How to Tell if Canned Food is Bad?

If you’re unsure whether a food can is terrible, you can check the lid for signs of spoilage. Many canned foods are vacuum-sealed to maintain freshness and hygienic conditions. If the lid seems to be loose, or if you notice moisture, the food may have gone wrong. If this is the case, it’s time to discard it. To make sure canned food is safe to eat, check its lid for mold or any other signs of contamination.

Canned food

Cans with screw bans are the easiest to identify. They can quickly leak and swell when they get damp. This can cause the lid to leak, and the jar’s seal may have broken. If you can’t see any of these signs, you can probably eat the canned food. Otherwise, discard it. You can also smell rotten food by inspecting the can. The smell and color of spoiled food are a sure sign of spoilage.

What is Canned Food?

Canning is a method of preserving foods in airtight containers for long periods. Canning was invented in the late 18th century to provide a consistent food supply for soldiers and sailors at war.
The canning process can vary by-product slightly, but there are three main steps. These include:

  • Processing- Food is peeled, sliced, chopped, pitted, boned, shelled, or cooked.
  • Sealing- The processed food is sealed in cans.
  • Heating- Cans are heated to kill harmful bacteria and prevent spoilage.

This allows food to be shelf-stable and safe to eat for 1–5 years or longer. Common canned foods include fruits, beans, soups, meats, and seafood.

How to Tell if Canned Food is Bad?

Here are the signs of bad canned food:

  • Food from cans should not cause bloating. As a result, a bulging lid or side indicates pressure from gas, bacterial activity, or spoilage. Avoid eating the contents of any bulging can or jar with a bulging lid at all costs.
  • When opening a sealed jar, a light “whoosh” is expected. A lot of pressure or even a surprising amount of pressure releasing on opening, on the other hand, is not a good sign. Gas may have built up inside the jar due to bacterial activity. Remember to throw out any can or jar that does this if something doesn’t seem right.
  • Bubbles usually indicate fermentation, a bacterial process that can be perfectly fine if done deliberately and under certain conditions. It’s also great for pickles, wine, beer, and other dishes.
  • In low-oxygen environments like canned food, botulism and other dangerous bacteria can survive (and even thrive).
  • The liquid in the can is usually straightforward. As a result, if the liquid is cloudy, it could indicate that the food has gone wrong.
  • Any mold on the underside of a lid indicates that the food should be discarded. Mold on the underside of a lid, regardless of color, is a bad sign, and the food in that can, or jar should not be consumed.
  • A lid that can be pushed up and down is not securely closed. When you first can something, the lid gets sucked down as the jar cools. As a result, depressing a lid and popping it back up should not be possible, which means it didn’t close properly. As a result, unopened and unrefrigerated jars are unsafe to consume.
  • If there are food traces on the outside of the container, it most likely leaked from the inside. If there is a leak, the seal is broken, and the food is potentially dangerous. Throw it out if you’re not sure.
  • If the contents of a can or jar smell “off” or unusual, or otherwise differ from what you remember, the food has most likely gone bad. Throw it out if it doesn’t pass the sniff test.

How does Canning Affect Nutrient Levels?

Canned food

Canned foods are frequently considered less nutritious than fresh or frozen foods, but studies show that this is not always the case. Canning preserves the majority of the nutrients in a portion of food.

The process does not affect protein, carbohydrates, or fat. The majority of minerals and fat-soluble vitamins such as vitamins A, D, E, and K are retained. As a result, research shows that foods high in certain nutrients maintain their nutrient levels after being canned. Water-soluble vitamins like vitamins C and B, on the other hand, can be damaged by the high heat used in canning.

Because these vitamins are heat and air-sensitive in general, they can be lost during everyday processing, cooking, and storage. While the canning process may destroy some vitamins, it may increase the amount of other beneficial compounds. When tomatoes and corn are heated, they release more antioxidants, making canned versions of these foods an even better source of antioxidants. Canned foods are good sources of essential vitamins and minerals, regardless of individual nutrient levels.

According to one study, people who ate six or more canned items per week had higher intakes of 17 essential nutrients than those who ate two or fewer canned items per week.

Canned Foods are Affordable, Convenient, and don’t Spoil Easily

Canned foods are a convenient and practical way to increase your intake of nutrient-dense foods. Many parts of the world lack access to safe, high-quality foods, and canning helps to ensure that people have access to a wide variety of foods all year. Almost any food can now be found in a can. Canned foods are also highly convenient because they can be stored safely for several years and require little preparation. Furthermore, they are less expensive than fresh products.

How Long does Canned Food Last?

Here are the shelf lives of different kinds of canned food:

Canned Ham

Canned ham (such as Spam) has two to five years of shelf life. It should be kept in the refrigerator for 3 to 4 days after opening.

Low Acid Canned Goods

Low acid canned goods include vegetables like potatoes, corn, carrots, spinach, beans, beets, peas, pumpkin, meat and poultry, stews, pasta products, and soups (except tomato soup). According to the USDA, canned goods will last on the shelf for 2 to 5 years after being canned and 3 to 4 days in the refrigerator after opening.

High Acid Canned Goods

Juices, tomatoes, fruit products (including grapefruit, pineapple, apples, peaches, pears, plums, and all berries), pickles, sauerkraut, and all foods treated with vinegar-based sauces or dressings, are all high acidic canned goods. These foods will last 12 to 18 months on the shelf but only 5 to 7 days in the refrigerator once opened.

Home Canned Foods

If you’re canning your food at home, keep in mind that it can last up to a year on the shelf. Boil high-acid foods for 10 minutes and low-acid foods for 20 minutes before using them as a precaution (even if you detect no signs of spoilage). After opening, your home-canned foods will last 3 to 4 days in the refrigerator.


Canned food is generally safe. However, botulism, a potentially fatal bacterial infection, can be found in improperly canned cans. Food contaminated with botulism should never be eaten because it can be dangerous. It’s also a good idea to properly dispose of your canned goods, and they may be contaminated with botulism if you don’t have a way to test them.

Some foods may appear to be healthy, but they contain microbial contamination. You don’t want to risk getting sick because of these bacteria. Food can be contaminated with bacteria even if it does not appear to be spoiled. A simple smell or taste test will not determine whether or not the food is safe. There are some exceptions to the rule that canned foods should be stored in the refrigerator after opening. When in doubt, refer to the label’s storage instructions.

Check the contents using the lid of a can as a guide. Botulism could be present if the can’s lid is loose. Botulism can kill a person in rare cases by paralyzing the muscles that allow them to breathe. If you suspect a food is poisonous, seek medical help immediately. Call your local food safety office if you notice any signs of a leak or bulge.