DisplayTitle

Influence of Stenocarpella maydis Infected Corn on the Composition of Corn Kernel and Its Conversion into Ethanol

¹Bioenergy Research Unit, National Center for Agricultural Utilization Research (NCAUR), U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), 1815 N. University St., Peoria, IL 61604. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. ²Corresponding author. E-mail: bruce.dien@ars.usda.gov ³Bacterial Foodborne Pathogens and Mycology, NCAUR, USDA-ARS, 1815 N. University St., Peoria, IL 61604. ⁴Agricultural and Biological Engineering, University of Illinois, Urbana-Champaign, Urbana, IL 61801. ⁵Sustainable Biofuels and Co-Products Research Unit, Eastern Regional Research Center, USDA-ARS, 600 East Mermaid Lane, Wyndmoor, PA 19038. ⁶Functional Foods Research Unit, NCAUR, USDA-ARS, 1815 N. University St., Peoria, IL 61604.

Widespread epidemics of Stenocarpella ear rot (formerly Diplodia ear rot) have occurred throughout the central U.S. Corn Belt in recent years, but the influence of S. maydis infected grain on corn ethanol production is unknown. In this study, S. maydis infected ears of variety Heritage 4646 were hand-harvested in 2010 from a production field in central Illinois and segregated into one of five levels of ear rot severity based upon visual symptoms. The concentration of ergosterol, a sterol produced by fungi but not plants, was observed to increase with the severity of ear rot (127–306.5 μg/g), and none was detected in the control corn. Corn test weight declined with progression of the disease and was 42.6% lower for the most severely rotted grain from ears infected early in their development. Accompanying changes in composition were also apparent. Crude fat and oil contents decreased (from 4.7 to 1.5%) and fiber increased (from 6.6 to 9.6%), but starch content remained largely invariant. Oil composition also varied among the infected samples. Control and infected corn samples were subjected to ethanol fermentation with a laboratory-scale corn dry-grind ethanol process. Ethanol yields for control and infected samples were similar on an equivalent weight basis (2.77–2.85 gal/bu). In comparison with the control, S. maydis infection altered the distillers dried grains with solubles (DDGS) properties, wherein the crude protein was significantly higher and oil significantly reduced, and ash, fiber, and yield per ton were not significantly different. Based upon these results, we conclude that Stenocarpella ear rot has the potential to affect DDGS composition but not ethanol yield on an equivalent weight basis.