Dynamics of fungi and related mycotoxins during cereal storage in silo bags

The aim of this work was to investigate the dynamics of fungi and related mycotoxins during cereal storage in silo bags. A 2-year trial was organised (2009-2011); in each year, two silo bags, filled with maize and durum wheat respectively, were prepared. During storage, meteorological data were collected from a close station and temperature, CO2 and O2 were measured inside the silos. Grain was sampled from silo filling (September) every 40 days until June (7/8 samples per silo per year). Water activity of grain, colony forming units (CFU) and mycotoxin content (fumonisins, aflatoxins and ochratoxin in maize, deoxynivalenol and ochratoxin in wheat) were determined.Temperature inside the silo bags followed the trend of external temperature, with a more limited variation. A decrease of O2 was observed from 16.4% to 2.0% in maize and from 15.7% to 15.1% in wheat; the decrease was balanced by CO2 increase. Minor variations were registered in grain water activity and CFU and mycotoxin content did not change significant throughout the storage period; the results were consistent in the two years. On the basis of these results, silo bags prove to be suitable for safe cereal storage.

► In cereals stored in silo bags the environment becomes anaerobic. ► Carbon dioxide percentage in interstitial air increases in maize. ► Viable fungi identified in cereals, mainly Fusaria, decrease during storage. ► No significant variations were observed in mycotoxin content during storage.