Thermometer Calibration & Use Shannon Rohall Stevie Arroyo

Learning Objectives Define thermometer calibration Describe the different methods of calibration. Explain anatomy of thermometer and different types of thermometers. Describe how to properly use a thermometer.

Thermometer Calibration Definition: Calibrating is checking the thermometer for accuracy against a standard (such as ice water) to confirm that it is currently giving a correct reading. Why necessary? Thermometers can easily be thrown off mark. Thermometers help to make sure your food is cooked to a high enough temperature to kill harmful bacteria and viruses.

Methods of Calibration Ice Point Method (most common)

How to Calibrate using Ice Point Method Fill a large glass with finely crushed ice. Add clean water to the top of the ice and stir well.

How to Calibrate using Ice Point Method Immerse the thermometer stem a minimum of 2 inches into the mixture. The thermometer should read 32 °F after 30 seconds.

Methods of Calibration Boiling Point Method Uncommon due to risk of burn injury. Bring water in a deep pan to a full rolling boil.

How to Calibrate using Boiling Point Method Immerse the stem of a thermometer 2 inches into the boiling water. The thermometer should read 212 °F after 30 seconds.

Methods of Calibration: How to Correct an Error If your thermometer does not read correctly after 30 sec. : Hold the adjusting nut with a wrench or other tool. Rotate thermometer head until its shows correct reading.

Recap http://www.ehow.com/video_2346020_calibrate-cooking-thermometer.html

Bimetallic Stemmed Thermometer Types of Thermometers Bimetallic Stemmed Thermometer Most common and versatile Sensing area is from the tip to a half-inch past the dimple Easy-to-read temperature on the dial face

Types of Thermometers Thermocouple - Measure temp with metal probe or sensing area. - Displays results digitally. - Come with interchangeable probes for liquids, flat cooking equip. and food.

Identification of Thermometer Proper Use Calibrate regularly and keep consistent records Thermometer Calibration Log Instructions: Check and calibrate all bi-metallic stemmed (instant-read) thermometers in this facility every two weeks and any time a thermometer is dropped or bumped. Maintain this log for a minimum of two years and until given permission to discard it. If corrective action is required, explain the action taken in the last column. Number of Stem Thermometers in Facility: __________ Identification of Thermometer Date (of Calibration) Temp. When Placed in Ice Calibrated By (Food Service Worker’s Initials) Corrective Action

Where would you place the thermometer? Proper Use Where would you place the thermometer? Into the center or thickest part & away from any bones

How would you test soups temperature? Proper Use How would you test soups temperature? Take it off the stove. Stir and then insert probe into center of pot.

Proper Use Clean and sanitize between uses to prevent cross contamination. One of the following can be used to sanitize: Boiling water Sanitizing solution One use alcohol swabs

Recap http://www.youtube.com/watch?v=HZ3t2HbdV0k DEMO

Proper Use Key points to remember: 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.

Proper Use 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. Never use mercury-filed glass thermometers Wait for reading to steady (usually 15 sec.)

Review Questions What is the most common type of thermometer used to test food temp? Bimetallic stemmed thermometer What temp. should your thermometer read after 30 sec. in ice water? 32 degrees Fahrenheit

Review Questions How & when should you sanitize your thermometer? Sanitize probe using boiling water, sanitizing solution, or single use wipes. Sanitize probe between uses

References http://www.fsis.usda.gov/Is_It_Done_Yet/Brochure_Text/index.asp http://www.fsis.usda.gov/PDF/BFS_Activity_Book_BW.pdf http://www.foodsafety.gov/~fsg/fs-therm.html http://www.fsis.usda.gov/food_safety_education/Types_of_Food _Thermometers/index.asp http://www.foodsafety.gov/~dms/sept/99-week3.html