Fractionation of Distillers Dried Grains with Solubles (DDGS) Through a Narrowing of Particle Size Distribution Followed by Aspiration

Distiller's 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 three screening and three 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 setup 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 complex.