1What is tea ?
Tea is a drink made by infusing leaves of the tea plant (Camellia sinensis , or Thea sinensis) in hot water. The name "tea" is also used to refer to the leaves themselves ; and it is also the name of a mid- to late-afternoon meal in the British Isles and associated countries , at which tea (the drink) is served along with various foods.
2Where did the name "Tea" come from ?
The word for tea in most of mainland China (and also in Japan ) is "cha". (Hence its frequency in names of Japanese teas : Sencha , Hojicha etc.) But the word for tea in Fujian province is "te" (pronounced approximately "tay"). As luck would have it , the first mass marketers of tea in the West were the Dutch , whose contacts were in Fujian. They adopted this name , and handed it on to most other European countries. The two exceptions are Russia and Portugal , who had independent trade links to China. The Portuguese call it "cha", the Russians "chai". Other areas (such as Turkey , South Asia and the Arab countries) have some version of "chai" or "shai". "Tay" was the pronunciation when the word first entered English , and it still is in Scotland and Ireland. For unknown reasons, at some time in the early eighteenth century the English changed their pronunciation to "tee". Virtually every other European language , however , retains the original pronunciation of "tay".
3What are the different kinds of tea ?
The three main categories are "Green tea" , "Black tea" and "Oolong tea". All three kinds are made from the same plant species. The major differences between them are a result of the different processing methods they undergo. Black teas undergo several hours of oxidation in their preparation for market; oolongs receive less oxidation, and green teas are not oxidized at all. There are , of course , many different varieties within these three main categories.
4What is White Tea ?
Sri Lanka traditionally produces one of the world's finest white teas in the form of Silver Tips and Golden Tips , entirely handmade from a special variant of the Camellia Sinensis plant , untouched by machines and prized for their rarity and subtle character. The Chinese also have a tradition of producing fine White Teas. In the production of white tea the "Bud" is selectively plucked and sun dried. Since the Bud remains undamaged the Catechins or the un-oxidised Polyphenols present remain intact. What we refer to as Flavonoids in tea , or the antioxidants in tea , include the un-oxidised Polyphenols or Catechins as in Green Tea and White Tea , as well as the Theaflavins and low molecular Thearubigins in conventional Black Tea. The Catechins (Flavonoids) content in the tea becomes progressively less as we go down from the Bud to the mature leaves in a tea shoot. The bud has the highest catechin content , next the first leaf, followed by the second leaf and so on. Hence the sun dried buds or White Tea will have a higher Flavonoid or Antioxidant property. Further , since the bud is sun dried (not subjected to high temperature in a drier) even the vitamin content in the White Tea will remain high and potent. So will be the Caffeine content. It has been already shown that the bad effects of caffeine is nullified in Tea by the presence of the Polyphenols in the tea (unlike in coffee and the colas). Hence the White Tea will have greater nutritive and therapeutic value than the conventional black tea.
5What is Real Tea ?
Tea in its true sense is defined by the International Standards Organisation (ISO) as , 'tea derived solely and exclusively , and produced by acceptable processes , notably withering , leaf maceration , aeration and drying , from the tender shoots of varieties of the species Camellia Sinensis , known to be suitable for making tea for consumption as a beverage. Real Tea is tea produced in the traditional , orthodox manner from the tender shoots of Camellia Sinensis. The process of manufacture , perfected over centuries is the most widespread in Sri Lanka with its drying , rolling , fermentation and baking into the form most people are familiar with - black tea , green tea , white tea. Orthodox Tea is distinct from the more recent process - CTC (or Cut , Twist and Curl) which was developed by companies seeking to offer quick colour in a teabag. CTC teas rob tea of its soul , losing the subtlety of flavour , aroma , variety and character that Orthodox Teas are prized for. CTC consists of just 3 grades or forms , whilst Orthodox .Tea produces almost infinite variety of leaf size , colour , subtlety of character and body.
6Why should one never reboil water when brewing tea ?
Taste , colour and mouth feel depend on the interaction between the two main components of tea , polyphenols and caffeine. Each component is astringent on its own , but as a complex the astringent character is reduced. Water is known to contain dissolved gases absorbed from the air. Carbon dioxide (CO2) gas that is present in water affects the acidity. Acidity of water plays a critical roll in the ionization of tea polyphenols and it contributes to the stability of the above complex. CO2 in water is gradually released during the boiling process. Re-boiling will in fact further reduce CO2 levels , resulting in a decrease in the acidity. As mentioned above this will affect the caffeine and polyphenol complexion , and bring about changes in the colour as well as the character of the brew. Twice boiled water will therefore affect the taste of a good tea and hence our request that only freshly boiled water is used for brewing tea.
