Google
Search WWW Search siakhenn.tripod.com
Web hosting
Website Index :
Home
Country Profile
Demographics
Health & Self-care
Humanities & Lifestyle
World Resources

Diseases & Medical Conditions:
Allergies
Alzheimer's Disease
Anemia
Asthma Control
Autism
Bad Breath
Cancer
Cholesterol
Common Cold
Common Illnesses
Costly Illness
Depression
Diabetes
E.Coli
Fatigue & Remedies
Gout
Health & Fitness
Heartburn
Heart Disease: Risks
Hemorrhoids
Hepatitis
Hypertension
Lupus
Medical Conditions
Medical Exams For Men
Metabolic Syndrome
Migraine Headaches Explained
Pains
Prostate Cancer
Senior Health & Safety
Shingles
Sleep Disorders
Stroke

Drugs & Health Foods:
Antioxidants
Caffeine: Pros & Cons
Cancer-Fighting Foods
Coffee
Diet Breakers
Drugs: Uses & Side Effects
Fruits: Health Benefits
High-Octane Foods
Spices: Healing Power
Tea: Health Benefits
Vitamins

Related Links:
A-Z index of drugs
Cancer Statistics
Cancer Types
Disease Index - CDC
Drugs and Medications
Find drugs by disease
Food & Drug Administration
Food Storage Guide
Health Canada
Health for Australians
Hospitals: Best in USA
Life Expectancy Calculator
Lists of Drugs & Supplements
Medical Encyclopedia

Tea

What Is Tea?
Tea is the agricultural product of the leaves, leaf buds, and internodes of the Camellia sinensis plant, prepared and cured by various methods. "Tea" also refers to the aromatic beverage prepared from the cured leaves by combination with hot or boiling water, and is the common name for the Camellia sinensis plant itself. Although tea contains various types of polyphenols, "contrary to widespread belief, tea does not contain tannic acid".

After water, tea is the most widely-consumed beverage in the world. It has a cooling, slightly bitter, astringent flavour which many enjoy.

There are at least six varieties of tea: white, yellow, green, oolong, black and pu-erh of which the most commonly found on the market are white, green, oolong and black. All teas are made from the same species of plant, though different varieties may be used, and the leaves are processed differently, and, in the case of fine white tea, grown differently. Pu-erh tea, a post-fermented tea, is also often used medicinally.

The term "herbal tea" usually refers to an infusion or tisane of leaves, flowers, fruit, herbs or other plant material that contains no Camellia sinensis. The term "red tea" refers to an infusion made from either black tea (mainly in Chinese, Korean, Japanese and other East Asian languages) or the South African rooibos plant (containing no Camellia sinensis).
Content of Tea
Tea contains catechins, a type of disease-fighting flavonoid and antioxidant, which are the keys to tea's health benefits. In a freshly-picked tea leaf, catechins can compose up to 30% of the dry weight. Catechins are highest in concentration in white and green teas, while black tea has substantially fewer due to its oxidative preparation. Research by the U.S. Department of Agriculture has suggested that levels of antioxidants in green and black tea do not differ greatly, with green tea having an Oxygen Radical Absorbance Capacity (ORAC) of 1253 and black tea an ORAC of 1128 (measured in μmolTE/100g). Tea also contains theanine and the stimulant caffeine at about 3% of its dry weight, translating to between 30 mg and 90 mg per 8 oz (250 ml) cup depending on type, brand and brewing method. Tea also contains small amounts of theobromine and theophylline, as well as fluoride[citation needed], with certain types of brick tea made from old leaves and stems having the highest levels.

Dry tea has more caffeine by weight than coffee; nevertheless, more dried coffee is used than dry tea in preparing the beverage, which means that a cup of brewed tea contains significantly less caffeine than a cup of coffee of the same size.

Tea has no carbohydrates, fat, or protein.

To get the best tea benefit, some studies suggest drinking three cups each day to cut heart disease risk. Since iced tea is diluted, it's a lighter source of flavonoids - but it still counts! The longer you steep the tea, the more flavonoids you'll get in your brew.

Choose to drink tea whenever you can, especially as a substitute for soft drinks. In the long run, drinking tea helps tote up the antioxidants you get in a day's time.
Processing and classification of Tea
A tea's type is determined by the processing which it undergoes. Leaves of Camellia sinensis soon begin to wilt and oxidize, if not dried quickly after picking. The leaves turn progressively darker as their chlorophyll breaks down and tannins are released. This process, enzymatic oxidation, is called fermentation in the tea industry, although it is not a true fermentation. It is not caused by micro-organisms, and is not an anaerobic process. The next step in processing is to stop oxidation at a predetermined stage by heating, which deactivates the enzymes responsible. With black tea, this step is executed simultaneously with drying. Tea harvest on the eastern shores of the Black Sea, ca. 1905.

