Original Professor Liu Shaowei Professor Liu Shaowei
"Poison vermicelli"
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Vermicelli is a kind of traditional food deeply loved by Chinese people, and it has a long history of processing. There have been records about making vermicelli in ancient books such as Qi Min Yao Shu and Compendium of Materia Medica. Vermicelli is a strip-shaped, filamentary or ribbon-shaped product mainly made of starch such as potatoes and beans through the processes of mixing, molding, cooling and drying. According to the standard GB/T23587-2009, vermicelli is called "vermicelli" if the product diameter is more than ≤1 mm, and vermicelli is called "vermicelli" if the diameter is less than or equal to 1 mm. Generally speaking, vermicelli is better than vermicelli.
Vermicelli is rich in raw materials, simple in production and operation, diverse in product forms, deeply loved by consumers, with broad market prospects and rapid development of the industry. Vermicelli products can be eaten in a variety of ways, such as mixing, frying, steaming, stewing and cooking. At present, vermicelli products have become one of the essential foods on the table of Chinese consumers, and many vermicelli products have been widely exported to Japan, South Korea, the United States and Europe and other countries and regions.
However, with the development of social economy and the improvement of people’s living standards in China, consumers’ demand for high-quality, nutritious, convenient and diversified foods is increasing day by day, as well as economic restrictions, the problems affecting the healthy development of vermicelli industry in China are becoming increasingly prominent, and counterfeiting incidents occur frequently, which has attracted the attention of our government and relevant departments.
What do you know about "poison vermicelli"?
Where did the vermicelli come from?

The picture comes from the Internet.
At the 315 party in 2022, CCTV exposed the "fake sweet potato vermicelli in Yuzhou" because cassava starch was used as the inferior sweet potato starch. The ingredients of an "iron stick yam vermicelli" produced in Yuzhou City, Henan Province read: whole juice of iron stick yam, sweet potato starch and drinking water, but the actual yam composition is only about 20%, and the main raw material is unlabeled cassava powder. Some responsible persons said that using cassava starch instead of sweet potato starch was a hidden rule in the industry for 10 years. "All of them are made of cassava, with a good conscience and more sweet potato powder."
What are the hazards of "poison vermicelli"

The picture comes from the Internet.
Sweet potato starch contains carotene and vitamin C, and it is also found that sweet potato contains anticancer substances with high nutritional value. Two kilograms of sweet potato starch can produce about one kilogram of vermicelli. The price of one kilogram of sweet potato starch is between 3.5 yuan and 4 yuan, while the market price of one kilogram of pure sweet potato vermicelli is about 8 yuan. The profit of producing sweet potato vermicelli with pure sweet potato starch is very thin, but the price of one kilogram of cassava starch is only 1.8 yuan, and the purpose of shoddy is to maximize profits. From the appearance, both kinds of starch are white and delicate, and it is difficult to distinguish the vermicelli if it is not compared in detail, so merchants use these characteristics to "confuse the fake with the real".

The picture comes from the Internet.
In addition to the price, consumers will be detrimental to the interests. The most daunting thing is that cassava starch is toxic when eaten raw. The roots, stems, leaves and skins of cassava all contain a toxic substance called "cyanosides". Fresh cassava is the most toxic, and eating 150g raw may lead to poisoning. In 2019, there were incidents of "eating cassava poisoning" in Yunnan and Guangxi. However, this kind of "cyanoside" will disappear at a high temperature above 70℃, so cassava starch needs to be heated before it can be eaten, while ordinary starch has no natural toxin and can be eaten directly. This kind of "fake sweet potato starch", once a large number of raw vermicelli are eaten by mistake, or cassava is not peeled when it is made into starch, the consequences are unimaginable and there are great security risks. Long-term consumption of this food containing "cyanosides" will also pose a serious threat to health.
How to distinguish "poison vermicelli"?
Look at the color


The picture comes from the Internet.
The color of sweet potato vermicelli is yellow and dark; Cassava vermicelli is white, transparent and smooth to the touch.
However, many manufacturers of vermicelli intentionally add food pigment instead of the color of sweet potato vermicelli in order to save costs and earn high profits to the maximum extent. In this case, we must use the second method to assist in identification-smell.
Smell
After the pure sweet potato vermicelli is soaked in hot water, the water in the bowl is still clear, the vermicelli does not fade, and the faint sweet potato flavor can be smelled; After cassava vermicelli was soaked in hot water, the water became turbid, and the vermicelli was crystal clear, but it smelled without any smell.
Toughness and bending degree


The picture comes from the Internet.
In the dry state, sweet potato vermicelli is very brittle and brittle, and it will break when it is folded. Therefore, there will be a lot of crumbs on the shelf where sweet potato vermicelli is placed, and it is easy to soften when cooked in a pot. On the other hand, if the vermicelli is very tough and needs scissors to cut it off, it means that the vermicelli is not pure sweet potato vermicelli because various ingredients such as gelatin and cassava powder were added in the production process.
Burn with fire
Sweet potato starch is made of sweet potato with high starch content, and its tissue shape is composed of tiny particles, which is not strong in water absorption and has the characteristics of crystallinity. After being lit with a lighter, it will emit black smoke, but it will not produce a pungent smell. After burning, it will produce black powder, which will become fine powder with a gentle pinch. However, if the noodles made of cassava powder are ignited with a lighter, they will not burn fully. If you pinch the powder by hand, you will find that the hardness of the powder is stronger, and even there will be tiny particles that cannot be pinched.
Tips
When buying sweet potato vermicelli, don’t be greedy for cheap, get what you want for a price, be vigilant about this matter and let your family and yourself have peace of mind.
Expert in this paper: Huang Xinhe, master candidate of food research and development in East China University of Science and Technology.
Liu Shaowei, doctor of food safety, member of expert group of Shanghai Food Safety Research Association, member of food safety professional committee of Shanghai Food Society, doctor of engineering from Pennsylvania State University, and postdoctoral fellow from Kansas State University.
~ references ~
[1] Chen Bing. Study on the preparation and preservation of fresh and wet spinach vermicelli [D]. Chongqing: Southwest University, 2016.
[2] GB/T 23587-2009 vermicelli [S].
[3] Chen An, Xu Yan, Zhang Zhiming, et al. Present situation and development countermeasures of vermicelli production in China [J]. Grain and Feed Industry, 2007(2):12-14.
[4] Yin Yuyun, Guo Xuguang, Wendy Wang. Sampling monitoring of starch and starch products in Henan Province and problem analysis [J]. Modern Food, 2019(12):192-196.
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