Is it true that just because a hamburger is brown on the inside does not necessarily indicate that it is fully cooked?
Food scientists at Kansas State University have determined that some ground beef can be cooked to a safe-to-eat temperature of 160 degrees Fahrenheit yet still be pink, while other ground beef can be well-browned but not yet safe to eat.
The only sure way to tell whether ground beef -- or any other meat or poultry, for that matter -- is cooked completely is with a meat thermometer. Ground meats can be more susceptible to food-borne pathogens because a greater surface area is exposed in the grinding process. That doesn't mean that ground beef can't be safe, but it does mean that it should be cooked properly. Heat will kill food-borne pathogens that may be present.
What kind of thermometer is best to buy for taking the temperature of meat?
A meat thermometer should be used. A meat thermometer, which is not the same as a candy thermometer, can protect consumers from potentially harmful pathogens such as E coli 0157:H7 and salmonella. A thermometer can be purchased for less than $10 in supermarkets, discount department, kitchen and hardware stores. Most stores offer one or more of the following choices:
- An oven-safe bimetal thermometer can be inserted before meat or poultry is placed in the oven; it can remain in place during cooking time. Oven-safe thermometers have a probe that usually is two or more inches long that should be inserted into the thickest part of meat or poultry. The probe should not touch the bone. To check the internal temperature in another part of the meat or poultry, gently remove the thermometer and re-insert it elsewhere. Use heat-resistant oven mitts or a potholder; allow one to two minutes for an accurate reading. Because an oven-safe bimetal thermometer depends on a probe, it may not be the best choice for thin foods such as burgers and chops.
- An instant-read bimetal thermometer can be used to check temperatures at the end of cooking time. Choose it for soups, stews, casseroles or a roast. Insert the probe 2 to 2 1/2 inches and wait 15 to 20 seconds for an accurate reading. An instant-read bimetal thermometer cannot be used in the oven during cooking time -- the top will melt. It also is less desirable for thin foods, such as burgers and chops, because it must be inserted sideways.
- A liquid-filled food thermometer can be used to check the temperature of casseroles, roasts or soups at the end of cooking time. Insert the probe at least two inches into the deepest part of the casserole dish, roast or soup pot and wait one to two minutes. A liquid-filled thermometer can be placed in food while it is cooking. The probe does, however, make this less desirable for thin foods such as burgers and chops because it must be inserted sideways.
- A thermistor can be used to obtain a reading in a few seconds. Thermistors have a dial attached to a long, thin probe (about 1/8-inch thick), which makes them a good choice for thin foods. The tip of the probe should be placed in the center of the food, which is likely to be cooked the least.
- A digital thermometer can be used to determine the temperature in most foods, but cannot be used in the oven while food is cooking. Digital thermometers can provide an accurate temperature reading in about 10 seconds; digital thermometers also can read temperatures when inserted only 2 inches deep, which makes them a good choice for burgers and chops. A digital thermometer is likely to be more expensive, but the cost is offset by convenience.
- A digital thermocouple thermometer can be used on foods that may be as little as 1/4-inch thick. It uses a needle-like probe to read food temperature in seconds. The high-tech thermometers are more expensive and may be more difficult to find. Look for them at kitchen or restaurant supply houses.
- Pop-up timers are packaged with some meat and poultry products and also may be purchased separately. They generally are not as accurate as traditional thermometers.
- Disposable T-sticks are becoming more available. A change in color signals a safe-to-eat temperature. They can be handy at picnics and other outdoor events where meat products are served.
Where do you place a thermometer?
For red meat, roasts, steaks or chops: Insert thermometer in the thickest part, away from bone, fat, or gristle.
Ground meat and poultry: Place thermometer in the thickest part of the meatloaf; for thin meats like a beef patty, insert thermometer sideways to center and/or thickest part.
Poultry: Insert thermometer in the inner thigh area near the breast of the bird. Thermometer should not touch the bone.
Casseroles and egg dishes: Insert thermometer in center or thickest part.
-- Susan Krumm is an Extension agent in family and consumer sciences with K-State Research and Extension-Douglas County, 2110 Harper. She can be reached at 843-7058.
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