Peanut products are the food that is very common in our lives, including peanut milk, peanut butter milk, spicy peanuts, tiger skin peanuts. Peanuts are made into a variety of foods for us. But today what we are talking about is that it is a toxin that peanuts are most likely to breed.
In recently, some netizens forwarded posts in Wechat. The post said that peanuts are easy to breed a toxic substances called aflatoxin, which can cause cancer. The detail is that once the peanuts get wet, it is quite likely to breed aflatoxins. When the pigeons eat aflatoxin peanuts for a long time, they will invade organs such as liver and kidney. The toxicity of aflatoxin is 68 times that of arsenic. After people eat food along with aflatoxin for a long time, they are easy to get liver cancer and stomach cancer.
Is this alarmist, or is it true?
In the survey, most people don't know about what is aflatoxin. Huashang Daily reporter visited some supermarkets and free markets in Xi'an on December 1and found that peanuts and peanut products are very popular, but most people don't understand the toxins that peanuts tend to breed. Our family usually ate porridge with peanuts, and do not know that peanuts will produce aflatoxin, Ms. Liu, said. I usually eat fried peanuts or vinegar-soaked peanuts, and I have not paid attention to whether peanuts also will breed toxins, Ms. Liu, said. When you shopping, you will select peanuts that do not have mold in the surface, Ms. Zhou, said.
Experiment to detect excessive aflatoxin in sampling
In the news, aflatoxin exceeded in two of the three samples. Is there any aflatoxin in the peanuts in our daily lives? Huashang Daily reporter purchased three kinds of red-skinned peanuts of bulk yesterday in a large chain supermarket, a convenience store in a community and a free market. These three varieties of peanuts with normal appearance, intact the surface, relatively uniform size, and without mildew. Subsequently, the Huashang Daily reporter took these three samples to test in the laboratory of Shanxi Zhongshi The Third Party Supervision Co., Ltd.
■Experimental purpose: To detect whether peanut is contained aflatoxin
■Experimental Location: Laboratory of Shanxi Zhongshi The Third Party Supervision Co., Ltd
■Experimenter: Huang Xiaohao, a Tester and Zhu Xihua, a Business Daily reporter
■Experimental sample: Peanuts purchased at supermarkets were sample 1, peanuts purchased at convenience stores in the community were sample 2, and peanuts purchased at the free-market were sample 3.
■Experimental theory: The aflatoxin B1 rapid detection card uses the theory of competitive inhibition of the immune layer. The aflatoxin B1 in the sample binds to the colloidal gold-labeled specific monoclonal antibody during lateral movement, inhibiting bind between antibodies and aflatoxin B1-BSA conjugate on the NC membrane assay line.
1. Prepare diluent in the sample: The process is dilute the sample in a volume ratio of 1:9 with deionized water, accurately weigh 1.5 g of sodium chloride in a 50 ml centrifuge tube, add 25 ml of deionized water to dissolve thoroughly and add 25 ml of methanol to mix thoroughly.
2. Take samples 1, sample 2, and sample 3 peanuts separately to break in a cooking machine. The process is weighed 2 g pulverized, placed in a 10 ml centrifuge tube, and then add 4 ml of the sample extract. The centrifuge tube lid was tightly sealed, shaken for 5 minutes, centrifuged at 4000 rpm for 2 minutes to obtain a supernatant. Then take 0.1 ml supernatant in a 1.5 ml centrifuge tube and add the sample diluent to mix according to the required detection limit.
3. Place the test card in flat. Draw the sample solution to be tested with a dropper. Slowly add 2-3 drops of the bubble-free sample solution vertically into a container for the test.
■Experimental results: If a red line appears in the T area of the detection, no aflatoxin is detected in the sample. If it does not appears, aflatoxin is detected in the sample. After 8 minutes, the result of the test card came out. There was no change in the T region of sample 1 and sample 3, and a red line appeared in the T region of sample 2. That is to say, aflatoxin was detected in both samples 1 and 3, and aflatoxin was not detected in sample 2.
The appearance of peanuts is intactness without mold. Why is excessive aflatoxin detected?
