pH sensors play an integral role in the food processing and preservation industry by measuring the acidity or basicity of a substance. They are essential for maintaining food quality, safety, and shelf life. This article discusses the importance of pH sensors in food processing and preservation and how they are used to maintain food quality.
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What is pH?
The acidity or basicity of a substance expressed on a scale of 0 to 14, with 0 being the most acidic, 7 being neutral, and 14 being the most basic, is known as pH. The amount of free hydrogen ions in food directly affects its pH. Food acids produce free hydrogen ions, responsible for acidic foods' unique sour taste. In this way, pH is viewed as a measurement of free acidity or as the negative log of the concentration of hydrogen ions. Since it influences the pace of microbial growth, enzymatic activities, and chemical reactions that may lead to food spoiling or degradation, pH is a crucial element in the processing and preservation of food.
Importance of pH Sensors in Food Processing and Preservation
pH sensors are critical in the food processing and preservation industries because they give precise and dependable measurements of pH levels in food products, which monitor and regulate processes such as fermentation, pasteurization, and preservation. The pH level of a food product may impact its safety, quality, and shelf life; thus, maintaining the optimum pH level throughout processing and storage is crucial.
Types of pH Sensors
Several types of pH sensors are available, including glass electrodes, ISFET (ion-selective field-effect transistor) sensors, and optical sensors. Glass Electrodes pH Sensors are made out of a glass bulb with a reference electrode and a sensitive electrode. When the glass electrode is submerged in the sample, the pH difference between the sample and the reference electrode produces a voltage that the sensor measures. In contrast, ISFET sensors employ a field-effect transistor to assess the pH of a sample.
Comparing Glass Electrodes and ISFET pH Sensors
Since an ISFET chip pH sensor does not employ fragile glass in its construction, it is more robust than a glass bulb, giving an option in situations where broken glass might be hazardous to workers, organisms, or operations. In addition, ISFET chip pH sensors can respond ten times quicker than glass bulb pH sensors, allowing faster readings and improved process control.
Moreover, compared to glass bulb pH sensors, ISFET chip pH sensors have a longer life, a smaller size, greater resilience to acidity and basicity, and greater stability at low temperatures, making them ideal for food processing and preservation.
Applications of pH Sensors in Food Processing and Preservation
pH sensors are used in various food processing and preservation applications, including fermentation, pasteurization, preservation, quality control, etc.
Fermentation and Pasteurization Processes
PH levels influence the development of the bacteria that cause fermentation; thus, using pH sensors to monitor pH levels during fermentation operations is crucial for the quality and safety of the finished product, such as yogurt. Similarly, during the pasteurization process, a heat treatment method used to eradicate hazardous germs and enhance the shelf life of foods, pH sensors are employed to guarantee that the pH level is within the appropriate range.
Food Preservation and Quality Control
The low pH of canned products inhibits the growth of microorganisms that can cause spoilage; hence, maintaining the appropriate pH level using pH sensors is critical to their safety and shelf life. Similarly, the acidity and sweetness range is crucial for assuring top-quality beverage manufacturing, which is also assured by pH sensors.
The electrochemical behavior of a carbon electrode based on salicylic acid for usage as a new solid-state reference electrode in a redox-based pH sensor is covered in a 2022 study. Using various compositions, conductivities, low buffer concentrations, and ionic strengths in solutions, this novel reference provided a pH-insensitive response spanning the pH 3–10 range.
A novel pH sensing element based on electropolymerized flavanone was combined with this reference system to create a pH sensor that does not need calibration and can detect the pH of different mediums with high viscosity and poor conductivity with a maximum error of 0.03 pH units.
Challenges and Future Prospects
While pH sensors are a vital instrument in the food processing and preservation sector, inherent challenges and factors need to be considered. One of the biggest issues is maintaining the sensor's accuracy and reliability since variables such as temperature, sample viscosity, and electrode drift may impact measurement accuracy.
More breakthroughs in pH sensor technology that will continue to enhance the accuracy and reliability of these critical instruments in the food sector are predicted as technology advances. For instance, pH sensors may be linked with IoT devices to provide real-time monitoring of pH levels, temperature, and other elements that might impact food quality.
Similarly, pH sensors may be combined with AI and machine learning algorithms to assess vast volumes of data and anticipate food product quality and safety, assisting in optimizing food processing and preservation procedures. Overall, pH sensors are likely to play a growing role in ensuring that food items are processed and maintained at the proper pH level to ensure quality and safety.
Continue reading: The World's First Edible Food Sensors
References and Further Reading
Ahmad, N. A., Yook Heng, L., Salam, F., Mat Zaid, M. H., & Abu Hanifah, S. (2019). A colorimetric pH sensor based on Clitoria sp and Brassica sp for monitoring of food spoilage using chromametry. Sensors. doi.org/10.3390/s19214813
Chen, Y., Sikkandhar, M., & Cheng, M. Y. (2022). Solid-state ion-selective pH sensor. IEEE Sensors Journal. doi.org/10.1109/JSEN.2022.3172717
Miranda Mugica, M., McGuinness, K. L., & Lawrence, N. S. (2022). Electropolymerised pH Insensitive Salicylic Acid Reference Systems: Utilization in a Novel pH Sensor for Food and Environmental Monitoring. Sensors. doi.org/10.3390/s22020555
The importance of food ph in commercial canning operations (2016) [Online] Oklahoma State University. Available at: https://extension.okstate.edu/fact-sheets/the-importance-of-food-ph-in-commercial-canning-operations.html#:~:text=common%20food%20types-,pH%20and%20microbial%20growth,to%20offer%20much%20preservative%20value (Accessed on 7 April 2023)
What are the advantages of using an ISFET chip pH sensor instead of a glass bulb pH sensor? [Online]. Available at: https://www.campbellsci.com/faqs?v=881 (Accessed on 7 April 2023)
What is ph? (2022). Cooperative Extension Service. [Online] Clemson University Available at: https://www.clemson.edu/extension/food/canning/canning-tips/44what-is-ph.html#:~:text=The%20pH%20value%20of%20a,a%20measure%20of%20free%20acidity (Accessed on 7 April 2023)