, in which catechins are oxidized and polymerized to form theaflavins; and consequently the astringent taste of green tea is replaced with more complex astringent taste.

Theaflavin constituting about 0.3 – 1.8% of black tea dry weight and 1- 6 % of the solid in tea infusion. It contributes significantly to the bright color and brisk taste of tea infusions.

During a few minutes infusion, catechins from tea leaves are not fully extracted. The preparation method will affect the extraction efficacy and consequently the content of polyphenols in the cup.
Taste of tea

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