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. Explain why use of a properly calibrated thermometer is important.

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) Fill a large glass with finely crushed ice. Add clean water to the top of the ice and stir well. Immerse the thermometer stem a min. of 2 inches into the mixture. The thermometer should read 32 °F after 30 seconds.

Methods of Calibration Boiling Point Method Bring water in a deep pan to a full rolling boil. Immerse the stem of a thermometer 2 inches into the boiling water. The thermometer should read 212 °F after 30 seconds.

Methods of Calibration 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.

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.

Types of Thermometers Infrared Thermometer - Used to measure surface temp. - Must be held as close to the product as possible. -Remove barriers between thermometer and product - Do not use through glass or metal surfaces

Proper Use Clean and sanitize between uses Calibrate regularly Insert stem or probe into thickest part of the product Wait for reading to steady before recording (usually 15 secs.) Never use mercury-filed glass thermometers to test temperature of food.

Illnesses prevented by thermometer use Salmonella Salmonella is a bacteria often living in raw meat, eggs, and fish/shellfish Symptoms of Salmonella exposure include: – Flu-like symptoms: headache, muscle-ache, chills and fever – POSSIBLE flu-like symptoms: nausea, vomiting – Non flu-like symptoms: RUMBLING IN THE BOWELS, diarrhea Duration: days!!

Illnesses Prevented by Thermometer Use Salmonella cont. Food needs to be fully cooked to kill the bacteria USDA recommended minimal internal temperatures - Steaks & Roasts °F - Fish °F - Pork °F - Ground Beef °F - Egg Dishes °F - Chicken Breasts °F - Whole Poultry °F

Illnesses Prevented by Thermometer Use E. COLI E. Coli is a common bacteria that normally exists in the bodies of animals, including ours. Symptoms of E. Coli exposure include: bloody diarrhea, severe abdominal pains and tenderness. Can be fatal in the young and elderly.

Illnesses Prevented by Thermometer Use E. Coli cont. Most commonly, E. coli 0157:H7 comes from eating raw or undercooked ground beef (hamburger) or from drinking raw milk. To prevent E. coli infection cook meat (especially ground beef) thoroughly.

Review Questions What is the most common type of thermometer used to test food temp? What temp. should your thermometer read after 30 sec. in ice water? What is the minimum internal temp. ground beef should be cooked to?

References _Thermometers/index.asp