How to Tell if Home Canned Food Is Spoiled: 7 Signs

Do you know how to recognize spoiled food? Sometimes it is obvious…sometimes not.

Prevent Spoiled Food By Using Up-to-Date Canning Methods

Botulism

Botulism is not anything you can see or smell. You will not know it is there until you get sick.

That is another reason to avoid unsafe canning methods. You just won’t know it is there. Be confident that your food is safe by using up-to-date canning methods.

Other Signs of Spoilage

Other spoiled food is apparent by just looking at the jars or smelling the contents.

Out of the 250 jars of various foods I canned last year…I had one that lost its seal and spoiled. It was a jar of canned whole tomatoes. There was scum on top of the food and the product was bubbly. It was pretty yucky. There was no doubt. I had no problem throwing that one out.

When you take your food out of storage, look for these signs of spoilage:

• bulging tops
• lost seals
• product is bubbly
• product spurts out of jar when opened, which indicates food might be under pressure
• scum on top of the food
• unnatural-looking colors
• unnatural smells

Do NOT taste test any food that you are not sure of!

If in Doubt, Throw It Away

• When you take food out of storage, don’t eat food from jars that have lost their seal or have bulging tops. And please don’t taste it to check!
• Keep a questionable jar where kids and pets can’t get to it. Family pets can get sick too.
• For getting rid of a spoiled jar safely, I send you straight to the experts. The National Center for Home Food Preservation has step-by-step directions, and they’re different for a jar that’s still sealed and one that’s open or leaking.

Don’t let this section scare you off canning. A spoiled jar is rare, and following tested recipes and checking your seals takes care of the big things.

Before Putting Jars in Storage…

• After jars have cooled, check the seals before storage. Remove the screw bands. Lift on the edges with your fingers and lift the jars in the air. If the lid holds, it has safely sealed.
• You can also push down on the center of the lid; if the lid is pushed down and does not move or ‘pop’ under your finger, it is sealed.

If you notice a failed seal right after processing, simply enjoy the food right away. Store it in the refrigerator and use it within a week. You have a few other options too, like reprocessing within 24 hours, and I cover those in Canning Mistakes: What to Do When Something Goes Wrong.

Storing your jars without the screw lid is a good idea. If the food comes under pressure, the seals will naturally break. The seals should not come off if the food is sealed properly and cooked properly.

It is also advisable to store your jars in a cool, dark, and dry environment. Don’t store in a room or area that may contain hot pipes or a furnace. A kitchen pantry is usually just fine.

Direct sunlight will decrease the quality of the foods as well.

Related Pages

Learn more about botulism (the risk you cannot smell or see) on this page. Hint: Thankfully, it’s very easy to avoid it altogether with some commonsense and best practices.

Have you ever heard of Flat sour? While it won’t harm you, flat sour can make your canned food very unappetizing.

How to Can Tomatoes Safely – A bit of acidification helps. But WHY?

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