Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/18/2007
Publication Date: 8/1/2007
Citation: Srinivasan, R., Dien, B.S., Rausch, K.D., Tumbleson, M.E., Singh, V. 2007. Fiber Separated from Distillers Dried Grains with Solubles as a Feedstock for Ethanol Production. Cereal Chemistry. 84(6):563-566. Interpretive Summary: Fermentation residuals from an ethanol plant that ferments whole ground corn are dried and marketed as an animal feed under the name of distillers dried grains with soluble (DDGS). For each bushel of corn fermented to ethanol, 17 lb of DDGS is produced. The market for DDGS is limited by its high fiber content. The elusieve process is unique in its ability to down shift fiber and up shift protein at the backend and, therefore, it requires no process modifications. The result should be a higher quality product with increased market appeal. In addition, the process produces a high fiber stream. This paper demonstrates that the high-fiber product from elusieved DDGS can be converted to ethanol, thereby, increasing the ethanol yield from a bushel of corn.
Technical Abstract: In the dry grind process, corn starch is converted into sugars which are fermented into ethanol. The remaining corn components (protein, fiber, fat, and ash) form coproduct, distillers dried grains with solubles (DDGS). The combination of sieving and elutriation (air classification), known as elusieve process, was found to be effective in separating fiber from DDGS. In this study, elusieve fiber was evaluated for ethanol production and results were compared with those reported in other studies for fiber from different corn processing techniques. Fiber samples were pretreated using acid hydrolysis followed by enzymatic treatment. The hydrolyzate was fermented using Escherichia coli FBR5 strain. Efficiency of ethanol production from elusieve fiber was 89 to 91%, similar to that for pericarp fiber from wet milling and quick fiber processes (86 to 90%). Ethanol yields from elusieve fiber were 0.23 to 0.25 L/kg (0.027 to 0.030 gal/lb); similar to ethanol yields from wet milling pericarp fiber and quick fiber. Fermentations were completed within 50 hr. Implementation of elusieve fiber conversion to ethanol within a dry grind plant may not be currently economically feasible due to the small scale of operation. Ethanol production from elusieve fiber in a 25 MMGY lignocellulose to ethanol plant would fetch 12 to 57% higher price for elusieve fiber than if it was used as animal feed. Elusieve fiber conversion could result in 1.2 to 2.7% increase in ethanol production from dry grind plants.