When withered, fresh leaves lose some water, and then knead (knead into strips or cut into particles).
Then fermented, so that the tea polyphenols contained in it are oxidized and turned into red compounds. This compound
Some are soluble in water, others are insoluble in water, and accumulate in leaves, thus forming red soup and red leaves.
There are three main kinds of black tea: competition black tea, kung fu black tea and red broken tea.
The difference between black tea and green tea
Green tea-unfermented tea
The unique refreshing aroma and health care function of green tea have been widely loved by people in China, Japan and North Africa since ancient times. The production method of green tea is to put the tea leaves into a large iron plate for drying and dehydration immediately after picking, so as to keep the dark olive green color and avoid further fermentation and deepen into brown.
Oolong tea-semi-fermented tea
According to Lu Yu's Tea Classic, oolong tea must be "folded like Tatar riding boots, rolled like the drooping skin of a steer, and scattered like the morning mist rising in the valley." Oolong tea is characterized by large leaves, all of which are rolled. Oolong tea only needs a short fermentation process, and its flavor has both the fragrance of green tea and the smoothness of black tea.
Black tea-full fermented tea
The biggest difference between black tea and green tea is not the type of tea used, but whether the tea has been fermented. Why do you want to ferment tea? Legends abound. It is said that in the17th century, when a ship belonging to the British East India Company transported green tea from China (Wuyi) to Britain, the tea was accidentally oxidized and fermented due to its long voyage. However, western businessmen are deeply attracted by this kind of "black tea" with heavy ups and downs, deep color and fragrant smell! From then on, China began to produce this "new" tea in large quantities. Today, fermented black tea accounts for about 90% of world tea production.
(Note: China fermented black tea first appeared in the Song Dynasty in10 ~13rd century).
Relationship between tea and caffeine
The longer the tea is fermented, the more caffeine it contains. The caffeine content of unfermented green tea is only one third of that of fully fermented black tea. The caffeine content of semi-fermented oolong tea is only about half that of black tea.
Of course, the brewing time will also affect the caffeine content of tea soup. The longer the brewing time, the more caffeine is extracted, and vice versa. Generally speaking, when black tea is brewed for four minutes, it will release 40 mg to 100 mg of caffeine; If the extraction lasts only three minutes, only 20 mg to 40 mg of caffeine will dissolve in the tea soup.
Which patients should not drink tea?
-People with constipation should not drink tea. Because polyphenols in tea have a certain astringent effect on gastrointestinal mucosa, constipation patients will aggravate constipation if they drink tea.
-People with neurasthenia or insomnia should not drink tea. Because caffeine in tea has obvious exciting effect on cerebral cortex, drinking tea will make the brain extremely excited and unable to rest.
-People with iron deficiency anemia should not drink tea. Because tannic acid in tea leaves will make iron in food form a precipitate that is not absorbed by the human body, which will aggravate anemia.
-People with calcium deficiency or fracture should not drink tea. Because the alkaloids in tea will inhibit the absorption of calcium in duodenum, it will also lead to calcium deficiency and osteoporosis, making it difficult to recover the fracture.
-People with ulcers should not drink tea. Because theophylline in tea will reduce the activity of phosphodiesterase and make gastric parietal cells secrete a lot of gastric acid. Hyperacidity will inevitably affect the healing of ulcer surface and offset the efficacy of some antacids.
-People with urinary calculi should not drink tea. Because tea contains more oxalic acid, drinking tea will aggravate the development of stones.
-Don't drink tea when you have a fever. Because theophylline contained in tea can raise human body temperature, the cooling effect of drugs is greatly reduced or even disappeared. Therefore, patients with fever should not drink tea.
Tea spa is unique.
Tea is an ordinary daily drink. If skillfully used, it can alleviate or prevent many common diseases.
—— Prevention and treatment of dental caries in children: Fluorine in tea can prevent teeth from dephosphorization and decalcification in acidic oral environment, so gargling with tea can prevent dental caries.
-Palpitation and nausea caused by bad breath or excessive smoking can be relieved by gargling with tea and drinking proper amount of strong tea.
