INDUSTRIALLY ROBUST ENZYMES AND MICROORGANISMS FOR PRODUCTION OF SUGARS AND ETHANOL FROM AGRICULTURAL BIOMASS
Location: National Center for Agricultural Utilization Research
Title: HYDROLYSIS AND FERMENTATION OF PERICARP AND ENDOSPERM FIBER RECOVERED FROM ENZYMATIC CORN DRY GRIND PROCESS
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 18, 2005
Publication Date: August 1, 2005
Citation: Dien, B.S., Johnston, D., Hicks, K.B., Cotta, M.A., Singh, V. 2005. Hydrolysis and fermentation of pericarp and endosperm fibers recovered from enzymatic corn dry-grind process. Cereal Chemistry. 82(5):616-620.
Interpretive Summary: Renewable sources of energy are needed to replace finite fossil fuels and meet energy needs in the future. Ethanol is fast becoming the renewable fuel of choice, and its production is increasing exponentially in the U.S. and around the world. Most of the ethanol in the U.S. is produced from corn. The U.S. ethanol production capacity is projected to increase to more than 6.0 billion gallons per year by the end of 2006. Most of this increase in the ethanol capacity, from a current capacity of 3.1 billion gallons, will come from the new dry grind corn plants. A process modification, called enzymatic milling (E-Mill), has been developed for conventional corn dry grind process for ethanol production. The E-Mill process recovers germ, pericarp (coarse) fiber, and endosperm (fine) fiber separately as co-products at the beginning of the dry grind process prior to fermentation. This paper demonstrates that the recovered coarse and fine fractions are readily fermentable to ethanol using either yeast or recombinant ethanologenic bacteria. The process increased ethanol yields from 2.58 to 2.84 gal/bu for E-milled corn.
A modified dry grind corn process has been developed that allows recovery of both pericarp and endosperm fiber as co-products at the front end of the process, prior to fermentation. The modified process is called enzymatic milling (E-Mill) dry grind process. In a conventional dry grind corn process, only the starch component of corn kernel is converted into ethanol. Additional ethanol can be produced from corn if the fiber component can also be converted into ethanol. In this study, pericarp and endosperm fiber recovered in E-Mill dry grind process were evaluated as a potential ethanol feedstock. Both fractions were tested for their fermentability and potential ethanol yield. Total ethanol yield recovered from corn by fermenting starch, pericarp fiber, and endosperm fiber was also determined. Results show that ethanol produced in g/100 g of fiber processed was 20% more for fine fiber compared to the coarse fiber. Total ethanol yield obtained by fermenting starch and both fiber fractions was 2.84 gal/bushel compared to ethanol yield of 2.58 gal/bushel obtained by fermenting starch only.