Black tea is fermented on the basis of green tea It is made from suitable tea bud leaves by typical technological processes such as withering, rolling (cutting), fermentation and drying. Black tea is named for its dry brown color and red tea soup. Black tea belongs to fermented tea, and its basic technological process is withering, rolling, fermentation and drying. There are many kinds of black tea in China, including Kung Fu black tea and small black tea unique to China, as well as broken black tea similar to Indian and Sri Lankan. Black tea is fermented tea, which is refined by typical processes such as withering, rolling, fermentation and drying with suitable tea leaves as raw materials. Black tea is named for its dry brown color and red tea soup. Black tea is called "black tea" when it is created. During the processing of black tea, a chemical reaction centered on the enzymatic oxidation of tea polyphenols took place, and the chemical components in fresh leaves changed greatly. Tea polyphenols decreased by more than 90%, resulting in new components such as theaflavins and thearubigins. Compared with fresh leaves, the aroma substances increased obviously. Therefore, black tea has the characteristics of black tea, red soup, red leaves and glycol. Qimen Black Tea is the most famous black tea in China and the second largest tea in China. Its export volume accounts for about 50% of China's total tea production, and its customers are located in more than 60 countries and regions. Among them, Egypt, Sudan, Lebanon, Syria, Iraq, Pakistan, Britain and Ireland, Canada, Chile, Germany, the Netherlands and Eastern European countries have the largest sales. The newer the new tea, the better. Improper drinking can easily hurt the stomach. Because new tea has just been picked, it has a short storage time and contains more unoxidized polyphenols, aldehydes and alcohols, which has little effect on healthy people. But for patients with poor gastrointestinal function, especially those with chronic gastrointestinal inflammation, these substances will stimulate gastrointestinal mucosa, and people with poor gastrointestinal function are more likely to induce stomach diseases. Therefore, it is not advisable to drink more new tea, and do not drink new tea that has been stored for less than half a month. In addition, new tea also contains more caffeine, active alkaloids and various aromatic substances, which will also excite people's central nervous system. Patients with neurasthenia and cardiovascular and cerebrovascular diseases should drink in moderation, not before going to bed or on an empty stomach. The correct way is to leave it for half a month before using it.