Laboratory measurement of yield and composition of dry-milled corn fractions using a shortened, single-stage tempering procedure

The objec tive was to describe a laboratory-scale dry-milling procedure that used single-stage tempering and determine the effect of hybrid on yields and fraction compositions in milled corn. Samples of 11 commercially available hybrids were processed through a lab o ratory dry-milling procedure that used 1 kg samples of corn to produce milling fractions of large grits, small grits, fines, germ, and pericarp. Compositions of milling fractions (protein, neutral detergent fiber, ash, and crude fat) were determined. The p rocedure used a single-stage tempering step that increased corn moisture from 15 to 23.5% wb during an 18-min tempering period. Germ were separated from endosperm particles using a roller mill followed by screening over a sieve with 1.68-mm openings. Coef f icients of variability were small, indicating acceptable repeatability. Overall yield means were 39.2, 25.3, 13.8, 78.2, 14.3, and 6.8 g/100 g (db) for large grits, small grits, fines, total endosperm, germ, and pericarp, respectively. There were effects due to hybrid (P < 0.05) on fraction yields and compositions of milling fractions. Correlations (r) among endosperm fractions (large grits, small grits, and fines) ranged from 0.54 to |-0.92|. Correlations among endosperm fractions and germ and pericarp were <0.68. The developed dry-milling method estimated milling yields among hybrids with low standard deviations relative to the means and should be a useful tool for research and industry in measuring dry-milling characteristics.