Find out all you need to know about measuring pH in acidified foods.
To succeed in creating high-quality foods, pH analysis should be at the heart of your strategy. Quantitative analysis needs to be a driving force behind decision-making for food formulations, quality control, and food safety.
Analytical testing can easily be integrated into the food production process. From hobbyists to food scientists, many involved in food quality and safety now use a variety of analytical testing techniques to create stable, safe, and most of all, great-tasting foods.
Analyzing data is of no use unless the data represents the actual condition of the food. The quality of analytical data depends on proper sampling, appropriate method selection, and effective measurement techniques.
This article will discuss how to utilize pH testing to ensure food quality and safety. It will cover how pH affects food quality, as well as the necessary tools and suggested measurement procedures, which will be highlighted for liquid, semisolid, and solid food samples.
How does pH affect food quality?
pH plays a crucial role in determining the quality of food by influencing its taste, texture, color, and shelf life. Thus, maintaining the appropriate pH level is critical for preserving food quality and safety.
Flavor: Organic acids, such as citric acid, can provide a tart or sour flavor to foods.
Fermentation: pH affects bacteria used in food production to make cheese, yogurt, vinegar, and soy sauce, to name just a few. Yeast performs best at a pH of 4.5-6.0.
Texture: Texture is particularly susceptible to pH changes. Low pH will result in a cheese without shape or hold while high pH causes cheese to crumble.
Appearance: pH plays a role in haze formation and contributes to pigment. Anthocyanins, the red pigments found in berries, turn blue, green, or yellow in alkaline conditions.
Shelf stability: pH prevents spoilage by inhibiting bacterial growth. Bacteria, such as E.coli, require a pH higher than 4.6 to thrive; anything lower will inhibit growth.
How to prepare samples?
Preparing food samples for pH testing involves several steps to ensure accurate and reliable results:
– Choose representative samples that accurately reflect the composition and characteristics of the food product. Ensure the samples are homogeneous and free from any contaminants.
– Direct insertion into liquid samples.
– Solids and semisolids should be processed as a paste of uniform consistency.
– Oil layers may be discarded to reduce clogging.
What do you need to measure pH accurately and efficiently?
- pH Meter: The pH meter must have a minimum 2-point calibration, automatic temperature compensation, 0.01 pH resolution, and a mV scale
- pH electrode
- Calibration solutions: The calibration buffers used should bracket the expected sample pH. Generally, pH 4.01 and 7.01 buffers will bracket most food samples.
- Cleaning solutions: Contamination on the glass sensing surface and clogged junctions are two of the most common reasons for poor electrode performance. In foods, this is particularly common because fat and protein residues can easily coat the electrode and clog the junction of the pH electrode.
- Storage solutions: A dry pH electrode can contribute to poor performance. A pH electrode will display one pH value when dry and a different value when hydrated. Every glass pH electrode will form a hydrated layer on the glass. It takes around 3-4 hours for the hydration layer to completely form. A storage solution is designed to keep the electrode bulb hydrated. Storage solutions are also formulated to prevent organic growth which can coat the electrode bulb.
- Fill solutions: The filling solution of a pH electrode diffuses slowly from the inside of the pH electrode, losing anywhere from 15 – 45 μL/hour (0.33 to 1 drops/hour). The fill solution must be topped off to maintain a proper level.
By having these tools and following proper procedures, you can measure pH accurately and efficiently, providing valuable insights into the quality and characteristics of various food samples.
An ideal pH meter for testing should have the following characteristics:
Accuracy: Provides precise pH measurements within a narrow margin of error, ensuring reliable results.
Speed: Offers fast response times, allowing for efficient testing without unnecessary delays.
Flexibility: Today’s meters offer a wider range of flexibility. A portable meter offers the ability of in-field use with the performance of a benchtop.
Ease of use: Measurement, configuration, calibration, and logging should be easy to do with data management features including direct / USB data transfer.
Simple maintenance: Advanced pH meters have diagnostics capability to inform of problems during the calibration process. Diagnostic messages should include the overall probe condition and whether the probe should be cleaned, or if the buffer is contaminated.
With these characteristics, an ideal pH meter simplifies the testing process while delivering accurate and reliable pH measurements for various applications.
