Separation of fiber from distillers dried grains with solubles (DDGS) using sieving and elutriation

A process was developed to separate fiber from distillers dried grains with solubles (DDGS) in a dry-grind corn process. Separation 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, called elusieve process, used two separation methods, sieving and elutriation, to separate the fiber. Material carried by air to the top of the elutriation column was called the lighter fraction and material that settled to the bottom of the column was 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 micrometer 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 contents in the heavier fractions. Elutriation at air velocities of 1.59-5.24 m/sec increased the protein content of the heavier fraction by 13-41% and increased the fat content of the heavier fraction by 4-127% compared with the bulk fractions of each size category. This process was effective in separating fiber from both DDGS samples evaluated. Elusieve process does not require changes in the existing dry-grind process and can be implemented at the end of the dry-grind process.