FOOD SCIENCE 85
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Hanna’s new electrode and app allow operators to use their iPhone or iPad as a research-grade pH meter
ncreasing numbers of people in the food industry are being required to test pH for both safety and quality reasons. Advances in technology mean that you don’t need to be a technician to deliver precise and accurate results consistently. In technical terms, pH is
the hydrogen ion activity in a solution. It’s measured on a scale of 0 to 14, with 7 being neutral. Effective monitoring of pH in the food industry begins with testing raw materials and continues throughout production to the finished product.
pH is an essential parameter because of how it effects food characteristics such as texture, flavour, aroma and others. Cheese is a great example of how pH influences the chemical and physical properties of food. Te casein matrix of cheese is created by protein bonding. In those with an initial pH of higher than 5.0, calcium phosphate crosslinking occurs and the casein interacts strongly with water, creating the elastic, smoother texture found in young Swiss and Cheddar cheeses. As the pH decreases, these
protein crosslinks are altered and the casein loses its ability to interact with water. Tis results in the harder consistency found in aged cheddars and white mould cheeses.
Food safety and regulation pH plays a crucial role in inhibiting the growth of microorganisms. It is for this reason that US government agencies, such as the Food and Drug Administration (FDA), regulate pH levels in many commercial food products. Generally speaking, food falls into two categories according to 21CF114. Tose that have a natural pH of less than pH 4.6 are known as acid foods while
low acid foods have a pH higher than 4.6.
Acidified foods When an acid is added to lower the finished pH of a low acid food to below 4.6, these foods become known as acidified foods. Examples include canned goods, salsas and sauces. In the production of acidified foods, a final pH higher than 4.6 will result in an environment that promotes the growth of harmful bacteria that, when consumed, can cause illness. Not only does ruined food present a health hazard to the public, it can also halt business operations if further evaluation is necessary. Determining best practices for measuring pH can be a challenge due to a variety of different sampling methods, meters and electrode designs. Across the globe, there
are numerous regulations regarding appropriate sampling methods and levels at which certain parameters must be in order to be considered safe for consumption. Some standard methods are even specific to the type of equipment and the required degree of resolution. Although pH strip indicators and other basic methods are available, the best possible accuracy comes with using a pH meter and electrode. Tis method provides the highest degree of precision and is less subjective than a chemical-based testing method that uses colour indicators to determine pH. Choosing a pH meter and
electrode specific to measuring pH in food is crucial to getting accurate and reliable results. It is important to consider the sampling points during production at which you will be testing. A durable, portable meter offers the mobility to test pH anywhere, at any time in a production facility, while a high- performance benchtop meter is
best suited for stationary lab use only.
Hanna’s new Halo Foodcare
Bluetooth electrode and Hanna Lab app allow people to use their iPhone or iPad as a research- grade pH meter or pair it with a Bluetooth-enabled meter. No wires are needed. Many portable and benchtop pH meters now have storage for data logging and advanced diagnostic capabilities to help make testing as user-friendly as possible.
Te minimum requirements for a pH meter recommended by Hanna Instruments for food testing would include: 0.01 pH resolution; two- point calibration; automatic temperature compensation (ATC); and electrode. Although the features in a
meter are important it is equally, if not more critical, to choose the appropriate pH electrode for your application. Hanna Instruments has a full line of Foodcare pH electrodes that are designed for specific applications. Te design considerations when making a pH electrode for a specific use include the shape and type of glass, junction material and body type. Of the design considerations, the type of reference junction used is one of the most important. Te reference junction is an electrical pathway between the sample and the internal reference cell. Tere are a variety of materials that can be used for the reference junction. Te most common
is a porous ceramic that works great in aqueous solutions. Another material is Polytetrafluoroethylene (PTFE) that repels solids. A sleeve junction made with PTFE is ideal for solutions that have a high solid content such as fruit juices as it helps to prevent clogging.
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