Natural co-occurrence of aflatoxins and ochratoxin A in ginger (Zingiber officinale) from Nigeria

The natural co-occurrence of aflatoxins (AFB1, AFB2, AFG1 and AFG2) and ochratoxin A (OTA) in dried split ginger purchased from different local markets in Lagos, South West Nigeria has been investigated. A total of 120 ginger samples, 31 collected during the rainy season and 89 during the dry season, were analyzed. Mycotoxins were determined according to the AOAC Official Method 2008.02 based on multi-toxin immunoaffinity column clean up and liquid chromatography quantification. The incidence of contamination with aflatoxins (AFs) and OTA was significantly higher during the rainy season (81% and 77%, respectively) than the dry season (46% and 37%, respectively). Average levels of AFs and OTA in positive samples were 3.13 and 5.10 ?g/kg in the rainy season (range 0.11-9.52 ?g/kg and 0.20-9.90 ?g/kg) and 1.18 and 2.76 ?g/kg (range 0.20-3.57 ?g/kg and 0.17-12.02 ?g/kg) in the dry season, respectively. Furthermore, the levels of AFB1 detected in 7 out of 31 samples (23%) collected during the rainy season were above the European Union (EU) maximum permitted level (i.e. 5 ?g/kg). No samples were found above the EU regulatory limits established for OTA in ginger (i.e. 15 ?g/kg). Moreover, a higher co-occurrence of AFs and OTA was observed in samples collected during the rainy season (65%) than the dry season (21%). Data showed that high humidity and temperature occurring during storage, which are prevalent in the rainy season, offer favorable conditions for AFs and OTA fungal production. This is the first report on the co-occurrence of AFs and OTA in ginger samples from Nigeria. Our results demonstrate that, in order to minimize the risks for consumers, the monitoring of the co-occurrence of these mycotoxins in ginger is highly recommended.