Infrared measuring instruments carry out non-contact temperature measurement, i.e. with no direct contact with the food. Optical sensors measure the thermal energy emitted by objects in the invisible infrared range and display the temperature.
Practical tips for measuring correctly in the food industry
Tips for measuring correctly
- Do not stand too far away from the measurement object, otherwise the measurement object and also its surroundings will be measured
- The measurement object should be larger than the distance between the two laser points
- Adjust the measuring instrument to the ambient temperature: Observe acclimatization time in a cool environment
- For accurate measurement results: Surfaces should be clean (free of dirt, dust, etc.), product and packaging should have direct contact (no air inclusions)
The core temperature measurement is carried out with a penetration probe. This measurement is extremely accurate, since the temperature is determined directly inside the refrigerated goods. Immersion/penetration probes are specially designed for measuring in liquids and viscoplastic substances (e.g. meat, fish, dough).
Tips for measuring correctly
- Non-frozen food: Immersion depth at least 5 times (ideally 10 times) deeper than the probe diameter (for good heat transfer from the food to the probe) Example: Penetration depth = 4 mm (diameter of probe tip) x 5 = 20 mm
- Frozen food: A special frozen food probe (with corkscrew tip) must be screwed into hard, frozen food until the thread is no longer visible
- The response time of the probe is approx. 15 seconds to 3 minutes longer than the so-called t99 time when measuring in food
- Measuring instruments with a thermocouple sensor and infrared measuring instruments require an acclimatization time of 15-20 minutes when used in cold environments (> 2 min)
With a cooking oil tester, the proportion of so-called Total Polar Materials (TPM) is measured directly in the hot oil.
Tips for measuring correctly
- Remove the food to be fried and wait until no more bubbles can be seen in the oil. Any water / fried food in the oil will falsify the results
- The ideal immersion depth is between the minimum and maximum marks on the probe • Temperature of the oil during measurement should be min. 40 °C, max. 200 °C
- Keep a minimum distance of 1 cm between the probe and the metallic components of the deep fryer
- Acceleration of the cooking oil test via small circular movements in the oil
High-precision measurement of the pH value in semi-solid, viscoplastic and liquid media is carried out using a pH measuring instrument.
Tips for measuring correctly
- Use an electrode and measuring instrument suitable for the application
- Check electrode (liquid level, broken glass), open storage cap, clean with water and pat dry
- Immerse the electrode in the measurement solution, stir it briefly, then leave it to stand – until a stable reading is obtained with the aid of the Hold function
- Record the temperature of the measurement solution and the pH value
From the transportation right through to the storage of food, it is crucial to carry out seamless and continuous monitoring and documentation of the ambient conditions. Data loggers and monitoring systems are ideal for monitoring food.
Tips for monitoring data correctly
- Freezers: Long-term monitoring of the air temperature with external probes in the vicinity of the air recirculation, at ground level and around the maximum fill level
- Refrigerated storage areas/storage rooms: Install a data logger for use as semi-stationary measuring technology. Measurement data is stored and can be read out on the PC
- Transportation: Place the data loggers in the immediate vicinity so that they are in contact with the goods (e.g. in the package or between packages) or semi-stationary on the side of the vehicle or transport box
- Data loggers must comply with EN standards. Legal regulations apply to the protection class, power supply, measurement errors, registration interval and measuring instrument testing
Whether core or ambient temperature, compliance with prescribed temperature limits is crucial in the food industry. Violations of limit values put the safety and quality of food at risk.
Tips on temperature limits
- Incoming goods: Key limit values for different frozen / chilled products are in the range between ≤ -18 °C (e.g. deep-frozen products) to ≤ +2 °C (e.g. fresh minced meat)
- Storage: Daily checking of the temperature of refrigeration equipment is mandatory. For deep freezers ≤ -18 °C, refrigerators ≤ +6 °C, fresh cold storage ≤ +2 °C
- Food production: Commercial temperature limits (EU) are between ≤ -10 °C (e.g. cold production of ice cream) and ≥ +80 °C (e.g. meat/fish with a cooking time of at least 3 minutes)
- Food service: Commercial temperature limits (EU) are between ≤ -18 °C (e.g. pre-packaged ice cream) and ≥ +65 °C (e.g. meat/fish for serving soon)
Lack of hygiene and incorrect temperatures during processing and storage result in food spoiling.
Tips for processing food
- Ensure sufficient cooling or heating of food • Do not store cooked food for too long without refrigeration
- Excessively high temperatures occur in overloaded refrigerated facilities
- Pay careful attention to the personal hygiene of employees
- Strict separation of "clean" and "unclean" work processes
- Do not store raw and already heated food together
- Prevent liquid from the defrosting process coming into contact with other food
