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I prepare yogurt, which I place in 200 ml jars with lug/twist off caps.

When I prepare the yogurt, the milk is first heated at 145F and cooled to about 108F before adding yogurt inoculant. The content is placed in jars for incubation, but they do not seal in the process (for obvious reasons).

To seal jars properly, they are normally submerged in boiling water with their content. In the case of yogurt though, this would probably cook the yogurt and kill off all the nice bacteria.

Is there any way to achieve sealing yogurt-filled jars without damaging the yogurt content?

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    What do you mean by "sealed?" Sealed for what purpose?
    – moscafj
    Jun 2 at 12:49
  • you're trying to can yogurt?
    – Esther
    Jun 2 at 15:03
  • Right, sealed for the purpose of product integrity. Due to the vacuum, lug caps do not open without effort and there is clear evidence of it happens. Jun 3 at 1:38
  • Changed tags. It is more of a packaging question than a food-preservation question. Jun 3 at 1:44

1 Answer 1

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Short answer: No. More detailed answer: strictly yes, you can seal it, but it is useless for any purpose, and specifically, it won't preserve your yogurt.

Yogurt is not preservable at home, in any way. Industrially, it is possible to produce shelf-stable yogurt-derived products, such as yogurt powder, but not completely shelf-stable yogurt.

To get a misconception out of the way: canned food is not canned only because it is sealed; in fact, your yogurt is probably sealed in the sense that there are no new microorganisms entering the jar after you have closed it. You don't actually need the strong vacuum of properly canned food to avoid this, that vacuum is more of a safety margin, and a marker of fermentation activity.

For preserving canned food, you need the full combination of:

  • a food that is capable of being preserved by canning. This applies to most fruits and vegetables, and, with some methods, meat.
  • a packaging which prevents contact of the ambient atmosphere with the food
  • a method for creating a temperature high enough to kill off whatever microorganisms may be present.

For all dairy, you are already outside of any possibility of home canning. There are no methods which can give you canned dairy, no matter how well you secure your packaging against air ingress.


I kept the answer of the literal question for the end, because it is likely to be uninteresting. But in principle, yes, you can seal yogurt which you are making in canning containers. I am skeptical that this will work with the screw-top jars common in Europe, but it works for certain for the old style weck jars with glass lids with separate rubber gaskets, and possibly with mason-style jars where the screw threads are not built into the actual lid.

To seal one of these glasses without heat, you have to place it into a larger container with a small hole in the lid, and use a home vacuuming device to create a vacuum in the outer container. This will also create a vacuum in the inner container, strong enough to seal it airtight. It is a neat trick to use with things like spices, to prolong their freshness. But it is not a preservation technique.

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  • Thanks. As much as the first part of your answer was very interesting and clarified some points I was missing, it is the second part of the answer I was looking for. In fact, I was not so much interested in the preservation of the yogurt (it being dairy product with active micro-organisms) but really I was interesting in having the jar seal tightly using a method that would not damage the yogurt. So perhaps the vacuum is an option but I doubt about the lugs caps working along this process. Jun 3 at 1:42
  • @neydroydrec if what you need is for your yogurt not to leak, then the easiest way is to ferment it in a leak-proof container. I doubt that there is a way to make twist-off glasses leak proof, and if somebody comes up with an idea, it will likely be quite a hassle. Usually, using the right tool for the job is the best way to go.
    – rumtscho
    Jun 3 at 6:34

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