Without careful moisture and temperature control during manufacture and packaging, the tea will grow fungi. The fungus causes real fermentation that will contaminate the tea with toxic and sometimes carcinogenic substances, as well as off-flavors, rendering the tea unfit for consumption.

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
The Health Benefits of Tea
A cup of tea eases frazzled nerves, helps your heart, and may even help fight cancer.

It's a rite of summer, setting out the sun tea jar. With all the health benefits of black tea, sun tea is even more welcome than ever. There's compelling evidence that tea reduces the risk of heart disease, and possibly even helps prevent cancer and Alzheimer's disease.

Indeed, tea is considered a superfood -- whether it's black, green, white, or oolong tea. All those tea types come from the same tea plant, Camellia sinensis. The leaves are simply processed differently. Green tea leaves are not fermented; they are withered and steamed. Black tea and oolong tea leaves undergo crushing and fermenting processes.

All teas from the Camellia plant are rich in polyphenols, antioxidants that detoxify cell-damaging free radicals in the body. Tea has about eight to 10 times the polyphenols found in fruits and vegetables.

Studies of humans, animals, and petri-dish experiments show that tea is high beneficial to our health. Research suggests that regular tea drinkers -- people who drink two cups or more a day -- have less heart disease and stroke, lower total and LDL cholesterol, and recover from heart attacks faster. There's also evidence that tea may help fight ovarian and breast cancers.

Tea also helps soothe stress and keep us relaxed. One British study found that people who drank black tea were able to de-stress faster than those who drank a fake tea substitute. The tea drinkers had lower levels of cortisol, a stress hormone.
Preparation of Tea
The traditional method of making a cup of tea is to place loose tea leaves, either directly, or in a tea infuser, into a tea pot or teacup and pour hot water over the leaves. After a couple of minutes the leaves are usually removed again, either by removing the infuser, or by straining the tea while serving.

Most green teas should be allowed to steep for about three minutes, although some types of tea require as much as ten. The strength of the tea should be varied by changing the amount of tea leaves used, not by changing the steeping time. The amount of tea to be used per amount of water differs from tea to tea but one basic recipe may be one slightly heaped teaspoon of tea (about 5 ml) for each teacup of water (200 ml) (8 oz) prepared as above. Stronger teas, such as Assam, to be drunk with milk are often prepared with more leaves, and more delicate high grown teas such as a Darjeeling are prepared with a little less (as the stronger mid-flavors can overwhelm the champagne notes).

The best temperature for brewing tea depends on its type. Teas that have little or no oxidation period, such as a green or white tea, are best brewed at lower temperatures, between 65 and 85 C (149 and 185 F), while teas with longer oxidation periods should be brewed at higher temperatures around 100 C (212 F). The higher temperatures are required to extract the large, complex, flavorful phenolic molecules found in fermented tea, although boiling the water reduces the amount of dissolved oxygen in the water.
Type Water Temp. Steep Time Infusions
White Tea 65 to 70 C (149 to 158 F) 1 to 2 minutes 3
Yellow Tea 70 to 75 C (158 to 167 F) 1 to 2 minutes 3
Green Tea 75 to 80 C (167 to 176 F) 1 to 2 minutes 4 to 6
Oolong Tea 80 to 85 C (176 to 185 F) 2 to 3 minutes 4 to 6
Black Tea 99 C (210 F) 2 to 3 minutes 2 to 3
Pu-erh Tea 95 to 100 C (203 to 212 F) Limitless Several
Herbal Tea 99 C (210 F) 3 to 6 minutes Varied
Some tea sorts are often brewed several times using the same tea leaves. Historically, in China, tea is divided into a number of infusions. The first infusion is immediately poured out to wash the tea, and then the second and further infusions are drunk. The third through fifth are nearly always considered the best infusions of tea, although different teas open up differently and may require more infusions of hot water to bring them to life.

One way to taste a tea, throughout its entire process, is to add hot water to a cup containing the leaves and after about 30 seconds to taste the tea. As the tea leaves unfold (known as "The Agony of the Leaves") they give up various parts of themselves to the water and thus the taste evolves. Continuing this from the very first flavours to the time beyond which the tea is quite stewed will allow an appreciation of the tea throughout its entire length.

Black tea

The water for black teas should be added near boiling point 99 C (210 F). Many of the active substances in black tea do not develop at temperatures lower than 90C (195F). For some more delicate teas lower temperatures are recommended. The temperature will have as large an effect on the final flavor as the type of tea used.

