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How Long Are Canned Foods Safe

Date: May 1989 (Reviewed June 1996)

Source: University of Wisconsin

Canned foods, whether in tins or glass jars, won't keep forever. Commercial canners work under tightly controlled conditions with careful sanitation and just the right heat and timing periods, but there are still limits to how long food quality can be preserved. Home-canned foods, processed under less carefully controlled conditions, may have even shorter storage lives.

There are several factors that limit the shelf-life of canned foods. First, cans or metal lids on glass jars can rust. When rust is deep enough, tiny holes open in the can or lid that may let spoilage agents in. Shipping accidents that dent or crush cans also cause container problems.

Then there is can corrosion. In all foods, especially high-acid foods like canned tomatoes and fruit juices, the food continually reacts chemically with the metal container. Over several years, this can cause taste and texture changes, and eventually lower the nutritional value of the food.

High temperature over 100 degrees F are harmful to canned foods, too. The risk of spoilage jumps sharply as storage temperatures rise. In fact, canned goods designed for use in the tropics are specially processed. Even at prolonged storage temperatures above 75 degrees F, the rate of nutrient loss in canned foods increases. Light can cause color changes and nutrient losses in foods canned in glass jars.

Never use foods from containers with these spoilage warning signs--loose or bulging lids on jars; bulging, leaking or badly dented cans, or foods with a foul odor.

To store canned food wisely, follow these guidelines:

If you have further questions, contact your county office of the NDSU Extension Service for additional information on how long canned foods are safe.

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