List of pH Resources for Foods
There are three basic rules for selecting samples and four criteria when selecting a portable pH meter. Sample selection: 1.Foods that are uniformly smooth in tex- ture, such as juices and sauces, can be measured directly. 2.Foods where liquid and solids are dis- tinct and separate, such as pickles and brine, measure the liquid. 3.Solid foods require some preparation if using a pH pen or meter. Blend, crush, or cut the food and add a small amount of distilled or deionized water to produce a slurry. The sample can then be assayed. Meter selection: 1. Accuracy: The best choice is a meter with an accuracy of ±0.02 units. Meters with an accuracy of ±0.10 are not as useful. 2.Function: The pH electrode should have a nonclogging tip if it is immersed in food. We find spear probes to be the most versatile and easiest to use in the field. 3.Calibration: All pH meters must be calibrated to ensure accuracy. The best meters require a 2-point calibration using pH 4.0 and 7.0 buer solutions. On occasion, when we have to assess alkaline foods, we make up a fresh pH 10.0 buer solution from a premeasured packet (alkaline buer is not stable over time). To ensure accuracy, pH meters should be calibrated at the same tem- perature as the samples being tested. As • Approximate pH of Foods and Food Products: https://webpal.org/ SAFE/aaarecovery/2_food_storage/ Processing/lacf-phs.htm • The pH of Food List from Preserve & Pickle: https://preserveandpickle. com/ph-of-foods-list • pH of Selected Foods from the U.S. Department of Agriculture: https://pmp.errc.ars.usda.gov/ phOfSelectedFoods.aspx • pH Food Chart from VitaFountain: https://www.vitafountain.com/ph- food-chart
Dierent examples of portable pH instrumentation, including a high-accuracy single electrode (top), a double electrode (middle), and a single electrode pen (bottom). Photo courtesy of Dr. Robert Powitz.
An example of pH indicator papers (1–14), along with pH indicator fluid, porcelain wells, and a color comparator. Photo courtesy of Dr. Robert Powitz.
uct after ingredients, including added acid, is thoroughly stirred and is homogeneous throughout the food matrix. Equilibrium is also dependent on temperature and time to
obtain a stable value. Let the sample reach room temperature before taking the measure- ment; changes in temperature cause pH val- ues to drift.
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September 2025 • Journal of Environmental Health
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