How to Know if Canned Food is Bad: 11 Signs Your Canned Food is Spoiled

Canned food is a staple for preppers, it is used to help build a stockpile cheaply and it can last for years.  Whether you can your own food or you buy cans they both have the same issue, how to know if canned food is bad. While canned food has a long shelf life, but it does not live forever. This article will help you know if your canned food is safe to eat.

Do canned foods really go bad?

Yes, they absolutely do go bad and in fact, you can really sick from eating bad canned food.  There are a bunch of reasons that can cause your canned food to spoil,  They can include things like improperly storing your cans at the wrong temperature.  They need to be stored in a cool dried place, not too hot, and not allowed to get frozen.  If they are improperly stored then metal can start to leech into your food.

Something as simple as dropping your cans on the floor is enough to cause the contents to spoil.  If you drop a can and it becomes dented you can create a small hole in the metal that allows in air and lets bacteria grow in the can.


What is botulism?

Botulism is a type of food poisoning that is caused by the bacteria Clostridium botulinum. It can happen when food is canned without sterilization, processed improperly, or left unrefrigerated for too long.  It is colorless, odorless, and tasteless so that is why it is so important to make sure that your canned food is safe to eat.

There are three main types of botulism:

  • Type A (most common) – occurs when the bacteria multiplies in foods that contain protein (like meat, fish, eggs, tofu).
  • Type B – occurs when the bacteria multiplies in foods with high carbohydrate content (like vegetables).
  • Type C – occurs when contaminated soil or water makes its way into food.



Other signs of spoilage

When taking a product out of the storage look for this sign of spoilage. Never taste the food you don’t know! Do something and discard it when you feel the need! If you see a broken seal immediately after processing, simply enjoy the food immediately. Storage without the lid is an appropriate option. Whenever food tries to get through pressure the seal breaks naturally. Don’t store anywhere where there’s hot water piping or a heating oven. Direct sunlight will also lower the quality the foods and direct sunlight will lower the value. If the jars fail to seal properly those seals shouldn’t emerge if the food is sealed correctly.


No sounds of liquid inside when shaken

A soft quiet Hiss when the air rushes into a can you open is normal but hiss loudly when open is a warning sign. It’s bursting with air, rusting rust. It leaks from the can and it’s dented, it’s smelly and it sounds noisy! Remove all contaminated food safely. Make sure this article can be shared on your social networks for Facebook and Twitter to all your followers. We’re looking forward. Does anyone know any Prep or Preppers? Send to us at link. Return to the pages you came from.

What if you find a can that is suspected of carrying the bacteria?

Botulism can come via ingestion or through pores. Upon disposal containers have their contents thoroughly depleted. Please follow these steps before disposal of a bottle suspected of carries botulism. Put the bags in a new bag and seal again. Place the bag inside a garbage container outside the building. It can infect humans, pets and children who may come across the bacteria in the trash. See the instruction sheets for removal of infected cans.

A Lid that Bulges Moving Up & Down

The safe can of entire potatoes was exposed to extremely cold temperatures and relatively hot temperatures throughout six months in my garage. Food storage shouldn’t be located in garages where it can’t be controlled by room temperatures.

Rising bubbles or unnatural looking colors

The photo above is a well shook can representing safety bubbles. I’ve never seen unsafe bubbles myself so i was going to show you what safe bubbles are. Bubbles. Keep eye on rise gas bubbles.

Rusting / Corrosion of Can

It was pulled up from a house fire and it was soot. Soot and damping affected metal. Corrosion ultimately forms holes and allow air and bacteria to pass.

How do I spot signs of botulism in cans?

Home canning may cause botulism. Inspecting your cans before use is recommended. There are several problems with canned jar labels.


Wear gloves and just so it’s safe to throw away everything the contaminated product touched.

Bubbles Actively rising in the Jar

If you see small bubbles in an airtight bottle you may have bacterial fermentation or an increase in its activity. You don’t know the exact level of activity happening so you have to throw it away. If you stored the jars without rings ( as you should ) this jar should be unsealed ( see above #3) and you may never see a single bubble. It’s another reason to not store jars with rings in. Note: This bubble thing can pull out new canners because there is a time when it is okay to see bubbles go on when you first prepare jars. You can hear immediately on processing – for almost an hour afterwards.


If you find any residue or stains on the lid of the container you must throw away all of the food from the container. You may not remove all mold and some mold are carcinogenic. Mold changes the pH of food. If everything has changed enough something can grow much more dangerous than the mold. Eliminate him. There is no chance you are contaminating your food as you take away the mold and just eat. If it isn’t taken away it could become carcinogenic for food in general, too much to eat. Mold can modify the pH of foods if the tentacles in the food expand downwards.

Mushy or Moldy Looking

If you find molds in or on packaged food this indicates that your food was not canned properly. Wrong equipment or the wrong method been used resulting in growing mold that is beginning to form inside the food causing it to become rotting. In the first instance there’s not enough scraping away mold because you don’t know where the other hygiene concerns have occurred in the canning process.

Loud hissing

The slight noise of opening a small can is fine. However a loud hissing may cause bacterial inactivation. If you notice the noise, stop. You have already done something and stop. If you don’t stop you might risk stoking up bacteria in that food. Want to learn how to do it? If not what to do? Click here for free one-year sustainable urban survival plan!

Strange colors

Your food should be the same colour that goes into the can as it leaves the bag. Discoloration is typically a sign that a metal, bacteria or an air leak is causing the substance. You probably do not want this. Need help to start prepping? Click here to take advantage of a FREE urban survival program! Check out this free 1- year urban survival plan.

A Funky or Slimy Texture

The foods can be prepared a little easier during their preparation. That’s because the process slows down a little. But when you open a jar but the food looks slimy and slippery or the texture disintegrates you should toss it. The texture of the contents isn’t what you expected it is a sign of spoilage says Simon Tisdall. See more info on our site.


When metal cans corrode, toxic metals like bisphenol A (BPA) can penetrate into your food. Furthermore, BPO creates holes which encourage the growth of bacteria. Corrosion could be caused by poor storage conditions or being covered with soot or ashes that moisten cans. When searching for corrosion look for small rusted holes in the box.

Bad smell

When you smell something out of air your body will detect this. Chemical and metallic smells smelt strange. Let us trust both our senses and our instinct. Rotten smells can make you sick or discourage you from eating possible spoilage food. Acidic scents make you feel uncomfortable when you open tupperware.

Spurting liquid when opened

When you open your green beans or tuna there’s sometimes a little liquid floating around and leaking from the top. What’s not naturally is fluid that erupts like geysers. This is probably a sign that bacterial infections caused an abnormal build up inside the can.

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