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Oven canning

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Is it really unsafe? I have read warning after warning about it, but there is a very popular cook/gardener here in Denmark that has been demonstrating it on TV for years and I just wonder how she can get away with it if it really is so dangerous. It's on a public broadcasting channel, so I'd think they'd be alert to that kind of thing.

On the other hand, she's been canning in the oven for years, and sells tons of cookbooks describing the process. Several of my neighbors have canned everything from meat to tomatoes to fruit using the method. It sure looks easier than the hot water bath method, and cheaper than the pressure cooker method since I don't have the equipment, so I'm determined to find out the facts here. Anyone?

I apologize if this has been posted a bazillion times already--I did a search and didn't find it, though.

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  1. It boils down to this. Food science/research has provided us with information to reduce the incidence of food born illness. If you have read the warnings then you have read about uneven or insufficient heating, jar breakage and the necessity of canning low acid food in a pressure canner. Oven canning MAY work under some circumstances. There other circumstances where it is not safe. Water bath and pressure canning have a higher degree of safety in their respective applications. You either take advantage of what has been learned or not. It is all about reducing your odds of getting sick. Food born illness can be mild or result in death. The choice seems pretty easy to me, as I have seen the results of severe food born illness, but you will find plenty who have used less safe methods for years and say "nobody ever got sick".

    1. First: Canning in the oven should mean placing jars filled with food in a shallow container with WATER!. Second: THE safety factor is whether the lid SEALS!!. If the lid seals, the food is good. Third: Anytime a lid does not seal (using ANY method of canning), when the lid is removed the smell will be the undeniable clue. Period.

      3 Replies
      1. re: launicaliz

        "If the lid seals, the food is good."

        This is not true. The spores that can cause botulism grow only in the absence of oxygen in low-acid, moist environments. The reason for pressure canning is to heat low-acid food in the middle of the jar to a high enough temperature to kill the spores (higher than the boiling point of water). High acid foods should still be heating in a boiling water canner to kill other microorganisms. From the National Center for Home Food Preservation:

        "When ideal conditions exist for growth, the spores produce vegetative cells which multiply rapidly and may produce a deadly toxin within 3 to 4 days of growth in an environment consisting of:
        - a moist, low-acid food
        - a temperature between 40° and 120°F
        - less than 2 percent oxygen

        Botulinum spores are on most fresh food surfaces. Because they grow only in the absence of air, they are harmless on fresh foods."


        1. re: launicaliz

          "THE safety factor is whether the lid SEALS!!. If the lid seals, the food is good. "


          There is quite a bit more to canning safety than that. Obviously, unsealed cans shouldn't be stored/used. But a sealed container can still make you sick or even kill you. Offhand, I would think that a highly reliable, accurate oven could pasteurize jarred food. Which is not at all the same as sterilizing it. You'd probably be quite safe if you froze the jars after canning - but then what was the point of canning?

          Wekick said it right. Just because you can do something a few times (or even habitually) and not get sick doesn't mean it's safe. Botulism is nothing to fool around with.

          1. re: launicaliz

            Wow. All three points are wrong.

            Because an oven is not under pressure, that means the temperature of any water, either inside the oven or inside the jars, can never rise above 212F, which is not enough to kill the botulinum spores, which need a temp of at least 240F.

            The second point has already been addressed. WRT point three: Botulism is invisible, tasteless and odorless.

          2. For many years people always canned in ovens. NEVER once did anyone get sick. My guess when one gets sick from home canned foods the lids seal on could be from some type of chemical put into the food before canning.

            2 Replies
            1. re: rhondamike

              Who do you know who puts "chemicals" into their home-canned food?

              1. re: rhondamike

                I'd like to know what authority you have to make a declarative statement like this about the general use of oven canning?