Hello Everyone!
As a mod team we've noticed a lot of questions and confusion about pH testing home canned foods recently so we're here today to give a more in depth explanation of why it's not recommended.
As I'm sure you all know, there are tons and tons of misconceptions about home canning and what we can and cannot do safely. One of the most common misconceptions is that if we pH test a food and it shows a pH below 4.6 it can be canned as a high acid food. There are two reasons why this isn't true.
- pH is not the only safety factor for home canning
- The options for pH testing at home are not necessarily the same as what's available in a lab setting.
Although pH is an important factor in home canning safely it is not the only factor. Characteristics like heat penetration, density, and homogeneity also play a role.
There are two types of pH test equipment; pH test strips and pH meters. pH test strips are not very accurate most of the time, they're just strips of paper with a chemical that changes color based on pH imbued in it. These strips expire over time and the color change is the only indicator which makes reading them rather subjective and likely inaccurate.
There are two levels of pH meters; home pH meters and laboratory grade pH meters. Home pH meters aren’t particularly expensive but they are often not accurate or precise at that price point. Laboratory grade pH meters are expensive, think hundreds to thousands of dollars for a good one. Many pH meters on sites like Amazon will claim that they are “laboratory grade” but they really aren’t. pH meters also need to be properly maintained and calibrated to ensure accuracy using calibration solutions which are also expensive.
The bottom line is that most people do not have access to the lab grade equipment and training that would be required to make sure that something is safe so the blanket recommendation is that pH testing not be used in home canning applications.
Recipes that have undergone laboratory testing (what we generally refer to as "tested recipes" on this subreddit) have been tested to ensure that the acidity level is appropriate for the canning method listed in the recipe. pH testing does not enhance the safety of an already tested recipe.
Because pH testing is not recommended for home use we do not allow recommendations for it on our subreddit.
Sources:
https://ucanr.edu/blog/preservation-notes-san-joaquin-master-food-preservers/article/help-desk-question-home-ph
https://extension.okstate.edu/programs/oklahoma-gardening/recipes/ph-and-home-canning.html
