The Population Density Effects of Aspergillus Spores on Pistachio Seeds in Aflatoxin Production

Introduction: Nuts are from among the most popular snacks worldwide and constitute a major part of Iranians’ food habits. The natural contamination of nuts with aflatoxins is unavoidable and poses a special challenge to food safety. Aflatoxins are carcinogenic secondary metabolites that are mainly produced by Aspergillus flavus and Aspergillus parasiticus and frequently contaminate food stuffs, such as pistachios. To find a suitable method for tracing and predicting the production of aflatoxins by fungal species in pistachios, especially in the field of exportation, this study was conducted to determine the ratio of the number of fungal spores to the sample value of pistachios. Materials and Methods: Firstly, some suspensions containing 5 to 5×106 spores of A. flavus were prepared and then used for the inoculation of 10 grams of pistachio nuts. After inoculation, the samples were kept under optimal conditions. Sampling was done 24 hours after inoculation and performed in six days. Pistachio nut slurries were extracted using methanol, water, and hexane (30ml, 7.5ml, and 10ml), and aflatoxins were analyzed using the high performance liquid chromatography (HPLC) method. Results: The results showed that the amount of aflatoxins inoculated at the concentration of the 106 spore suspension was more than the standard values after day 5. Conclusion: It can be concluded that the use of mechanized pistachio processing lines accompanied with the proper use of pistachio washing methods can contribute to the reduction of the fungal sporulation of inoculums, thereby reducing the production of aflatoxins. Findings of this paper can support decision making at transport and storage levels for producers and processors to predict the time for AFB1 production by A. flavus in pistachio nuts in the postharvest phase.