Incidence of Aspergillus flavus and extent of aflatoxin contamination in peanut samples of Pothwar region of Pakistan

Incidence of aflatoxin producing fungi and level of aflatoxin was examined in peanut samples from main markets of Pothwar region that is, districts of Chakwal, Rawalpindi, Attock and Jehlum. Total number of collected samples was 40 having 10 samples from main market of each district. Seeds were plated on PDA, water agar and filter paper and incubated at 29 degrees C. Aspergillus parasiticus was not found on any of the samples, thus, only isolated aflatoxin producing fungus Aspergillus flavus was identified on the basis of morphological characteristics. The results (14 out of 40 samples showed incidence on PDA, 4 on water agar and no results on filter paper) indicated that PDA was the best substrate amongst three. Mean location wise incidence on PDA and water agar on samples collected from Chakwal was 21.1 and 7.7% respectively. In case of samples from Jehlum, incidence on PDA and water agar was 14.44 and 6.6% respectively, whereas 21.1 and 6.6% incidence (only on PDA) was found to be in samples from Attock and Rawalpindi respectively. Aflatoxin contents in peanut samples of these four districts ranged from 2.01 to 3.54 ppb (mu g/ kg), 2.09 to 2.86 ppb, 2.00 to 2.78 ppb and 2.33 to 2.58 ppb in the order earlier mentioned when detected through enzyme linked Immunosorbent Assay. This study depicts a clear picture about the current incidence of A. flavus on peanut samples and extent of aflatoxin contamination in them. The highest value of aflatoxin (3.54 ppb) was found within safe limit (20 ppb, regulatory limit of FDA/WHO) and hence, freshly collected peanut of Pothwar region may be said to be non-hazardous for human consumption.