Which Of The Following Is True About Thermometers Used In Cooking

Pop-up Timers
Pop-up Timers are commonly used in turkeys and roasting chickens, the 'pop-up' temperature device is constructed from a food-approved nylon. Inside is a firing material, and a stainless steel spring. The firing material may be an organic salt compound or an alloy of metals commonly used in other thermo-sensing devices. The tip of the stem is embedded in this hardened material until it melts, releasing the stem, which is then 'popped up' by means of the spring. This indicates that the food has reached the final temperature for safety and doneness. Pop-up thermometers are reliable to within 1-2°F if accurately placed in the product.

T-Stick Disposable Thermometers
T-Stick Disposable Thermometers are disposable, single use, cardboard thermometers which indicate 160°F(+/- 1 F). At 160°F or higher, a white material inside the plastic coated tip becomes clear. As a result, the tip changes from a white to black indicating a safe temperature has been reached. The T-Stick is made from materials accepted by the FDA for contact with food.

Using a Thermometer
Most thermometers will give an accurate reading within 2-4°F. The reading will only be helpful, however, if the thermometer is placed in the proper location in the product. If not inserted correctly, or if the thermometer is placed in the wrong area, the reading will not accurately reflect the internal temperature of the product. In general, the thermometer should be placed in the thickest part of the food, away from the bone, fat or gristle.

Check the Manufacturer's Instructions First
Before using a food thermometer, read the manufacturer's instructions. The instructions should tell how far the thermometer must be inserted in a food to give an accurate reading. Most thermometers also come with instructions on how to recalibrate the thermometer (see below for more information on calibrating thermometers). If instructions are not available, check the stem on the thermometer for an indication, or 'dimple' that shows one end of the location of the sensing device. Most digital thermometers will read the temperature in a small area of the tip. Dial types must penetrate about 2-3" into the food.

Calibrating a Thermometer
There are two ways to check the accuracy of a food thermometer. One method uses ice water, the other uses boiling water. Many thermometers have a calibration nut under the dial that can be adjusted. Check the package for instructions.

Ice Water
To use the ice water method, fill a large glass with finely crushed ice, and clean tap water to the top of the ice, and stir well. Immerse the thermometer stem a minimum of 2" into the mixture, touching neither the sides nor the bottom of the glass. (For ease in handling, the stem of the thermometer can be placed through the clip section of the stem sheath and, holding the sheath horizontally, lowered into the water.) Without removing the stem from the ice, hold the adjusting nut under the head of the thermometer with a suitable tool and turn head so pointer reads 32°F. Allow a minimum of 30 seconds before adjusting.