Kinds of Thermometers
Thermocouple: This is the fastest-working thermometer: It displays a digital temperature within 2 to 5 seconds. Since it reaches the accurate temperature so quickly, it’s useful when you’re cooking something big like a turkey or a roast where you need to check the temp in a few places. The extremely thin probe makes it perfect for checking flat foods, like hamburgers, chicken breasts, and pork chops. This kind of thermometer shouldn’t be left in the food while it’s cooking, but should be used to test just before you expect the meat to be done.
Thermistor: This digital thermometer works in about 10 seconds and can be used for thick and thin foods. The tip registers the temperature, so it should be placed in the food’s thickest part. Like a thermocouple, it should be used to test just before the meat’s is supposed to be done.
Oven Cord Thermometer: This two-part thermometer is designed to stay in the meat for the entire cooking time and consists of a thermistor-like thermometer attached to a base unit (with a digital screen) by a long metal cord. The base unit goes outside the oven. Once the meat reaches the temperature you’ve programmed, the thermometer will beep.
Thermometer Fork Combination: This uses the technology of either a thermocouple or a thermistor, but has a fork-like end with two tines (a temperature sensor is embedded in one of them). It’s good for grilling and can measure the temp of the very thinnest foods in 2 to 10 seconds.
Bimetallic-Coil Thermometer: This thermometer uses a dial and senses temperature from its tip and about 2 to 2 1/2 inches up its stem to come up with an average temp.
Oven-Safe Bimetallic-Coil Thermometers: Like the bimetallic-coil thermometer, this senses temperature through about 2 1/2 inches of meat. This means it shouldn’t be used for any meat under 3 inches thick. Generally, this is the kind of thermometer used for big roasts or turkeys. Since it’s oven safe, it can be used throughout the entire cooking process. To achieve a valid temperature, you should test it in two or even three different places. If you don’t have that many thermometers, once you stick it in the meat you’ll have to wait about a minute to get another accurate reading.
Instant-Read Bimetallic-Coil Thermometer: Unlike a traditional bimetallic-coil thermometer, this one will give a reading in 15 to 20 seconds. It isn’t oven safe, though -- rather, it should be placed in the meat once it’s almost done. Like other bimetallic-coil thermometers, the entire sensing area -- about 2 or 3 inches -- needs to be inserted to get an accurate temp. You can always put it in sideways if you’re cooking something thin like a hamburger or chicken breast.
Single-Use Temperature Indicators: These are specifically designed for a certain temperature range -- say, 160 to 170°F -- and must only be used for a meat where that’s the appropriate final temperature. They can’t be left in the food while cooking, but when you suspect it’s almost done, put in the sensor and see if it changes color. If it doesn’t, you can insert it again until it does change color.
Pop-Up Timers: These were probably used by your mother or grandmother in the mid ’60s, and literally “pop up” when the steam inside the turkey or chicken reaches a temperature that dissolves the organic firing material. The temperature you get from one of these thermometers should be verified with a more conventional thermometer.
Always make sure you’re using a thermometer specifically designed for meat, not a candy thermometer or any other type.
How to Use
Generally, you should stick the thermometer in the thickest part of whatever you’re cooking. For whole poultry, it should go in the inner thigh area close to the breast, without touching any bone. The same goes for roasts, steak, or chops -- keep the thermometer away from bone, fat, and gristle. For thinner items, you can insert the thermometer sideways.
Ground meat and meat mixtures
Beef, pork, veal, lamb: 160°F
Turkey, chicken: 165°F
Fresh beef, veal, lamb
Medium rare: 145°F
Well done: 170°F
Whole chicken, turkey: 165°F
Roast poultry breasts: 165°F
Poultry thighs, wings: 165°F
Duck, goose: 165°F
Stuffing (inside or out of bird): 165°F
Fresh pork: 160°F
Egg dishes: 160°F
Leftovers, casseroles: 165°F
Source: USDA http://www.fsis.usda.gov/Fact_Sheets/Use_a_Food_Thermometer/index.asp
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