7Can over-boiled water affect the quality of tea ?
Boiling water for too long does dramatically affect the quality of tea. The desirable brisk taste of tea is created by the interaction of two of its main components , caffeine and polyphenols. Each component is harsh on its own but as a complex the compounds moderate each other. Acid levels of water affect the behaviour of these components. Water contains minerals and gases absorbed from the earth bed and air. Carbon dioxide absorbed by air makes the water slightly acidic that influence the colour and taste. High temperature changes the acidity of water and the acidity is reduced by gradually driving out carbon-dioxide. Therefore re-boiled water might well brew tea of a different colour and strength and is unsuitable to brew a good cup of tea.
8Does the water affect the tea brew ?
The water used to brew the tea significantly affects the colour and the taste of a cup of tea. Tea brewed in soft water or permanently hard water (which contains CaSO4) appears brighter than if it is brewed in temporary hard water (that contains Calcium bicarbonate CaCO3). High pH water that contains bicarbonate makes the infusion look darker brown due to the greater ionisation of the tea polyphenols. While lower pH as in lemon tea the infusion turns yellow. As for taste some teas are more suited to softer water such as the orthodox manufactured Assam leaf, while high grown Ceylon and CTC manufactured teas are better with temporary hard water.
9How much caffeine is there in tea ?
Caffeine from natural sources has been consumed and enjoyed by humans throughout the world for centuries. The widespread natural occurrence of caffeine in a variety of plants undoubtedly played a major role in the long-standing popularity of caffeine incorporated products , especially the beverages. The human body requires a certain amount of caffeine and research indicates that up to 10 - 12 cups of tea daily will not have any detrimental effect on the body. The species or the variety of the tea plant determines content of caffeine in tea , as it is a genetic feature. Camellia Sinensis , the variety that is grown in Sri Lanka has caffeine levels of approximately 2.5 - 4%. However the distribution of caffeine in the plant depends on the part of the plant it is derived from. For example : Bud 4.70 % First leaf 4.20 % Second Leaf 3.50 % Third Leaf 2.90 % Upper stem 2.50 % Lower stem 1.40 % Both tea and coffee contain the methylated xanthines , caffeine , theophylline and theobromine. Brewed coffee is said to have the highest caffeine content among those dietary items containing caffeine - approx. 100 mg / cup. A 300 ml bottle of cola has 30 - 60 mg caffeine and approx. 37 mg caffeine is there in 56g dark chocolate bar. There are a wide variety of drug products that contain caffeine - typically 200 mg / tablet or capsule (pharmacologically active dose of caffeine). A cup of tea has approx. 28 - 44 mg caffeine- (FDA 1980). The quantity of caffeine in tea , on dry solids basis , is more than the quantity of caffeine in an equal weight of dried coffee beans. However , as a result of getting more cups of tea from a unit quantity of black tea than from an equal quantity of ground coffee beans, the quantity of caffeine per cup of tea is less than the caffeine in an equal cup of coffee. Excessive caffeine is said to have adverse effects on the human system and brewed tea has only half the caffeine levels in brewed coffee. However, it is important to note that research proves that the presence of caffeine in tea does not produce unhealthy results due to its combination with tea polyphenols.
10How much caffeine is considered safe ?
The Food Guide to healthy eating recommends caffeine consumption in moderation. According to the current findings for most people an intake of caffeine up to 400 - 450 mg / day does not increase the risk of heart disease , hypertension or have an adverse effect on pregnancy or the foetus. This level of caffeine is equivalent to approximately 10 to 12 cups (170 ml) of tea per day.
11Does green tea have the same Caffeine level as black tea ?
Green tea , as well as Oolong tea & Black tea , are produced from the herb Camellia Sinensis. They all contain the same amount of caffeine. Caffeine content in a cup of tea is 2.5% to 4% , which is about a third of that in coffee. It is claimed that 80% of the caffeine in tea remains unabsorbed by the human body. From the above you would realise that Green tea , Oolong tea & Black tea may taste different but the caffeine content is the same.
12Are the antioxidants in green and black tea the same ?
