Occurrence and stability of masked fumonisins in corn silage samples.

Corn plants contaminated with Fusarium verticilloides were harvested at two dates and ensiled in laboratory silos. The stability of Fumonisins B1 and B2 (FB1, FB2) was studied and the effects of inoculant use (Lactobacillus buchneri) and of the ensiling time were assessed. The occurrence of masked fumonisins was also investigated. After the extraction of the free forms (FB1, FB2), the residue was subjected to an alkaline hydrolysis resulting in the release of derivates subsequently detected by LC-HESI-MS/MS. The ensiling time has shown to be a significant factor for the evolution of free FB1 and FB2 at the 2nd harvest date. Moreover, the use of inoculant had a significant effect on the stability of hidden and total FB1 at the two harvest dates. Samples previously ensiled and exposed to aerobic conditions for 7days have shown higher fumonisin levels than those not exposed to air. Our results showed that 65% and 39% of the total FB1 and FB2 contents in silage were due to hidden fumonisins.