The contents of fresh leaves are the material basis of Tieguanyin's aroma and taste. The fresh leaves of Tieguanyin are rich in organic components. According to the determination, the total water extract of Tieguanyin three-leaf tip is 36.29%, the content of tea polyphenols is 2 1. 14%, and the total catechin is 146.75438+0 mg/g, and the content of alcohol catechin (L-EGCG, L-ECG) in Tieguanyin catechin. According to the anti-cancer experiment of Institute of Nutrition and Food Hygiene, Chinese Academy of Preventive Medicine, Tieguanyin and Fujian scented tea have the best anti-cancer effect, followed by Hangzhou green tea, Hainan black tea and green tea. Tieguanyin can completely block the endogenous production of nitrosamines in the body. Yes S, G and others have studied the antioxidant effects of green tea (stir-fried and steamed), oolong tea and black tea extracts, and think that the crude catechins of oolong tea such as Tieguanyin tea have the strongest antioxidant activities, among which EGCG content is the highest, which can eliminate intracellular reactive oxygen molecules and improve the damage or influence induced by reactive oxygen species, thus protecting human body from aging diseases (such as dementia). The total amount of amino acids in Tieguanyin is 2.22%, which is at a medium level. However, the contents of glutamic acid, threonine, histidine, methionine, alanine and glycine in Tieguanyin are higher than those in general oolong tea, especially the contents of glutamic acid, methionine and alanine are very high. The content of glutamic acid is 78.09 mg/ 100 g, which is 2-4 times that of common oolong tea varieties, and methionine is 9.09 mg/6544.
2. Mineral nutrition in Tieguanyin
According to the test, Tieguanyin oolong tea contains more than 30 mineral elements. Among these elements, the content of potassium is the highest, reaching 65438 09.2 mg/g, followed by phosphorus, calcium and magnesium, with the content range of 65438 0.6 ~ 4.7 mg/g, followed by silicon, aluminum, manganese and chlorine, with the content range of 0.2 ~ 0.2. The contents below 0.0 1 mg/g are tin, lead, barium, titanium, nickel, chromium, vanadium, cobalt, cadmium and selenium.
Compared with other teas, oolong teas such as Tieguanyin have higher contents of manganese, iron, fluorine, potassium and sodium, higher contents of zinc, magnesium and selenium, and lower contents of sodium and nickel.
Because the fresh leaves of Tieguanyin are relatively mature, the manganese content in Tieguanyin is very high, reaching 0.87 ~ 1.45 mg/g, and the leaching rate is also high, reaching 23.9%. Drinking tea 15g every day can meet more than 50% of daily needs.
Among oolong tea, green tea, black tea and scented tea, oolong tea such as Tieguanyin has the highest fluorine content (about 15 ~ 55%), which is much higher than ordinary food. Fluorine is the main medium of bone structure, which has a significant effect on preventing and treating dental caries and osteoporosis in the elderly. Therefore, Tieguanyin is a good fluoride supplement drink in low fluoride areas.
Oolong tea has a high ratio of potassium to sodium and is an ideal drink for patients with diabetes and hypertension.
The selenium content of Tieguanyin is 0. 168ug/g, ranking first among the six major teas, which is higher than that of general oolong tea (for example, the average selenium content of Narcissus and Huang Jingui 1 ~ 3 is 0.08 17ug/g). Selenium is a component of glutathione oxidase, which can stimulate the production of immune proteins and antibodies, enhance the body's resistance to diseases, have a certain curative effect on coronary heart disease, and inhibit the occurrence and development of cancer cells. However, more than 40 countries and regions in the world lack selenium, and there is a large selenium-deficient area from northeast to southwest in China. If each person drinks 20g Tieguanyin every day, the daily intake of selenium is about 1.2 ug, which is close to the normal daily safety standard of 1/40. Therefore, drinking Tieguanyin can supplement a certain amount of organic selenium.
3. Aromatic substances of Tieguanyin
There are 70 kinds of aroma components in Tieguanyin and other Niaolong teas, among which 10 is a typical characteristic aroma component of oolong Tieguanyin, and the * * * feature of these components is the aroma of various flowers. For example, the sweetness and aroma of heavy alcohols and their oxides are similar to those of lily of the valley; Benzyl alcohol, tea ethanol and geraniol are like roses. Guyuronolide, cis-jasmonate and low-concentration indole have rich sweet floral fragrance such as jasmine and gardenia. Benzaldehyde, methyl salicylate, β -ionone and nerolidol are fruity. Pyrazine is similar to sweet caramel aroma; Jasmonate is similar to peaches and apricots. Compared with the aroma characteristics of Oolong tea varieties such as Eriocheir sinensis, Narcissus and Huang Dan, Tieguanyin has the richest aroma components, and the contents of low-boiling aroma components and high-boiling aroma components are relatively uniform. The total volatile essential oil of Tieguanyin is also high in oolong tea, reaching 40.6 mg/ 100 g. Among the aroma components of Tieguanyin, the relative contents of nerolidol, cis-jasminolactone, linalool, α -phenylethanol and indole are relatively high, reaching 26.29%, 3.09%, 3.93%, 3.04% and 3.83 respectively. Tieguanyin has a long fragrance because of its rich variety and high content of aromatic substances, which has a positive effect on pleasure and health care.