The essential difference between different kinds of tea lies in the different oxidation degree of flavanol (for example, polyphenols will change color after a period of cutting, and the processing of different kinds of tea is a process of inhibiting or promoting polyphenols. First of all, yellow tea is so rare that even people living in yellow tea areas may not know it. But everyone who can cook knows that vegetables turn yellow when they are stuffed in the pot. The same is true of yellow tea. After yellow tea is deactivated like green tea, the leaves of green tea can turn yellow through damp heat and dry heat (mild fermentation). Dry tea yellow, tea soup yellow, yellow leaf bottom. However, the production of yellow tea has not completely changed, and it looks too much like green tea.
Speaking of the famous green tea in China, green tea is a kind of natural substance that retains many fresh leaves. Among them, tea polyphenols and caffeine retain 85% of fresh leaves, and 50% of chlorophyll vitamins lose less, thus forming the characteristics of green tea, such as clear soup color, green leaves color and strong taste convergence. Green tea has the medicinal value of reducing blood lipid and preventing arteriosclerosis. It is very hot in summer, so it is recommended to drink bitter and cold green tea, which has the functions of clearing away heat and toxic materials and quenching thirst. Green tea contains a lot of tea polyphenols, caffeine, amino acids and so on. It can stimulate oral mucosa and promote the secretion of digestive glands. Conducive to the production of body fluid, it is a good product for relieving summer heat and quenching thirst in summer.
In China, black tea is second only to green tea. Withering, rolling and fermentation are all aimed at promoting the oxidation (complete fermentation) of tea polyphenols in black tea. Tea polyphenols itself is a colorless substance. During the processing of black tea, catechins polymerize to form yellow theaflavins and red thearubigins, so the tea soup of black tea is bright red and the bottom of leaves is red. However, in the drying process of black tea, due to the loss of water, the color of tea pigment on the surface of tea deepens, so the dry tea of black tea is black tea.