When the component parts of the kernel are separated during wet milling, this refining process also releases protein, fiber, vitamins, and minerals. Traditionally, these elements have served as feed for cattle, fish, hogs, and poultry, which serve as an excellent source of energy and, in turn, enrich our own diets.
Corn refiners produce four major feed products:
- Steepwater: Steeping, or soaking corn kernels in water, is an early and important step in the refining process at corn wet mills. After steeping is complete, the remaining liquid is called steepwater. This nutrient-rich mixture is condensed and can be utilized as a protein supplement for cattle or as a binder in feed pellets.
- Germ meal: The germ is the embryo at the center of every corn kernel. After refiners steep and grind the kernels, the germ is separated and the valuable corn oil is extracted. The ground germ, known as meal, remains. It becomes an important source of protein and energy in animal feed, and is sometimes used as a carrier for liquid nutrients. It may also be added back to corn gluten feed.
- Gluten feed: After most of the starch, gluten, and germ are extracted from the kernel and separated during the wet milling process, the residuals and fiber are mixed to make corn gluten feed. Providing both protein and energy, corn gluten feed is given to dairy and beef cattle, poultry, and hogs. It is also used as a carrier for added micronutrients.
- Gluten meal: Once the corn kernel is separated into its component parts, corn refiners then further separate the starch and gluten that is contained in the endosperm. The gluten is dried and sold as gluten meal. Gluten meal supplies essential vitamins and minerals and is considered a high-protein and high-energy feed ingredient. Poultry and pet food processors value it for its high digestibility.
Roughly 35 to 40 percent of the corn used by the corn refining industry becomes feed products. High quality animal feed ingredients derived from corn are an important staple of America’s meat and poultry industries.
In recent years, scientists have discovered additional uses for corn protein, known as zein, which can be extracted from corn gluten meal. The unique structure of zein makes it a successful platform for growing human cells in the laboratory and, at the nanotechnology-level, a candidate for improving the delivery of drugs that fight cancer. It can also be spun into fibers and used as biological scaffolding to help repair damage in and around teeth.