Is soaking food dangerous? Will it cause aflatoxin poisoning? Friends who love rice noodles and black fungus, please pay attention!

gossip

"A woman in Yongcheng, Henan died after eating cold noodles", "Heilongjiang sour soup poisoning incident", "Guangdong rice noodle poisoning incident"... In recent years, there have been frequent cases of fumonisin poisoning caused by soaked food. Fumonisin is a toxin produced by the fermented rice flour subspecies of the genus Pseudomonas cereus, which can cause food poisoning. It is the main cause of poisoning in fermented cornmeal products, spoiled fresh white fungus and other spoiled starch products.

Since soaking food is convenient and quick, and tastes good, foods such as cold noodles and wide noodles have long become part of people's daily diet in many areas, and people never thought that these foods could cause death. After realizing the potential dangers of soaking food, rumors spread on the Internet for a while, and many netizens believed that soaking food is very dangerous and will cause aflatoxin poisoning .

analyze

The main cause of aflatoxin poisoning is that the soaking time is too long, the storage is improper or the soaking environment is unsanitary, which leads to the production of aflatoxin . Under normal circumstances, if the soaking ingredients are carefully selected and the time and environment are well controlled, the soaked food is safe and there is no need to worry too much . You can still eat rice noodles when you want, and drink sour soup when you want.

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Next, we will explore from a scientific perspective how fumonisin toxin is produced, its toxicity, and how to prevent and protect yourself. We also hope that after reading this article, everyone will have a more objective understanding of the risks of soaking food.

Production of fumonisin

The toxin is produced by the Pseudomonas cerebroventris subspecies, a bacterium that is ubiquitous in nature and particularly prefers an acidic environment (pH 5-7) with a temperature of 26-28°C [1]. The hot and humid summer and autumn are very suitable for the reproduction of this type of bacteria, and the damp and airtight kitchens and production workshops are hotbeds for the growth of this type of bacteria .

Foods that cause aflatoxin poisoning have one thing in common during the production process, which is that they have to undergo a long period of fermentation or soaking . In daily life, the foods that people come into contact with more often are mainly fermented grain products, potato products, fungus and white fungus. Among them, fermented grain foods include rice noodles, rice rolls, sour soup, hanging rice cakes, rice cakes, corn starch, etc. Potato products include vermicelli, sweet potato noodles, wide noodles, sweet potato starch, etc. During the production process of rice and flour foods, if the environment is unsanitary, the raw materials are spoiled, and the storage is improper, such as soaking for too long or the storage environment is humid, they may be contaminated.

It should be noted that if the soaked white fungus and black fungus are not eaten in time and are left in a high temperature and humid environment for a long time, bacteria will grow seriously and it may also cause aflatoxin poisoning.

Toxicity and symptoms of fumonisin poisoning

Fumonisic acid is highly toxic and can inhibit the function of ADP/ATP transporter (also known as mitochondrial ADP/ATP carrier), preventing ATP synthesized by mitochondria from leaving the mitochondria and thus providing energy to other parts of the cell [2]. In 2019, the binding structure of fumonisic acid and ADP/ATP transporter was discovered, showing that fumonisic acid is bound to the substrate binding site of the transporter, preventing ATP in the mitochondrial matrix from binding to the transporter [3].

The target organs of fumonisin are the liver, brain, kidney and other major solid organs . Therefore, the main symptoms of poisoning are damage to the digestive system, urinary system and nervous system, such as upper abdominal discomfort, nausea, vomiting (coffee-colored discharge in severe cases), mild diarrhea, etc.; severe patients often suffer from hepatic coma, central nervous system paralysis, and die of respiratory failure.

Fumonisic acid is extremely heat-resistant, and even 100°C boiling water and pressure cookers cannot destroy its toxicity . After eating food contaminated with fumonisic acid, symptoms of poisoning generally begin to appear within 30 minutes, starting with nausea and vomiting, diarrhea, abdominal pain, dizziness and weakness, and then progressing to severe liver damage, unconsciousness, and even death. Unfortunately, there is currently no specific antidote, and once poisoning occurs, the mortality rate is as high as 40% to 100% [4].

