Pu 'er tea contains aflatoxin, and drinking Pu 'er tea will cause cancer.

Rumors:

China has a long history of tea drinking, and tea drinking habits in most parts of the world originated in China. However, in recent years, there have been rumors on the Internet that "drinking Pu 'er tea causes cancer". To find out the truth, let's find out.

What is Pu 'er tea and how is it processed? According to China's national standard "geographical indication product Pu 'er tea" (GB/T 2211-2008), Pu 'er tea is made of Yunnan large-leaf sun-dried green tea within the scope of geographical indication protection. Tea with unique quality characteristics can be divided into raw tea and cooked tea according to processing technology and quality characteristics. Pu 'er tea usually refers to Pu 'er cooked tea, which is made by artificial fermentation. In the early stage of fermentation, Aspergillus Niger and Rhizopus were the main microorganisms in tea, and Aspergillus virens, Penicillium and yeast appeared in the later stage, which were harmless to human health.

Is there aflatoxin in Pu 'er tea? Aspergillus flavus is a common mold in nature, and not all Aspergillus flavus will produce toxins. Only Aspergillus flavus with toxin-producing gene can produce toxin under suitable nutritional conditions and environment. During the fermentation of Pu 'er tea, high temperature and superior Aspergillus Niger not only inhibited the growth of Aspergillus flavus to some extent, but also produced bioactive enzymes that degraded aflatoxin B 1. In addition, caffeine and tannin rich in tea can also inhibit the production of aflatoxin.

For raw materials with guaranteed quality, after good fermentation and correct storage, aflatoxin will not appear in Pu 'er cooked tea. When consumers buy Pu 'er tea, the following four situations should not be chosen.

1. Don't choose too cheap Pu 'er tea. The fermentation cost of Pu 'er tea includes raw material cost, storage cost, production cost, time cost and big loss cost. Therefore, Pu 'er tea, which is too cheap, probably uses inappropriate fermentation and aging to accelerate the fermentation process. The quality of Pu 'er tea obtained by this shortcut is greatly reduced, and there is also the risk of being contaminated by mycotoxin.

2. Don't choose Pu 'er tea with water stains on the paper and obvious mildew on the tea cake. Water stains on paper bags often cause mildew, which is an obvious sign of improper fermentation or improper preservation. Such Pu 'er tea is not suitable for purchase.

3. Don't choose Pu 'er tea with soft and rotten leaves, mottled leaves and hard stalks. The color of high-quality Pu 'er tea is even. If it is soft, rotten, mottled and burnt, it may be caused by improper methods during fermentation and storage.

4. Don't choose Pu 'er tea with turbid and musty tea soup. The high-quality Pu 'er tea soup is chestnut red, clear, heavy in taste, fragrant and old, and has no peculiar smell. The tea soup is dark chestnut or black. Thin and even musty taste is a sign of poor quality, so we should pay attention to the distinction in the process of purchasing.

Rumor expert: Gao Jie, Associate Professor, College of Food Science and Technology, Hebei Agricultural University; Yi Song, Associate Professor, School of Food Science and Nutritional Engineering, China Agricultural University.

Evaluation expert: Chen Zongmao, academician of China Academy of Engineering, former director and researcher of Tea Research Institute of Chinese Academy of Agricultural Sciences.

(Provided by China Institute of Food Science and Technology)