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How to Know if Canned Food has Botulism

Elsie Goycoolea
By Elsie Goycoolea. Updated: August 3, 2020
How to Know if Canned Food has Botulism

Food companies must submit their products to rigorous food inspection programs to ensure that food is safe to eat. Botulism is a rare disease that is often contracted as a result of eating canned food. If you eat contaminated food with Clostridium botulinum you may experience symptoms such as blurred vision, dry mouth and even trouble speaking. If your diet includes a large number of canned foods or if you tend to use canning as a homemade food preservation system, then you may benefit from learning how to detect food contaminated with botulism.

In this OneHowTo article we explain how to know if canned food has botulism.

Steps to follow:


Before we dig into the signs of food contaminated with botulism we want to highlight that botulism is a rare disease with a very low death rate; therefore you shouldn’t be scared to eat canned foods. If you are canning food at home, we suggest you collect as much information and advice from trustworthy sources before you actually commit to doing it yourself.


The first step in learning if canned food has botulism is to inspect the can for any bruises or cuts. Sometimes food has to travel long distances to get to the store and it is possible that during the transportation process it may have become damaged exposing the contents of the food to harmful bacteria. Inspect for any leakages, dents or lids that bulge up and down.


How to Know if Canned Food has Botulism - Step 2

Secondly, read the label on the can for any indications that it may not be optimal to eat. For instance, if you buy a refrigerated product but on the touch it is warm or even hot, that is a sign that the product was not manipulated correctly. Generally, food should be kept at low temperatures in order to stop bacteria reproducing.

How to Know if Canned Food has Botulism - Step 3

If you believe your canned food has passed these first steps, then it is time to open the can. Take it slowly and see if you notice any air coming out of the can and any unpleasant smells. If it hisses it isn’t a good sign. Bacteria proliferates in high oxygen environments at very fast speeds; as well as, in foods that contain a large percentage of liquid.


Finally, remove the contents out of the can and take a look at the texture and feel. If you have bought this product before, notice if it looks different. Don’t leave any food in the can. Instead move it to another container for storage. While you may be tempted to taste the food, it is important that you follow all these steps and when in doubt discard the food to avoid food poisoning.

How to Know if Canned Food has Botulism - Step 5

If you suspect that your homemade canned foods are unsafe to eat, before tasting the food, boil the can unopened for a minimum of 10 minutes. You may do so safely for up to 20 minutes for items such as corn or spinach. Canning is a simple yet technical food preservation system that must be done cautiously by following a recipe.



How to Know if Canned Food has Botulism - Step 6

This article is merely informative, oneHOWTO does not have the authority to prescribe any medical treatments or create a diagnosis. We invite you to visit your doctor if you have any type of condition or pain.

If you want to read similar articles to How to Know if Canned Food has Botulism, we recommend you visit our Healthy living category.

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Sharyn Connett
Hi I am worried that I bought a case of tomato paste and one can leaked a little bit. I discarded that can. are the other cans safe? I'm worried about botulism.Thank you
OneHowTo Editor
Hi Sharyn,

If the other cans are intact and there is no damage, it could be that only the one was affected. It would depend on their integrity.
I have often read that if you see "bubbles" in the jar or hear a "hissing sound" while opening canned goods, that it's a sign of botulism. However, I'm recently wanting to can fermented goods, such as pickles, kimchi, and sauerkraut, etc. Wouldn't it be natural to see some bubbles or hear hissing while opening a can of fermented foods like sauerkraut? Just thought I'd ask around before I begin.
OneHowTo Editor
Hi Jenna,

The process of fermentation and how bacteria work on food are really quite similar. They are both chemical changes caused by microorganisms. The difference is what happens when you eat it. The fermentation process does release gases such as carbon dioxide, so there may indeed be a hiss when the jaws open due to built up pressure of the gas.
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How to Know if Canned Food has Botulism