In a survival situation, expiration or "use by" dates can be taken with a grain of salt. As far as commercially prepared foodstuffs with preservatives and such, expiration dates usually denote a marked decrease in taste and/or nutrient stability. Not necessarily a safety concern. Of course anything at or past the marked date would need checked before consumption for things such as funny smell, off consistency, bulged containers(cans, MRE pouches, etc.) "When in doubt, throw it out." is a good guidepost here.
For those of us who home can, it's a different world however, because we don't add preservatives to the food we are processing. With that in mind--
I have spent several days reviewing canning "how to'" video clips on sites such as you tube, and I have some words of caution for anyone considering canning their own food-A lot of what I see people doing has a very strong possibility of making the consumer gravely ill, possibly even KILLING them.
Please, if you have decided home food preservation is for you, do your homework
first. Pressure canners misused can explode, and incorrect pressures or processing times can lead to food poisoning. Understand why "high acid" foods can be water-bath processed, and "low acid" foods must be processed under pressure. In home canning we are relying on basically two things for food safety- Sterile canning supplies and food, and certain temps for certain amounts of time to kill any possible bad microbugs in our food. DO NOT SKIMP ON PROCESSING TIMES, EVER. Make sure you adjust your processing times for the altitude you are canning at. Make certain you are using sanitized jars, lids, and bands.
Basically, we treat home canning like reloading- Have at least 2(or more) reliable sources of information(you tube and grandma's cook book are not considered such). We're talking about recipes and canning procedures verified safe by the USDA. Just like loading your own ammo, home food preserving can be educational and fulfilling. But it must be done correctly to be safe. That means doing it by the book.
One very good reference every home canner should have on the shelf is a current copy of a book titled The Ball Blue Book Guide to Preserving
Online help? Here's one excellent source- http://nchfp.uga.edu/index.html
Also here for much useful info and a huge number of specific recipes- http://www.pickyourown.org/allaboutcanning.htm
Failing you use any of those, at the VERY LEAST contact your local university's extension service for guidance.
CAN SAFELY out there folks. Now, let's get back to ammo, guns, and tales of range trips, shall we?