Cereal Chem 67:523-528   |  VIEW ARTICLE

Effects of Hardness and Drying Air Temperature on Breakage Susceptibility and Dry-Milling Characteristics of Yellow Dent Corn.

A. W. Kirleis and R. L. Stroshine. Copyright 1990 by the American Association of Cereal Chemists, Inc. 

Kernel density, test weight, Stein and Wisconsin breakage susceptibilities, stress cracking, and Stenvert hardness were determined for three corn hybrids that were classified as soft, hard and of intermediate hardness. A stress crack index was developed for quantifying degree of stress cracking. Severity of stress cracking was directly related to hardness with the hardest hybrid showing the most severe cracking. Surprisingly, stress cracking was most severe at the intermediate (60 C) drying temperature. Stein breakage was greatest for the soft hybrid and least for the hard hybrid, whereas Wisconsin breakage was greatest for the hard hybrid and least for the hybrid of intermediate hardness. Stein breakage susceptibility was primarily influenced by hardness, whereas Wisconsin breakage susceptibility was correlated with stress cracking. Milling quality, as measured by a milling evaluation factor (MEF), decreased linearly with increasing drying temperature. For all drying temperatures, the hard hybrid had the highest MEF and the soft hybrid had the lowest MEF. Kernel density was the best single predictor of MEF (R2 = 0.773). A two- variable model that combined test weight and kernel density improved the prediction of MEF (R2 = 0.907). Incorporation of additional variables into the model did not significantly improve the two variable MEF prediction model.