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The reason given for pressure-canning non-acidic food is that botulism spores can survive boiling temperatures, which would spoil the food while in the jars.

If that's the case, would it be possible to hot pack pressure-cooked food into a sterilized jar?

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  • Sorry I am not 100% on your question: Do you propose simple "water-bath" type canning of food that has previously been pressure-cooked (therefore presumably does not contain the botulism spores)?
    – Lorel C.
    Commented Jan 16, 2017 at 18:46
  • Yes. So Sterilize the jar, keep them in the hot water. Pressure-cook the food. Get a jar out of the water, hot pack the food into the jar. Finish in a water-bath canning. The main reason is I already have a pressure cooker, so getting another pressure canner takes up room and can be costly.
    – Calyth
    Commented Jan 16, 2017 at 18:55

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While that'd be a lot less risky than no pressure cooking at all, it's not fully safe. For complete safety, it's important that the actual canning processing be pressure cooking.

The problem is, even if the jar is sterilized, and the food is safe before you put it in, there's no way to completely ensure that no additional spores make their way into the jar before you close it. I don't think there's really any good way to assess the actual level of risk, but it's a "why take the chance" thing - in the unlikely event the food does get contaminated, there'll be no sign, and the botulinum has been given an ideal environment to grow in.

Note also that in order to actually sterilize the jars, killing any botulinum spores, you'd have to pressure cook them too, so you already need a canning pot big enough to hold them even for this plan. (It sounds like maybe you were thinking of using just a boiling water bath, but then they're only safe for use for high-acid foods that you can in a boiling water bath, not for low-acid foods that you need pressure canning for.)

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No. This is not a safe method of canning low acid food.

When we talk about "sterilization" in a home environment, we are utterly fooling ourselves. The SECOND the sanitized jars come out of the hot water they are exposed to everything in the air and on our hands and utensils and are no long sanitized. This is also the reason why it is not longer advised to bother sanitizing jars before filling them with food if the processing time will be at least 10 minutes or longer.

Additionally, the vacuum seal created in a pressure canner is FAR stronger than the weak vacuum seal created in waterbath canning. For reference: I can fairly easily pry a waterbath canned lid off of a jar, but there is NO WAY I am able to pry a pressure canned lid off of a jar.

I don't know of any references that specifically address this particular point however if you are unfamiliar with it, the NCHFP website has a lot of very useful information about how to can safely.

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    re your 2nd paragraph: If the jar is sealed against air entering, then isn't it sealed against organisms entering? Does it matter how difficult it is to pry the lid open? Stronger vacuum, ...or even more rugged adhesive,...ok it's harder to open, but don't they guard against germs equally?
    – Lorel C.
    Commented Jan 17, 2017 at 1:23
  • Yep, that part is irrelevant, but the point about organisms entering between you "sterilizing" (which if you really did, would mean you have a pressure cooker the jars fit in, so...) and sealing is very real and valid. If you are "sterilizing" with a boiling water bath, you are sanitizing, not sterilizing, and there's a very important difference if you then put low-acid food in there.
    – Ecnerwal
    Commented Jan 17, 2017 at 2:56

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