However, the ancient people's role in tea is mostly the accumulation of experience, but they don't know why. Only by analyzing the essence of tea with modern medicine and science can we gradually have a further systematic understanding of tea. The efficacy of tea is very complicated, and the medical function of tea is often the result of the comprehensive action of various effective components and nutrients.
Tea contains caffeine, phenolic derivatives, fragrances, vitamins and other known and unknown substances.
However, drinking tea may not give full play to the single effect or group effect of these ingredients, even if drinking tea too hard or too much will cause insomnia, headache, or other physical discomfort symptoms; Drinking tea and taking medicine will reduce the efficacy of some drugs.
Only by fully understanding your physical condition and drinking tea in a timely and appropriate amount can you give full play to the health care function of tea.
Polyphenols. (Polyphenol)
15-30% dry matter; Among tea extracts, the proportion of soluble components in general tea is the highest, about 30%, and that in Yunnan Daye tea is 30-40%. In the process of tea fermentation, as the matrix of polyphenol oxidase, oxidative condensation and other reactions occur, in which catechin is the main component with bitter taste, which is related to the color, aroma and taste of tea soup. It is generally believed that vitamin E has a high antioxidant effect. According to the research results of Japanese scholars, the antioxidant effect of polyphenols in unfermented tea is as high as 74%, which is more than 18 times that of vitamin E.
Catechin (catechin)
Commonly known as tea tannin, its chemical structure and physiological function are different from tannin and tannic acid. It can be divided into lipid catechins and free catechins, which account for about 80% of polyphenols and are the most active substances in tea. In terms of varieties, the catechin content of Yunnan Daye tea is higher than that of oolong tea and green tea. In terms of seasons, the catechin content of summer tea is higher than that of spring and autumn tea, and the content of winter tea is the lowest. In the process of tea production, catechins undergo oxidative polymerization, which is one of the important mechanisms of tea fermentation.
Medical experiments have found that catechin can effectively slow down the side effects of caffeine in tea on human body, and has health care functions such as antioxidation, reducing blood lipid and cholesterol content, inhibiting hypertension, strengthening blood vessel wall, anti-tumor, antithrombotic, antibacterial and antiallergic.
Theaflavins and thearubigins.
In the process of making tea, catechins are oxidized and polymerized into theaflavins and thearubigins, and other derived chemicals (such as amino acids, carotene, lipids, etc. ), they are the main pigments in tea. In the process of oxidation, generally speaking, theaflavins are first produced, then converted into thearubigins, and finally oxidized into theabrownin by thearubigins. This can explain why the color of raw tea will change from green to yellow, then to red and brown after aging.
In the evaluation criteria of fermented tea and black tea, tea red and tea yellow are one of the indicators of tea quality. In Pu 'er tea, cold fermented tea and old tea are stored and aged, and the contents of tea yellow and tea red in tea soup are related to some tastes. From this point, we can know that some raw Pu 'er tea products are lightly fermented, or old tea that has not been stored by anyone, and cold soup will have a similar curd phenomenon (milk pours after cold).
chlorophyll
It is directly related to the color of tea cyanine, and its molecules are extremely unstable, afraid of light, heat and strong acid, with good fat solubility and insoluble in water. When making, it can quickly destroy the active substances at high temperature, so that chlorophyll can be fixed in fresh leaves with bright green color; This can help to understand the reasons why Yunnan cyan and Yunnan cyan have different colors.
Chlorophyll will quickly demagnetize when it meets light, heat and strong acid, which will lead to the color variation of tea cyanine. If the tea absorbs moisture and the temperature is high, the decoloration will be more obvious. This shows that if the pressed product is dried in the sun after high temperature, high humidity and high pressure, it will soon change color and turn red.
Caffeine (caffeine)
It accounts for about 3~4% of the weight of tea seeds, and is one of the main sources of bitter taste of tea soup, which has the functions of excitement, diuresis and accelerated metabolism. In the production of tea, the combination with catechin can slow down the stimulation to human body and reduce the bitterness of tea soup. In terms of seasons, the caffeine content of autumn tea is the highest, followed by summer tea and spring tea, which is one of the reasons why autumn tea is more bitter than spring tea.
amino acid
The content of amino acids is directly proportional to the tenderness of tea, with the highest content in spring and less in summer and autumn. The content of free amino acids in tea stems is higher than that in young leaves, and the ratio of theanine is as high as 50? 60% is an important index to determine the aroma and taste of tea.
Minerals (ash)
The mineral content in tea is about 5-7%, of which about 70% is soluble in hot water and absorbed by human body. Among them, potassium, calcium, iodine and phosphorus are the most, followed by magnesium, aluminum, manganese, copper, zinc, sodium, nickel, beryllium, boron, fluorine and selenium. The content of cation in tea soup is much higher than that of anion, which belongs to alkaline food in food acid-base classification (pH value of ash is 9.40), which can keep blood weakly alkaline and prevent the occurrence of chronic diseases.
Potassium is easily soluble in water, which can eliminate the blood sodium content and prevent the occurrence of hypertension. Fluoride plays an important role in preventing dental caries. Manganese can prevent reproductive dysfunction and convulsion, and has the functions of enhancing immunity and super antioxidant, but it is difficult to dissolve in water and be absorbed by human body. Zinc can promote children's growth and development, prevent myocardial infarction and sudden death, and has anti-cancer effect. Copper and iron in tea contribute to hematopoietic function.
