Determination of mycotoxins in nuts, cereals, legumes, and coffee beans and effectiveness of a selenium-based decontamination treatment

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for the rapid quantification of multiple mycotoxins, specifically aflatoxins B₁, B₂, G₁, and G₂ (AFB₁, AFB₂, AFG₁, and AFG₂), ochratoxin A (OTA), deoxynivalenol (DON), and zearalenone (ZEN), in walnuts, pistachios, peanuts, coffee beans, rice, and chickpeas from various countries. Total counts of fungi, Aspergillus flavus, and Aspergillus parasiticus were also assessed, along with the effectiveness of a decontamination treatment with inorganic selenium to reduce mycotoxin levels. Of the 78 samples tested, 69% were contaminated with mycotoxins. ZEN, the predominant mycotoxin contaminant, was detected in all the contaminated samples in concentrations often exceeding the maximum level, followed by AFG₁ (28% of the contaminated samples), DON (22%), AFG₂ (11%), and AFB₁ (5.5%). The occurrence of aflatoxins was associated with high proportions of A. flavus and A. parasiticus. Complete removal of AFB₁ from walnuts and DON from roasted coffee beans was achieved by treatment with aqueous selenium, while the levels of ZEN and AFG₁ were respectively lowered by 65% to 89% depending on the commodity and by about 56% in roasted coffee beans. While this novel treatment is a promising approach for mycotoxin decontamination, it is not intended to replace safe practices upstream.