Canning recipes, such as those found on university-extension websites and those supplied with boiling-water canners, undergo pH testing to ensure they meet the pH threshold for safe preservation: 4.6 or less. Unlike pressure canners, which kill microorganisms with heat, boiling-water canners rely on foods' acidity for preservation. If you're preserving food made from an untested recipe using a boiling-water canner, you have to test its pH before you can it, and 24 hours after you can it. You can use a pH meter or strips for testing. However, pH meters are relatively inexpensive and more accurate than strips.
Things You'll Need
- pH test meter or pH test strips
- Distilled water
Divide 1 cup of food into 4 portions. Add 1 of the portions to a blender.
Blend the food until smooth. Add distilled water to the food as needed to create a loose slurry and blend it again. Transfer the food to a plastic food container or glass jar.
Insert the test meter's probe into the food and record the pH on paper. The food must cover the metal electrode at the tip of the probe. If using pH strips instead of a meter, insert one in the food and compare its color to the supplied color-gradient scale.
Blend and measure the remaining 3 portions of food individually and record the results; rinse the metal electrode at the tip of the probe in distilled water between tests.
Add the recorded results and divide their sum by 4 to get the pH of the food.
Tips & Warnings
- Use a pH meter with an accuracy of +/-0.01-0.02 pH u for food testing.
- Don't test pH of oil. For example, if you're testing the pH of an oil-based salad dressing, blend and test all the ingredients except the oil.
- Follow the pH meter's supplied instructions for specific information on cleaning and calibrating the meter.
- Photo Credit Pumba1/iStock/Getty Images
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