379 Recovery of fiber in the corn dry-grind ethanol process: A new feedstock for valuable co-products.

V. SINGH (1), R. A. Moreau (2), L. W. Doner (2), K. B. Hicks (2), and S. R. Eckhoff (1). (1) University of Illinois, Urbana, IL 61801; (2) USDA, ARS, ERRC, Wyndmoor, PA 19038.

Removal of non-fermentable substrate from the fermentors increases the efficiency of the corn dry- grind ethanol process. The possibility of generating valuable co-products from these non-fermentable residues offers additional opportunities to decrease overall production costs. A process in which corn fiber is recovered from the mash before fermentation in dry-grind ethanol production was developed. In this process corn is soaked in water (no chemicals) for a short period of time and then degermed using conventional degermination mills. In the remaining slurry corn coarse fiber is floated by increasing the density of the slurry and then separated using density differences. The fiber recovered is called “quick fiber” to distinguish it from the conventional wet-milled fiber. The “quick fiber” was analyzed for levels of corn fiber oil, levels of Ferulate Phytosterol Esters (FPE) and other valuable phytosterol components in the oil and compared to conventional wet-milled corn coarse and fine fiber samples. Fiber samples were also analyzed and compared for yields of corn fiber gum (CFG), another potentially valuable coproduct. An average “quick fiber” yield of 6–7% was recovered and represented 46–60% of the total fiber (fine and coarse) that could be recovered by wet-milling. With “Quick fiber” samples approximately 26.0 to 42.2% of the original level of FPE measured in the kernels were recovered compared to 71.0 to 93.0% FPE recovered from the total wet-milled fiber. Comparisons were made between the “quick fiber” samples obtained with and without steep chemicals in the soakwater. Adding steep chemicals to the soakwater significantly increased the “quick fiber” yields, FPE recoveries and total phytosterols in the oil. Adding steep chemicals had no effect on the yields of CFG.