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Canning -- Miscellaneous

After processing, is it safe to assume that food is safe to eat?

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People think that the only purpose in processing food is to get the lid sealed on the jar. Therefore, when they follow a non-recommended procedure (like water bath processing green beans) and the jars seal, they think they have a "safe" product. A seal only indicates that a vacuum has been formed. You can get a weak seal, vacuum, by placing hot food into a hot jar and placing a prepared lid and screw band on it. It will draw a weak vacuum as the jar contents cool but the products inside may be unsafe. The purpose of processing food is to treat it with the prescribed temperature (boiling water temperature or 240 degrees F. at 10 pounds pressure) for the prescribed amount of time. These processing times and temperatures have been tested with that specific food when it was inoculated with bacteria to see if the processing time/temperature combination is adequate to kill the bacteria that were intentionally placed in the product. The purpose of the seal is to keep the food that has now had any microorganism or spores destroyed from becoming contaminated with other microorganisms during storage.

PREPARED BY: Angela M. Fraser, Ph.D., Associate Professor/Food Safety Specialist, and Carolyn J. Lackey, Ph.D., R.D., L.D.N., Professor/Food and Nutrition Specialist, North Carolina State University (August 2004)

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