Review of process for producing corn fiber oil and ethanol from "Quick Fiber"

Approximately 10% of the 10 billion bushels of corn harvested in the U.S. is used for fuel ethanol production (2003; Renewable Fuel Association), more than half of which is prepared for fermentation by dry grinding the whole kernel. University of Illinois has developed a modified dry grind process that allows for recovery of the germ and pericarp fractions prior to fermentation. The process could potentially generate an additional 5-7 cents of income per gallon ethanol produced from enhanced fermentation efficiency and from recovering the corn oil. This process also allows for the possibility of converting the fractionated pericarp, termed "quick fiber," to ethanol. This review summarizes results reported earlier (1) on the feasibility of using Quick Fiber (QF) as an ethanol feedstock. QF was converted to ethanol using an industrial Saccharomyces cerevisiae strain and ethanologenic Escherichia coli strain FBR5. For the S. cerevisiae fermentation, the ethanol yield was 0.096 gal/bu of processed corn assuming a QF yield of 3.04 Ib/bu. For the bacterial fermentation, the final ethanol concentration was 30 g/l or 85% of the theoretical yield. The residuals from the fermentations were also evaluated as a source of corn fiber oil. Corn fiber oil, which is extracted from the pericarp fiber fraction, is a nutraceutical being developed by the ARS that has cholesterol lowering properties. Corn fiber oil yields were 1.12% w/w for the residual material from the SSF process. For the FBR5 fermentations, the residual fiber was recovered after hydrolysis and prior to fermentation. The corn fiber oil yield in this case was 8.28% w/w.