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Canning -- Miscellaneous

When should I remove canning jars from a water bath?

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Jars should be removed from the water bath canner as soon as the processing time is up. The spores of certain thermophilic (heat loving) bacteria may survive water bath processing and then thrive while left in the water bath. Flat sour spoilage in tomatoes is one example of thermophilic bacteria spoilage. They do not grow rapidly at room temperature. Jars in a pressure canner, though, must remain in the canner while the pressure is returning to zero after the canner is removed from the heat (about 34-40 minutes). Attempting to quickly reduce the pressure will result in liquid loss from jars (resulting in a poor quality product and a likely seal failure). Also, the product may be under-processed since the cool down time may be counted as part of the processing requirement.

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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