More than 7 million tons of distillers dry grains are created in domestic dry grind ethanol production. For every bushel of corn made into ethanol, 18 pounds of DDGS are created and must maintain value to contribute to plant profitability.

The corn kernel is mostly starch at 61% of the wet weight, with protein, fiber, corn oil and water making up the remaining 39%. The dry grind ethanol process uses most of the starch present in the corn kernel during ethanol fermentation, leaving protein, fat, minerals and vitamins behind in a concentrated form. The forms of this ethanol co-product are Corn Distillers Dried Grains (DDG), Corn Condensed Distillers Solubles (CDS), Corn Distillers Dried Grains/ Solubles (DDGS), and Wet Distillers Grains with solubles (WDGS).

Dry grind ethanol production begins by grinding corn into a coarse flour and combining with water and enzymes. The enzymes begin the conversion process of starch to sugar creating a mash that is then cooked and sterilized. After cooling, yeast is mixed with the mash to ferment the sugars into ethanol, carbon dioxide and other metabolites. The fermented mash is then sent to distillation to extract the ethanol. The mash is now considered spent mash which then goes onto either a screen press or centrifuge, where as much liquid as possible is separated.

The liquid that is separated either goes back into the cooking system and is sold as livestock feed, or is partially dehydrated into syrup called condensed distillers solubles (CDS). The spent grains can also be sold as livestock feed as wet distillers grains or dried, in which case they are called distillers dried grains (DDG). If the syrup is added to the wet distillers grains and then dried, the resulting product is referred to as distillers dried grains with solubles (DDGS).