The Role of Early Splitting in Contamination of Pistachio Nuts by Aspergillus Species and Aflatoxin in Kerman Province

Early splitting Pistachio nuts in is one of the critical sources of aflatoxin contamination before and during harvest. In this research work physical characteristics,fungal, pest and aflatoxin contaminations were evaluated in early splitting pistachios.

Physical characteristics, fungal contamination and aflatoxin content were assessed in pistachio nuts employing advanced methods. This study was carried-out using three varieties of commercial nuts consisted of Ohadi, Kalleghoochi and Ahmadaghaii.The data was analyzed in a randomized complete block design using Mstatc statistical analysis software.

The highest levels of Aspergillus infection was observed in early splitting pistachios with dry and semi-dry hull. These pistachios also had the highest levels of carob moth infestation and shell staining as well as low kernel weights. In early splitting pistachios with soft hull the fungal infection, carob moth and shell staining were 0.75-10.3%, 1.5- 9.5% and 21.5- 44.1% respectively. This indicates the critical effects of early splitting pistachios as well as the risk of aflatoxin formation. The results showed that the levels of Aspergillus infection are increased by the presence of carob moth and ants, while there was low kernel weight. Aflatoxin was not detected in pistachio with healthy hulls. On the other hand, shell and kernel of early splitting pistachios contain different levels of aflatoxins (P<0.05). Aspergillus flavus isolates was alike to produce 67% aflatoxins B1 and B2 and 24% aflatoxins B1 and 9% were nontoxigenic.

Sorting out early splitting pistachios based on physical and appearance characteristics would reduce the levels of aflatoxins during or after processing. Early peaking is a critical factor to reduce fungal and aflatoxin contaminations. About 95% and 5% of aflatoxin contents were related to kernel and shell, respectively. Therefore, assessing the risk of contamination should be based on kernels.