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Marisa: It's actually a very different process.

The reason we're able to can fruits and some vegetables in nothing more than a boiling water canner is that they are high acid foods. Botulism cannot grow in a high acid environment and so we can safely process these products by boiling recently filled jars for a prescribed amount of time in a boiling water bath to kill off any remaining bacteria and to produce a good seal.

However, meat is a low acid food, which is the ideal environment for botulism. Because of this, low acid foods need to be processed in a pressure canner. Pressure canners raise the temperature of the jar and its contents well above the boiling point, which kills off even botulism and makes the product shelf stable. So please don't try to process a meat sauce the same way you do a basic marinara.

Additionally, you should really follow a tested recipe when making tomato sauce that's to be processed in a boiling water canner. Onions and garlic are both lower acid foods, which mean that adding too much of them into a batch of sauce (though delicious it might be) destined for canning can push it into the pH danger zone. Recipes from the Ball Blue Book and other well-researched canning cookbooks are designed to maintain the correct acidity for canning, so make sure to consult them before making 12 gallons of sauce.

Marisa McClellan, our guest expert this week, is answering your questions on canning and preserving. Marisa writes Food In Jars, a blog devoted to canning, preserving, and other food in jars. She also teaches canning workshops.

Related: Canning Questions? Ask Marisa McClellan

(Image: Faith Durand)