As a food safety instructor for restaurant managers, one of the things I earnestly teach is the use of food thermometers. Standing on my soap box, I preach…
If you don’t use a thermometer, then how can you know for sure that the food is safe to serve?
A key part of my lesson on thermometer use is a discussion of how to actually calibrate the thermometers. We start by checking to see if the thermometer is correct. If it isn’t correct, proper calibration is necessary in order to make adjustments until the thermometer reads temperatures accurately. After all, if the thermometer isn’t right, then there really isn’t any point in checking the food’s temperature. It is recommended that employees of restaurants calibrate their thermometers each time they come to work.
Here’s how to calibrate a thermometer.
Start with a bowl of ice water. The temperature of a slushy mix of 1 part water to 1 part ice should register as 32 degrees Fahrenheit (F). When it doesn’t, the students are instructed on how to adjust the thermometer until it is correct.
Why do these thermometers change?
There are lots of reasons for a shift in thermometer accuracy. Being dropped in the sink or on the floor can mess up the calibration. If they go through a severe temperature change, this may also make them inaccurate. Rolling around in the back of a silverware drawer can also bump thermometers, causing changes. I’ve checked brand-new thermometers out of the box and some have even needed calibrating then!
At home, I’m an avid advocate for using a food thermometer.
That said, I have to confess that I don’t remember the last time I calibrated my home thermometer.
After a recent class, I chastized myself, jumped down off my soap box, and checked my own thermometers. Two were good. One needed an adjustment with a wrench to make it accurate. Even my brand-new digital thermometer needed some adjustment. One thermometer that couldn’t be calibrated was pitched.
When buying a thermometer, look to see that they can be calibrated. Not all thermometers can be calibrated. Bi-metallic stemmed thermometers should have a calibration nut on the back that allows you to adjust the dial. Many newer digital thermometers have a self-calibration feature. Digital thermometers with a thin tip and quick reads are really nice. They allow for easier testing of thin pieces of meat and quicker response.
Another piece of advice: when buying a digital thermometer, a good feature to have is a shut-off timer so you don’t burn down the battery. I learned this from experience.
I know it’s hard enough to get people to use food thermometers in the first place, much less calibrate them, but this is an important step that shouldn’t be forgotten.
When was the last time you checked your thermometer?
Cheryle Jones Syracuse, MS Professor Emeritus at The Ohio State University
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