(31c) Extraction of Proteins from Corn Dry Mill Co-Product by Bio-Based Solvents

Distiller's grains and solubles (DGS) is the primary co-product in dry grind ethanol production. DGS are a suitable feed for ruminants such as cattle. DGS suffers from two disadvantages: 1) Due to high fiber content, DGS are not suitable for monogastrics such as hogs and poultry; 2) Drying DGS to produce dried distiller's grains and solubles (DDGS) is energy intensive and requires about 1/3 of the energy consumer in dry mills. Drying is required so that DDGS can be transported from the corn ethanol belt to the southern cattle belt. To address these disadvantages, we are developing a process to recover the high value protein and oils from DGS. In specific, we employ food-grade biobased solvents to extract the nutritional components.

Typical DGS contain about 30 % protein and 50-60 % moisture. The extracted protein could be used as a high value feed to a wider variety of animals. The energy requirement for drying would also be significantly reduced. The separated fiber could be used as a captured cellulosic stream to be used either to produce additional ethanol or as a fuel source for the mill. This process will also help build markets for biobased products. Overall, the process economics of the corn dry mill could be improved dramatically by reductions in energy costs and increased value of the animal feed co-products.

In this study, effects of different process parameters, such as, time, temperature and ratio of DGS to solvent, on the recovery of proteins have been examined. Hydrophilic, hydrophobic and mixtures of both types of solvents have been used for the protein recovery and their effects on the recovery have also been studied. We report that solvent extraction using bio-based solvents were able to recover significant amount of proteins from DGS. We also report that hydrophobic solvents are more efficient for the protein recovery than to hydrophilic solvents.