Physical properties and dry-milling characteristics of six selected high-oil maize hybrids

The physical properties and dry-milling characteristics of six low-temperature-dried, high-oil maize (corn) hybrids (HOC) were evaluated and compared to three regular yellow dent hybrids (YDC) representing a range of endosperm hardness that were not selected for dry-milling characteristics. The test weights, true densities, and 100-kernel weights of the six HOC hybrids ranged from 732.8 to 758.6 kg/m(3), 1.272 to 1.291 g/cm(3), and 26.6 to 28.2 g, respectively (12.5% mc). Test weights and densities for HOC were higher than for two of the three YDC hybrids, 100-kernel weights were lower than all three YDC hybrids. The HOC hybrids had higher test weights and true densities than two of the YDC hybrids. The HOC hybrids had higher prime grit yield, milling evaluation factors, and oil yields than the YDC. The flaking grit yield and milling evaluation factor (MEF3) increased, and the pericarp yield decreased with increasing test weight of the HOC. The dry mill products of the HOC had higher crude fat and crude fiber contents, but lower ash contents than those of the YDC. The germ and pericarp fractions of the HOC had lower crude protein contents than those of the YDC. The HOC hybrids tested resulted in high grit yields but also high oil content in the grit fractions. Unless the source of the higher oil content in the grits can be elucidated and corrected, the HOC hybrids tested would not be satisfactory for most dry-milling applications.