Corn starch is made through a process called wet milling of corn kernels. This process separates the different components of the corn—primarily starch, protein, fiber, and oil—and then isolates and dries the starch.
Here's a more detailed breakdown:
1. Cleaning: The process begins by cleaning the harvested corn kernels to remove any debris, such as dirt, stones, and plant matter.
2. Steeping: The cleaned corn is then steeped (soaked) in warm water containing sulfur dioxide for 24 to 48 hours. This steeping process softens the kernels and loosens the gluten bonds, making it easier to separate the components.
3. Grinding: The softened kernels are coarsely ground to release the germ (which contains the oil).
4. Germ Separation: The ground mixture is then passed through hydroclones to separate the corn germ, which contains the corn oil. The germ is further processed to extract the corn oil.
5. Fine Grinding and Screening: The remaining mixture (containing starch, fiber, and protein) is finely ground. This grinding further liberates the starch granules.
6. Fiber Removal: The ground mixture is screened to remove the fiber. The fiber is often used as animal feed.
7. Starch and Gluten Separation: The remaining slurry of starch and gluten (protein) is then centrifuged to separate the starch from the gluten. The gluten is often used in animal feed or processed into other products.
8. Washing: The separated starch is washed multiple times to remove any remaining impurities or protein.
9. Drying: Finally, the purified starch is dried, typically using hot air, to reduce the moisture content and produce the final product: corn starch, a white, fine powder.
Therefore, corn starch production essentially involves separating the starch from the other components of the corn kernel, purifying it, and then drying it.
