the contamination rate of stored wheat samples of mazandaran province by aspergillus flavous and aflatoxin (2003)

introduction: in respect of underground cultivation, production and consumption wheat is the major alimentary seed in iran. the contamination of wheat to fungi especially aspergillus flavous (the most important aflatoxin producer in nature) and aflatoxin is a risky factor to community health. the aim of this study was to identify aspergillus flavous and aflatoxins in the stored wheat of mazandaran province in 2003. materials and methods: wheat samples (n=118) were collected from all 12 warehouses of mazandaran province. to isolate and identify aspergillus flavous, 100 kernels from each sample were selected and their surface sterilized with 1% sodiumhypochlorite per l min, followed by washing with sterile distilled water (three times). then kernels were placed on saboruaud's dextrose agar containing chloramphenicol and streptomycin (20 kernels per plate). the plates were incubated at 27-30 0c for 7 days. at the end of this time the kernels were examined to observe the grouth of fungi. the percentage of kernels with fungi was determined. aflatoxins were identified and quantified by thin layer chromatography with immunoaffinity column as described by european commission joint of research center(ecjrc). results: 63.7% of wheat samples were contaminated with aspergillus spp. among the species of aspergillus, the most frequently occurring were a.flavous (64.6%). aflatoxins identified in 2.54% of samples (mean value of 3.12 ppb) and the minimum and maximum levels of contamination were 1.30 ppb and 7.10 ppb, respectively. aflatoxin b1 and g1 were found in 2.54% and 3.39% of samples (mean values of 1.53, 2.75 ppb), respectively. conclusion: the results showed that, in spite of high percentage of a flavous, contamination of wheat samples with aflatoxins was not considerable. with regard to proposed standards given by the fao/who/unicef/and standard administration of iran under which the content of aflatoxin should not exceed 30 ppb in food products, none of samples meet these criteria.