NCDA&CS - Meat & Poultry Inspection

CALIBRATING THERMOMETERS AND TAKING TEMPERATURES PROPERLY

Calibrating Thermometers

In this activity, you will discuss why thermometers need to be calibrated, how often they should be calibrated, and how to calibrate them. Employees will demonstrate how to correctly calibrate a thermometer of their choice.

Begin the discussion by explaining that thermometers must be calibrated regularly to ensure that product temperatures are correct.

If thermometers are used on a continual basis, they should be calibrated at least once a day. They should also be calibrated whenever the thermometer is dropped, before it is first used, and when going from one temperature to another.

There are two methods of calibrating thermometers: the ice point method and the boiling point method. Explain the steps for each method, then have employees calibrate their thermometers using either method (note to remember: the ice point method is more accurate and easier to do).

Ice Point Method

Fill a large glass with crushed ice. Add clean tap water until the glass is full and stir well.

Put the thermometer stem or probe in the ice water mixture so that the entire sensing area is submerged. Do not let the stem of the thermometer or probe touch the sides or bottom of the glass. Wait at least 30 seconds or until indicator stops moving.

With the stem of the thermometer or probe still in the ice water mixture, use a wrench to turn the adjusting nut until the thermometer reads 32°F (0°C). If calibrating a digital thermometer, press the reset button to automatically calibrate the thermometer.

Boiling Point Method

Bring clean tap water to a boil in a deep pan.

Put the thermometer stem or probe into the boiling water so that the sensing area is completely submerged. Do not let the stem or probe touch the bottom or sides of the pan. Wait at least 30 seconds or until indicator stops moving.

With the thermometer stem or probe still in the water, use a wrench to turn the adjusting nut until the thermometer reads 212°F (100°C) at sea level. If calibrating a digital thermometer, press the reset button to automatically calibrate the thermometer.

Points to Remember

The boiling point of water decreases as elevation increases.

Altitude (elevation above sea level) Water Boiling Point 0 (sea level) 212°F (100°C) 1000 feet (305 meters) 210°F (98.9°C) 2000 feet (610 meters) 208°F (97.8°C) 3000 feet (914 meters) 206.4°F (96.9°C) 4000 feet (1219 meters) 204.5°F (95.8°C) 5000 feet (1524 meters) 202.75°F (94.9°C) 8000 feet (2438 meters) 197.5°F (91.9°C)

Taking Product Temperatures

In this activity, you will review how to take the temperature of various hot food items. Then, quiz your employees on how to take the temperature of various food items.

Begin discussion by reminding employees to properly wash and sanitize their thermometers prior to use and in between uses. Also, remind employees to use the right thermometer for the food and situation, and to calibrate the thermometer whenever necessary. Key points you may want to discuss before you begin:

Take the temperature of a product in several places, particularly irregularly shaped items.

Stir product before taking temperature.

Place stem or probe in the thickest part of the food item.

Do not rest the stem or probe on a bone - this may give an inaccurate reading.

Make sure entire sensing area is completely submerged in the food.

Prior to starting this activity, set out different types of foods to have employees demonstrate how they would take the temperature of each (pretending or simply discussing can be just as useful).

Ask employees how they would take the temperature of such food items as roast chicken, pork chops, bone-in ham, hamburgers, soup in a large stock pot on the burner, a 10 lb. roast in a large pan, or a thin sauce in a crepe pan.

For added benefit, ask the employees what the final minimum internal temperature should be for each food item.

To finish the session, have the employees play the "Cook It Safely" Crossword Puzzle.

Common Mistakes to Avoid When Using a Thermometer

Not Calibrating thermometer.

Not immersing entire sensing area into product.

Taking temperature in incorrect location in the food product.

Failing to stir product prior to taking temperature.

Not using the appropriate thermometer for the type of food.

Touching the surface of the cooking vessel or equipment.

Equating air temperature with product temperature.

Equating equipment thermostat temperature with product temperature.

Failing to allow thermometer to level off.

Failing to wash and sanitize thermometer prior to use.

Additional Information from Kansas State University on Thermometer Calibration

NCDA&CS - Meat and Poultry Inspection Division, W. Alan Wade , Director
Mailing Address:1001 Mail Service Center Raleigh, NC 27699-1001
Physical Address: 2 West Edenton Street , Raleigh, NC 27601
Phone: (919) 707-3180; FAX: (919) 715-0246; TA Office: (919) 707-3195