Corn DDGS is a by-product of ethanol extraction from corn. During fermentation, corn starch  is converted to ethyl alcohol and CO2, so the concentration of remaining nutrients in the residue increases about 2-3 times.

Distillation is a grain co-product produced by distillation. Starch in cereal flour is converted to ethanol and CO2. The remaining nutrients (protein, fat, fiber, minerals and vitamins) are relatively unchanged, but concentrated. These nutrients are present in the co-product, which is commonly known as dry wine residue (DDGS).