Impact of fungal contamination of wheat on grain quality criteria

The aim of this study was to investigate the spread of minimal, field born Fusarium infections in wheat during storage and the resulting impact on grain quality. Therefore, Fusarium culmorum was chosen as the representative strain. Wheat grains were artificially infected and stored for 6 weeks in a model system. To estimate the fungal growth, the ergosterol content was determined as this correlates with the fungal biomass. Ergosterol levels revealed a rapid spread of the infection during storage conditions. Furthermore, analysis of nine mycotoxins showed that Deoxynivalenol and Zearalenone occurred in concentrations exceeding the maximum residue limits. Scanning electron microscopy illustrated the penetration of the fungus into the endosperm and showed the degradation of important seed constituents, such as starch and storage proteins. This is mainly due to the increased activity of proteases and amylases by the fungal metabolism. The results of this study show how small levels of field contamination can easily spread during storage and so lead to significant losses in grain quality and present a potential consumer health hazard. Thus, it demonstrates the need to develop efficient methods for crop protection during storage, without compromising the quality.