Stacking Fermentation and Microorganism
Sun-dried green tea with water is beneficial to microbial growth due to the increase of moisture and temperature. In the process of heap fermentation, microorganisms involved include yeast, bacteria, Aspergillus Niger, Penicillium, Aspergillus, Rhizopus and so on. No pathogenic bacteria have been found in the whole normal pile-up fermentation production process, but due to climate, environment, water quality, technology and other factors, the proportion of fungi produced is different, which will eventually produce a special flavor representing the pile-up fermented cooked tea in various factories.
Sun Ling smell
Some substances in tea contents will change qualitatively after illumination, such as catechin, chlorophyll and carotene. At present, it is known that humidity, temperature and oxygen have less influence on tea deterioration than light damage. Beauveride (ketone) will be produced when tea is irradiated by light, which is an important index to test the qualitative change of tea after exposure to light.
A rancid smell
In the process of making or storing tea, if excessive oxidation occurs, such as exposure and ventilation of Pu 'er tea, which leads to the oxidation of unsaturated fatty acids related to tea aroma to generate volatile substances such as alcohols and aldehydes, it will produce oil-consuming smell.
Jinhua
Aspergillus CRI status and Aspergillus Sheva, with golden particles scattered. It exists in pressed tea, represented by Hunan Liangqian tea (flower roll) and Fuzhuan tea. The reason lies in the real-time temperature and humidity control, which is called (flowering) from the inside out, which is dry outside and wet inside, cold outside and hot inside.
draw
Water-soluble components in tea, such as caffeine, polyphenols, amino acids, etc. Most people think that tea with a high proportion of extracts has a clear aroma and taste, and the soup is slippery and thick, otherwise it is light. Yunnan cultivated wild tea extract, up to 46? 52%, the highest among all teas.
Moisture content
Moisture content directly affects the stability of tea quality. Generally, the water content of oolong tea in Taiwan Province Province is controlled at 3? 5% to prevent oxidation deterioration. Pu 'er tea is post-fermented, 9% of cooked tea is fermented by heap, and 9.5% is the export standard. Fresh tea is about 7-8%.
Generally, the storage condition of Pu 'er tea is about 70-80% relative humidity, and the moisture content of tea leaves is 12- 16%, which will age quickly without mildew. However, in the current market, high humidity is a favorable environment for rapidly changing the quality of tea. For tea stored in wet warehouse, its water content is as high as 20-30%. Therefore, the water content standard and quality stability of Pu 'er tea need to be continuously studied and verified.
blood fat
It usually includes cholesterol and triglycerides (commonly known as neutral fat). Cholesterol is divided into high-density cholesterol (HDL), low-density cholesterol (LDL), very low-density cholesterol (VLDL) and chyle granules. High-density cholesterol, also known as good cholesterol, can prevent cardiovascular and cerebrovascular diseases, and the rest is also known as bad cholesterol, which is easy to deposit on the blood vessel wall, leading to vascular sclerosis and stenosis.
It has been proved by French, Japanese, Chinese mainland, China Taiwan Province Province and other medical clinics that Pu 'er tea can reduce the contents of triglycerides and cholesterol in human blood and reduce the occurrence of cardiovascular diseases.
Epigallocatechin gallate (EGCG)
Scientific name: epigallocatechin gallate (EGCG) belongs to catechin and is a strong antioxidant.
It mainly exists in green tea, and the proportion of other fermented teas decreases. For example, the content of EGCG in black tea is only one tenth of that in green tea. Due to the low degree of fermentation, the proportion of polyphenols and catechins in newly-made Pu 'er raw tea (Dianqing) is much higher than that of ordinary tea varieties, and the relative EGCG content has also increased.
Modern medicine has proved that EGCG can reduce serum total cholesterol, low-density cholesterol and increase high-density cholesterol, thus preventing cardiovascular diseases, enhancing human immune system and inhibiting tumor growth and metabolism.
The research scope of modern medicine covers a variety of cancers or cancer cells inhibited by EGCG, including prostate cancer, breast cancer, ovarian cancer, colorectal cancer, melanoma, skin cancer, oral cancer, lymphoma, lung cancer, bone cancer, pancreatic cancer, cholangiocarcinoma and cervical cancer. The mechanism of EGCG is not very clear, and it is only in the experimental stage of cell culture at present, and there is no guarantee that EGCG can inhibit the growth of this cancer 100% in clinic. In addition to preventing cardiovascular diseases, enhancing immune system and anti-cancer, it is also considered to have weight loss or beauty effects. At present, no paper has suggested that there will be side effects in normal and appropriate doses, whether it is anti-cancer or slimming beauty.
Dimethoxybenzene
During the stacking and fermentation of sun-cured green tea, microorganisms participate, tea polyphenols and catechins are oxidized and degraded, the contents of theaflavins and thearubigins are not high, and the contents of amino acids and sugars are also reduced, but many specific aroma compounds are also formed. At this time, dimethoxybenzene and trimethoxybenzene increased obviously. Therefore, the antioxidant effects of raw Pu 'er tea are mainly polyphenols and theaflavins, while the antioxidant effects of cooked Pu 'er tea are mainly molecular oxygen and its derivatives.