In Xian Yi, tea is not only a drink suitable for all ages, but also its efficacy in treating diseases and strengthening the body cannot be underestimated. Various nutrients contained in tea are the material basis for tea to benefit human health, and it also makes tea more and more popular among people all over the world. Some people call tea "the drink of the atomic age" and "the drink of 2 1 century", which really makes sense.
The composition of tea is very complicated. As a kind of food, tea contains a lot of energy and nutrients needed by human body, which has high nutritional value.
Energy is a necessary substance to maintain the metabolic activity of the body, which is provided by thermogenic nutrients such as carbohydrate, protein and fat. Compared with other foods, tea is a low-energy food, but different kinds of tea can provide different energy. Generally speaking, the better the quality of tea, the higher the energy. Green tea provides the highest energy per100g of tea, while brick tea provides the lowest energy, because the quality of tea as raw material is not high. If you add milk and sugar to tea and drink 6 cups of tea every day, about 1 100 ml, the energy obtained can account for 7% ~ 10% of the energy provided by the whole day's diet. So people at home and abroad like to drink milk tea or sugar tea.
Protein's "life is the existence form of protein", that is to say, there is no life without protein. Protein has a very important nutritional function. When evaluating the nutritional value of protein, it is mainly to see whether the types of essential amino acids are complete, whether the proportion is appropriate and whether the quantity is sufficient. Tea contains various amino acids, but the proportion is not reasonable enough. Interestingly, tea also contains a lot of theanine, which is unique to tea and the main component of tea fragrance.
Compared with ordinary food, the content of protein in tea is very high, reaching 20% ~ 30%. Its content is closely related to the quality of tea, and protein in green tea is higher than other types of tea. However, less than 2% of protein can be dissolved in water when making tea, and most of the rest can't be used for tea residue, so protein is rarely consumed when drinking tea every day. However, if you drink tea, you can get a considerable amount of protein, and adding milk, ghee or cheese to tea soup can also add a lot of high-quality protein to tea, which can effectively improve the original nutritional value of tea in protein, such as Tibetan butter tea and Mongolian milk tea.
Carbohydrates, commonly known as carbohydrates, can be divided into monosaccharides, disaccharides and polysaccharides according to their chemical structures. According to previous data, the content of carbon hydrate in tea is not high, generally below 10%. The new report shows that the carbohydrate content in tea is about 40%, and some high-quality tea can reach more than 60%, which may be due to the difference from the previous determination method. Most carbohydrates in tea are polysaccharides, but only about 2% of polysaccharides can be dissolved in boiling water, accounting for 4% ~ 5% of water-soluble substances in tea. Therefore, tea is generally regarded as a low-energy and low-sugar beverage, which is suitable for diabetics and other patients who hate sugar.
The main function of fat is to provide energy. The same volume of fat provides 2.25 times as much energy as carbohydrates or protein. The lipid content in tea is not too high, green tea and black tea generally do not exceed 3%, and a certain amount of fat may be added to brick tea during processing, and its content can reach about 8%. Lipids in tea include phospholipids, sulfur lipids, glycolipids and triglycerides, among which linoleic acid and linolenic acid are essential fatty acids for human body. Therefore, drinking tea can make people get a certain amount of fatty acids, but the amount provided is very limited because of its low content.
Vitamins are an organic compound necessary to maintain health. They cannot be synthesized in the body and must be supplied by food. Although these substances account for a small proportion in the body, they play a great role in regulating the metabolism of substances in the body.
Tea contains a lot of vitamin C, and the content of different kinds of tea varies greatly, among which green tea is higher than black tea, and the content of high-grade green tea is higher. Vitamin C has a very important physiological function, which can prevent and treat scurvy, cancer and other diseases. During World War II, in order to prevent the scurvy of the Japanese Expeditionary Force, almost all Japanese coarse tea was controlled by the navy at that time.
Tea is rich in B vitamins, such as drinking 25 grams of tea every day, which can meet 25% of human needs. Usually, the content of B vitamins in green tea is higher than other types of tea, especially tender tea. B vitamins participate in many physiological and biochemical metabolic processes in the body and maintain the normal functions of nerves, heart and digestive system.
Minerals and trace elements in tea account for 4% ~ 9%, of which 50% ~ 60% can be dissolved in hot water, which can be absorbed and utilized by human body and is beneficial to health. The most inorganic components in tea are potassium and phosphorus, followed by calcium, magnesium, iron and manganese, with less copper, zinc, sodium, sulfur and fluorine, and the contents of different teas are slightly different. In addition, because tea has the characteristics of concentrating toxic substances in the environment, it sometimes contains some elements harmful to human body, such as aluminum, lead and cadmium. Its leaching rate is about 60%, which has attracted the attention of relevant parties.
The minerals and trace elements in tea are very beneficial to human body. Among them, iron, copper, fluorine and zinc are much higher than other plant foods. Scientists in the former Soviet Union found that copper and iron in tea can improve erythropoiesis and treat anemia, and vitamin C in tea can promote the absorption and utilization of iron. Fluorine is an indispensable substance for the growth of human bones and enamel. Fluorine in tea is much higher than that in general plant foods, reaching10 ~15 mg/100 g, of which 80% is soluble in tea soup. Drinking 10g of tea every day can get 1mg of fluoride, which basically meets the needs of human body. It is effective to gargle with tea liquid after meals, especially for preschool children, but children should not drink more tea, especially strong tea. Selenium is an indispensable element in human myocardial metabolism, and it also has anti-cancer and anticancer effects. Shaanxi Ziyang tea is rich in selenium, and experimental research shows that it has antimutagenic effect.
In a word, tea is rich in nutrients, especially protein, vitamins, minerals and trace elements, which are incomparable to general plant foods. As a low-energy and low-fat food, it has high development and application value. Because some steps in the processing will destroy nutrients such as amino acids or vitamins, the nutritional value of green tea is higher than other kinds of tea. But so far, tea is mainly used as a drink, both at home and abroad. It is a pity that some effective components in tea are insoluble in water, only a small amount is dissolved when making tea, and most of them are discarded as waste, which greatly reduces the nutritional value of tea. If tea is added to other foods, it will become a veritable tea and give full play to the nutritional function of tea.
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