The world has placed great emphasis on the control of aflatoxins in foods, which is the most important mycotoxins in control of global food safety.
Experts in the interview includes Wang Xingguo, Professor of Jiangnan University, Deputy Director of the Oil and Fats Technical Committee of the National Grain Standardization Technical Committee, Liu Xiumei, Technical Consultant and Researcher of National Food Safety Risk Assessment Center and Wang Qiang, Researcher and Deputy Director, Agricultural Products Processing Institute, Chinese Academy of Agricultural Sciences.
In recent years, pure natural and original ecology have become the pursuit of some consumers. In addition to the purchase of Tuza oil, there are also ways to make homemade oil. In these two methods of oil extraction, experts believe that there are major safety risks. At the same time, the relevant media exposed the presence of aflatoxin in some bulk peanut oil sold in the markets of Ganzhou and Guangdong Zhaoqing. Experts explained that except for the quality of raw materials, Tuza oil or self-extracting oil has the following problems. It has not been refined with many impurities and is easily oxidized and deteriorated. The equipment of oil extraction is not easy to clean thoroughly, residual oil stains and grains will be mildewed after oxidation, and the risk of food safety is very large.
What is aflatoxin? What is the toxicity of aflatoxin? Experts will explain this issue in detail for you.
The contamination of aflatoxin is widespread in the world. Aflatoxin (AF) was first discovered in 1960. It is a secondary metabolite of Aspergillus flavus and Aspergillus parasiticus. More than 12 species have been isolated and identified, and aflatoxins B1, B2, G1, G2, M1, M2, B2a, G2a, BM2a, GM2a are common. The thermal stability of aflatoxins is very good, so conventional cooking and heating methods are not easy to decompose it.
Aflatoxins are widely polluted in the world, including grains, nuts, seeds, and cow's milk, especially corn and peanuts. The main reason is that the food is infected with toxigenic bacteria such as Aspergillus flavus before harvesting in the field, and it is propagated and produced under conditions of suitable temperature and humidity, or it will produce a large amount of toxin during storage with sufficiently drying.
Edible oil also has the problem of being easily contaminated by aflatoxin, but the aflatoxin in the refined oil can be reduced to a very low level through raw material screening, alkali refining, and adsorption.
In the production industry of livestock, we must not only pay attention to the harm of mycotoxins to pig and poultry production but also the damage caused by mycotoxins to dairy cows and dairy products. Although the cow's resistance to mycotoxins is stronger than that of pigs due to the unique physiological effects of the cow's rumen, the effect of mycotoxins on the production ability of dairy cows cannot be ignored. With the development of the Chinese dairy industry, the problem of contamination of mycotoxins is highly valued.
In China, the main sources of mycotoxin in dairy cows are aflatoxin corn, aflatoxin cottonseed, aflatoxin peanuts meal, forage, and silage corn. Domestic corn does not control the growth of mold during the process of harvesting, and there are many opportunities for mold to attack during natural drying. The corn dried by the machine is sometimes with high internal moisture, which is easy to cause serious pollution of mold. In general, the production of corn flour during the crushed corn or harvesting process has a higher content of mycotoxin. The aged corn with bad storage and the content of toxin is often exceeded. When the silage is not properly stored, the vomiting toxins in the silage will increase a lot. When the hay or the grass is seriously moldy, the proportion of dairy cows will increase in the susceptibility to other diseases, especially the chance of liver damage. The growth of mold and hay is mainly caused in the period of harvesting, and usually, rain is the main reason for the serious overproduction of mycotoxins.
Aflatoxin is absorbed through the intestine. Toxin B1 can be converted into toxin M1 in milk. The concentration of toxin M1 in milk is positively correlated with the content of toxin B1 in the feed. After a few hours of feeding aflatoxin by a cow, the content of aflatoxin in milk occurs. And if the cow continues to ingest aflatoxin B1, the content of aflatoxin M1 in the milk will increase until equilibrium is reached. However, after 2d~3d of ingestion in a normal diet, the level of toxin in the milk returned to the level of baseline. The ratio of conversion from aflatoxin B1 to M1 averaged 66:1 (51:1~80:1), depending on the source of contaminated feed and the level of milk production.
The US FDA stipulates that the aflatoxin in the feed should be less than 20 μg/kg (B1) and the aflatoxin in milk should be less than 0.5 μg/kg (M1), while the EU specifies that the aflatoxin in milk should be less than 0.05 μg/kg. When the aflatoxin in the feed reaches 33 μg/kg, the aflatoxin M1 in the milk will reach 0.5 μg/kg. The allowance of aflatoxin in corn is 50 μg/kg as specified in the Chinese Feed Hygiene Regulations. When a large amount of corn is used in the feed, the aflatoxin M1 converted from corn to milk will exceed 0.3 μg/kg. While aflatoxin was quite stable during milk processing, it was stored at 4 ° C for 17 days, and the concentration of aflatoxin M1 was consistent with the concentration of M1 in raw milk.
Whether aflatoxin causes acute poisoning depends on the intake.
Several acute poisoning of aflatoxins in humans food safety news have been reported in the world, such as mold cassava poisoning in Africa and mold corn poisoning in India. In 2004-2005, Kenya broke out the largest incident of acute poisoning of aflatoxins in history. More than a thousand people were poisoned and 125 people died in the incident. The content of aflatoxin B1 detected in poisoned corn is as high as 4400 ppb (μg/kg), which is rare in the event of acute poisoning of aflatoxins.
The aflatoxin symptoms are usually the same as hepatic poisonings such as transient fever, vomiting, anorexia, jaundice, ascites, and lower extremity edema. In severe cases, fulminant hepatic failure and death will occur.
According to the standards of China and other countries in the world, if the content of aflatoxin is within the safety limit, it will not pose a risk to the health of consumers.
The global control of aflatoxin in food has been highly valued.
Aflatoxin B1 is one of the major mycotoxins affecting human and animal health and is the leading mycotoxin in control of global food safety. According to the 2003 report on the regulation of food and feed in mycotoxins published by the Food and Agriculture Organization of the United Nations (FAO) in 2003, in addition to the provisions of the Codex Alimentarius Commission (CAC), aflatoxins have been formulated limited standard in various foods in more than 100 countries and regions around the world. . The limited range of aflatoxin B1 in food is 1-20 ppb, and the total amount of aflatoxin (AFB1, B2, G1, G2) is in the range of 0-35 ppb.
In 2011, the National Food Safety Standard for Food Safety (GB2761-2011) specifies that the limit of aflatoxin B1 in peanuts and peanut products is 20 ppb.
In this regard, experts suggest that researchers should first increase the research on pollution of aflatoxin and methods of control from field management to processing to provide more effective scientific and technological support for food safety. In particular, food production and processing enterprises with corn, peanuts, etc. as the main raw materials. And the Tuza oil production workshops should strictly implement the national food safety standards and relevant technical specifications, actively take effective measures, pay attention to the safety of raw materials, and strictly control every production process to ensures the quality and safety of the products.
Besides, experts also recommend that consumers should pay attention to cultivate good consumption habits, pay attention to the labeling of products, and make proper storage during the warranty period. Special attention should be paid to purchasing edible oil through regular and reliable channels, and should not to buy natural and original products produced by small individual workshops.