Reason:

When making tea in a thermos cup, the tea leaves are soaked in high temperature and constant temperature water for a long time. First, a large number of tea polyphenols, tannins, tannins, theophylline and so on. Seepage makes tea soup rich in color, bitter in taste and rich in harmful substances. Second, vitamins and flavonoids are not resistant to high temperatures, and long-term high-temperature soaking will destroy the nutrients in them, greatly reducing the nourishing and health-care functions of tea. Third, the aromatic oil in tea will evaporate quickly, reducing the fragrance of tea.

In addition, it is best to soak tea for 4-6 minutes before drinking. At this time, 80% of caffeine and 60% of other soluble substances have been soaked out. However, soaking in the thermos for a long time at high temperature will extract too much caffeine, theophylline and tannic acid from tea, which is too irritating to the gastrointestinal tract and is not conducive to health.

Extended data

Precautions for making tea:

(1), choose a tea set.

A good tea set should be pottery, which has certain air permeability, keeps warm in winter, does not rot in summer and does not produce any chemical reaction. Therefore, the purple sand teapot enjoys a high reputation. Ordinary teacups are the most suitable.

(2), brewing with boiling water, pay attention to control the temperature.

Some people like to make tea with freshly boiled water, which is actually very harmful. The high water temperature just boiled can destroy a large number of nutrients (such as vitamin C) that are not resistant to high temperature in tea, and make the tea fragrance disappear quickly. The water temperature of making tea should be divided according to the age and tenderness of tea. Old tea can be directly brewed with boiling water at 95℃, while tender tea is lower, and about 80℃ is more suitable.

(3) Don't make the same tea many times.

Drink tea often, but not too much. It should be soaked with drinks and should not be left for too long. Tea leaves are soaked for too long, and many harmful substances are soaked out. If the brewing time is too long, tea polyphenols, lipids and aromatic substances in tea will automatically oxidize, which will not only make the tea soup darker in color, worse in taste and less fragrant, but also lose its taste value. At the same time, due to the pollution of the surrounding environment, the number of microorganisms (bacteria and fungi) in tea is increasing, which affects hygiene. You don't need to make tea after three or four cups.

People's health network-health tea and thermos cup

People's Health Network-Drinking tea is better than drinking tea. Pay attention to the following points when making tea correctly!