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Old 11-13-2003, 10:52 AM
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Linda Lou Linda Lou is offline
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Laurie, apples are a high acid food, since they are a fruit. Apple butter is fine, due to the acid content. High acid foods may be safely water bath canned. Pumpkin is a low acid food. Foods with a ph level of more than 4.6 must be pressure canned. But, with the pureed pumpkin, it gets too dense and the heat cannot safely penetrate to the center of the jar enough to destroy all the botulism spores. That is why chunks of pumpkin may be pressure canned, because you lightly pack them in the jars, then fill the rest of the jar with water. Then they can be safely pressure canned to destroy any botulism spores.

Safe canning of foods is based on different things, the main ones, density of the food, and acid or ph level. There are other factors,too.
The USDA used to publish a recipe for home canning pumpkin butter, but with reports of botulism, the recipe was retested, found to be unsafe, and pulled in 1994, I think was the year. You may find all sorts of recipes still around, but unless a preserving recipe comes from a reliable source, such as the USDA or Ball company, we do not recommend canning it. You would be amazed at how many recipes and methods are in books and on the computer that are unsafe.

Learning about all this has sure been an eyeopener to me. I really find it so fascinating.

This time of year folks want to "can" breads and cakes in jars. Again, this is very dangerous, like the pumpkin butter. It is too dense, the ph level too high, and not even canned, but just a lid put on them. (You can freeze them.)

The commercial industry has machinery and also chemical preservatives to add to their foods to make them safe. We can't duplicate those things in our home kitchens. That is one reason people like to can their own foods, to get away from the preservatives.
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