sealing applesauce jars

Have you ever opened a can of applesauce only to have it explode in your face? Or perhaps you home-canned a batch of applesauce, and the cans started leaking everywhere? Read on if you’ve ever wondered why your applesauce exploded and how to prevent it.

Applesauce can explode when the contents are under too much pressure. This may be from the canning process when not enough air was removed from the sauce or the airspace in the jar was too small. Explosions can result from the fermentation process in unpasteurized applesauce.

applesauce canning jars

Home canning can result in a  bounty of delicious tangy-sweet applesauce to enjoy for months—or a massive mess of exploded runny sauce all over the pantry. How you prepare and can your apples will make a huge difference, and there are some guidelines you should follow when canning applesauce.

Why Did My Applesauce Explode?

There are a few reasons applesauce may have exploded. If an unopened jar explodes or starts leaking through the lid, it is likely due to the cooking and canning process. I’ll detail below how to ensure your applesauce is correctly processed to prevent leaks and explosions.

Another reason an applesauce jar breaks is if you put hot food into cold jars. This is why it’s recommended that you keep your jars in hot water for sterilizing until you are ready to use them.

Saying that, I do not follow that recommendation personally. It is in my family tradition to do it differently. And to this day, no issues whatsoever. Check out my homemade canning process here.


Suppose you have an already-opened jar of applesauce in the refrigerator that explodes. In that case, this is likely due to a fermentation process that released extra c02 into the jar’s headspace.

I’ll discuss how applesauce ferments and if it is still safe to use.

How To Prevent Applesauce Exploding

Home canning applesauce is perfect for beginners, as it’s a relatively straightforward process and yields excellent results. However, there are a few tips to follow that will help prevent spoilage and spillage.

When making applesauce for canning, you must ensure that you get rid of air bubbles in your sauce before sealing. The air is driven out of the mixture as you cook the applesauce. You add air to the sauce when you process your cooked apples in a blender, food mill, or sieve.

After processing, returning your applesauce to the heat is a good idea. While you are canning, keep the applesauce heated to a simmer. Most home canners use a water bath method that sterilizes the jars and lids by boiling them for ten minutes.

This quick video from Crouton Crackerjacks walks you through the simple process:

Headspace Canning Tips For Applesauce

When you add your applesauce to the warm jar, the air left in the sauce will expand. This expanding air needs more room, which causes later problems of leaking or siphoning.

You can use a plastic knife, spatula, or wooden skewer to dislodge and remove any visible air bubbles from the can before you seal it. Slide it inside the jar to help release bubbles and improve the seal when you close the can.

Leave some air space at the top of your jar, known as headspace or headroom. The USDA recommends a ½ inch space for fruits canned with a water bath method. This space is necessary to prevent spillage or overflow once the jar is sealed.

The headspace is needed to create a vacuum seal once the jar’s lid is closed. The applesauce could be forced out as it cools if you have insufficient space. If you leave too much headspace, your applesauce will brown.

Can Applesauce Ferment In The Fridge?

The biggest culprit for exploding applesauce is the fermentation process. Much like other lacto-fermented foods like sauerkraut, kimchi, and pickles, it is due to healthy bacteria that convert sugars into lactic acid.

Suppose your applesauce has added salt and lemon juice and has plenty of sugar. In that case, it is the perfect ground for Lactobacillus to grow. Fermentation usually requires a period where the applesauce is warm enough for the bacteria to begin to culture the sauce.

Fermented Applesauce 2 jpg

So, if you left your opened jar of applesauce out of the fridge overnight—or longer—the fermentation process has likely begun simply from wild strains of Lactobacillus in the air. Because of the high sugar content in applesauce, it will ferment very quickly.

Once you put the applesauce in the refrigerator, the process slows down, but it does not stop. Those little bacteria work to break down sugars.

The process releases Co2 gas, which collects in the headspace of the jar, building up pressure inside the container. Eventually, if there is no more room for the gas to expand, the jar will burst open. Or, if you open it, explode all those pressurized contents everywhere.

How to Tell if Applesauce Has Fermented

If applesauce has not been pasteurized, it will likely ferment, even in the fridge. Homemade applesauce will begin to ferment sooner, but even store-bought applesauce can ferment.

Some signs that your applesauce has fermented:

  • A sour, slightly beer-ish smell when you open the container 
  • gas bubbles forming, especially if they are fizzing at the top of the jar.

Some people make fermented applesauce on purpose, as they like the taste and health benefits. This process is about usually adding whey or water kefir to uncooked, processed apples.

The applesauce cultures for 1-3 days to develop the taste and texture, then transfer it to the fridge to create a more intense flavour. They ‘burp’ the jar daily to release the excess c02 and prevent explosions.

While this process is deliberate, you can see how an opened jar of cooked applesauce can ferment if it comes into contact with good bacteria. Without the burping process, it’s also easy to see why a fermented jar can quickly explode.

Will Fermented Applesauce Make Me Sick?

If you make fermented applesauce yourself, you should have no problems, provided you follow safe food preparation guidelines. Making probiotic foods at home, like yogurt, kombucha, or fermented applesauce, is relatively safe.

However, if your opened can of applesauce is fermented on its own, you should discard it. You don’t know what other organisms or molds may have entered the applesauce, causing potential spoilage.

Some wild yeasts, for example, while fermenting your applesauce, will also leave a foul-tasting by-product.

Especially if the applesauce smells sulphurous, vinegary, or disgusting rather than like beer or alcohol, it should be thrown away.

Why Does My Applesauce Smell Like Alcohol?

Applesauce that smells like alcohol or beer has begun to ferment. The sugars and starches in your applesauce have started to break down.

Bacteria such as Lactobacillus and yeast spores convert sugars into alcohol and carbon dioxide. This process can take a while, so the longer your applesauce has been left, the more it will have broken down into alcohol.

Cooler conditions slow the process, so an applesauce jar in the fridge will take much longer to ferment than a jar on the kitchen counter.

Read more: Is Baby Applesauce The Same As Regular Applesauce?


To avoid the problem of exploding applesauce, ensure that you remove most of the air from the jar and mixture when canning. Leave approximately ½ an inch of headspace at the top of the jar to help the vacuum sealing process while allowing the air to expand.

Prevent natural fermentation by sealing your applesauce correctly and keeping it in the fridge. Open jars allow wild yeast strains and bacteria to get in the sauce, while heat will encourage the fermentation process.

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