It was thought until comparatively recently that green tea was the most effective antioxidant-containing tea and that green-tea catechins (the unoxidized polyphenols present in tea leaf) alone were the antioxidants giving tea its health-giving attributes. It is now well known that the theaflavins and thearubugins produced by the condensation of oxidized catechins , during the fermentation stage of black tea manufacture , are equally effective antioxidants (Leung et al 2001). The catechins present in tea flush and as such in green tea are Expressed as a % of dry weight Epicatechin 1 - 3% Epicatechin gallate 3 - 6% Epigallocatechin 3 - 6% Epigallocatechin gallate 9 -13% Catechin 1 - 2% Gallocatechin 3 - 4% During manufacture of Black Tea these catechins get oxidized & polymerized (condensed), for example : Epicatechin + Epigallocatechin gallate + Oxygen => Theaflavin The paired catechins as they appear in Black Tea are now known to be equally effective antioxidants. The body produces free radicals (FRs) under certain conditions. Carcinogens and radiation from the environment facilitates the formation of FRs. These FRs within the body cause oxidative changes to DNA (the genetic material present in all cells). Changes to DNA carry the risk of cancers. The FRs are inhibited and destroyed by the antioxidants in tea , both green and black tea. Green and black tea comes from Camellia Sinensis. Green tea is unfermented , steamed immediately after plucking , and retains a lighter colour and flavour. Black tea is allowed to ferment and is then dried , resulting in a darker leaf colour and a more flavour and aroma.
13Does drinking tea during pregnancy affect the foetus ?
Questions surrounding caffeine intake and risk of miscarriage and health of the foetus continue to be raised by pregnant women. A study published in the journal of American Medical Association found no evidence that moderate caffeine use increases the risk of spontaneous abortions , growth retention or account for other factors. Another seven-year epidemiological study on 1,500 women examined the effect of caffeine , during pregnancy as well as on subsequent child development. Caffeine consumption equivalent to approximately 3 to 5 cups of tea per day had no effect on birth weight , birth length and head circumference of the baby. A follow-up examinations at age's eight months , four and seven years also revealed no effect of caffeine consumption on the child's motor development or intelligence. A number of factors influence the metabolism of caffeine and the individual's response to caffeine indigestion. These include pregnancy , age , sex , body weight , diet , exercise and stress smoking and alcohol consumption. Pregnancy hampers caffeine metabolism. For example : in non pregnant women the break-down of half of the caffeine takes an average of 2.5 - 4.5 hours , 7 hours during mid-pregnancy and 10.5 during the last few weeks of pregnancy. As caffeine retention is longer during pregnancy , women sensitive to caffeine may be affected. As a result a moderate consumption of approximately 3-4 cups a day, is recommended for women during pregnancy.
14What is tea scum or the dark skin on top of the brewed tea ?
It is the result of the high molecular weight components which are formed due to the influence of calcium and bicarbonate ions at the liquid water interface. The scum can be removed in two ways : 1. by filtering the calcium ions , 2. by adding acids to covert bicarbonate ions to CO2. Very little scum is formed on a cup of very strong tea. As the acidic tea polyphenols themselves partly neutralise the bicarbonate ions. It also should be noted that less than one mg of scum is formed in a cup of tea and it is not known to be harmful to human health.
15Why does tea cloud when it is cooled ?
Clouding in tea is a result of the colloidal precipitate that is formed. This is called 'tea cream'. Tea creaming takes place when black tea is cooled below 400 C. A weak complexion is formed between caffeine and polyphenols (theaflavins and thearubigins). The tendency to cream down varies from tea to tea. In black tea without milk complexation and subsequent precipitation that occurs is negligible due to just 4% of caffeine. In tea with milk a similar association takes place between the milk protein casein and various polyphenols. Due to the availability of casein in milk tea the complexion is greater resulting in larger precipitation.
16Does tea reduces the diuretic effect in comparison to coffee ?
The diuretic can be attributed to the caffeine present in tea and coffee. Caffeine increases diuretic action on the kidneys, increasing urinary volume and sodium extraction as a result of a decrease in the tubular re-absorption of sodium and water. Coffee contains a higher content of caffeine compared to tea. Research has shown that a 170ml (6-oz) serving of tea contains , on average 34mg of caffeine in comparison to 99 mg of caffeine in 170 ml serving of brewed coffee. As a result the diuretic effect of coffee is greater compared to tea.
17Can tea be part of a healthy adult's daily fluid intake ?
