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Unsealed jar of preserves sealed itself in refrigerator over night. Safe to remove from fridge?

The jar sat on the counter all day and still did not seal properly. (The center was still popping) so I put it in the refrigerator before bed. In the morning I noticed that the the jar was sealed and the center tab didn't budge. Did the sealing process just continue in the fridge, or is the cold temp playing a trick on me and once the jar gets back to room temp, will the seal open up again?

asked by Emily Nordby almost 3 years ago
6 answers 2828 views
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added almost 3 years ago

Air contracts as it cools, so when you put the jar in the fridge, it must have been sealed enough to create a partial vacuum when the air trapped under the lid contracted, pulling the center down. It will most likely pop back up when it warms to room temp and the air re-expands, but this doesn't mean your jar isn't sealed. Was the jam not very hot when you put it in the jar? Hot air contracting is why jam jar lids ever pop down when they seal -- when you put hot jam in the jar and close it, if the lid forms a seal, the lid will suck down as the jam and air cools.

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added almost 3 years ago

While everyone is coming down on the side of caution, to be very clear just because something sealed does not mean it is sterile. Sealing works after processing because any bacteria have been killed by the heat. So something that sealed in the fridge might be teaming with microbs and may not belong on the pantry shelf.

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added almost 3 years ago

I have always read not to test the seal until the jar was completely cool. That said, I would keep it in the fridge, and use that jar first. Jams and jellies tend not to be very volatile. My grandmothers would just seal the jars with a layer of paraffin .

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