Preps

[Paul]

Preps life span is down to selection and storage more than anything else.

Dry foodstuff i.e. flour, rice, pasta can last years IF it is correctly stored.

Cans the same BUT some contents contain natural acids which can "eat" the can from the inside out.

Jar fanatics come unstuck for the same reason, the acidic contents can literally eat the metal tops.
It's no good relying on Kilm jars either. Again choice of contents is important as the seals are "rubber".

Having said all that, Use by dates are only compulsory because of some obscure law so don't get too swayed by their information.

For long term storage facts and figures you could do worse than download the LDS manual.
it's "comprehensive" to say the least.