A small field search on the effects of hand sorting process on aflatoxins and sterigmatocystin occurrence in raw hazelnut kernels

Abstract

The efficiency of a hand sorting process on aflatoxins (AFs) and sterigmatocystin (STC) occurrence in hazelnuts was investigated by high-performance liquid chromatography coupled with fluorescence and ultraviolet detection (HPLC-FLD-UV) after post-column derivatization. Raw hazelnut kernel samples were obtained from five different hazelnut processing plants in Turkey. Sound (undamaged) and moldy samples were collected from sorting bands according to the size, and their AF and STC contents were investigated. Trace amounts of AFs were detected in the sound kernel samples, and all of the moldy kernel samples (100%) contained AFs ranging from LOQ to 433 µg/kg. Six (40%) of the moldy kernel samples contained STC ranging from 9 to 101 µg/kg. The sorting efficiency ranged from 85% to 100% for AFs and 100% for STC. STC may also be considered as amycotoxin indicator for observing the situation of hazelnut lots during storage. Novelty Impact Statement AFs and STC are structurally closely related mycotoxins that share common biosynthetic pathway. Although previous studies have been mostly focused on the occurrence of AFs in hazelnut kernels, this study was focused on detecting of AFs and STC together in sound and mouldy hazelnut kernels by one step Immunoaffinity clean-up method. Current work claims that hand sorting has still been an effective way to eliminate flawed/moldy (possibly contaminated high amounts of AFs and other mycotoxins) hazelnut kernels from a healthy lot and STC may be considered as a mycotoxin indicator for observing the situation of hazelnut lots during storage in terms of mycotoxin contamination.