Skip Navigation

Bulletin #4273, Using Home-Preserved Food Safely

Print Friendly

Food Safety Facts

Using Home-Preserved Food Safely

By Mahmoud El-Begearmi, Extension professor, nutrition, and food safety

For information about UMaine Extension programs and resources, visit extension.umaine.edu.
Find more of our publications and books at extensionpubs.umext.maine.edu.

pickles in canning jarsPreserving foods at home by canning, freezing or drying can save you money and provide nutritious meals for the future. However, home-preserved foods can spoil (see Bulletin #4277, Can Home-Canned Foods Spoil?). Spoiled foods may contain microorganisms that can make you sick. Food poisoning can cause vomiting, stomach cramps, and flu-like symptoms. Children and elderly people may experience more severe symptoms, even death. This fact sheet will explain steps you can take to use home-preserved foods safely.

Canned Foods

Examine them. Here are some tips on how to check canned foods.

Inspect the can before opening it. If it is a glass jar, the metal lid should be firm and flat or curved slightly inward. There should be no sign of leakage around the rubber seal. If there is mold around the outside neck of the jar, there may be mold inside. Check for signs of “gassiness,” including floating food, bubbles rising in the food or a swollen can lid.

As the jar is opened, notice whether there is an inrush or an outrush of air. Air rushing out or liquid spurting out indicates spoilage.

Smell the contents at once. The odor should be characteristic of the food. An “off” odor probably means spoilage (acid, acrid, sour, putrid, etc.).

Check the food carefully to see that it has a normal texture and color. Liquids in all foods should be clear. Any change from the natural texture or color of the food indicates spoilage. Do not taste any questionable food.

Discard canned food with signs of spoilage. If it is a high-acid food (fruit or tomatoes), throw it in the garbage or garbage disposal. If it is a low-acid food (vegetables, meat, fish, or poultry), it must be discarded more carefully because it could contain botulinal toxin. Be careful not to contaminate your work area by spilling the food. Wear rubber gloves when handling the food or containers. Then dispose of it in one of the following ways: 1) boil at full rolling boil for 20 minutes and discard; 2) burn; or 3) mix the food with 1 to 2 Tablespoons household lye or 1 cup chlorine bleach in a non-metal container, and let stand overnight. Flush it down the toilet or discard it in garbage or garbage disposal.

NOTE: Any containers or utensils that come in contact with spoiled canned foods should be washed carefully. Use soap and hot water to wash containers used for high-acid foods. Containers that come into contact with low-acid foods should be sterilized with chlorine bleach or boiled for 20 minutes. Discard all lids, screw bands, washcloths, sponges and rubber gloves used while detoxifying low-acid foods.

As a safety precaution, boil all canned low-acid foods (meats, fish, poultry, vegetables), before tasting them. Boiling destroys any botulinal toxin, if it is present. Boil most vegetables for 10 minutes at a full, rolling boil. Boil thick vegetables (potatoes) for 20 minutes. Boil meat, fish and poultry for 15 minutes.

Frozen Foods

Food is safe from spoilage as long as it stays frozen. Microorganisms can start to grow as soon as food begins to thaw. To keep microbial growth at a minimum, thaw frozen foods in the refrigerator. Thawed food may be safely refrozen if ice crystals are still present in the food. However, refreezing often changes the quality of food (texture, color, flavor). Microorganisms that can make you sick may not be killed by freezing, so food that’s not safe to begin with won’t be safe after it’s frozen, either.

Dried Foods

Dried foods that take more than one to two hours to rehydrate or reconstitute, should be rehydrated either in the refrigerator or in simmering water to prevent the growth of microorganisms. Once vegetables are rehydrated, they will support the growth of Clostridium botulinum, so they must be handled safely. Discard any dried foods with signs of spoilage or mold.

For more information about food safety, call USDA’s Meat and Poultry Hotline at 1-800-535-4555 or contact your University of Maine Cooperative Extension county office.


Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

© 2001

Call 800.287.0274 (in Maine), or 207.581.3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit extension.umaine.edu.

The University of Maine does not discriminate on the grounds of race, color, religion, sex, sexual orientation, including transgender status and gender expression, national origin, citizenship status, age, disability, genetic information or veteran status in employment, education, and all other programs and activities. The following person has been designated to handle inquiries regarding non-discrimination policies: Director, Office of Equal Opportunity, 101 North Stevens Hall, Orono, ME 04469, 207.581.1226, eoinfo@umit.maine.edu.