How to prevent fumonisin poisoning

In order to prevent fumonisin poisoning, we can pay attention to the following points:

1. When purchasing wet rice noodles, wet rice noodles, rice noodles, cold noodles and other foods, pay attention to the shelf life and storage conditions. If they are out of the shelf life, do not buy or eat them. Check the appearance and pay attention to whether there is mold or color change. Buy small amounts each time and eat them as soon as possible. If they are not to be eaten for the time being or there are any leftovers, they should be stored in the refrigerator, but not for more than 48 hours.

2. When making homemade fermented cereal foods, do not use moldy cereal ingredients such as moldy corn, rice, etc.; change the water frequently during production to prevent the proliferation of microorganisms, maintain hygiene, and ensure that the food has no odor; when storing cereal foods, pay attention to moisture-proofing to prevent mold.

3. Do not eat spoiled or moldy black fungus and white fungus; use clean water and containers when soaking dried black fungus and white fungus; eat them immediately after soaking, and the soaking time should not exceed 24 hours.

4. Maintain food handling and cooking hygiene: use clean kitchen utensils and countertops, wash hands frequently, handle different types of food separately, and cook food thoroughly, especially meat.

5. Prevent flies, cockroaches and other animals from coming into contact with food: The best protection measure is to store food in airtight containers to prevent the above pests from bringing pathogenic microorganisms into the food.

How to save yourself after fumonisin poisoning

Once someone shows symptoms of food poisoning such as vomiting, diarrhea, abdominal pain, etc., they should first stop eating the suspicious food and call 120 for help immediately .

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Before the ambulance arrives, you can take the following self-rescue measures.

1. Induce vomiting : For those who have been poisoned for a short time and have not vomited obviously, you can use fingers, chopsticks, etc. to stimulate the root of the tongue to induce vomiting, or let the poisoned person drink a lot of warm water and induce vomiting repeatedly to reduce the absorption of toxins. If bloody liquid is found in the vomit, it indicates that there may be bleeding in the digestive tract or pharynx, and vomiting should be temporarily stopped.

2. Catharsis : If the patient has eaten the poisonous food for a long time (more than two hours) and is in good spirits, laxatives can be used to promote the excretion of the poisonous food. Rhubarb and senna leaves can be decocted or taken with boiled water to achieve the purpose of catharsis.

3. Keep food samples : Since identifying the poisoning substance is crucial to treatment, after food poisoning occurs, keep the food sample that caused the poisoning and provide it to the hospital for testing. If there is no food sample around, you can also keep the patient's vomit and excrement to facilitate the doctor's diagnosis and treatment.

in conclusion

The toxicity of fumonisin cannot be underestimated, but don’t blindly think that all soaked foods will cause fumonisin poisoning. As long as we develop good hygiene habits, pay attention to the freshness of food, and understand the symptoms of poisoning and how to save ourselves, fumonisin will not be so scary .

Author: Chen Qiao, PhD student in Microbiology

Reviewer: Zhang Na, Associate Researcher, Doctoral Supervisor, Peking University School of Public Health

References:

[1] Toxicants Occurring Naturally in Foods. National Academy of Sciences. 1973: 472.

[2] Ruprecht, JJ, King, MS, Zögg, T., Aleksandrova, AA, Pardon, E., Crichton, PG, ... & Kunji, ER (2019). The molecular mechanism of transport by the mitochondrial ADP/ATP carrier. Cell, 176(3), 435-447.

[3] Garcia, RA (1999). The effect of lipids on bongkrekic (Bongkrek) acid toxin production by Burkholderia cocovenenans in coconut media. Food Additives & Contaminants, 16(2), 63-69.

[4] De Bruijn, J., Frost, DJ, Nugteren, DH, Gaudemer, A., Lijmbach, GWM, Cox, HC, & Berends, W. (1973). The structure of bongkrekic acid. Tetrahedron, 29(11), 1541-1547.

Planning丨Zhong Yanping

Editor: Li Mengxin

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