Calibration of some instruments used in monitoring and measuring parameters related to food safety is of great importance. However, the data we obtain from not properly calibrated tools or whose calibration is interrupted may be misleading. Calibration is a set of measurements used to measure the accuracy of other measuring instruments. It is a test to determine their deviations and documents them using a measurement standard or system whose accuracy is known under specified conditions. In other words, calibration means determining and documenting the deviation of the indicator of a measuring device from the actual value of the measured magnitude. Calibration is an observation and does not involve setting operations. For a manufacturer who owns the process(es), the calibration of tools should be an ordinary activity because these tools/instruments used daily are trusted to provide up-to-date and accurate information. In sectors such as the food and beverage and pharmaceutical industry, where safety is especially important to the consumer, having a regular calibration program guarantees that instruments such as thermometers, pH meters and scales work correctly.

Common Food Safety Tools/Instruments to be Calibrated:

Calibration of some instruments used in monitoring and measuring parameters related to food safety is of great importance. The data that we will obtain from tools that are not properly calibrated or that are not calibrated may be misleading and may endanger consumers’ health in products produced as a result of misleading data. Some of these common tools/instruments are:

1. Temperature Measuring Devices:

Temperature monitoring and measurement is a widely used application in food industries. Temperature measurement is used at many points, such as sterilizing the product microbiologically, storing it appropriately or maintaining the quality of the product. In the production of frozen or canned vegetables, when the appropriate temperature cannot be reached during boiling, the peroxidase enzyme cannot be inactivated, and this may lead to deterioration in the colour and taste of the product. Likewise, storage of liquid eggs above +4 C will increase the microbiological load, and when used in production, there will be a risk of contaminating the product and the enterprise.

2. Metal Detectors and Magnets

The use of magnets and metal detectors in the food industry is widely used and extremely important. There is a risk of metal mixing in the product at different stages of production processes. At points where the metal can contact metal, such as mechanical cutting or mixing, there may be metal mixing from moving wire cuts, injection needles, or screw welded products. There is also a risk of metal parts coming from the raw materials used. In this context, the level of detection sensitivity of the metal detector used according to the part size should be minimized against these risks. In addition, the product composition can affect the metal detector’s sensitivity. For example, some electrically conductive materials, such as metal, may affect the metal detector’s sensitivity, such as salt or high water content in the product. For this reason, the metal detector in product transitions should be readjusted according to that product if necessary and checked with detection kits before production starts. Care should be taken to obtain the metal detector detection kits with calibration certificate at the first purchase. In addition, worn kits should be replaced with new ones. The magnets should be placed so that the entire product passing through the line contacts the surface of the magnet. For a magnet to be used for the first time, it should be ensured that the Gauss value is 10,000. A lower limit (Gauss) should be determined due to the decrease in the magnet’s power due to the use, and the magnet should be replaced when it is seen in the calibration reports that it falls below this lower value. According to the ‘0909MAGSEP 1-2010 Food Safety Standard, it is stated that the Gauss value of the last magnet in the line should not fall below 8,500.

3. pH Meters

As with temperature and water activity, pH measurement plays a vital role in bacterial growth. If the H+ ions in the raw material or product are more than OH- ions, that is, acidic, it will be difficult for the bacteria to survive in this environment. While the decrease in the pH level in some products such as cow’s milk, that is, decreasing to around 5-6 pH, may indicate microbial deterioration, low pH in some products such as ketchup and canned vegetables is deliberately desired in terms of having a protective effect against microorganisms.

Issues to be Considered

• The calibration document of the instrument (reference device) in which the values of our measuring instrument are compared must be questioned.
• It must be ensured that the parameters used during calibration are also tested according to the parameters in which the tool/equipment operates actively. For example, if the temperature probe is used to measure temperatures between 120 and 190 C, it should be ensured that measurements during calibration are made not only at ranges such as 20-40-60 C, but at 120, 190 C, where they are actually used.
• The tolerable deviation values of these measuring instruments used in our processes should be determined. If the deviation values measured after calibration are more significant than these values, the use status of this device should be re-evaluated. In addition, it should be determined what kind of process will be applied to the products produced by controlling with the deviating device in such a case.
• Deviation tolerance range, which devices will be included in the calibration list and calibration frequencies should be selected at reasonable levels that do not jeopardize product safety, compliance with laws and product quality by performing the necessary risk analysis and examinations by the food safety team of the factory.
• If all or part of the calibration service is performed by the enterprise’s own personnel, the person performing this service must obtained a training certificate from an accredited organization for the respective measurement types such as weight, temperature, etc.
• Calibration methods should be according to nationally or internationally accepted practices.
• All devices should be coded in order to match the devices in the calibration list with the devices in the field and the calibration report to facilitate the follow-up of the calibration list and to prevent confusion. These codes should be included in both the calibration list, on the devices in the field and the calibration report.