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Title: Enhancing water removal from whole stillage by enzyme addition during fermentation

Author
item HENRIQUEZ, ANA BEATRIZ - WASHINGTON UNIV.ST.LOUIS,
item Johnston, David
item AL-DAHHAN, MUTHANA - WASHINGTON UNIV.ST. LOUIS

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2007
Publication Date: 4/11/2008
Citation: Henriquez, A., Johnston, D., Al-Dahhan, M. 2008. Enhancing water removal from whole stillage by enzyme addition during fermentation. Cereal Chemistry. 85(5):685-688.

Interpretive Summary: The dry grind process for producing fuel ethanol from corn requires a significant amount of energy (usually from natural gas) to be used in the drying of the residual material so it can be used as an animal feed product known as Distillers Dried Grains with Solubles (DDGS). Finding ways to decrease the amount of energy required can improve the overall energy efficiency of the process and improve the economics. In this work, the addition of cell-wall-degrading enzymes was investigated to determine whether or not certain enzymes could reduce the amount of water bound within the wet grains. This would have the effect of allowing more water to be removed during centrifugation, reducing the time and energy needed during the drying process. Results of this study should be of value to fuel ethanol processors looking for new ways of improving processing and the overall economic competitiveness of the industry.

Technical Abstract: The removal of water from coproducts in the fuel ethanol process requires a significant energy input. In this study, the addition of cell-wall-degrading enzymes was investigated to determine whether or not the enzymes could reduce the amount of water bound within the wet grains. This would have the effect of allowing more water to be removed during centrifugation, reducing the time and energy needed during the drying process. The experiment screened 15 cell-wall-degrading enzyme preparations. The experiment was repeated and two enzymes were identified to have the highest distillers grains (DG) dewatering effect. A scale-up experiment was also performed to validate the results from the small-scale runs. A maximum reduction of 16% in water content of the solid phase of the DG after centrifugation was observed. These results can translate into a significant decrease in the energy input of the drier since the DG entering the drier would contain less moisture than in the conventional process thus requiring a shorter residence time in the drier.