Wet Milling: The Basis for Corn Biorefineries

The corn wet milling process is one of the most sophisticated grain processes used worldwide. Coproducts from wet milling include starch, fuel ethanol, and glucose in highly purified forms, as well as lower valued coproducts such as corn gluten feed which is a mixture of proteins, carbohydrates, fiber, ash, and residual fat. The primary coproduct, starch, is used to make many products, such as sweeteners, ethanol, and modified starches for food and industrial uses. The initial step of the process, steeping, is key to effective fractionation, separation, and purification of the starch-based prime products. Coproducts have a range of market values. Corn gluten meal is highly valued for companion animal, poultry, and swine diets, while corn gluten feed has value similar to or less than that of incoming maize and is widely used in ruminant animal diets.