From small parents that can not drink overnight tea, I believe a lot of people are aware of the overnight tea can not drink it, then gradually grew up when I heard that the tea will be drinking every night, this is true? From a scientific point of view Talk about the night tea is actually the time to place the tea, such as the morning bubble tea into the evening, is not ruthless similar?
These long-term tea, where the chemical composition is indeed a big change, the weather during the day and night than the high temperature, placed in the daytime changes in tea even more than we said overnight tea is more obvious.
After a long period of time after the tea is placed, the most important change is the tea contained in the tea polyphenols after oxidation to form a yellow red, reddish brown oxidation products, so lose the original green, while increasing the yellow, red Degree, the clarity of tea is naturally falling, becoming more and more turbid. But do not worry Oh! In fact, these oxides are not toxic, and will not produce any harm to the human body.
We often heard of the overnight tea can not drink, otherwise it is easy to get cancer. The reason why this is because the tea after overnight, which contains secondary amine substances can be transformed to form a carcinogen, is the nitrosamine, but in fact this argument is not scientific basis. Here we have to analyze.
1, secondary amines are widely found in a variety of foods, not only in the tea only, and we from the tea intake of secondary amine substances is very small, super limited, this is far Less than the amount of intake from any kind of staple food or vegetables.
2, secondary amine substances themselves are not carcinogens, but the need for specific conditions with the nitrate chemical reaction after the formation of nitrosamines. The so-called specific environment is to include pH, microbial temperature and other factors, so it can not be said that tea contains secondary amine substances and nitrates will produce nitrosamines.
3, nitrosamines in the human body to achieve a certain content will produce carcinogenic effect. According to the relevant research shows that nitrosamines do not reach 100-200 mg per kilogram of body weight and sustained high doses may be carcinogenic. Although we said that the overnight tea may contain nitrosamines, but these levels are not higher than the content of other foods, it is not carcinogenic harm. When we drink tea in the normal time, from the tea intake of tea polyphenols to drink vitamin C can effectively prevent the synthesis of nitrosamines, these are nitrosamine day inhibitor.
But not to say that there is no hidden danger of overnight tea, because the tea placed for too long, one of the protein and sugar and other substances can continue to breed bacteria, mold, so the tea in the case of long-term presence of harmful micro-organisms, May cause deterioration of tea.
Tea in the long process of placing, tea, tea polyphenols and vitamins will occur in some chemical reactions, because the placement of a long time, the temperature in the tea will naturally decline, this process also naturally occurs a variety of reactions. Resulting in decreased antioxidant capacity of tea, nutritional value will decline. So from a scientific point of view should try to avoid drinking too long to place the tea, drink plenty of tea, so as to give full play to the value of tea, so that tea can provide healthy energy for our body delivery