Ethanol Yields Increased 20% by Soaking Corn First

Ethanol production has its detractors in those who point out the inefficiencies of the process and the use of agricultural land and water involved, but a new process may help to change some of that. Soaking the kernels of corn before grinding them in ethanol production results in more ethanol and usable co-products – about 20 percent more – says a new study published in Cereal Chemistry.

A team of researchers at the University of Illinois found that by using a wet fractionation process, which includes soaking the corn and then grinding into a slurry, the fermenter produces higher ethanol concentrations and better quality co-products than the dry fractionation method.

“The conventional ethanol production method has fewer steps, but other than distillers dried grains with soluble, it doesn’t have any other co-products. Whereas in both wet and dry fractionation processes, the result is ethanol, distillers dried grains with soluble, as well as germ and fiber. Corn fiber oil for example can be extracted from the fiber and used as heart-healthy additives in buttery spreads that can lower cholesterol.” -Esha Khullar, University of Illinois Agricultural Engineer

The wet fractionation process washes the germ of the corn, resulting in a cleaner separation due to less starch sticking to the germ, yielding an increased oil concentration. In the dry method, the corn kernels are crushed, which flattens the germ and leaves some starch attached to it, lowering the oil content, according to Khullar. With wet fractionation, after the corn is ground to a slurry, it is mixed with enzymes to raise the specific gravity, which causes the germ to float and can then be removed from the top.

Removing the germ and pericarp fiber prior to the fermentation process is more efficient because those components are not fermentable. The authors said that it’s preferable to remover them first in order to have more starch in the fermenter. According to the research, the new wet fractionation process does not require new equipment, simply a modification of the process already in place in the corn processing industry.

The research, Ethanol Production from Modified and Conventional Dry-Grind Processes Using Different Corn Types, was published in the journal Cereal Chemistry. The team included Erik D. Sall, Kent D. Rausch, M.E. Tumbleson, and Vijay Singh.