For China people, drinking tea for health preservation is a tradition that has been passed down for thousands of years. There are many forms of tea in China, which can be divided into six categories according to different processing techniques: green tea, black tea, green tea, black tea, white tea and yellow tea. This issue of Life Times interviewed Lin Zhi, director of Science and Technology Department of Tea Research Institute of Chinese Academy of Agricultural Sciences, and Lv Haipeng, associate researcher of Tea Research Institute of Chinese Academy of Agricultural Sciences, and referred to the book "Health Functions of Tea" edited by Academician Chen Zongmao of Tea Research Institute of Chinese Academy of Agricultural Sciences and Academician Zhen of China Academy of Medical Sciences, and summarized the health functions of different teas.

Green tea reduces fire and prevents cancer.

Green tea production in China has the longest history and the most categories, such as West Lake Longjing, Huangshan Mao Feng, Dongting Biluochun and Taiping Monkey Kui. Green tea belongs to non-fermented tea, with various shapes, unique aroma and taste, clear soup color and green leaves, which is very attractive. This is the most famous and widely studied tea.

Tea polyphenols, such as catechins, are considered as the key components in green tea, which have many health functions, including preventing cancer, improving cardiovascular health, losing weight and resisting ionizing radiation. In addition, green tea is the tea with the most kinds of vitamins and the richest content. According to the existing literature, compared with other teas, green tea has better anticancer effect. Many studies have shown that green tea can reduce the cancer risk of breast, prostate, lung, mouth, bladder, colon, stomach, pancreas and other parts. From the perspective of traditional Chinese medicine, green tea is slightly cold, which helps to reduce fire. People with cold stomach should drink less, people with hot and dry constitution who are easy to get angry and people with strong constitution should drink.

Generally speaking, the water temperature of green tea brewing is 85℃. Brewing time is 2~3 minutes. The ratio of green tea to water is 1∶50. For tea sets, you can choose porcelain cups or transparent glasses, and don't cover them when brewing. ▲

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Oolong tea, also known as green tea, has both the fragrance of green tea and the mellow fragrance of black tea. Oolong tea in China is mainly divided into four categories, namely southern Fujian oolong (such as Tieguanyin), northern Fujian oolong (such as Dahongpao), Guangdong oolong (such as Lingtou Danzong) and Taiwan Province oolong (such as frozen top oolong). Oolong tea belongs to semi-fermented tea, and its processing technology is between green tea and black tea.

Oolong tea contains not only catechins, tea polysaccharides and tea saponin which are common in green tea and black tea, but also some special functional components. For example, some oolong tea varieties are rich in? Methylated catechin Has antiallergic, anti-inflammatory, antioxidant, liver cell protecting and blood pressure lowering effects. According to some related literature reports, compared with other teas, oolong tea has a better weight loss effect. From the point of view of traditional Chinese medicine, oolong tea is flat and can clear away accumulated heat in the body, which is especially suitable for drinking in autumn and can relieve autumn dryness.

It is best to use a teapot or a bowl or cup with a lid to make oolong tea, and it must be boiled at 100℃ and covered after brewing. ▲

Black tea warms the stomach and protects the heart

There are many kinds of black tea in China, which are generally divided into three categories: Kung Fu black tea, small black tea and broken red tea. The reason why black tea is widely drunk lies in its dark brown and oily color, rich and sweet aroma, mellow and fresh taste, red and yellow soup color, tender and even red leaves and many other characteristics. Black tea belongs to fully fermented tea. During the processing, tea polyphenols are oxidized into theaflavins and thearubigins, and most of the carbohydrates are hydrolyzed into soluble sugars, thus producing the unique aroma and taste of black tea.

Theaflavins are the most important functional components in black tea. A large number of medical studies show that drinking black tea can help regulate the contents of low-density lipoprotein and high-density lipoprotein in human arteries, thus reducing the probability of cardiovascular diseases. Besides, theaflavins can also resist oxidation and cancer, and prevent chronic inflammation and obesity. According to the existing literature, compared with other teas, general black tea is more effective in preventing cardiovascular diseases. From the perspective of traditional Chinese medicine, black tea is warm and has the effect of warming the stomach. People with deficiency-cold constitution and the elderly should drink warm black tea.