There weren't no expiration dates ..... back-in-the-day.
I recall eating C rations in 1966, that were packaged in 1942.
Common sense about canned or jarred store bought foods led one to reject the product, if the can was leaking or the top on jars was bulging.
When "canning" (put into sterile jars) produce like tomatoes, green beans, etc., jars and produce was cooked in a large pressure cooker ....... then one would observe the lids as they cooled to make sure they popped in (assuring a seal).
If, after you retrieve the jars from the fruit cellar, if the top is bulged up or the contents are milky, feed it to the hogs.
Jams were cooked then the jars sealed with paraffin.
If in doubt if a dented canned good had lost it's seal and could contain a food poisoning agent, first feed some to a younger sibling, then after about an hour, ask them how they were feeling or just feed it to the hogs.
Spoiled meat (beef and pork) is easy to detect ...... just smell it ...once you have smelled spoiled beef ...... you will never forget it.
If fish smells too much like "fish" ...... and a cat won't eat it ....... don't you eat it.
If chicken is red in the center ...... you just might get a tummy ache.
If milk tastes like buttermilk ....... it is.
If bread or cheese has mold on it ..... just scrape it off ......and use the rest of it ....... they will never know.
Well ........ you asked .........
humfrz