—— People who are prone to bleeding when brushing their teeth: You can drink tea often, because tea is rich in vitamin C, iron and hemostatic ingredients, which can make the gums tough, increase the elasticity of capillaries and prevent bleeding.
-Motion sickness and seasickness: drink a small cup of warm tea in advance with 2-3 ml of soy sauce.
-Diarrhea: Tannic acid in tea has astringent and antidiarrheal effects. Drinking strong tea can stop diarrhea.
-When the baby's skin is wrinkled and swollen: you can boil water with tea and rinse it for the baby at a suitable temperature.
—— Overwork: A cup of fresh tea can quickly eliminate fatigue and restore energy.
-People who suffer from overeating and greasy: You can drink strong tea, such as brick tea or Tuocha, and the greasy effect is better.
-Patients with high cholesterol and cardiovascular diseases: Drinking a cup of tea and water every day can lower cholesterol and protect the cardiovascular system.
-loss of appetite and yellow urine: drink more light tea.
Tea that is too fresh is not suitable for drinking.
Many people think that the fresher the tea, the better. The tea just picked from the tea tree is the best. In fact, this understanding is incorrect. From the point of view of nutrition, the freshest nutrients are not necessarily the best, because the so-called new tea refers to the tea that has been picked for less than a month. Because these tea leaves have not been placed for a period of time, some substances that have adverse effects on the body, such as polyphenols, alcohols, aldehydes, etc., have not been completely oxidized. If you drink new tea for a long time, you may have discomfort such as diarrhea and bloating. Too fresh tea is even worse for patients, such as some people with gastric acid deficiency or elderly patients with chronic gastric ulcer, which is even more unsuitable for drinking new tea. New tea will stimulate their gastric mucosa, cause gastrointestinal discomfort and even aggravate their condition.
Drink tea in moderation and don't be greedy. Normal people, especially middle-aged and elderly people, should drink 4-5 cups a day. Tea should be light. People who like to drink strong tea should drink 1-2 cups of strong tea every day. If you drink too much tea, there will be more water in your body, which will increase the burden on your heart and kidneys. Strong tea will make the brain too excited, the heart beat faster, frequent urination, insomnia and so on. It is advisable to make tea with boiling water. Oolong tea is brewed for about two minutes, and then poured into the teacup from the teapot for drinking. The beneficial chemical components extracted from warm tea are not as sufficient as boiled water, but it is better to drink warm tea, and it is not suitable to drink overheated and scalded tea, which will cause strong irritation to throat, esophagus and stomach, and may cause mucosal lesions of these organs; Leng Cha and tea brewed for too long should not be drunk, because Leng Cha has negative effects on the body, such as cold coagulation and phlegm accumulation. If the tea is brewed for too long or overnight, its effective components will be greatly reduced, and harmful microorganisms in tea will increase. Never drink tea on an empty stomach, because tea will cool the spleen and stomach and get drunk easily. It is not advisable to drink tea immediately before and after meals, because drinking tea before meals will dilute gastric acid, make the diet tasteless and affect the absorption function of digestive organs. When drinking tea immediately after meals, tannic acid in tea will solidify with protein and iron in food, which will affect the absorption of protein and iron. Tea should not be used instead of medicine, because tannic acid in tea will combine with many drugs to produce precipitation, which will affect the efficacy. Drinking tea after drinking doesn't help hangover, it only hurts the kidneys. Although drinking tea has many benefits to people's health, drinking tea varies from person to person. Because tea contains caffeine, and caffeine will have adverse effects on the fetus, pregnant women should drink less tea or not drink tea, especially strong tea. Theophylline can stimulate the gastric wall to secrete a lot of gastric acid and affect the healing of ulcer surface. Therefore, patients with ulcer should also drink less tea instead of strong tea. Caffeine in tea has obvious exciting effect on the central nervous system, so patients with severe hypertension and arteriosclerosis and insomnia should not drink more tea, let alone strong tea. Theophylline can stimulate the body temperature center and aggravate fever, so patients with fever should not drink tea and avoid drinking strong tea.
Tea experts advocate drinking scented tea in spring, green tea in summer, oolong tea in autumn and black tea in winter.