Assessment of mycoflora and aflatoxin contamination of stored wheat grains

Pakistan exports wheat to many countries. Therefore, post-harvest activities for analyzing good quality of wheat in a scientific manner duly approved by ISO are prerequisite. To meet the challenges of competition in the foreign market, particularly from the long established export giants like USA, Canada, Australia and France this has become essential for all the wheat exporters to establish quality control system. In present study stored wheat grains were randomly sampled. Each sample was divided in to three portions for their complete survey of moisture status, fungal flora and aflatoxin contamination. The moisture content of all samples was found less than 12%. All these samples were found positive for fungal contamination when analyzed by plating under unsterilized and sterilized (with 1 % chlorox) conditions on moistened filter paper, Czepaks agar and Aspergillus flavus and A. parasiticus Agar medium (AFPA). A total number of 30 species of fungi viz., A. candidus, A. flavus, A. fumigatus, A. parasiticus, A. niger, A. restrictus, A. sulphurus, A. sydowi, Alternaria alternata, A. brassicae, A. humicola, A. solani, Rhizopus oryzae, R. spp., R. stolonifer, Acremonium spp., Geotrichum candidum, Mucor heimalis, M. spp., Cochliobolus lunatus, Fusarium spp., F. culmorum, Rhizoctonia, Curvularia lunata, Cladosporium herbarum, Penicillium frequentus, Botrytus spp., Nigrospora spp., Humicola, Helminthosporium spp. were isolated. A. flavus and A parasiticus population ranged from 0 - 5.4 CFU/10 seeds and 0 - 5.0 CFU/ 10 seeds respectively. AFPA proved excellent in the isolation of A. flavus and A. parariticus strains. None of the samples was found aflatoxin contaminated when analyzed by ELIZA technique. The efficiency of ELIZA confirmed by the percent recovery of aflatoxin from positive and spiked controls and samples was found hundred percent.