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How to Choose and Use a Food Thermometer

Our recent article about why thermometers are important for food safety may have gotten you thinking about getting one or using the one you have more often. If so, here’s some advice on how to select and use one.

If you’re in the market for a new food thermometer, there are a lot of options out there from the $6 dial thermometer to the $99 digital thermometer that sends alerts to your smartphone from the grill.

http://www.dreamstime.com/stock-photo-checking-meat-image3197530Any food safety educator you ask will probably tell you about a particular instrument that’s their personal favorite, but in general, they recommend that consumers pick a digital one because it’s tip-sensitive.

From there, the choice to spend $20 or $90 probably depends on how much you cook.

“It’s a tool just like a frying pan,” says Benjamin Chapman, associate professor of food safety at North Carolina State University. “The more you cook, the more investment you put into your tools.”

An inexpensive thermometer makes sense for someone who doesn’t cook a lot of raw meat and poultry.

The different prices for digital thermometers typically have to do with their durability, their speed, and special features such as a smartphone connection or being fully dishwasher-safe.

“You’ll generally pay more for a faster response time,” says Tom Woodbury, chef and national account manager for Thermoworks.

He advises people to be careful with thermometers labeled “Instant Read.”

“Some thermometer manufacturers use that term to describe the frequency with which the display is updated, but not necessarily the speed that the thermometer display reflects an accurate temperature,” Woodbury notes.

As for dial thermometers, or bi-metallic stems, they’re “not great tools,” Chapman says. “They’re fine in a jam, but they do have to be calibrated.”

Over time, the expansion and contraction of the probe’s metal housing can cause the mechanical works inside to shift and then show an incorrect temperature.

To calibrate a thermometer, you place it into either ice water or boiling water and adjust the dial accordingly.

Woodbury recommends that people check the accuracy of their dial thermometers at least one a month, prior to a big cooking event such as Thanksgiving, and if it’s been dropped or possibly damaged in some way.

Chapman says you can also calibrate digital thermometers and that he checks his once or twice a year — typically around Thanksgiving.

“Everyone who’s cooking or eating food should probably have a thermometer,” he says, “but how often you use it is definitely going to dictate how much you would want to invest in it.”

Once you’ve got a thermometer that works for you, you’ll want to use it to find the “cool spot” of whatever you’re cooking. If it’s meat or poultry, try to get the thermometer’s sensor into the thickest part of the muscle, away from bone. This is where it takes the heat the longest to penetrate.

Woodbury says that most digital thermometers have a sensor an eighth of an inch away from the tip, but in dial types, they can stretch up to an inch away.

If you take a reading and find out the meat you’re cooking is at less than the minimum temperature, be sure to wash the thermometer before you take another reading. If the food is contaminated, washing the probe helps to keep from reintroducing any pathogens to the meat.

Chapman adds that it’s a good idea to take the temperature at multiple spots of your food item since the heat could be unevenly distributed, especially when cooking ground meat products and microwaving.

And thermometers aren’t just for omnivores. People who are immunocompromised — those going through chemotherapy, for example — and need all their food to be thoroughly cooked can use a food thermometer to ensure that their fruits and vegetables are safe to eat.

© Food Safety News
  • Angus McAngstybritches

    Thanks very much for this very helpful article.

  • Rob de Jonge

    Food thermometers and meat, dangerous stuff! You prick your thermometer through the potentially microbiologically contaminated surface of meat and bring the bugs to the safest area: the cool spot!
    In addition, when using a stainless steel thermometer is an oven, the thermometer itself will also become hot and as the thermometer is made of steel, it will conduct its heat to a more cooler spot. Consequence: over-estimation of the temperature at the cool spot of your meat!

    • Apple Snob

      Food thermometers are not dangerous if you properly sanitize them between uses.

    • Jade

      That’s why thermocouples are ideal.

  • Terri R.Waller, MPA,CFSM,HACCP

    Thank you for the article I would like to elaborate on a few things:

    The establishments I have worked in primarily use digital thermometers. However, if and when
    thermometers are lost or broken they temporarily convert to bi-metallic stemmed thermometers until another shipment of digital thermometers come in. Here are a few training gaps I have seen and would just like to give you something to think about:

    Because the primary use of thermometers are digital and a lot of digital thermometers
    don’t have to be calibrated. I have noticed that members who work in temperature sensitive positions forget how to calibrate. So, if and when the time comes to use a bi-metallic stemmed thermometer they don’t know how to calibrate using the ice-point method 32F or the boiling point
    method 212F to arrive at a calibrated thermometer in which we are allowed a +/- 2F for accuracy. In Georgia this is an 11D violation on an inspection and can cost you 3 points.

    The sensing area on a digital thermometer is at the tip. With a bi-metallic stemmed
    thermometer the sensing area is larger and in order for you to get an accurate read the entire sensing area has to be submerged in the product. The training gap I have seen here is when temperatures are taken and the entire sensing area is not covered it leads to documenting
    inaccurate reads. Inaccurate readings are truly detrimental and can affect your food safety program in many stages in the flow of food and can cost you a lot of points on your inspection ranging from Foodborne Illness Risk Factors and Public Health Interventions to Good
    Retail Practices.

    Lastly, and I hope I’m not reading too much into this particular area in the article but we actually use sanitized probe wipes to sanitize our thermometer in between taking temperatures of different products instead of just washing. If not, in Georgia this is a 4-2B violation on an inspection and can cost you 4 points.