Li Ming, a food engineer at Shanxi Zhongshi the Third Party Supervision Co., Ltd., said that Aspergillus flavus checked by the eyes is green color, but aflatoxin is odorless, tasteless, and colorless. When such toxins sneak into peanuts, it's hard to find with the naked eye. Therefore, even if you buy peanuts that look fine, they may contain aflatoxins. If you see the peanuts that are yellowish and green, it means that it has been infected by aflatoxin very seriously.
Li Ming said that since aflatoxin is easily propagated in soil and grains, it is difficult to avoid aflatoxin in peanuts. Therefore, China has set an upper limit on aflatoxin in food. According to national standards, The allowable amount of aspergillus in corn is ≤ 12 μg / kg. The two of the three samples we tested today have exceeded this standard, and they are not safe to eat.
How strong is the toxicity of aflatoxin?
The acute toxicity of aflatoxin B1 is 68 times that of arsenic. Aflatoxin is a class of compounds with a similar chemical structure and is a derivative of dihydrofuran coumarin. Aflatoxin is a secondary metabolite produced mainly by Aspergillus parasiticus. It has the highest probability of contamination of aflatoxin in food and feeds in hot and humid regions. They are found in soil, animals and plants, nuts, especially grain and oil products that are easy to contaminate, including peanuts, corn, rice, soybeans, wheat, etc., and it is a class of mycotoxins that are extremely harmful to human health.
The World Health Organization's International Institution for Research on Cancer published a preliminary list of carcinogens on October 27, 2017, aflatoxins are in a list of carcinogens.
Li Ming said that aflatoxin B1 is one of the most carcinogenic toxins among known chemicals. The acute toxicity of aflatoxin B1 is 10 times that of potassium cyanide and 68 times that of arsenic. And chronic toxicity can induce cancer.
Aflatoxin enters the human body through the digestive tract, so it mainly causes liver cancer, stomach cancer, etc. It can also induce cancer in bone, kidney, rectal, breast, ovarian, etc. Only foods with severe mildew may contain a large amount of aflatoxin and cause acute poisoning, Li Ming, said. And a single intake of aflatoxin is very dangerous. If you are 70 kg, a single dose of 20 mg aflatoxin will be fatal.
Even if you only find one or two pieces of moldy peanuts, you can’t eat the rest of the peanut pulp. Peanut is one of the most susceptible crops to Aspergillus flavus, Li Ming, said. Many people like to order a cup of peanut pulp when they dining out in the winter. But if there are one or two pieces of bad moldy peanuts, the whole bottle of peanut pulp will be polluted with aflatoxin. Peanuts and marinated peanuts should also be eaten less because it is difficult to estimate whether it is contaminated with aflatoxin or not after cooking.
When aflatoxins are eaten by humans or animals, some of them will accumulate in the body of humans or animals and others will be converted into milk and urine. Therefore, if the cows eat cereals contaminated with aflatoxin, the milk will be contaminated too.
Tips to deal with aflatoxin
Aflatoxin is a see also of mycotoxin. The chemical structure of aflatoxin is a cyclic structure of macromolecules, which is very stable and not easily destroyed. The decomposition temperature of aflatoxin B1 needs to reach about 268°C. So, how to remove aflatoxin from food? Li Ming said that paying attention to prevention in life can still effectively avoid the harm of aflatoxin. The best method of prevention is to prevent mildew of grains such as peanuts. The temperature required for the production of Aspergillus flavus is 12°C~42°C, and the optimum temperature is 25.7°C~32°C. The higher the temperature is, the faster the Aspergillus flavus grows and the higher the content of aflatoxin is. The products prone to mildew is better stored in dry and low temperature.
When buying nuts, peanuts, grain, etc., you should try to choose a small package and don’t store it for too long. When you eat peanuts, it is better to open the raw kernels. If you find that the nuts are slightly yellow, it means it has been contaminated. If the peanuts have buds, you can't eat it for the reason that aflatoxin grows faster when the peanuts get wet.
Li Ming suggested that peanuts, walnuts, etc. are best preserved in shells. After drying, they can be stored in a closed box with a storage box to preventing mildew.
Aflatoxin is mostly present on the surface of the food. Before the family consumes food, it should be washed thoroughly to remove toxins to a great extent from the surface of the food and fully simmered.