Cornmeal is an important and delicious ingredient in a lot of homemade breads, pastas, and other grain-based dishes. While foods made from cornmeal can go bad surprisingly fast, cornmeal itself has a surprisingly long shelf life.
Quick Answer
How fast cornmeal goes bad depends on whether or not it was germinated, or if the oil in the corn has been removed. Germinated cornmeal can last up to a year before going bad while ungerminated cornmeal can go bad in 3 months once the packaging has been opened, since the oils in the corn can go rancid fairly quickly.