Then why do they put expiration dates of one year on canned foods?
Government regulations. The determination of the dates is highly subjective. Most mfg don't want to fool with it, so they put dates on that will make the government happy.
If it isn't bulging or leaking, it's eatable.
I've got canned goods with dates of 2015 on them, right now.
“Then why do they put expiration dates of one year on canned foods?”
IIRC it was some government thing that would warrant they still had 99% or some stupid number of the vitamins, etc. in it. SOME of the vitamins will degrade over time, and in some things the taste may not be quite up to par. But as long as the seal is not bad, no bulges, etc. the canned food is safe to eat.
I think it is tomato products (and their acidic nature) that can either degrade the cans more quickly and/or not taste as good.
Lots of stuff on the internet if you’re serious about long-time storage with regards to canned foods. I think all and all most of it stores well and long.