🗓 27/07/2021 👤 Anne Sophie

Why do some jars make a popping sound when opened and others do not?

You bought a nut puree in a jar and wonder why there was no popping sound when you first unscrewed it? Don't worry, it's not because the product was already opened. Why some jars "pop" when opened and others don't, we explain here.

Why do some jars make a popping sound when opened and others do not?

"Plopp" - this melodious sound reveals a lot about the type of closing mechanism of a glass. Only jars that are filled in a vacuum closing system also "pop" when unscrewed. In this process, the product is heated before it is filled into the jar. When the product then cools again, the air contracts and a vacuum is created. This causes the lid to tighten. When the lid is opened for the first time, air enters the jar again and the vacuum escapes. The familiar plopping sound can be heard.

No vacuum, no plop!

If jars are to be sealed without a vacuum, only the lid is heated instead of the product. The material layer integrated in the lid thus softens and adheres to the jar when it is sealed. Since this process does not create a vacuum in the jar, it is somewhat easier to unscrew the jars and accordingly no popping sound is heard when opening them. The vacuum-free sealing technique allows the product to be filled in a way that is gentle on the nutrients, as it does not undergo any additional heating.

KoRo Glas

High quality even without a plopping noise

So if our jars of nut puree don't pop when you open them, that's by no means a lack of quality or freshness. Because of their high fat content, nut purées keep well even without a vacuum. The naturally settling oil layer also acts as protection against oxygen ingress and thus preserves. By the way, we have tested how you can get the puree creamy again in no time in an article for you!

Whether one of our products has been filled in a vacuum sealer, you can easily tell from the lid: Vacuum-sealed jars have additional slight bulges on the lid. Jars that are sealed without vacuum, on the other hand, can be recognized by a lid with a smooth surface.

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