why glass container lid is sucked in on itself

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Howdy all,
Hope this is the right flair.
Yesterday I discovered one of our glass Tupperware containers in the hatch of my wife’s car and the lid is sucked in on itself.
The lid has four clips that snap under the lip of the glass and it’s air tight I would assume. It has remnants of her buffalo chicken chili in it. That has dairy in it.
It’s also been relatively warm here until yesterday when I discovered it. It was 15 degrees F difference.
Thanks in advance for your answers.

In: Biology

6 Answers

Anonymous 0 Comments

Hot air? Less dense

Cold air ? more dense

The process of “canning” requires heating the food containing jar to near boiling, which heats the remaining air in the jar as well. Then the lid is screwed on.

As the jar cools down from nearly 100C to room temp around 20-30c. The air goes from less dense hot air. To dense cold air. This creates a vacuum as the higher density air creates a low pressure zone. Basically there is less mass of air inside than there typically would be. So the atmosphere around the jar, pushes in on the lid.

That’s the what. But why? Well 3 reasons in a trench coat disguised as one. Bacteria. Bacteria is bad, and is what actually “spoils” your food. Food going bad without bacteria is “stale”.

So reason #1. Heating it to nearly boiling kills a LOT of bacteria. This is good.

Reason #2. Bacteria (at least the ones that hurt us) need oxygen to eat and replicate. By starving them of oxygen, by reducing the total mass of air, and therefor by extension the total mass of oxygen? You’ve forced the remaining bacteria in your food to go dormant, and not replicate.

Reason #3. Bacteria, need to eat to replicate. Just like people. When they do, their little bacteria bodies consume oxygen, and food, and emit carbon dioxide. When they do this, they increase the total air mass in the jar, and therefor increase the pressure in the jar! This happening once? Twice? A hundred times? No problem. This happening a million or billion times? You’ve got a small bacterial colony. This would hurt you. This increased the total air pressure in the jar so much that the “sucked in” lid, is actually pushed out. This serves as an easy way to tell humans that the jar belongs to the bacteria now, and we shouldn’t eat it.

A few things to note. Sorry to tell you this. Bacteria don’t hurt you! Their poop does. So when you get sick with a bacterial infection? It’s micro poop.

Bacteria farts make can lids pop

All your food has bacteria. A little? Your immune system easily takes care of it. A lot? Oh boy are you in for a world of hurt. This is because the bacteria overwhelm the antibacterial capabilities of your body, basically allowing the bacteria to out produce the white blood cells that try to take them down.

This is what C diff, and E. coli infections are. You have C. Diff and E. coli in your intestines right now! A lot of it. But your immune system, and other bacteria in your gut biome are totally capable of keeping it at bay! No issues. When the C Diff or E. coli gain too much traction, and have too large of colonies? That’s what we consider an “infection”

Introducing large amounts of this bacteria (looking at you romaine lettuce) from outside sources can cause serious imbalances.

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