Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/13/2005
Publication Date: 8/22/2005
Citation: Srinivasan, R., Moreau, R.A., Rausch, K.D., Belyea, R.L., Tumbleson, M.E., Singh, V. 2005. Removal of fiber from distillers dried grains with solubles (ddgs) using sieving and elutriation. Cereal Chemistry 82, p.528-533. Interpretive Summary: In the past three years there has been a 100% increase in the production of fuel ethanol in the US. It is expected that this rapid rate of expansion will continue. Currently, 70% of all of the ethanol made in the US is via the fermentation of corn in a "dry grind" process that yields one co-product, Distillers dried Grains with Solubles (DDGS). DDGS is a good animal feed for ruminants, but its high content of fiber limits it from being used as a feed for non-ruminants. If the levels of fiber in DDGS could be reduced, it could become a valuable feed for poultry, swine, and aquaculture. Previous strategies to remove the fiber have involved size separation (sieving) and separation of particles based on density. This manuscript describes a two-step process which combines these two approaches and it is the first approach that results in a removal of a significant amount of fiber from DDGS. This process could be implemented in existing dry ethanol plants and could increase the value of DDGS by reducing the levels of fiber and also increasing the levels of protein and fat. The rapid expansion of fuel ethanol production is likely to soon create surpluses of DDGS. This new technology provides a process to increase the value of DDGS by converting it into a form that is now acceptable as a feed for the poultry, swine, and aquaculture industries.
Technical Abstract: A process was developed to remove fiber from distillers dried grains with solubles (DDGS) in a dry grind corn process. Removal of fiber from DDGS would provide two valuable coproducts: 1) DDGS with reduced fiber, increased fat and increased protein contents and 2) fiber. The process is called the elusieve process and uses two separation methods, sieving and elutriation, to remove the fiber. Material carried by air to the top of the elutriation column is called the "lighter fraction" and material that settles to the bottom of the column is called the "heavier fraction". We evaluated the compositions of fractions produced from sieving and elutriation. Two commercial samples of DDGS were obtained from two dry grind corn plants. Sieving over four screens (869, 582, 447 and 234 micron openings) created five size categories. The two smallest size categories contained > 40% (w/w) of the original DDGS and had reduced fiber and increased protein and fat contents relative to the original DDGS. Elutriation of the remaining three size categories increased protein and fat contents and reduced fiber content in the heavier fractions. Elutriation at air velocities between 1.59 m/s and 5.24 m/s increased the protein content in the heavier fraction by 13 to 41% and increased the fat content in the heavier fraction by 4 to 127% compared to the bulk DDGS fractions. This process was effective in removing fiber from both DDGS samples evaluated. The elusieve process does not require changes in the existing dry grind process and can be adapted at the end of the dry grind process without any major modification.