How long does cornmeal last after expiration date?

Degerminated cornmeal keeps quality for up to a year past its date if stored at room temperature, and a couple of years if frozen. Whole grain variety is best for only a couple of months past its date. You can store degerminated cornmeal in a cabinet in the kitchen or pantry at all times.

What does bad cornmeal look like?

If it smells rancid or sour, it's past its prime, and you should discard it. Another thing to remember is that black and grey specs in whole-grain cornmeal are normal. Those flecks can be attributed to the germ of the corn. Other than that, you should use the guidelines for degerminated corn.