Mycotoxins in green coffee: Occurrence and risk assessment

Our study investigated the occurrence of a wide range of mycotoxins in coffee, most of them rarely analyzed in this commodity, and the safety relevance of mycotoxin exposure from coffee consumption. A new liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of 31 regulated and emerging mycotoxins was therefore developed and validated. Quantification was performed by the matrix-matched calibration curve approach. Analyses were conducted on green coffee which permitted to reach low limits of quantification, i.e. from 0.25 μg/kg to 150 μg/kg. A total of 71 green coffee beans samples, harvested in 2015 and 2016, were collected from various geographical origins (nine countries) and comprised of Arabica or Robusta species. Types of post-harvest processes and storage times in bags were also considered during sample collection. Diversity, occurrence and levels of mycotoxins in the surveyed green coffee samples were quite low. The mycotoxins most frequently found and at highest levels were Ochratoxin A, Fumonisin B2, Sterigmatocystin, Beauvericin and Enniatin A with maximum levels at 12.2, 76.3, 19.8, 4.4 and 1.7 μg/kg, respectively. Contamination with Aflatoxin B1 was sporadic with maximum level at 1.2 μg/kg. Co-occurrence of multiple mycotoxins per sample was rare, at very low levels and mostly limited to two different toxins. A risk assessment performed on our data set indicates that coffee is a minor contributor to mycotoxin exposure from the diet and is not expected to represent a safety concern.