Whether testing pH in-process or on finished foods, the pH testing equipment you use influences how reliable and efficient your pH measurements will be. 

Measuring pH can seem like such a simple thing, so why can it sometimes be so difficult and cumbersome? Given the pivotal role pH plays in many aspects of food production, choosing the right pH electrode and meter is an important step in solving your top pH testing headaches.

Have you ever measured pH and thought the following:

• Why does my reading take so long? 
• What causes my meter to give the wrong result?
• How come my electrode dies and doesn’t last as long as I expected?

It may be surprising to know that many of these problems can be traced back to the electrode, while the right meter offers other benefits. This article delves into the importance of pH in food processing and offers practical tips on selecting the right pH electrodes and meters.

Why Is pH Testing Important When Processing Food?

pH plays a key role in various aspects of food production. One of the primary reasons for monitoring pH in food processing is to ensure compliance with food safety laws and manufacturing specifications set by agencies such as the FDA, USDA and Codex Alimentarius. Documented pH data forms part of the Hazard Analysis and Critical Control Points (HACCP) plan, which is mandatory for most food producers. pH meters with data logging and calibration tracking support audit readiness and testing reliability in commercial and industrial food labs. For example, the U.S. Food and Drug Administration (FDA) mandates a maximum pH of 4.6 for acidified foods, such as sauces and pickles. While pH test strips and pens are available, a pH electrode and meter are used for accurate, reliable, documented pH testing of food products, especially in the critical range from pH 4.0 to 4.6.^1-6  

pH directly influences the taste, color and texture of foods. In fermentation processes, such as those used for yogurt, kimchi or cheese, pH affects enzyme activity and microbial metabolism. For instance, in cheese making, controlling pH during curd formation can result in either a soft cheese like Brie or a hard cheese like Parmesan. In baked goods and meats, pH affects protein structure, influencing tenderness, dough strength and color stability. 

pH stability testing is important for predicting and extending product shelf stability. Shifts in pH can signal spoilage, product breakdown, loss of preservative effectiveness or a packaging failure.

How Can pH Testing Be Easier?

Given the value of pH food testing, making your pH measurements as reliable and efficient as possible will improve your manufacturing process and your food product. The electrode and meter kit you choose for your sample testing can make the difference.

The wrong choices can lead to inaccurate results, slow response, and short electrode life. Choosing the right electrode and meter leads to: 

• Fast response and quick answers. You can get results more quickly and test more samples in less time.
• Accurate, consistent results. There is less retesting and less recalibration.
• Longer electrode life. There is less time wasted in troubleshooting, trashing and starting up a new electrode. Your ultimate replacement cost and cost per test will be lower when you replace electrodes less frequently. 

Here are some tips for choosing the ideal pH electrode and meter kit.

Low maintenance: Keeping a pH electrode working well requires some maintenance. The right low-maintenance electrode can make it easier. There’s no need to refill and replace the electrolyte fill solution, or open/close the fill hole cover for measurements vs. storage. 

Refillable electrodes: While refillable electrodes require more maintenance, they tend to last longer and have longer warranties. And many can be used at high temperatures.

High temperature samples: Many low-maintenance electrodes cannot function properly once the sample temperature rises, for example above 50°C. Check the electrode specifications and choose a refillable model that can take the heat.

Temperature differences: When measuring cold or hot samples, you will need automatic temperature compensation (ATC) to keep the pH calibration accurate even when the sample is not at room temperature. ATC capability can be built into a pH electrode or can be added as a separate ATC probe.

Sample consistency: When samples are oily, sticky or creamy, they can clog the pH junction of the electrode and cause readings to become slow, drifty, unreliable and incorrect. The electrode malfunctions and needs to be replaced too often. A pH electrode with a clog-resistant junction (such as a flushable or capillary junction) will continue to work well and can be cleaned easily. After oily and greasy samples, swish the electrode gently in a warm, mild laboratory detergent mixture and rinse with purified water.

Testing location: Is your team taking pH readings on the production floor? A durable epoxy body electrode with a protective plastic housing around the pH bulb will protect it from breakage. Using ATC will give better agreement between the production floor and quality control (QC) lab results.

Calibration: Since the best results happen when the pH electrode and meter are calibrated every day, choose a meter kit that makes it easy. A meter with onscreen guides for calibration and step-by-step screen prompts is especially useful for ensuring accurate, reliable and reportable measurements. Automatic storage of calibration data makes documentation simple. If needed, activate the secure mode to restrict calibration access to personnel qualified to make valid calibrations. 

Meter durability: Meters in the lab or on the production floor are subject to spills and cleaning routines. Ensure the meter has a suitable IP rating such as IP54 to protect it from splashes and spills. A capacitive touchscreen can be operated when wearing disposable gloves, and the smooth meter face makes cleaning easier by eliminating cracks and crevices where food can build up. A rugged protective cover can be useful. Protect your investment by choosing a meter with a longer warranty period.

Testing pH of your food products is an important part of ensuring food safety, quality, taste and shelf life. While pH testing of food can be surprisingly challenging, making informed choices for your pH electrode and meter can make your measurements routine, reliable, and accurate.

References

1. Carson City Health and Human Services, Carson City, NV   USA. Acidification and Fermentation HACCP Guidance. 
2. 21 CFR § 114.90 (2017). Food and Drugs, Part 114 – Acidified foods, Subpart E - Production and process controls.
3. Pennsylvania Department of Agriculture, Bureau of Food Safety and Laboratory Services, Harrisburg, PA   USA. Canning of Acid, Acidified, & Fermented Foods Guidance for Commercial Food Establishments Licensed by PDA. Rev 12/2022. 
4. 'AOAC Official Method 981.12 pH of Acidified Foods', in Dr. George W Latimer, Jr. (ed.), Official Methods of Analysis of AOAC INTERNATIONAL, 22nd Edition (New York, 2023; online edn, AOAC Publications, 4 Jan. 2023).
5. ISO 1842:1991 Fruit and vegetable products – Determination of pH. International Organization for Standardization. ISO 1842:1991 - Fruit and vegetable products — Determination of pH.
6. ISO 11289:1993 Heat-processed foods in hermetically sealed containers - Determination of pH. International Organization for Standardization. ISO 11289:1993 - Heat-processed foods in hermetically sealed containers — Determination of pH.