As brewed tea contains almost 98% water it makes a healthy contribution to the delay fluid balance. Tea contains no additives or artificial colours. Research indicates possible antioxidant benefits so drinking tea can be a calorie-free way to increase intake dietary antioxidants.
18Is regular tea consumption good for my immune system ?
Harvard Medical School discovered that regular consumption of tea could boost the body's defenses against infection. A component in tea was found in laboratory experiments to prime the immune system to attack invading bacteria , viruses and fungi , according to a study in the Proceedings of the National Academy of Sciences. A second experiment , using human volunteers , showed that immune system blood cells from tea drinkers responded five times faster to germs than did the blood cells of coffee drinkers. Researchers claim that the results give clear proof that five cups of tea a day sharpen the body's disease defenses. In the study a substance called L-theanine was isolated from ordinary black tea. L-theanine is broken down in the liver to ethylamine , a molecule that primes the response of an immune system element called the gamma-delta T cell , considered the first line of defence against bacteria , viral , fungal and parasitic infections. The T cells prompt the secretion of interferon , a key part of the body's chemical defense against infection. To further test the finding , the researchers had 11 volunteers drink five cups a day of tea , and 10 others drink coffee. Before the test began , they drew blood samples from all 21 test subjects. After four weeks , they took more blood from the tea drinkers and then exposed that blood to the bacteria called E-coli. The immune cells in the specimens secreted five times more interferon than did blood cells from the same subjects before the weeks of tea drinking researchers claimed. Blood tests and bacteria challenges showed there was no change in the interferon levels of the coffee drinkers.
19Does tea affect the absorption of Iron ?
Although concerns have been expressed about consumption of iron, existing research and dietary knowledge indicate that tea is not likely to cause health risk , in individuals consuming a typically Western diet. Dietary iron exists in two forms , heme iron (derived from animal) and non-heme iron (found in plants). The body better absorbs heme iron than non-heme iron. Between 15-35 % of heme iron is absorbed, while 2-20% is absorbed of non-heme iron. Non-heme iron is generally modified by other dietary components. Certain components in grain , fruit and vegetables as well as polyphenols in tea reduce the availability of iron to the body. However , studies have shown that tea only decreases iron absorption when it is consumed simultaneously with food containing non-heme iron. Tea drinking between meals has no effect on iron absorption. Moreover the ability of tea polyphenols to decrease iron absorption is reduced by the presence of other dietary constituents particular ascorbic acid (known to increase absorption of non-heme iron) and milk.
20What are the nutritional benefits of tea ?
Tea composition varies with climate , season , horticultural practices and variety. Polyphenols are the most important component in tea , as they constitute approximately 36 percent of the dry weight of tea. Other components of fresh green leaf include caffeine , protein and amino acids , carbohydrates , lipids , vitamins and minerals. Green and black tea have similar chemical make-up. The primary difference between the two types lies in the chemical changes that take place during their production. In black tea the plant Polyphenols are oxidized and this is prevented in the manufacture of green tea. One of the most important groups of Polyphenols in tea is the catechins in green tea , theaflavins and thearubigens in black tea. A variety of physiological effects have been attributed to tea catechins which are currently best known for their antioxidant activities. Black tea is all-natural (non flavoured) and contains no additives. It is virtually calorie-free (1 calorie per 100 ml) and sodium free and is therefore a suitable beverage for individuals on calorie-reduced or low sodium diet. Tea includes fluoride , traces of vitamins A , K , C , B carotene and B vitamins. Average daily consumption of tea in the United Kingdom , 3.43 cups (650 ml), provides very few calories and only a small amount of fat , whilst contributing valuable minerals and vitamins to the diet. It provides : Over half of the total intake of dietary flavonoids Nearly 16% of the daily requirement of calcium Almost 10% of the daily requirement of zinc Over 10% of the folic acid need Around 9% , 25% and 6% of vitamins B1 , B2 and B6 respectively.
21What is decaffeinated tea ?
For teas to be labelled decaffeinated , the caffeine content should not exceed 0.4% by dry weight , which is equivalent to approximately 4 mg of caffeine per 170 ml serving. The process of decaffeination extracts the caffeine in tea. The current commercially available methods for decaffeinating black tea are solvent based extraction using ethyl acetate or methylene chloride , and extraction using supercritical (solid) carbon dioxide. All three methods extract caffeine with minimum effect to the quality of tea.