I make soup in a slow cooker and I'd like to store individual servings. If I take the freshly made hot soup from the slow cooker and ladle it into mason jars and screw down the lids, is that safe? I don't have any experience with canning.

  • How are you hoping to store the jars?
    – user293
    Oct 16, 2016 at 19:33
  • 2
    If you intend to keep the jars at room temperature: Absolutely not! But in general, @TimPost's question should be answered and please tell us, for which time frame you want to store the soup.
    – Stephie
    Oct 16, 2016 at 19:55
  • Good question! I'd be fine storing in the fridge (and maybe some in the freezer). What kind of time frame would that give me?
    – Joseph
    Oct 16, 2016 at 20:27
  • 2
    I think this is probably just a duplicate of cooking.stackexchange.com/questions/21068/… - food in the fridge or freezer should always be airtight, and there's nothing special about soup and mason jars. (What you're talking about isn't canning, it's just a container that happens to also be used for canning.) Or did you want to know about basic canning processes?
    – Cascabel
    Oct 16, 2016 at 20:32
  • To sum up the canonical post: three to four days in the fridge, freezer time is unlimited as far as safety goes, for quality reasons aim for ca. three months storage. If we are not talking about "real" canning, this is a duplicate of the canonical post.
    – Stephie
    Oct 17, 2016 at 6:31

1 Answer 1


Since you are asking about canning then what you are describing is not a canning process which will give you a result you can store long term at room temperature. Long-term storage of soup would require pressure canning to raise the internal temperature high enough to kill any foodborne illnesses.

If you plan to freeze the soup then mason jars aren't ideal, they'll work but they are bulky and take up a lot of room. In any case you don't get any real benefit from putting the lid on when hot if you are going to freeze them, you're better off letting it cool so you don't end up overwhelming your freezer's cooling capacity.

  • Perhaps mason jars are not the best choice if we are looking for optimal packing in the freezer, but I can see a few reasons why OP might want to use them anyway, from the posibility of using the jars from freezer to table (not w/o thawing, please!) to aesthetic reasons or simply b/c that's what he has on hand...
    – Stephie
    Oct 17, 2016 at 6:34
  • Plus, if it's boiling-hot, and you put a lid/cover on it, won't that help to limit organisms from getting in once the soup has cooled? I don't disagree that you don't need to put it straight into the freezer, but I'd definitely cover them while they are cooling on the counter at room temps. Oct 17, 2016 at 19:45
  • OP says slow cooker, so it probably won't even be boiling hot. And contact with the cool jar will cool it even further, so you might not even get the mostly-pasteurization you get with "open canning". Oct 18, 2016 at 10:18
  • Does it make a difference if the jars have been sanitized first? E.g, I'm a home brewer so I already have sanitizing solution (starsan or IO star)? Let's say the soup was boiling hot and the jars were sanitized, room temperature storage is still unsafe without following a proper presure canning, yes?
    – Joseph
    Oct 18, 2016 at 17:42

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