Squeezing More Out Of Corn Leftovers

There’s a lot more to corn than the sugar used as a sweetener and to make ethanol. A characterization study on one of the by-products of corn processing, a condensed liquid known as defatted corn syrup (DCS), suggests that it has been overlooked as a potential valuable source of biobased chemicals (ACS Sustainable Chem. Eng. 2014, DOI: 10.1021/sc400508p). When corn is milled and processed, a major part of the starting material is drawn off to ferment into ethanol. Most of the leftover solids, called dried distillers grains, are repurposed as animal feed. David R. Shonnard and coworkers at Michigan Technological University decided to take a closer look at DCS, which is often added to the dried distillers grains, by carrying out a detailed compositional analysis. The researchers found that the waste liquid is rich in fiber, carbohydrates, protein, and more. They then calculated the potential yields of various chemicals that could be made via fermentation processes using the roughly 700,000 metric tons of the material produced annually in the U.S. Although DCS doesn’t appear useful for making fuels, it could be used to meet current U.S. demand for succinic acid (about 25,000 metric tons) or global demand for histidine (360 metric tons). Biobased chemical manufacturer Working Bugs, which was involved in the study, is considering options for capitalizing on the findings.