Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/23/2005
Publication Date: 1/3/2006
Citation: Corredor, D.Y., Bean, S.R., Schober, T.J., and Wang, D. 2006. Effect of decorticating sorghum on ethanol production and composition of DDGS. Cereal Chem. 83(1): 17-21. Interpretive Summary: Sorghum is a drought resistant cereal crop grown in the central U.S. The majority of the U.S. sorghum crop is currently used for animal feed. However, increasing amounts are being used for fuel ethanol production. For ethanol plants located in the sorghum growing region of the U.S., sorghum is the major feedstock. During ethanol production, the starch in cereal grains is converted to glucose and then fermented to ethanol. The material left after this process, the distillers dried grains (DDG) contains mainly protein, fiber, and lipids. To improve the conversion of sorghum to ethanol, we investigate the use of decorticated sorghum. Decorticated sorghum has the outer layer of the grain removed, which contains mostly fiber that is not converted to ethanol. This allowed for higher starch loading during fermentation and also increased the protein content of the DDG. DDG with higher protein content should have improved feed value. Thus, decortication is one method to increase ethanol conversion of sorghum and improve the value of the DDG co-products.
Technical Abstract: The use of a renewable biomass that contains considerable amounts of starch and cellulose could provide a sugar platform for the production of numerous bioproducts. Pretreatment technologies have been developed to increase the bioconversion rate for both starch and cellulosic-based biomass. This study investigated the effect of decortication as a pretreatment method on ethanol production from sorghum as well as its impact on distiller’s dry grains with solubles (DDGS) quality. Eight sorghum hybrids with 0, 10, and 20% of their outer layer removed were used as raw materials for ethanol production. The decorticated samples were fermented to ethanol by using Saccharomyces cerevisiae. Removal of germ and fiber prior to fermentation allowed for a higher starch loading for ethanol fermentation and resulted in increased ethanol production. The ethanol yields increased as the percentage of decortication increased. The decortication process resulted in DDGS with high protein content and low fiber content, which may improve the feed quality.