Aflatoxin contamination in pistachio nuts: A farm to storage study

Abstract

The aim of this study was to follow the whole production chain of pistachio nuts from farm to storage and determine the production steps, the conditions and/or handling practices that affect aflatoxin production in Greek pistachio nuts. Eighty trees from four pistachio orchards (20 trees from each orchard) of the Greek variety Pistachia vera cv Aegina were selected for monitoring and sampling. Five samples were taken from every orchard for aflatoxin analysis. The first sample was taken at early maturity on 31st of July, the second at maturity on 13th of August, the third at harvest (20th–30th August), the fourth at the end of drying and the last at storage (45 days after drying). The results showed that the most critical step for aflatoxin contamination is maturity because it was the first stage that aflatoxin was detected above permitted limits ranging from 11μg/kg to 1361μg/kg among orchards. At harvest, aflatoxin concentration was even higher reaching 1420μg/kg in Orchard A. Higher levels of aflatoxin (>1000μg/kg) were detected in orchards with heavy insect infestations indicating a positive correlation between aflatoxin contamination and insect infestation. At post-harvest, aflatoxin contamination detected in three out of four orchards, varying from 40μg/kg to 1200μg/kg at drying and 650μg/kg to 1100μg/kg at storage, depending on the aflatoxin level at pre-harvest stage and on storage conditions. These results could contribute to understand where the problem of aflatoxin contamination of pistachio nuts lies in the production chain from farm to storage and improve production, processing and storage practices in order to eliminate or reduce aflatoxin in pistachio nuts.