Ochratoxin a levels in fermented specialty coffees from Caparaó, Brazil: Is it a cause of concern for coffee drinkers?

Although postharvest coffee fruit fermentation can improve coffee flavour and quality, the mycotoxin ochratoxin A (OTA) can also be a result of microbiological activity, albeit in the later drying step of coffee processing. To evaluate the possible occurrence of OTA contamination in postharvest fruit fermentation, fourteen coffees that entailed two different postharvest fruit fermentation times were evaluated. These coffees originated in the surroundings of the village of Pedra Menina in the qualified Denomination of Origin and coffee producer region of Caparao on the border between Minas Gerais and Espirito Santo states in Brazil. All coffees were classified according to the Specialty Coffee Association (SCA) protocol and 12 achieved specialty level. OTA was determined in all 14 coffees using immunoaffinity for sample clean-up and high-performance liquid chromatography with fluorescence detection for quantification. One sample presented an OTA concentration of 0.75 µg kg-1 and two samples showed OTA concentrations of 0.87 µg kg-1. The other samples had concentrations of OTA below the limit of quantification obtained in this work (0.64 µg kg-1). Thus, all samples showed OTA concentrations far below the most stringent maximum residue limit (MRL) of 5 µg kg-1 established for roasted coffees by European legislation. These low levels were similar to most of the previous results for Brazilian coffees listed and tabled in this work. This comparison showed that OTA contamination due to this kind of postharvest process - fruit fermentation - should not be a concern for producers and consumers of these fermented coffees.