How long are canned goods edible?

Inspired by The Walking Dead.

How long would canned goods be good for sustenance?

My gut reaction is good enough that the first generation would not need to farm, only kids born AFTER the zombie apocalypse would learn the expiration date of canned goods.

When a really cheap and poor 20 something my deceased grandmother’s cache of 5 years past expiration date canned goods…all tasted fine and identical to new ones, like tuna fish.

What is the SD?

My microbiology profs said that as long as the can is not opened at all, the food will remain safe to eat indefinitely. The quality will suffer. I have tried canned pears several years past their prime- the flavor was OK, but they were strangely mushy. I also have had bulging tomato sauce cans spew when opened, not even past their “best by” dates. That’s just improper processing that caused that.

For most canned goods, the “expiration” date is really more of a vague suggestion than anything else. I’ve eaten food that was easily 10-12 years old, probably more.

It seems the actual expiration date of a can would be when the can (or the seams) would physically break down and allow air in. Not sure when that would be, but I’d be interested to know what the results are if anyone has actually studied it. I assume it would be heavily dependent on conditions.