How to Calibrate A Kitchen Thermometer

By Brian Harris

A working thermometer is crucial to any kitchen. At times, calibrating that thermometer may seem like a menial or obsessive task, but failure to do so can have far-reaching and devastating consequences in the form of foodborne illnesses.

Restaurants need to put it in the daily routine when they self-audit their kitchen, and while it can get crazy in the kitchen during peak hours, it’s always important for managers to make time for this task. There’s simply no other way of knowing what the temperature of your food products are when cooking or storing them. In the restaurant and foodservice industries, there’s no room for this kind of guesswork.

There are two different methods for calibration, but each require just three steps.

Method 1: Ice Water

1. Fill a container with ice cubes, then top off with cold, distilled water to form a watery slush.
2. insert thermometer probe into the container, making sure not to touch the sides.
3. The temperature should read 32°F (0°C) after 30 seconds. If it doesn’t, the thermometer needs to be recalibrated. Record the difference and offset your thermometer as appropriate.

Method 2: Boiling Water

1. Boil a clean container of distilled water.
2. Once the water has reached a rolling boil, insert your thermometer probe. Once again, make sure the probe does not touch the sides or bottom of the pot.
3. The temperature should read 212°F (100°C). Record the difference and offset your thermometer as appropriate.

[Note: The boiling point of water will vary with altitude. Use this handy water boiling point calculator to find the right temperature for your elevation.]

Non-adjustable thermometers should be removed until they have been professionally serviced.

How to Calibrate a Traditional Thermometer

Traditional dial thermometers have a little screw or nut that adjusts the dial to the correct temperature. Turn the adjuster until the dial reads the correct temperature according to the method you’re using to calibrate.

Re-calibrate a dial thermometer after you drop it, before you use it for the first time, if you use the same thermometer to measure very cold or very hot temperatures. Also calibrate if you use the same thermometer multiple times daily or weekly. This definitely is the case for restaurants.

How to Calibrate a Digital Thermometer

This is where digital thermometers have a clear advantage for ease-of-use  — simply push the reset button! Some thermometers, like ThermoWorks’ BlueTherm Bluetooth Probe, are also compatible with mobile checklists for HACCP compliance. Readings are recorded quickly and easily on the mobile device.

For more information on BlueTherm’s integration with Zenput, check out this article.

The Takeaway

Staff Requirement
Every restaurant should require their kitchen staff to learn how to calibrate the thermometers.

Self-Auditing
As a part of their daily routine, restaurant managers should have “calibrate thermometers” on their checklist. Doing so will lock in food quality and significantly reduce the risk of foodborne illness.

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