'Two leaves and the bud' that give us the cheering cup of tea, are universally liked, the world over, mainly for its refreshing and stimulating after effect. After water tea is the most widely consumed beverage, exceeding all others like coffee, soft drinks, juices etc. Beverages from tea leaves are made either before processing or after converting into black tea. Water extract of unfermented tea gives green tea which is liked by oriental people, especially in China and Japan. Brewed tea made from fermented and dried leaves yield dark colored extracts which are consumed as such or with milk. White tea, yellow tea, green tea, oolong tea and black tea differ depending on whether the leaves have been wilted, bruised or crushed and oxidized. Flavored tea preparations using spices, aromatic substances, cocoa and herbs are popular products known for their soothing effect. 'Dip' tea packed in edible sachets with micropores is a convenient version that can be used to prepare extracts by immersing in hot water.
Tea leaves contain over 700 phytochemicals including flavonoids, amino acids, vitamins, caffeine, theobromine and polysaccharides. Though the caffeine content is higher in tea leaves than in coffee, due to smaller quantities used to prepare beverages from tea, effective caffeine intake per cup is more in case of coffee. Presence of the polyphenols like catechins in tea makes it an awesome protective food of very high health value. Almost 30% of dry tea is catechins, the most predominant being the widely studied Epigallo Catechin Gallate (EGCG). Green tea has 52 to 85 mg of catechins per gm on dry weight basis. Hundreds of animal studies have confirmed that catechin is a powerful antioxidant, 100 times more effective than Vitamin C and 25% better than Vitamin E. How ever if results of animal studies are to extrapolated on humans, ridiculously high dosage of catechin intake is necessary, making it unrealistic. On an average Indians take tea to the equivalence of 750 gm per capita per year, annual tea consumption in UK is almost 3-fold, about 2.31 kg per capita.
Tea is supposed to be anti-hypertensive, anti-inflammatory, anti-proliferative, anti-thrombogenic and lipid depressant. The antioxidant activity as measured on an ORAC scale is between 1128 for black tea and 1253 for green tea, implying that technology for making black tea does not reduce the antioxidant potential to any significant extent. Regular consumption of tea helps in boosting beneficial intestinal flora, providing immunity against GI disorders and protecting cell membranes against oxidative changes.
Catechin is some what unstable under non-acidic environment that exists in the intestine and the extent of absorption from GI is affected by this constraining factor. The recent finding that green tea beverage combined with ascorbic acid and sugar significantly raised catechin absorption offer technologists opportunity to develop products based on this combination. Lemon tea prepared with lemon juice and tea extract is already popular and a beverage designed accordingly can be a better option than soft drinks. In countries like Indonesia bottled lemon tea is already a popular drink available commercially like soft drinks. Whether synthetic ascorbic acid is equally effective like lemon juice is not clear while the role of sugar is still to be ascertained. Industry must take the clue and come out with tea based products, not necessarily beverages alone but also other products to cater to a wide section of the consuming community.