If you make home-made preserves, jams, jellies and pickles, the US Department of Agriculture recommends that you use pressure canning to destroy the types of bacteria that can grow in a sealed environment (such as botulism).
The spores in bolutism can survive boiling water (212F or 100C), but cannot survive at the higher temperatures produced by pressure canners (240F to 250F or 121C).
Low acid foods, such as meat, poultry, most vegetables (e.g. cabbage) and fruits such as figs are particularly prone to botulism, and are best canned in a pressure canner. Acidity does tend to destroy botulism spores, but to be safe you can use pressure canners to can tomatoes, lemons and oranges as well, you just use it for a shorter time than when canning the low acid foods.
Some foods such as pesto, oils, pumpkin puree, have such a low amount of acid that they need higher temperatures than 250F to can them - you cannot can these at home, they need a commercial canner.
Always be safe when preserving foods..
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