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United States Department of Agriculture

Agricultural Research Service

Title: Saccharification of Corn Fiber by Combined Treatment with Dilute Sulfuric Acid and Enzymes

Authors
item Grohmann, Karel
item Bothast, Rodney

Submitted to: Process Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 16, 1996
Publication Date: N/A

Interpretive Summary: Corn fiber is a byproduct of the corn milling industry. Approximately 4.7 million dry tons of this material are produced annually in the United States and it is marketed as an animal feed ingredient of very low value. The corn fiber contains residual starch and a cell wall fraction of kernel, which are both rich in polymeric carbohydrates. We have investigated a sequential saccharification of these carbohydrates by a treatment with hot dilute sulfuric acid followed by neutralization and enzymatic hydrolysis with mixed cellulolytic and amylolytic enzymes. The sequential treatment achieved a very high conversion of all polysaccharides to monomeric sugars. The sugars were fermentable to ethanol in most cases by a recombinant bacterium Escherichia coli KO11, but formation of inhibitors was also observed when harsher conditions of acid treatment were used.

Technical Abstract: Corn fiber is a coproduct of the corn wet milling industry which is usually marketed as a low value animal feed ingredient. Approximately 4.7 million dry tons of this material are produced annually in the United States. The fiber is composed of kernel cell wall fractions and residual starch which can all be potentially hydrolyzed to a mixture of glucose, xylose, arabinose and galactose. We have investigated a sequential saccharification of polysaccharides in corn fiber by a treatment with dilute sulfuric acid at 100 to 160 degrees C followed by partial neutralization and enzymatic hydrolysis with mixed cellulase and amyloglucosidase enzymes at 45 degrees C. The sequential treatment achieved a high (approximately 85%) conversion of all polyssaccharides in the corn fiber to monomeric sugars. These hydrolysates were in most cases fermentable to ethanol by the recombinant bacterium Escherichia coli KO11.

Last Modified: 10/23/2014
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