Raw cashew nut quality as function of contamination by mycotoxins and other secondary metabolites of Aspergillus spp. and farmer practices

Cashew nut is a cash crop in tropical regions of Africa including Benin, providing substantial revenues to small-scale farmers and contributing significantly to the national gross domestic product. In Beninese context, about 95% of raw cashew nuts are exported. Therefore, the production of raw cashew nuts of good quality is mandatory to enter the international market. Moreover, health issues related to the consumption of nuts contaminated with mycotoxins are of high concern for human being. The objective of this research was to investigate the occurrence of mycotoxins and other secondary metabolites of Aspergillus sp. on raw cashew nuts and to evaluate farmers’ practices that affect the quality of raw nuts.In surface disinfected samples 90.2% of raw kernels were contaminated by strains of A. section Nigri in the northern guinea (NG) zone compared to 87.2% in the southern guinea (SS) zone. The level of contamination of raw cashew kernels by strains of A. section Flavi was 6.7% in the NG zone whereas it was 4.6% in the SS zone. When non disinfected kernels were plated, A. section Nigri was predominant in both NG and SS zones, with percentages of 89.7% and 93.4%, respectively. Ten and 15.7% of raw cashew kernels were contaminated by strains of A. section Flavi in NG and SS zones, respectively. A. flavus, A. tamari, A. costaricaensis, A. minisclerotigenes and A. nomius were identified as strains in A. section Flavi. The average water content and the cashew nut count were respectively 8.6% and 172 nuts/kg in the NG zone and 8.7% and 174 nuts/kg in the SS zone.The occurrence of aflatoxins, analysed by ultra-high performance liquid chromatography tandem mass spectrometry, showed that none of the analysed samples was positive for natural occurrence of aflatoxins with a detection limit of 0.05 - 0.2 µg/kg. All the above results showed that, at present, cashew nuts from Benin were in the range of good quality for export.Seven species of black aspergilli were isolated based on