The effect of grain storage conditions on the viability of Fusarium and deoxynivalenol production in infested malting barley.

A continuing outbreak of Fusarium head blight occurred on barley in the upper Midwest from 1993 to 1995. This resulted in barley with levels of the mycotoxin deoxynivalenol (DON) reaching levels of concern for maltsters and brewers. This study evaluated the effect of 7 months of storage under different conditions (ambient outdoor temperature from October to April), -20 degrees C, 4 degrees C, 24 degrees C with quiescent air, and 24 degrees C with forced air) on the viability of Fusarium and Alternaria infesting stored grain. Additionally, the ability of Fusarium to produce DON after storage and during malting was evaluated. Initial levels of infestation of barley by Fusarium and Alternaria were 85 and 75%, respectively. All storage conditions reduced the viability of both molds slightly and significantly for Fusarium. Forced air ventilation at 24 degrees C was the type of storage most effective in reducing the viability of Fusarium, dropping the percentage of infected kernels to 66%. DON levels did not change after 7 months with respect to storage conditions. However, DON levels were lower in malt produced from barley stored at 24 degrees C with or without aeration. On-farm storage of infected barley at elevated temperatures may provide a means to reduce the level of DON in finished malts.