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Choosing the right thermometer: a guide for cold chain professionals

Selecting the right temperature measurement device is critical to ensure pinpoint accuracy in your cold chain monitoring and HACCP compliance processes.  However, there are many different brands and types of thermometers available for cold chain practitioners and it can be difficult to know which is the best choice for your business. 

If your business is part of the supply chain that produces, stores, transports, prepares, cooks or sells chilled food, it’s critical to have an appropriate, accurate and properly calibrated thermometer so you can conduct constant temperature monitoring. This is to help prevent breaches in the cold chain, or to identify and manage them quickly if they do happen. 

Any producers and transporters of meat, fish, dairy products, eggs, ready-to-eat foods, frozen produce, vaccines and other temperature-sensitive products need to ensure that their teams at the forefront of the cold chain know how to select and use these thermometers to maintain cold chain integrity. 

Let’s take a look at the different types of thermometers and data loggers available in the Australian market, and how to ensure you’re taking accurate readings.  

Types of thermometers

Probe thermometers

Probe thermometers are one of the most common temperature measuring devices used in the cold chain sector. 

Consisting of a handheld digital display and a metal probe that can be inserted into food, a probe thermometer provides temperature readings that are typically accurate to +/- 0.5 degrees for most common cold chain applications. 

This tolerance is critical to ensuring you comply with cold chain regulations and HACCP requirements, and it can be managed through regular and accurate calibration of your device. 

Probe thermometers are lightweight, easy to use and give immediate readings for a variety of foods and liquids. An advantage of these types of thermometers over surface types is that they can give an accurate core temperature by penetrating the centre of the food item.

Infrared or surface thermometers

Infrared thermometers are also small handheld units, but rather than having a probe that pierces the food item, they measure the temperature via infrared sensors designed to measure the surface temperature of food without coming into contact with it. 

These thermometers are ideal for quick checks, but when used in isolation they typically aren’t accurate enough to comply with the requirements in the Australian & New Zealand Food Standards Code. This is because the surface temperature of the food may vary from its core temperature, giving an incomplete picture of the food’s temperature.

This means you’ll likely need both a probe and an infrared thermometer in your cold chain business. 

Infrared thermometers can be deceptively tricky to use, as the reading depends heavily on the way the operator uses the device. Measuring from too close or too far away can skew the results and give an incorrect reading, so it’s important to understand concepts like emissivity and spot size. 

Why understanding emissivity is important for cold chain businesses

Emissivity refers to the food’s ability to emit infrared energy, which determines its temperature reading, and it is expressed as a value between 0 and 1, with objects more readily able to emit infrared energy giving a reading closer to 1, and those that reflect very little giving readings closer to zero. 

In practical terms, this can result in temperature variations when measuring different areas of a single packaged product, as different labels, packaging, shrink wrap or cardboard sleeves can impede the accuracy of the infrared reading. 

What about ‘spot size’?

Spot size refers to the ideal distance between an infrared thermometer and the product, which is determined by the instrument’s distance to target ratio. This fixed ratio is determined by the manufacturer and typically printed on the body of the thermometer. 

The ratio is important because it determines how far away the operator needs to position the thermometer to get an accurate reading. 

So, what seems like a simple ‘point and shoot’ device has a number of nuances that your team must understand to ensure safe and accurate cold chain temperature monitoring. 

How often should I calibrate my thermometer? 

Regular calibration is vital to maintain the accuracy of your thermometer. And whilst regular calibration and certification is an important part of maintaining an efficient cold chain, it can easily be overlooked. 

If your equipment isn’t accurately calibrated it’s likely that it will still seem to be working correctly, however it may not be as accurate as it should be. General wear and tear and regular use of your device can gradually knock it out of its proper calibration range, so testing it under controlled conditions is the only true way to judge its accuracy. 

Cold chain practitioners and management teams need to understand the calibration requirements of their chosen device, such as calibration intervals, how to calibrate the device and whether a guarantee or certification is provided by the calibrating party. 

Some thermometers can be calibrated in-house using specialist machines, enabling cold chain businesses to check the performance of temperature probes on site whilst connected to their control or monitoring system.

Other devices can be sent away for calibration, for example to a NATA-accredited lab or testing facility. 

In any situation, it’s important to follow the advice of the manufacturer and ensure your calibration procedure is appropriate for your instruments. 

The key to getting the best out of your temperature measurement system

Whilst it’s true that a thermometer needs to be accurate, a single device can provide a range of different readings depending on how it’s used. This indicates that incorrect readings are more commonly due to a lack of understanding on how to properly measure temperature throughout the cold chain, as opposed to a dud thermometer. 

Depending on the type of product that you manufacture, handle or transport, all these thermometers have their place and one is not necessarily better than the other. Different types are commonly used together to measure both surface and core temperature, giving a more holistic view of the product’s temperature.

Ultimately, using the right thermometers in the right situations and ensuring everyone is trained in how to use them is key to maintaining a successful cold chain. 

Having a deep understanding of how to effectively use your chosen thermometer is often where businesses can improve their temperature monitoring processes, rather than just blaming a gadget for inaccurate readings. 

Cut down on waste by learning how to properly use thermometers

Food waste is such a huge issue in Australia, and whilst a vast amount of food is wasted at the consumer end, a good proportion of it happens in production and transit due to failures in the cold chain. 

Inaccurate temperature measurement and monitoring, transport failures and breaches at critical control points contribute heavily to the country’s alarming waste statistics

Of course, this has a significant effect on the bottom line of cold chain businesses too; with companies discarding large portions of stock due to issues that are often avoidable. 

If you have experienced the (expensive!) pain and frustration of turfing out wasted products, looking deeper into your cold chain monitoring practices and reviewing how staff conduct temperature checks is a quick and easy way to start tackling food waste. 

We’ve found that in many cases, providing targeted training to staff has a positive impact on waste reduction. Plus, businesses begin to see results immediately as teams use their newfound skills to more accurately measure and record temperature throughout the cold chain.

Train up your team with SuperSchool

Short, manageable courses such as Thermometers and the Cold Chain Practitioner have been designed to provide cold chain businesses with practical, down to earth training that has a direct impact on your bottom line. This course covers how to use thermometers to accurately measure temperature, and the expanded Managing Practitioner Course has an additional module covering the selection and calibration of temperature measurement devices. 

How much food are you wasting?

Get in touch to find out more about short courses on temperature measurement that can drastically reduce food waste in your business.