A product of dried corn kernels, cornmeal is a versatile ingredient used in baked goods and side dishes. Processing involves grinding the whole corn kernel into different textures that range from fine to coarse, and each lends itself to different cooking applications. Because of its high moisture content, improperly stored cornmeal can turn rancid quickly, become infested with insects or develop mold. Under cool and dry conditions, however, you can keep it for as long as a year and even longer if you refrigerate or freeze it.
Store small unopened bags or containers of cornmeal in a dark, cool and dry place. Once opened, the University of Minnesota Extension recommends placing the bag inside a slightly larger container that has a tight-fitting lid. When transferring the cornmeal into another container, make sure that it’s food-safe; otherwise, dangerous chemicals in some types of plastics could leach into the cornmeal.
When buying cornmeal in large amounts, repackage it into smaller tightly sealed containers. Label the containers according to their contents and date, and freeze at zero degrees Fahrenheit. Cornmeal can be safely frozen for up to two years.
References and ResourcesUniversity of Missouri Extension: Using and Storing Cornmeal
Still Tasty: Cornmeal, Commercially Packaged or Purchased in Bulk--Regular, Degerminated