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).

• Corn Distillers Dried Grains (DDG) is obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or a grain mixture by separating the resultant coarse grain fraction of the whole stillage and drying it by methods employed in the grain distilling industry.
• Corn Distillers Dried Grains with Solubles (DDGS) is the product obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or grain mixture by condensing and drying at least ¾ of the solids by the methods employed in the grain distilling industry.
• Corn Condensed Distillers Solubles (CDS) is the product obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or a grain mixture by condensing the thin stillage fraction to a semi-solid.