Determination of Aflatoxin in Peanut and Sesame Cakes by Enzyme-Linked Immunosorbent Assay (ELISA

Abstract

Food security and safety is a basic human need and is considered as a hot issue for national and international organizations in the recent years. Chemical as well microbial food hazards are the most important concern nowadays, and among microbial food and feed hazards, mycotoxin attracted world’s attention towards fungal invasion to food elements. Several oilseed cakes and meals are produced in Sudan on large amount as by-product of industry of vegetableoil for human consumption. In Sudan, groundnut, sesame, cotton seed and sunflower are the most common oilseeds. These cakes and meals are rich in protein content and usually used for livestock feed . Sorghum, peanut cake ,sesame meal and wheat bran are considered the main source of protein and energy for poultry in Sudan. Although groundnut meal is used commercially as the main source of protein for poultry in Sudan, it has anti-nutritional properties and highly susceptible for aflatoxin contamination. Aflatoxin, which is produced by Aspergillusflavus and AspergillusParasiticusfungi metabolism, is one of the compounds in the mycotoxin group. The main types of aflatoxinsare AFB1, AFB2, AFG1 and AFG2.Aflatoxin can cause serious biological effectswhen it is consumed regularly at high levels . Some of the effects are inhibition of protein synthesis; inhibition of enzyme induction,inhibition of lipid synthesis and transport, immunosuppression, fatty degeneration and liver cancer. Enzyme linked immunosorbent assay (ELISA) technique(thesimple ,sensitive, safe reagents and veryaccurate) was used to assess the levels of aflatoxin in peanut and sesame cakes. Randomandhomogenous 40 samples, collected from different markets inKordufan and Darfurin western Sudan during March and April 2013 were extracted with 70% (v/v) methanol. The extracted samples and horse radish proxidase-conjugated aflatoxinwere mixed and addedto the antibody coated microwell. On removal of non-specific reactants, tetra methyl benzidine chromogenic substrate was added and the microwellsmeasuredoptically by microplate reader at 650nm. The results showed that aflatoxin contents of peanut cakes ranged from 20.80µg/kg to 88.30µg/kg. The sesame cakes samples contained between 0.2µg/kgand 5.8 µg/kg aflatoxin.100 % and 90% aflatoxin contamination was found in thetwenty samples of peanut cake and eighteen samples of sesame cake respectivelyinvestigated. With a safe limit of 20 µg/kg set by food and drug administration agency, only the peanut cake samples were higher than allowable levels.Aflatoxin levels were consistently high in peanutcakes indicating that nuts are the most commonly contaminated food commodity.