Why the centre and not the surface
Heat and cold move through food from the outside in. A roast out of the oven can be well past 75°C on the outside and under 60°C in the middle; a large container of curry going into the fridge can be cold at the edges and still warm at the core hours later. The centre is the last part to reach a safe temperature, so it's the only reading that tells you anything useful.
For thin items, probe the thickest section you can find. For a bulk container, probe the geometric middle. If you're checking a delivery or a display of packed items, take readings from more than one pack rather than trusting a single one.
This comes up on the test — and the training that covers it is free to read.
Start the Free TrainingUsing the thermometer properly
A food business handling potentially hazardous food is required to have a thermometer accurate to plus or minus 1°C and readily accessible. Getting the reading right takes a few seconds of care.
- Clean and sanitise the probe before and after every use, and between different foods
- Insert into the thickest part, avoiding bone, fat and the container itself
- Wait for the reading to settle rather than taking the first number
- Check the fridge's own display against a probe reading — displays drift
- For hot holding, check the food, not the air temperature of the bain-marie
- Record the reading if your workplace keeps temperature logs
The numbers you're checking against
Cold potentially hazardous food should be at or below 5°C. Hot food being held for service should be at or above 60°C. Potentially hazardous food is generally cooked to 75°C in the centre. Anything found between 5°C and 60°C is in the temperature danger zone, and the 2-hour / 4-hour rule then decides whether it can be saved.