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Fusarium infections in grains have been a persistent problem for the upper Midwest. These infections result in mycotoxin contamination of grain. Mycotoxins can cause chronic and acute toxicoses in humans and animals. Infected grain also causes severe economical consequences due to lost income from discounted sales. A problem with malting barley is that during malting, mold can begin to grow and produce more mycotoxins, which survive kilning and remain biologically active. This post-harvest growth of the Fusarium also affects the quality of the malt produced. The industry has set tolerance levels for any deoxynivalenol (DON or vomitoxin) present in barley at or below 0.5 µg/g. The Food and Drug Administration's guideline level for DON in food ingredients destined for human consumption is 1 µg/g. The theory behind these severe industry restrictions is that if any DON is present, then there is Fusarium present that may grow during malting. In recent years it has been difficult for producers to get premium prices for malting barley and much of the barley from the upper Midwest has ended up as animal feed, even though it may contain levels of mycotoxins well within FDA guidelines for human consumption.The investigators will study the effectiveness of two irradiation methods to "pasteurize" barley. These physical treatments may prevent growth of mold during malting while not seriously affecting germinative capacity of the barley or other malting attributes. This pasteurizing process will allow the use of mildly Fusarium infected barley for malting without the safety concern of further mycotoxin production.
NON-TECHNICAL SUMMARY: Fusarium infections in grains have been a persistent problem for the upper Midwest. These result in mycotoxin contamination of grain. Mycotoxins cause chronic and acute toxicoses in humans and animals. Infected grain also causes severe economical consequences due to lost income from discounted sales. A problem with malting barley is during malting, mold can begin to grow and produce more mycotoxins which survive kilning and remain biologically active. This post-harvest growth of the Fusarium also affects the quality of the malt produced. The industry has set tolerance levels for any deoxynivalenol (DON or vomitoxin) present in barley at or below 0.5µg/g. The Food and Drug Administrations guideline level for DON in food ingredients destined for human consumption is 1 µg/g. The theory behind these severe industry restrictions is that if any DON is present, then there is Fusarium present which may grow during malting. In recent years it has been difficult for producers to get premium prices for malting barley and much of the barley from the upper Midwest has ended up as animal feed, even though it may contain levels of mycotoxins well within FDA guidelines for human consumption. We will investigate the effectiveness of two irradiation methods to pasteurize barley. These physical treatments may prevent growth of mold during malting while not seriously affecting germinative capacity of the barley or other malting attributes. This pasteurizing process will allow the use of mildly Fusarium infected barley for malting without the safety concern of further mycotoxin production.
OBJECTIVES: 1. To determine the effect of two different types of irradiation on Fusarium survival in and malting characteristics of three cultivars of Fusarium infected barley. 2. To determine the effects of two different types of irradiation on the mycotoxin producing ability of surviving Fusarium graminearum isolates.
APPROACH: Objective 1. This will be a randomized complete block design. Three, naturally infected barley cultivars will be compared for the effect of irradiation on barley germination, Fusarium survival, and mycotoxin (DON, 15-acetylDON, 3-acetylDON, nivalenol and zearalenone) content. Other variables will be the dosage of electron-beam irradiation and UV-C irradiation distance and time of exposure. Controls will be non-irradiated barley samples. The treatments will be repeated three times and the results compared. The barley samples showing the most significant decreases in Fusarium levels, as shown by percent kernel infection, while maintaining germinative ability will be malted and the malt tested for malt quality parameters, ergosterol content as an indicator of fungal biomass and mycotoxin content (DON, 15-acetylDON, 3-acetylDON, nivalenol and zearalenone). Again, controls will be non-irradiated samples. Objective 2. This will be a completely random design. Isolates of Fusarium graminearum from the three barley cultivars treated at the different irradiation doses (including non-irradiated control samples) will be taken and grown under defined laboratory conditions. The mycotoxin producing ability will be determined by testing the cultures for DON, 15-acetylDON, 3-acetylDON, nivalenol and zearalenone production in culture.