The most common fault when making black tea is to use water at too low a temperature. Since boiling point drops with increasing altitude, it is difficult to brew black tea properly in mountainous areas.

It is also recommended that the teapot be warmed before preparing tea, easily done by adding a small amount of boiling water to the pot, swirling briefly, before discarding.

Black teas are usually brewed for about 4 minutes and should not be allowed to steep for less than 30 seconds or more than about five minutes (a process known as brewing or mashing in Britain). It is commonly said that a steeping time above five minutes makes the tea bitter (at this point it is referred to as being stewed in Britain), but in reality the precise time depends on a number of factors, such as the type of tea and the water quality, and bitterness can occur as early as three minutes, or not at all even after prolonged steeping.

When the tea has brewed long enough to suit the tastes of the drinker, it should be strained while serving. The popular varieties of black (red) tea include Nepal tea, Darjeeling tea, Nilgiri tea and Ceylon tea.

Green tea

Water for green tea, according to most accounts, should be around 80 to 85 C (176 to 185 F); the higher the quality of the leaves, the lower the temperature. Hotter water will burn green-tea leaves, producing a bitter taste. Preferably, the container in which the tea is steeped, the mug, or teapot should also be warmed beforehand so that the tea does not immediately cool down. High-quality green and white teas can have new water added as many as five or more times, depending on variety, at increasingly high temperatures.

Oolong tea

Oolong teas should be brewed around 90 to 100 C (194 to 212 F), and again the brewing vessel should be warmed before pouring in the water. Yixing purple clay teapots are the traditional brewing vessel for oolong tea. For best results use spring water, as the minerals in spring water tend to bring out more flavor in the tea. High quality oolong can be brewed multiple times from the same leaves, and unlike green tea it improves with reuse. It is common to brew the same leaves three to five times, the third steeping usually being the best.

Premium or delicate tea

Some teas, especially green teas and delicate Oolong teas, are steeped for shorter periods, sometimes less than 30 seconds. Using a tea strainer separates the leaves from the water at the end of the brewing time if a tea bag is not being used. However, black Darjeeling tea, the premium Indian tea, needs a longer than average steeping time. Elevation and time of harvest offer varying taste profiles, proper storage and water quality also have a large impact on taste.

Pu-erh tea

Pu-erh tea is also called Pu'er tea. Pu-erh teas require boiling water for infusion. Some prefer to quickly rinse pu-erh for several seconds with boiling water to remove tea dust which accumulates from the aging process. Infuse pu-erh at the boiling point (100 C or 212 F), and allow to steep for 30 seconds or up to five minutes.

Serving

In order to preserve the pre-tannin tea without requiring it all to be poured into cups, a second teapot may be used. The steeping pot is best unglazed earthenware; Yixing pots are the best known of these, famed for the high quality clay from which they are made. The serving pot is generally porcelain, which retains the heat better. Larger teapots are a post-19th century invention, as tea before this time was very rare and very expensive. Experienced tea-drinkers often insist that the tea should not be stirred around while it is steeping (sometimes called winding in the UK). This, they say, will do little to strengthen the tea, but is likely to bring the tannins out in the same way that brewing too long will do. For the same reason one should not squeeze the last drops out of a teabag; if stronger tea is desired, more tea leaves should be used.

The addition of milk to tea in Europe was first mentioned in 1680 by the epistolist Madame de Svign. Many teas are traditionally drunk with milk in cultures where dairy products are consumed. These include Indian masala chai, and British tea blends. These teas tend to be very hearty varieties of black tea which can be tasted through the milk, such as Assams, or the East Friesian blend. Milk is thought to neutralize remaining tannins and reduce acidity.

The Chinese (Hans) do not usually drink milk with tea (or indeed use milk at all) but the Manchurians do, and the elite of the Qing Dynasty of the Chinese Empire continued to do so. Hong Kong-style milk tea is based on British colonial habits. Tibetans and other Himalayan peoples traditionally drink tea with milk or yak butter and salt.

The order of steps in preparing a cup of tea is a much-debated topic. Some say that it is preferable to add the milk before the tea, as the high temperature of freshly brewed tea can denature the proteins found in fresh milk, similar to the change in taste of UHT milk, resulting in an inferior tasting beverage.

