Emulsifying properties of an arabinoxylan–protein gum from distillers’ grains and the co-production of animal feed

In order to improve corn ethanol profitability and energy efficiency, a natural gum consisting of primarily arabinoxylan and crude protein (CP) was extracted from distillers’ grains (DG), a major byproduct from the dry grind corn ethanol production. DG was fractionated into an alkali-soluble gum fraction and an alkali-insoluble residue fraction by extracting with 1–5 % NaOH at 25–75 °C for 1–5 h. The extraction conditions, which significantly affect the yields and compositions of DG gum and residue, were statistically modeled to optimize yields and compositions. DG gum had 8–22 % CP, which could all be reduced to about 8 % by purification with bentonite clay. The isolated gums (purified and unpurified) were made into emulsifying agents, whereas residues were characterized as animal feed. The results demonstrated that the purification process affects the emulsifying properties of the DG gum-derived emulsifying agents. In parallel, the DG residue was found to have increased fiber digestibility and metabolizable energy compared to the original DG. An economic analysis determined that concurrent productions and utilizations of DG gum and DG residue could improve the cost and energy balance of the current corn ethanol process.