In most of them, the survivors wind up scavenging food from the remnants of human society, usually in the form of canned goods. Seems that produce and freeze pops don't keep well.
It occurred to me this morning, that not a single one of the apocalypse scenarios I've ever seen has had its characters resort to eating one particular item: pet food.
Now, given how many pets there are out there, and how much of their food is canned, there should be tons of the stuff hanging around. It's mostly meat, so should be very edible. Furthermore, it's not generally seen as "people food", so it would be one of the last items scavenged, and thus one of the more likely items for scavengers to find. Even better, being reduced to eating dog food would be a great illustration of how desperate the characters are.
Yet, I can't think of a single time that I've seen a character scarf down a can of Fancy Feast or Alpo. Very weird, and something that's lacking in apocalypse fiction.
Of course, you also never see anyone find any Twinkies, which would obviously survive the apocalypse. Maybe the whole genre is just screwy.