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Flender/Flender Gear Units/Bevel-helical gear units B4

tal components of human metabolism. Green tea is claimed to protect againstthe incidence of cancer, especially lung, esophageal, skin, and gastrointestinal cancers. Another important nutritional function of tea is that of maintaining uid balance, which is due to its versatility, absence of harm, and potential health benets. In addition,tea is apparently good source of uoride and manganese, which prevents dental cavitiesand aids protein and energy metabolism, respectively (3, . 7 BY-PRODUCTS OF TEA Tea waste is rich source of number of by-products, such as caffeine, polyphenols, pigments, polymer extenders, vitamins, minerals, growth regulators, and foaming agents.Tea seed, another waste product, is utilized for production of oil, saponins, and furfuralfrom its husk. Spent tea and sludge obtained during manufacture of cold-soluble instanttea are used for making -triacontanol, caffeine, and other minor constituents (1, . 7 Nagalakshmi 7.1 Caffeine Although caffeine is produced synthetically there is always signicant preference for the natural caffeine extracted from tea waste. Tea waste is rst denatured with lime oralkali; caffeine is extracted with solvents such as benzene, chloroform, methylene chloride, and other halogenated hydrocarbons; and the solvent is evaporated and the residue ex- tracted with hot water, puried, and crystallized. In another method, the denatured teawaste is extracted with hot water, followed by transfer of caffeine to any of the water-immiscible solvents, concentration of the organic phase, purication, and crystallization(1, . 7.2 Polyphenols and Pigments Polyphenols and pigments from tea waste mainly comprise theaavins, thearubigins, and catechins, which constitute about 1%1% of the tea extractives. Tea polyphenols haveconsiderable potential as food antioxidants and in the production of food color. When teaextracts are coupled with beet root pigments, red dye is obtained; an orange dye isproduced by mixing with the ethylacetate-s