Canned Food Shelf LifeCredit: Wikimedia.orgWhenever you clean out your pantry and cabinets you no doubt wonder about canned food shelf life.  Maybe you stocked up on canned tomatoes two years ago with the intention of making your own pasta sauce but never found the time.  Perhaps you stocked up on green beans because the price was too good to pass up.  Whatever the reason we all seem to have our own collection of canned goods that languish in the dark corners of our cabinets.  Canned goods seem have a bit of mystery surrounding their expiration date.  Because we can't see inside the can without opening it we never bother to throw it away or dare to give it a shot.  So what exactly is the verdict on those cans of tomatoes and green beans?

When to Cut Your Losses

Before getting into the expiration of various cans of food we should touch on the obvious signs of risky canned food.  The biggest issue with eating expired canned food is the risk of botulism which can be a life threatening in some cases.  The canning process typically eliminates the spores that cause botulism and prevents other bacteria from growing.  However, if the can is physically damaged, than the food is at risk.  There are three situations where canned food should just be tossed and not risk eating them.

  1. If the can is badly dented, than it could mean there is even the smallest puncture in the can.  A punctured can is no longer sealed and is dangerous to eat.
  2. If the can is expanding or bulging, than it means gas of some sort is forming inside which means the canning process did not work and bacteria have grown inside. 
  3. If you open the can and the food doesn't smell right, than toss it and don't risk it.  Looks can be deceiving but oder is something that shouldn't be much affected.  The only exception would be foods that are highly acidic can smell a bit metallic from leaching the metal of the can.

What Does the Expiration Date Really Mean?

The expiration date on canned goods isn't so much a date to throw away food but a date where certain attributes begin to decline.  Canned goods are usually given a two-year expiration date from the day it was canned.  In general, after two years the vitamin content begins to drop, particularly vitamins A and C.  The mineral content does not change.  Two years is also when highly acidic foods like tomatoes have begun to take on a slight metallic taste from the can.  The color of certain foods can also take on a brownish tone but this is not evidence of bacteria but the oxidation and breakdown of the food.  Tests have been done on canned goods that were over 100 years old which were found perfectly safe to eat.  It wasn't of the highest quality anymore but the food was not unsafe.  When canning is done correctly there really is no expiration date.

How to Store Canned Goods to Extend Shelf Life

While canned goods are extremely durable they are not immune to outside conditions.  Two factors to keep in mind when storing canned food are temperature and humidity.  Canned food should ideally be kept at a moderate temperature.  If the contents freeze, than the liquid in the can turn to ice and expand causing the can to burst.  If the contents are heated, it can cause gas for form which can also cause the can to burst.  These temperatures are on the extreme ends of the household temperatures so it generally isn't a problem.

Humidity is a more likely concern in a home depending where the cans are stored.  If you store your canned goods in a basement, than the humidity can cause the cans to potentially rust through.  Once the can has been breached it can no longer be safely stored.  If you do store you canned food in the basement, than keep it off any cement floors.  For damp basements you may want to look into getting a dehumidifier.

Overall, the storage of canned goods is simple and most cabinets will suit the job just fine.  So don't be scared of that can of peas tucked behind the cereal boxes.  Canned food shelf life is longer than you might think.