Occurrence of Deoxynivalenol-3-Glucoside on Barley from the Upper Midwestern United States

Abstract

The natural occurrence of deoxynivalenol-3-glucoside (DON-3-G) on wheat was first reported in 2005. Subsequent research has shown its occurrence on wheat, maize, and barley grains that have been infected with Fusarium head blight (FHB), as well as in processed products derived from the grain, including malt and beer. The mycotoxin, deoxynivalenol (DON), is produced by several species of Fusarium during infection, and DON-3-G is subsequently formed by a detoxification mechanism of the host plant. There has been considerable interest in DON-3-G because it is not detected by most routine methodologies that are employed for DON, but may contribute to the overall DON if broken down during digestion or processing. As such, it has been designated as a “masked” mycotoxin. The objective of the current work was to assess the levels of DON-3-G on infected barley from the upper Midwest region of the United States. Three sets of commercially grown barley samples, representing multiple crop years, were selected for this study. FHB-infected samples were purposely selected, based upon previous results of DON analysis. Analysis of barley samples collected from 2001 to 2012 showed that DON-3-G was present at levels of <0.20–3.11 mg/kg. In the case of the 2001–2011 crop, DON-3-G was always at levels that represented less than 10 mol% of the DON present on the same samples. However, the overall average ratio was higher with the 2012 crop (19 mol%), and results of this study suggest that levels of DON-3-G might be impacted by environmental/cropping conditions. It was also observed that DON levels were a poor predictor of DON-3-G. Samples where the proportion of DON-3-G was high, or even in excess of DON, were very few and were found only within a single crop year. However, because similar results have been observed in previous studies conducted in both Europe and Asia, grain processors need to be well aware of DON-3-G.