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Tuesday, March 8, 2011

The Shelf Life of Commercially Canned Foods

The Shelf Life of Commercially Canned Foods

stored cans naelyn@flickr 200x266 The Shelf Life of Commercially Canned FoodsA reader asked me the other day about how long canned food stays good, and whether or not the ‘use by’ dates were particularly accurate. I figured the answer to that question would be interesting to more than just him…
As is all too often the case, the answer is ‘longer than you are being told by the folks that are selling it to you’ but for more details, read on!  Be sure to read the last section to learn how to avoid a sneaky trick the food companies try to pull on you!
Rudy’s Disclaimer: It should go without saying, but I will say it anyhow.  Be careful what you eat. Don’t push it if you’re not in a full on emergency. Botulism poisoning isn’t a fun thing.
You can’t hold me responsible for you eating bad food…etc etc…Be smart, be responsible.  Your health is more important than a can of food.

The Shelf Life of Commercially Canned Food

soupcan stevendepolo@flickr 200x133 The Shelf Life of Commercially Canned FoodsGenerally speaking commercially canned foods are good for two to five years from the date they were packed. Of course the date they were packed and the ‘use by’ date stamped on the can are usually only vaguely related.
The packing date is generally also coded on the can but is generally in a code that is specific to the manufacturer. There are a couple of websites out there that have repositories of codes if you want to be sure.
The acid content of the food itself will change the shelf life as well. A high acid food like tomato sauce will not keep as long as a can of beans, for example.
Nutritionally speaking, canned foods don’t lose minerals but absolutely lose vitamins as time goes by. Vitamin A and C are the ones most affected, so you’ll want to consider making supplements for those vitamins part of your preps. While the vitamin content of foods is impacted the most when the food is canned, you will still lose anywhere from 5% to 20% of Vitamin A and C every year.
As with most food storage items, the storage conditions are a key factor in the shelf life of canned foods. You want to store them in a cool, dark, and above all dry place. Keep the cans away from fluctuating temperatures which can easily break seals.
Unlike some kinds of food, you really don’t want your cans to freeze because it can change the food texture, rust or rupture cans, or break the can seal. And be sure to store your cans off the floor to avoid moisture wicking. Absolutely avoid bare concrete.
It’s a good idea to label the cans with the purchase date to aid your ‘first in – first out’ rotation scheme.

So Rudy, This Can Is 8 Years Old, But Looks Perfect!

rustycan christianspenceranderson@flickr 200x133 The Shelf Life of Commercially Canned FoodsIn many cases, cans are fine when older. The vitamin content may not be there, and the food quality may be barely above canned dog food, but it may not kill you.
If a can is badly dented, rusty, or bulging, toss it without opening it. If it’s leaky get rid of it. If the can itself passes visual inspection, go ahead and open it and take a look.
If you feel like passing out from the stench when you open it, it’s a safe bet that you shouldn’t eat it. In all seriousness, if it smells off, don’t eat it. If it looks wierd, you may want to avoid it as well, though there are some common appearance flaws that are actually ok.
A brown or dark color of the food is actually fine. It’s caused by the food pigments oxidizing or breaking down chemically, and doesn’t affect the safety of the food itself.
Mushy or soft food is also generally fine, as it’s simply just a chemical or age related breakdown of the food textures themselves.
Canned fish can have crystals formed, which are also just fine. They’re naturally formed Magnesium ammonium phosphate crystals and will dissolve when you heat the fish.
If the food looks generally ok, and smells ok, taste a little bit. Just a tish. Maybe feed some to your kids and see if they keel over (just kidding, Honey) … if it tastes off, toss it.
Highly acidic foods can get a metallic flavor from leaching some of the metal from the cans if the food has been stored too long or sits in an open can for too long. This is ok.
You might consider boiling the food or heating it to 165 degrees as a final safety measure if you’re in doubt … but honestly, if you’re in doubt and it isn’t a life and death situation … just toss the damn can. Your health isn’t worth a $0.75 can of green beans.

Those Tricksy Food Companies

dehydrated water eraphernalia vintage@flickr 200x242 The Shelf Life of Commercially Canned FoodsIn closing, one last note. Lately those tricksy food companies have been trying to bump up their bottom lines a bit by tweaking the use by dates they print on the cans.
In many cases they’re cutting the time in half or more, just because they know that most people will abide by those dates and go buy new cans. Talk about a sneaky way of increasing sales in an economic downturn…
Pretty insidious if you ask me, so try to figure out what the packing date was and go by that. You can also always call the company themselves and ask what the shelf life is (vs the use by dates) and get a better idea then.

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