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Oral
Presentation 5-01
Enzymatic
and Thermochemical Hydrolysis of Corn Fiber
Kyle Beery1, Charles Abbas1,
Todd Werpy2, and Rick Orth2
1Archer Daniels Midland
Company James R. Randall Research
Center 1001 N. Brush College Road Decatur, IL 62521
2Pacific Northwest National
Laboratory P.O. Box 999 / MS K2-40 Richland, WA 99352 Phone: 217-451-4213, Fax: 217-451-4230, Email: beery@admworld.com
Corn
fiber is composed of approximately 20% starch, 35% hemicellulose, 18%
cellulose, 11% protein, 3% oil, and 6% ash.
The hemicellulose is primarily composed of xylose (~55%) and arabinose
(~36%). The oil contains approximately 20% ester-linked sterols and free
sterols.
Corn
fiber can be fractionated using enzymatic or thermochemical (heat plus acid or
base) methods. Many different
hydrolysis schemes have been carried out on the corn fiber to obtain various
industrially useful components. The
hydrolysate extracts contain mainly oligosaccharides, with lower concentrations
of monosaccharides and degradation products.
The oligosaccharides in the liquid hydrolysate extracts can be further
hydrolyzed to monosaccharides by a secondary hydrolysis step. Several components in the liquid hydrolysates
are of interest industrially: Glucose, Xylose, Galactose and Ferulic Acid. The options for the corn fiber extracts are
extensive. If an initial enzyme
hydrolysis step occurs, then the liquid hydrolysate from that step (containing
glucose) can be sent to ethanol fermentation by an industrial strain of Saccharomyces cerevisiae. The monosaccharides in the acid or base
liquid hydrolysates, containing xylose, arabinose, galactose, and glucose, can
be either fermented or sent to catalytic conversion to polyols. Finally, the ferulic acid in the extracts
can be separated and converted microbially or enzymatically to vanillin. The remaining solids will be extracted with
a solvent to remove the lipid components and then the residue will be utilized
as an animal feed. By this method, over 60% of the corn fiber will be utilized.
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