Fractionation of distillers dried grains with solubles (DDGS) through a narrowing of particle size distribution followed by aspiration

Authors: Garcia, Rafael; Rosentrater, Kurt

Submitted to: Food and Bioprocess Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2011
Publication Date: 5/1/2012
Citation: Garcia, R.A., Rosentrater, K.A. 2012. Fractionation of distillers dried grains with solubles (DDGS) through a narrowing of particle size distribution followed by aspiration. Food and Bioprocess Technology. 5:2623-2629.

Interpretive Summary: Distillers dried grains with solubles (DDGS) are a byproduct from the production of fuel ethanol. They are primarily used as animal feed, but this use is limited by their high fiber content. DDGS would be more useful and valuable it they could be split into two fractions, one fraction having high protein and one fraction having high fiber. The high protein fraction would be more valuable for animal feed than regular DDGS and the high fiber fraction would be useful for making products such as ‘corn fiber gum’ and phytosterols. In this research we demonstrate a simple process for achieving such a fractionation of DDGS. This process achieves a fractionation that is as good as what has been achieved by other research groups, but with less expensive equipment, thus being more attractive to industry. Further development, however, will be required before completely satisfactory DDGS fractionation is achieved.

Technical Abstract: Distillers dried grains with solubles (DDGS) may have more value and utility if they can be separated into high protein and high fiber fractions. A variety of such separation processes have been proposed; two of the most promising processes involve 3 screening and 3 air classification unit operations. In the present study, an alternative process involving fewer unit operations is demonstrated. DDGS are subjected to a single screening, and the oversize particles are processed in a mill set up so that it narrows the particle size distribution of the oversize fraction. The milled DDGS is then processed in an air classification device known as an aspirator, which separates it into high and low terminal velocity fractions. The combination of the undersize fraction and the low terminal velocity fraction were substantially enriched in protein. The separation achieved by this process compares favorably to other reported processes while being less capital intensive.