Learn how to identify spoiled cans of food, and how to properly dispose of any contaminated items.

Store canned foods in a cool and dry place, at a temperature between 50°F and 70°F, for the recommended times only. When in doubt, throw it out; spoiled canned foods are not only unsafe to eat, but can contain botulinum, the dangerous—and deadly—toxin responsible for botulism.

When disposing of canned foods, an adequate level of protection is a non-negotiable: Put on gloves, double-bag anything you put in the trash, sanitize all utensils and surfaces that came into contact with the food item, and remember to wash your hands and launder your clothes.

Learning how to identify potentially spoiled food will keep you—and the members of your family—in good health. Keep reading as we look at how to dispose of this food, and how you should detoxify in extreme cases.

Recognizing Spoiled Canned Food

Whether you buy your canned goods at the supermarket or can the foods yourself, one of the most important skills you need to learn as a cook is how to tell when they have spoiled. The good news is that this isn’t all that hard, as long as you know what to look for.

When it comes to canned foods, the golden rule is to trust your senses and err on the side of caution. If anything looks suspicious or smells strange, get rid of it immediately and never—we repeat, never—taste it. Ingesting botulinum, even small quantities, can be deadly.

To determine if canned food has spoiled, take a look at the can. If the can is damaged, bulging, or leaking, the food inside it has almost certainly spoiled, and is therefore unsafe to eat. If you’re still unsafe, observe and smell the food. Fizzing and an off odor are tell-tale signs of bacterial activity.

The Outside Appearance of the Can

Right off the bat, you can condemn any cans that show signs of damage and/or contamination, including corrosion and rust, severe denting, bulging tins, and leaking liquids.

When it comes to spoilage, cans with screw bans are the easiest to recognize. As the food spoils, the bacteria inside it start to churn out gas, which builds up inside the chan and pressurizes the food. This causes the lid to swell, and it can even break the jar’s seals.

Hold any transparent cans or jars at eye level—and look at what is on the inside. Streaks of dried food are a sign of contamination, as well as any rising air bubbles or moldy, green to blue colors in the jar. Canned food is sterilized and, as such, there shouldn’t be bacterial activity inside it.

The Liquid and the Surface of the Food

If you cannot identify spoilage based on appearance alone, then you can try opening the can or jar to get a closer look at things. Make sure you wear gloves to protect yourself from bacterial contamination and keep the can pointed away from your face and body.

Suspect a can if you notice spurting liquid, an off odor that just doesn’t seem right, and fuzzy mold, green or blue—floating on the liquid, on the underside of the lid, and/or covering the surface of the food—when you open the can.

White, green, blue, and black are not colors you want to see on a canned food item (unless your food contains ingredients that gave it this color when it was fresh in the first place). Spoilage is usually more evident when opening, but you should still dispose of suspect food that does not show these signs.

High-Acid Canned Foods

According to the World Health Organization, “Botulinum will not grow in acidic conditions (pH less than 4.6), and therefore the toxin will not be formed in acidic foods.” Low storage temperature, the organization adds, and high salt content can also prevent bacterial growth.

If the canned food is on the acidic side and/or you have no reason suspect botulism, the steps for disposing of it are to put on rubber or latex globes, put the food or can in a sealable bag, seal it tightly, double-wrap it in another bag, tape it shut, and dispose of it outside the home.

Make sure you are not using a recyclable trash receptacle, and keep it out of the reach of other people and pets. After you are done you should wash your hands with soap and water for at least two minutes, even with wearing protective gloves.

Low-Acid Canned Foods

You should take extra care when handling low-acid foods. According to WHO, the list of low-acid foods includes vegetables, including green beans, spinach, mushrooms, and beets; fish, including canned tuna, fermented, salted, or smoked fish; and meat, including ham, hot dog, sausage.

This is because a low-acid storage condition (pH of higher than 4.6) provides a breeding ground for botulinum, the bacteria that cause botulism. This type of food poisoning can be fatal, and treatment for it requires immediate medical attention.

Botulism is relatively rare in the United States, but the risk of it, particularly with canned foods gone bad, is not to be underestimated. According to the Centers for Disease Control and Prevention, 242 cases of botulism were reported in 2018 within the United States, of which 18 (7%) were food-borne.

All of the cases of food-borne botulism that year were related to homemade canned foods: three in New York related to canned beans and peas, two New Jersey cases related to feseekh, a salt-cured fish, two in Pennsylvania related to fermented bean curd, and two Oklahoma related to turkey soup.

As you can tell by the statistics, botulism is more common with homemade canned food. However, it can occur in store-bought canned food if improperly manufactured or stored: if the spoiled food is in a can that is open, leaking, or unsealed, then it should be detoxified before disposal.

Detoxification for Suspected Botulism

“If the suspect cans or glass jars are unsealed, open, or leaking, they should be detoxified before disposal,” the University of Georgia’s National Center for Home Food Preservation says on its website.

When detoxifying, start by wearing heavy-duty rubber gloves that you can dispose of at the end. Place any of the contaminated cans and their lids on their sides in a pot or pan that is 8 quarts or larger, such as a stockpot, a pan, or a water canner.

Add enough water to the pot to cover the jars, cans, and lids. This water should cover at least 1 inch above their highest point. Put a lid on the pot, and then heat the water to a boil. For adequate detoxification, make sure you boil for at least 30 minutes.

Allow the lids, jars, and cans to cool down before disposing of any of them. Then dispose of in the trash or in a nearby landfill.

Cleaning Up After Disposal and/or Detoxification

After you dispose of spoiled or contaminated food, you should clean up any work surface that it came into contact with, wash your hands thoroughly, then launder your clothes.

A solution of ¼ cup bleach to 2 cups of water should be sufficient for disinfecting. Use this solution to completely cover any spills or affected areas, and then place a layer about 5 to 10 paper towels thick on top of the bleach.

Let this sit for 15 minutes before removing the layered paper towels and throwing them in the trash. Wipe up any remaining solution with a fresh paper towel, and then clean the area with a liquid soap and water solution to remove leftover bleach.

Wash your hands and throw away anything that came in contact with spoiled food or containers, including sponges, paper towels, and gloves. Launder any clothes immediately, along with any cloths used during the disposal process.

Final Thoughts

By properly identifying spoiled canned food you will know when you can hold on to it and when it is time to let it go. Throw out anything that you are unsure of, and make sure to do it in a way that reduces contact between humans and animals.

Take care to clean up afterward, and you should be free of any spoilage or contamination.