Cereal Chem 58:343 - 347.  |  VIEW ARTICLE
Protein-Rich Residue from Corn Alcohol Distillation: Fractionation and Characterization.

Y. V. Wu, K. R. Sexson, and J. S. Wall. Copyright 1981 by the American Association of Cereal Chemists, Inc. 

The material from the base of stills after corn alcohol distillation was screened to separate a slurry from screened residue. The slurry was centrifuged to obtain a centrifuge cake and a supernatant. The supernatant contained materials that were smaller than 10,000 in molecular weight and accounted for 20% of the dry weight and 20% of the total nitrogen. The screened residue and the centrifuge cake were combined into base-of-still residue, which accounted for 80% of the dry weight and 80% of the total nitrogen. The base-of- still residue was extracted sequentially with water, sodium chloride, 70% ethanol, 70% ethanol plus dithiothreitol, sodium hydroxide plus dithiothreitol, and sodium hydroxide plus sodium dodecyl sulfate plus dithiothreitol at pH 11.9. The nitrogen content and amino acid composition of each fraction were determined. The nitrogen in base-of-still residue was considerably less soluble than that in ground corn when extracted with water, sodium chloride, 70% ethanol, 70% ethanol plus dithiothreitol, and borate plus sodium dodecyl sulfate plus dithiothreitol at pH 10. The lower nitrogen solubility of the base-of-still residue is probably a result of denaturation of protein and may account for the greater feed efficiency for ruminants of corn distillers' grains than of corn. The denatured protein is degraded less in the rumen, and a higher proportion is digested and absorbed from the lower gastrointestinal tract for maximum growth.