I’ve had a sealed bag of flaked maize for about 6 months now. I’ve never used the stuff before, so I don’t know how long it lasts. Searches say it goes stale quickly. How about if it’s unopened?
Here’s a really unscientific explanation:
Corn and corn products tend to go rancid rather quickly because the middle part of the corn, the little seed part, contains oils that will become rancid over time. It isn’t due to oxygen exposure as much as it is just a result of the oils breaking down. Cornmeal, for example, has the middle part removed to prevent that from happening. I don’t believe they do that for flaked maize.
Cold will delay the process. I’d say open it up and smell it. If it smells ok, taste it. If it tastes ok, put it in your freezer until you can use it. If you don’t want to put it in the freezer, at least put it in the fridge.
In our Home Brew Store we keep the Flaked Maize in our Freezer. Moisture will let the bugs grow over night.
Good Brewing
Freshness is huge with corn (think about reheating corn grits a few days later).
Flaked corn is cheap - just pitch it.