Natural occurrence of zearalenone in Tunisian wheat grains

Fusarium mycotoxins are worldwide occurring in cereals and they are frequently reported in fresh or stored grains. Cereals represent a staple food for the Tunisian population; it therefore has a high social, economic and nutritional relevance. Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by a variety of Fusarium fungi in temperate and warm countries. Fungi-producing ZEN contaminates corn, barley, wheat, sorghum and rice. A total of 205 samples of wheat were collected during the harvest year of 2010 from the major cropping areas in Tunisia and they were analyzed for zearalenone contamination. The aim of this study was to investigate for the first time the presence of ZEN in widely-consumed cereals in Tunisia, especially durum and tender wheat, to compare the levels of contamination by ZEN with the European norms and to suggest some factors that can promote the production of ZEN in Tunisia. To perform this study, we developed and validated in our laboratory conditions an HPLC method for quantitative analysis of ZEN in solid cereal samples. Our results showed that the incidence of ZEN contamination was 75%. The levels of contamination determined in the positive samples ranged between 3 and 560 μg/kg with a mean value of 60 μg/kg. These important amounts of ZEN in wheat can be attributed to the Tunisian climate, warm temperature and prolonged wetness witch are favor to Fusarium growth and mycotoxin production during the cultivation and the final ripening period of wheat grains.

► We evaluate the ZEN occurrence and levels in the fresh harvested wheat. ► Wheat samples were analyzed by IAC followed coupled to HPLC-FLD. ► 75% of the 205 wheat samples contained ZEN. ► The contamination average of the positive samples is 60 μg/kg. ► Exact situation of wheat-contamination by ZEN in Tunisia was provided.