Take a Sip...

The recent release of the Alice in Wonderland film, spots an extravagant tea party that had left me yearning to earn a seat and join in merrymaking with Alice, the Mad Hatter and all the imaginary mystical creatures that had enliven the movie. The fashionably exclusive setting, intricate decorations of flowers, ornaments, delectable delicacies and fine china adorn the lengthy table appealed no less charming and pleasing to the eye. What a bizarre experience that would be if this fantasy….

Oiiii, wake up!!! *sigh*

Back to reality a.k.a Earth........


Tea or ‘cha’ in Chinese language is an ancient crop that has been cultivated for thousands of years. It is the agricultural product of the leaves, left buds and internodes of the Camellia sinensis plant, prepared from the cured leaves by combination with hot or boiling water. Its exact origins have yet to be defined by historians, but the first records of tea date back to the 4th century AD in China. It is woven into the fabric of many cultures where tea is a cause for pomp and ceremony as demonstrated in Sha-no-yu (the Japanese tea ceremony), and the western High Tea. The mental clarity and Zen-like calm it provides inspired Emperor Shen Nung to lead a religious following of tea, outlined in eight steps. After water, tea is the most widely consumes beverage in the world. It has a cooling, slightly bitter, astringent flavour which many enjoy.

There are more than 1500 teas to chose from, originating from more than 29 different countries. It is cultivated as a plantation crop in acidic soil and a warm climate with at least 50 inches of rain per annum. Just as red white and rose wine all comes from the same grape, Black, Green and Oolong teas all come from one plant Camellia sinensis. Like wines, it is the processing which creates the different grades and flavours. Tea is traditionally classified based on the techniques with which it is produced and processed.

• White tea: Wilted and unoxidized
• Yellow tea: Unwilted and unoxidized, but allowed to yellow
• Green tea: Unwilted and unoxidized
• Oolong: Wilted, bruised, and partially oxidized
• Black tea: Wilted, sometimes crushed, and fully oxidized
• Post-fermented tea: Green tea that has been allowed to ferment/compost

Let’s take a closer look at the leaf. Tea leaf is composed of a number of different elements and compounds all of which are interconnected with the chemical reaction of its processing. Inorganic components mainly found in salts in the cell sap include:

• Potassium
• Calcium
• Phosphorus
• Magnesium
• Manganese
• Iron
• Sulphur
• Aluminium
• Sodium
• Zinc
• Copper

The most important parts of the leaf in terms of its chemical reaction are the enzymes and polyphenols. The most important enzymes are polyphenol oxidase (PPO) and peroxidase (PO) because it catalyzes oxidation. The polyphenols occurring in the tea plant are derivative of gallic acid (C6H2 (OH).3COOH) and catechin C15H14O6.4H2O). Catechin, the main polyphenol of green tea scavenges free radicals. Any biological system creates free radicals as a by-product of living. Oxygen accepts electrons to become active oxygen and hydroxyl free radicals. These free radicals attempt to oxidize lipids, contributing to old-age diseases. Catechins protect the system against the oxidation of lipids and suppress cancer growth by combining protons with the free radicals and stopping potential reactions. Catechins have been shown to be more effective scavengers than other antioxidants like vitamins C and E, making them very good for human systems.

The main components tea:

~Caffeine

Caffeine is a purine derivative, which is 1, 3, 7-tri- methyl xanthine. Caffeine content in black tea is around 3 – 4% of dry weight. It has stimulating property and removes mental fatigue. The contribution of caffeine to the infusion is the briskness and creamy property resulting from the complex for med by caffeine with polyphenols. Briskness is a taste and sensation while creaming is the turbidity that develops from a good cup of tea when cooled.

~Tea fibre

The leaf cell wall containing cellulostic materials surrounded by hemi-cellulose and a lignin seal, prevents the penetration of hydrolyzing enzymes. The reduced succulence in the matured shoot is believed to be due to structural bonding between phenolic components of lignin, polysaccharides and cutin of cell wall.

~Carbohydrates
The free sugars found in tea shoot are glucose, fructose, sucrose, raffinose and stachyose. Pectic substances contain galactose, arabinose, galacturonic acid, rhamnose and ribose. Free sugars are responsible for the synthesis of catechins in tea shoot, formation of heterocyclic flavour compounds during processing of black tea and contributing towards water-soluble solids in tea liquor. Cellulose, hemi-cellulose, pectins and lignins are responsible for the formation of crude fibre content in black tea.Tracer studies using 14C-glucose in detached tea shoot showed that glucose was one of the precursors of polyphenols in tea. Except theanine all amino acids present in tea shoot were biosynthesized using 14C-glucose, 14C-sodiam carbonate and 14C-sodium propionate. Theanine was mainly synthesized in the root and translocated to the shoot.

~Amino acids

Aspartic, glutamic, serine, glutamine, tyrosine, valine, phenylalanine, leucine, isoleucine and theanine (5-N-ethylglutamine) were found to be the principal amino acids present in tea leaf. Theanine alone contributed around 60% of total amino acid content. Asparagine was formed during withering. The amino acids play an important role in the development of tea aroma during the processing of black tea.

Volatile Carbonyl Compounds formed from the amino acids during processing:

Glycine —› formaldehyde
Alanine —› acetaldehyde
Valine —› isobutyraldehyde
Leucine —› isovaleraldehyde
Isoleucine —› 2-methylbutanol
Methionine —› methional
Phenyl alanine —› phenylacetaldehyde

There are many health benefits connected with the regular consumption of tea. Links have been made with the reduction of incidences of cancer, heart disease, high blood pressure and tooth decay.

~ Prevents cancer

Results of recent studies show that tea may protect against the development of pancreatic and prostate cancer. It is thought that the theaflavins and polyphenols present in tea are compounds that inhibit the growth of tumour cells. Tea is also thought to have a role in changing the genes involved in the processes of causing cancer. Studies have shown that men who drink between 2 and 3 cups of tea a day may reduce their risk of developing prostate cancer by up to 30% compared to non tea drinkers.

~ Antioxidant
These natural antioxidants may help to reduce the risk of developing heart disease because antioxidants help to repair the cells that are damaged by free radicals. Polyphenols and flavenoids are the active compounds and they help to reduce blood cholesterol, high blood pressure and blood clotting. Oxygen in the air is partially incorporated into free radicals which are very reactive. They cause damage to cells and have been connected to heart disease and cancer. Cholesterol levels have been shown to go down with an increase in tea consumption. The risk of heart attacks in people who drank one or more cups of tea a day was half that of those who drank no tea. The best known antioxidants are vitamins A, C and E and flavenoids.

~ Rich in fluoride
Tea is one of the few natural sources of fluoride, which is one of the most successful agents against tooth decay and gum disease ever discovered. Scientists believe that drinking tea helps to prevent dental caries and heavy tea drinking could provide enough fluoride to prevent tooth decay. It is also suggested that plaque is decreased by drinking tea. These effects could be due to the antioxidants and the fluoride in tea working together.

~ Rich in minerals
Tea is a rich source of two essential minerals, namely manganese and potassium. Manganese is essential for bone growth and body’s development. 5-6 cups of tea a day provides 45% of the daily requirement. Potassium if essential to maintain a healthy heart beat. It helps nerves and muscles function properly and helps regulate fluid levels within cells. 5-6 cups of tea provides 75% of the daily requirement.

Reference:
http://www.angelfire.com/pro/chemist_emily_f/chemistsinabigworld.html
http://www.fmltea.com/Teainfo/tea-chemistry%20.htm
http://en.wikipedia.org/wiki/Tea#Tea_culture