Others insist that it is better to add the milk after brewing the tea, as most teas need to be brewed as close to boiling as possible. The addition of milk chills the beverage during the crucial brewing phase, if brewing in a cup rather than using a pot, meaning that the delicate flavor of a good tea cannot be fully appreciated. By adding the milk afterwards, it is easier to dissolve sugar in the tea and also to ensure that the desired amount of milk is added, as the color of the tea can be observed.
25 reasons why you should drink green tea
Green tea has increasingly become a very popular drink worldwide because of its immensely powerful health benefits. It is extraordinarily amazing what green tea can do for your health. And if you're not drinking 3 to 4 cups of green tea today, you're definitely NOT doing your health a big favor.
1. Green Tea & Cancer: Green tea helps reduce the risk of cancer. The antioxidant in green tea is 100 times more effective than vitamin C and 25 times better than vitamin E. This helps your body at protecting cells from damage believed to be linked to cancer.
2. Green Tea & Heart Disease: Green tea helps prevent heart disease and stroke by lowering the level of cholesterol. Even after the heart attack, it prevents cell deaths and speeds up the recovery of heart cells.
3. Green Tea & Anti-aging: Green tea contains antioxidant known as polyphenols which fight against free radicals. What this means is that it helps you fight against aging and promotes longevity.
4. Green Tea & Weight Loss: Green tea helps with your body weight loss. Green tea burns fat and boosts your metabolism rate naturally. It can help you burn up to 70 calories in just one day. That translates to 7 pounds in one year.
5. Green Tea & Skin: Antioxidant in green tea protects the skin from the harmful effects of free radicals, which cause wrinkling and skin aging. Green tea also helps fight against skin cancer.
6. Green Tea & Arthritis: Green tea can help prevent and reduce the risk of rheumatoid arthritis. Green tea has benefit for your health as it protects the cartilage by blocking the enzyme that destroys cartilage.
7. Green Tea & Bones: The very key to this is high fluoride content found in green tea. It helps keep your bones strong. If you drink green tea every day, this will help you preserve your bone density.
8. Green Tea & Cholesterol: Green tea can help lower cholesterol level. It also improves the ratio of good cholesterol to bad cholesterol, by reducing bad cholesterol level.
9. Green Tea & Obesity: Green tea prevents obesity by stopping the movement of glucose in fat cells. If you are on a healthy diet, exercise regularly and drink green tea, it is unlikely you'll be obese.
10. Green Tea & Diabetes: Green tea improves lipid and glucose metabolisms, prevents sharp increases in blood sugar level, and balances your metabolism rate.
11. Green Tea & Alzheimer’s Disease: Green tea helps boost your memory. And although there's no cure for Alzheimer's, it helps slow the process of reduced acetylcholine in the brain, which leads to Alzheimer's.
12. Green Tea & Parkinson’s Disease: Antioxidants in green tea helps prevent against cell damage in the brain, which could cause Parkinson's. People drinking green tea also are less likely to progress with Parkinson's.
13. Green Tea & Liver Disease: Green tea helps prevent transplant failure in people with liver failure. Researches showed that green tea destroys harmful free radicals in fatty livers.
14. Green Tea & High Blood Pressure: Green tea helps prevent high blood pressure. Drinking green tea helps keep your blood pressure down by repressing angiotensin, which leads to high blood pressure.
15. Green Tea & Food Poisoning: Catechin found in green tea can kill bacteria which causes food poisoning and kills the toxins produced by those bacteria.
16. Green Tea & Blood Sugar: Blood sugar tends to increase with age, but polyphenols and polysaccharides in green tea help lower your blood sugar level.
17. Green Tea & Immunity: Polyphenols and flavenoids found in green tea help boost your immune system, making your health stronger in fighting against infections.
18. Green Tea & Colds & Flu: Green tea prevents you from getting a cold or flu. Vitamin C in green tea helps you treat the flu and the common cold.
19. Green Tea & Asthma: Theophylline in green tea relaxes the muscles which support the bronchial tubes, reducing the severity of asthma.
20. Green Tea & Ear Infection: Green tea helps with ear infection problem. For natural ear cleaning, soak a cotton ball in green tea and clean the infected ear.
21. Green Tea & Herpes: Green tea increases the effectiveness of topical interferon treatment of herpes. First green tea compress is applied, and then let the skin dry before the interferon treatment.
22. Green Tea & Tooth Decay: Green tea destroys bacteria and viruses that cause many dental diseases. It also slows the growth of bacteria which leads to bad breath.
23. Green Tea & Stress: L-theanine, which is a kind of amino acids in green tea, can help relieve stress and anxiety.
24. Green Tea & Allergies: EGCG found in green tea relieves allergies. So, if you have allergies, you should really consider drinking green tea.
25. Green Tea & HIV: Scientists in Japan have found that EGCG (Epigallocatechin Gallate) in green tea can stop HIV from binding to healthy immune cells. What this means is that green tea can help stop the HIV virus from spreading.
Make your own free website on Tripod.com
Copyright © 2000 Siakhenn
Last modified on
arrw_tp_blu.gif (131 bytes)