While it’s shelf-stable and has a long shelf life, cornmeal can go bad if it’s not stored properly. Cornmeal should be stored in an airtight container in a cool, dry place. If it’s exposed to too much moisture or heat, it will start to spoil. Keep out of warm damp conditions to avoid mold. Once opened store in a Ziploc bag and place it inside an airtight container. Cornmeal can also be placed in an airtight container and stored in the freezer. Cornmeal has a shelf life of up to two years when properly stored. However, its flavor and nutritional value will start to diminish after about one year. If your cornmeal has gone bad, you’ll notice that it has a musty smell and/or a sour taste. If it’s been stored improperly, it may also be covered in mold. If you notice any of these signs, discard the cornmeal immediately.