مقالات پذیرفته شده در نهمین کنگره بین المللی زیست پزشکی
Aflatoxin and its detoxification in food and feed
Aflatoxin and its detoxification in food and feed
Roozbeh Yalfani,1,*
1. Department of Nursing, Faculty of Medical Sciences, Islamic Azad University,Varamin-Pishva branch, Tehran, Iran
Introduction: Mycotoxins are toxic secondary metabolites mainly produced by filamentous fungi at both field and storage condition. As per Food and Agricultural Organization (FAO), 25% of agricultural commodities produced worldwide are affected by mycotoxins. Aflatoxins, Fumonisins, Deoxynivalenol, Zearalenone, Ochratoxin, and Patulin, are the most frequently reported mycotoxins in agricultural commodities. Among the mycotoxins, aflatoxins have received much attention due to its frequent occurrence in agricultural commodities and health affects in a wide variety of animals including poultry, turkey, fish, rodents, swine, cattle, and humans. Aflatoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus in agricultural products such as groundnuts, corn, sorghum, rice, spices, nuts, and several other cereals. AFs production normally occurs in the field, particularly when stimulated by drought, stress, and high temperature or during prolonged drying. In a large global survey, the percentage of aflatoxin in Asia (38% of the samples) was shown to be highest compared to other continents. These genotoxic compounds target many organs like kidneys, liver, and immune systems. Their symptoms include: fatty liver, anorexia, diarrhea, vomiting, liver necrosis, and liver cancer. Also, their immunosuppressive effects include reduced resistance to secondary infections by bacteria, fungi, and parasites.
Methods: Other related symptoms include encephalopathy and interstitial fibrosis. Among the 400 known mycotoxins, Aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) are the most significant mycotoxins in foods and feeds. Among aflatoxins, Aflatoxin B1 (AFB1) is the most toxic and has been classified by the International Agency for Research on Cancer as Group 1 carcinogen component because of its carcinogenic and cytotoxic effects in humans. When lactating animals consumed a ration contaminated with AFB1, the toxin can be converted to AFM1 and excreted into the milk. The key route of AFB1 contamination is through the infection of field crops and stored products by A. flavus. In addition, many crops are reported for their ability to uptake AFB1 from contaminated soil. They can contaminate various types of agricultural and food products such as cereals, oilseeds, spices, tree nuts, and dairy products. Several health authorities have been established the maximum tolerance levels for total AFs and AFB1 in feedstuffs. In European Commission (EC, 2006b) regulation, the permitted level for total AFs and AFB1 in feed is 20 and 5 mg/kg, respectively.
Results: Also, according to the Institute of Standards and Industrial Research of Iran (ISIRI, 2002), the maximum level allowed in feed for AFB1 and total AFs is the same as European Commission regulation. And the maximum acceptable levels for AFB1 and total AFs in pistachio nuts in Iran are 8 and 10 μg/kg, respectively. The complete elimination of these saprophytic fungi from the agricultural field is impractical, and it also affects natural nutrient cycle. Therefore, detoxification of contaminated food and feed through different methods are receiving more importance. Several strategies have been applied to prevent aflatoxins production or to destroy, to inactivate, or to decrease their bioavailability in contaminated foods. Physical, chemical, or biological methods are used to detoxify aflatoxins. Main Physical approaches applied to decrease aflatoxin can be classified as cleaning, heating, irradiation and adsorption from solution. A large number of chemicals include acids, bases and oxidising agents can react with AFs and convert them to non-toxic or less toxic compounds.
Conclusion: Some chemical compounds have been brought to test their effectiveness on detoxification of AFs and other mycotoxins including hydrochloric acid, citric acid, lactic acid, ammonium persulphate, calcium hydroxide, sodium bicarbonate and potassium carbonate, formaldehyde, hydrogen peroxide, sodium bisulfite, ozone gas (O3), sodium hydroxide and sodium hypochlorite. Compare to physicochemical methods; biological methods are getting much attention due to its added advantages such as minimum loss of product qualities, safe, economical and eco-friendly nature. Biological methods are based on the action of microorganisms on mycotoxins and their mechanism of action is based on competition by nutrients and space, interactions, and antibiosis, among others. Biological control of mycotoxin is a promising approach for reducing both pre harvest and post harvest mycotoxin contamination in food crops. Different organisms, including bacteria specially, probiotics and dairy strains of lactic acid bacteria (LAB), yeasts strains of Saccharomyces cerevisiae and nontoxigenic Aspergillus fungi, have been tested for their ability in the control of AFs contamination. Since probiotics can bind to aflatoxins into the gastrointestinal tract, thus can prevent the absorption of toxins and reduce the effects of toxins on the animal/human health.