Boiling Water Bath Canning

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The boiling water bath method of home canning is recommended for processing high-acid foods. The pH is the measurement of how acidic a food is: Foods with a 4.6 pH or less are considered high-acid, and foods with more than a 4.6 pH are considered low-acid.
Boiling water bath canning involves packing jars with food, completely covering the jars with water, heating Techthe water to boiling (212 degrees Fahrenheit (F), 100 degrees Celsius (C)), and processing for 5 to 85 minutes, depending on the food product, style of pack, and jar size. Boiling removes the oxygen remaining in the jar, which helps to form a tight seal between the lid and the rim. The heat used for this method of canning is sufficient to kill vegetative bacterial cells found in the food.
Only high-acid food with a pH of 4.6 or less can be processed using the boiling water bath method. This is because high-acid foods prevent the growth of spores of the bacterium Clostridium botulinum, which can’t be killed by boiling. Foods with a pH more than 4.6 allow the spores to grow. If spores of C. botulinum are allowed to grow, toxin will form, and consumption of C. botulinum toxin is deadly.

Renee R. Boyer
Julie McKinney
Virginia Cooperative Extension