The Rule of pH in home canning.

In home canning, the "rule of pH" is that foods with a pH of 4.6 or lower are considered high-acid foods and can be safely processed using a boiling water bath canner. Foods with a pH greater than 4.6 are low-acid foods and require the higher temperatures of a pressure canner to destroy the spores of the bacteria Clostridium botulinum. This pH threshold of 4.6 is the critical factor for determining the safe canning method for a food product.  

How to apply the rule

·         High-Acid Foods (pH < 4.6): 

This category includes most fruits, jams, jellies, and acidified foods like pickles, relishes, and salsa. These can be processed in a boiling water bath canner. 

·         Low-Acid Foods (pH > 4.6): 

This includes most vegetables, meats, and seafood. These foods must be processed in a pressure canner. 

·         Acidifying: 

For foods with a pH near or above 4.6, such as certain tomatoes or other vegetables, acid (like lemon juice or vinegar) must be added to the recipe to lower the pH to a safe level. 

·         Using Tested Recipes: 

Always use tested, up-to-date canning recipes from reliable sources like the USDA to ensure the pH is properly adjusted and the final product is safe to eat.