In every kitchen or processing area, a food thermometer is one essential tool that shouldn’t be missed. It helps us prevent overcooking or under cooking of food and food poisoning, and monitor temperature inside the fridge and it also minimizes wastage. However, if the thermometer is not calibrated, you won’t get these benefits—so it’s still a hit or miss.
The most critical thing when using a food thermometer that is not property calibrated is how you would be able to keep the food from staying 40°F (5°C) and 140°F (60°C), in which microorganisms doubles in number in as fast as 20 minutes (the temperature danger zone).
So keep your thermometers accurately working by calibrating them regularly. Keep reading to know how.
How to calibrate a food thermometer
There are two methods that you can use. Do not worry because these are quick and easy to do.
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Ice Point Method
Use this method for food processes that require low temperatures.
- Fill a cup or container with crushed ice or ice cubes
- Top it off with cold water
- Stir and let it sit for 3 minutes for the temperature to stabilize at 32°F (0°C)
- Put the thermometer’s probe (submerge 3 inches at least) into the container for 30 seconds. Make sure the probe isn’t touching the container (at least 1 inch from the bottom).
- The thermometer should be reading 32°F (0°C)
- Record reading
Boiling Point Method
Use this method for food processes that require high temperatures.
- Fill a pot with distilled water
- Bring it to full rolling boil
- Place inside the thermometer for 30 seconds (submerge 3 inches of the probe at least). Make sure the probe isn’t touching the container (at least 1 inch from the bottom)
- The thermometer should be reading 212°F (100°C)
- Record reading
It is better to calibrate in 3 trials for precision.
If the thermometer doesn’t read 32 °F (0°C) for Ice Point Method, or 212°F (100°C) for boiling point method, here’s what you should do:
Without removing the probe in the container, simply adjust the thermometer by adjusting the calibration nut located underneath the head of the thermometer until it reads 32°F (0°C) or 212°F (100°C) .
Now there are thermometers that can’t be adjusted. If yours can’t, just adjust your values every temperature check.
Further read: Korean Study: Overcooking With Air Fryers Creates Toxic
For example, your thermometer reads 214°F (101°C) instead of 212°F (100°C) during ice point calibration. If you check your food’s temperature and it reads 210°F, the food’s true temperature should be 208°F, a 2°F adjustment.
When should you calibrate your thermometer?
Like most equipment that are regularly used, food thermometers lose accuracy over time, especially if it is frequently used.
Ideally, food thermometers must be calibrated before use, just like in food factories where calibration of food thermometers daily is a norm. There are special cases when calibration must be made between testing like when the thermometer is dropped or it hit a hard surface during testing. Even small impact can significantly reduce its accuracy.
Additional Tips
- In food factories, every calibration done is recorded in a log book for traceability.
- Do not use a thermometer for checking cold and hot temperature. Secure two thermometers: one for cold, and one for hot temperature.
- Long storage of a thermometer may affect its condition and its accuracy. Calibration is a must.
- Always keep thermometers away from direct sunlight, high temperature and humidity. Store them at room temperature.
