Effect of Packaging and Storage Temperature on the Population of Aspergillus section Flavi and Aflatoxin Production in Fresh Pistachios

The study was performed to investigate the Aspergillus growth and aflatoxin production in fresh pistachios stored in different packagings. Forty kg of fresh pistachios of the Abbasali cultivar were sampled and kept in different temperature conditions including 4°C and ambient conventional temperatures in plastic baskets or polyethylene plastic bags. Sub-samples were taken at 4 days intervals for 32 days to measure aflatoxin and evaluate the population of Aspergillus section Flavi. Aflatoxins were quantified by HPLC and the fungal population was monitored by dilution series method and AFPA medium. The results showed that on the first day of storage in all conditions the amount of aflatoxin was undetectable. Aflatoxin infection started on the fourth day after storage in the ambient conventional temperature and increased over time. The lowest production of aflatoxin B1 was in the 4°C treatment. Pistachios stored at ambient conventional temperature and packed in plastic baskets showed the highest amount of aflatoxin B1 production. The effect of the treatments on the production of aflatoxin B1 showed that the samples in polyethylene plastic bags at ambient temperature were the highest. The results showed that in the 4°C treatment, the fungal population was significantly less than in ambient temperature treatments. The lowest fungal population was in the 4°C plastic baskets packaged treatment. This treatment was not significantly different from the 4°C polyethylene bag treatment but was significantly different from other treatments (P≤0.01). In general, keeping fresh pistachio at 4°C and suitable plastic is trustworthy. Storage for more than 8 days in the ambient conventional temperature greatly increases the risk of fungal and aflatoxin contamination.