A true scale study of the maize chain with focus on free and hidden fumonisins and related fungi

The aim of this work was to study the dynamic profile of mycotoxin producing fungi as well as the accumulation of free and hidden fumonisins along the maize chain. Raw maize was sampled at harvest, at the storehouse and after drying. The study continued on the dried maize bulk along the storage period in a commercial silo, which was sampled during discharge at 6, 7, 8 and 10 months. Finally, the flour obtained after kernel milling and corresponding to the silo discharges was investigated. The sampling approach, designed in agreement with EU regulations and tested for reliability, was used along the maize chain, obtaining very good results. The prevalent fungi found in maize kernels belonged to Fusarium section Liseola. Comparable results, in terms of both fungal incidence and fumonisin contamination, were obtained for the samples collected at harvest and at the storehouse, opening the possibility to adapt the maize chain monitoring to the needs of the farmer/enterprise. A reduction in fungal colony forming units was noticed after drying, supposedly due to the thermal treatment. Very similar amounts of free and hidden fumonisins were detected in raw maize and after drying, confirming the reliability of the sampling approach. During silo storage, up till to 10 months, a significant decrease was recorded for both free and hidden fumonisins. A significant increase in the free-to-total fumonisin ratio was observed moving from stored kernels to commercial flour, suggesting that milling leads to a reduction of the masked fraction. This result, together with the increase of free fumonisins after maize drying, should be considered in future studies. Especially the effect of drying conditions and milling treatments on the fumonisin masking phenomena should be further investigated.