Green tea extract
Green tea is obtained from the tea plant Camellia sinensis, for instance, freshly gathered tea leaves, fresh green tea leaves that are dried immediately after gathering, fresh green tea leaves that have been heat treated before drying to inactivate any enzymes present, and aqueous extracts of these leaves. Green tea materials are tea leaves and their extracts which have not undergone substantial fermentation to create black tea. Green tea is almost inodorous and has an astringent and pleasantly bitter taste. The bitter taste is caused by the polyphenols present in the tea. Green tea catechins are associated with lowering blood cholesterol and are also known to be scavengers of free radicals and chelators of metals in the body, making them effective antioxidant nutrients. In green-tea there have mainly been found catechins, flavonol glycosides, bisflavonols and chlorogenic acid. The small-molecule components in these polyphenols, particularly the dimers, have capillary-sealing and anti-inflammatory effects. Green tea is unfermented retaining high levels of unoxidized catechins. Fermentation is an enzymatic oxidation process induced by abrasion and aeration of the tea leaves to produce oxidative condensation of catechins that form catechin polymers, such as theaflavins and thearubigins, etc. Major constituents of green tea are epigallocatechin gallate, epicatechin gallate, epigallocatechin, gallocatechin, catechin. Green tea extracts contain high levels of unoxidized flavanols, especially monomeric catechins such as epicatechin, epigallocatechin, epigallocatechingallate and epicatechingallate that impart a desired taste quality (astringency) to the tea beverage. Polyphenols, e.g., epigallocatechin gallate (EGCG), in green tea are useful to protective against certain cancers, and they are also potent antioxidants. Green tea preparations are useful to promote immune function and to prevent and treat high cholesterol, heart disease, infection (e.g., Staphylococcus aureus infection, skin infection, bacterial infection, viral infection), acne, aging, immune disorders, dental caries, periodontitis, halitosis, dandruff, cancer, cardiovascular disease (e.g., hypertension, thrombosis, arteriosclerosis), diabetes, elevated blood glucose, diseases of the alimentary canal and respiratory system, influenza hepatitis, liver disease. Green tea contains enormous amounts of nutrients, such as vitamins E, C and A, catechin and theanine. It has been said in recent years that active oxygen is one of the factors affecting disadvantageously human health and promoting aging. Meanwhile, green tea contains a higher content of superoxide dismutase (SOD) as an enzyme eliminating active oxygen. Besides catechols, tea contains caffeine, the diuretic effect of which is well known. This diuretic effect is the reason for the traditional use of green tea as a medicinal plant to promote the elimination of water by the kidneys, either in the case of urinary disorders or as a supplement to weight-reducing diets. The presence of caffeine is also the reason for the traditional use of tea in conditions of fatigue (asthenia). The long-term consumption of green tea is thought to be anti-atherogenic on account of its hypocholesterolemiant effects and its ability to prevent the oxidation of LDLs in the circulation. Green tea is also known for its anti-mutagenic and anti-carcinogenic effects. Thus, it has been shown that green tea significantly reduces the risk of colorectal, skin and breast cancers. Green tea is typically extracted with hot or cold water to form a dilute extract containing soluble tea solids. This green tea extract can be concentrated to form a concentrated extract which is sold in frozen, refrigerated or dried form. This green tea extract can also be combined with other beverage ingredients such as fruit juice, nectar, etc., to provide beverages having at least some of the desired flavor and sensory characteristics of green tea.
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