A Study Concerned with the Factors Affecting the Fungal Growth and Aflatoxin Production During Storage of Pistachio in Kerman Province

Aflatoxin contamination might occur due to the improper storage conditions of harvested pistachios. Different environmental factors affect the fungal growth and mycotoxin production as the harmful secondary metabolites. Improved storage conditions can be effective to prevent the contamination of pistachios. Environmental factors consisting of kernel moisture content, relative humidity, temperature, water activity and fungi and pests might affect the contamination of pistachio. These were studied in 47 stores and warehouses in the cities of Kerman, Sirjan, Zarand and Rafsanjan regions at three month intervals for the storage period of 12 months. The levels of water activity and kernel moisture content in this study ranged from 0.12 to 0.46 and 3.1 to 5.3 (%), respectively. In most stores, the average of relative humidity ranged from 24 to 26 % with minimum and maximum values of 13.7 and 36.5 respectively and average temperature of 23.3 to 26.1 ZC. On the other hand, observed low levels of kernel moisture content and water activity remained at a constant level for most sampling times. These results indicated that equilibrium moisture content was not in favor of Aspergillus flavus growth and aflatoxin production. The observation also showed that the frequency of storage pest contamination was less than 1% and Aspergillus contamination varied from undetectable to 1 %. The stores or warehouses conditions concerned with pistachio in Kerman province are not in situations to create and promote fungal growth and aflatoxin production.