Tips for Thermometer Use: Cooking Meat Safely

One of the critical factors in controlling bacteria in food is controlling temperature. Pathogenic microorganisms grow very slowly at low temperatures, multiply rapidly in mid-range temperature and are killed at high temperatures. For safety, food must be cooked thoroughly. It is essential to use a thermometer when cooking meat to take the guesswork out of cooking and to assure that a safe temperature has been reached to destroy harmful bacteria such as salmonella.

Using a thermometer is the only reliable way to ensure safety and to determine the “doneness” of most foods. To be safe, a product must be cooked to an internal temperature high enough to destroy any harmful bacteria that may have been in the food. Recent research has shown that color and texture changes are not reliable indicators to ensure that all bacteria have been destroyed.

For example, ground beef may turn brown before it has reached a temperature at which bacteria are destroyed. A consumer preparing hamburger patties and depending on visual signs to determine safety by using the brown color as an indicator is taking a chance that pathogenic microorganisms may survive. A hamburger cooked to 160°F, regardless of color, is safe.

The temperature at which different pathogenic bacteria are destroyed varies, as does the “doneness” temperature for different meat and poultry products. A roast or steak that has never been pierced in any way during slaughter, processing or preparation and has reached an internal temperature of 145°F is safe to eat. A consumer looking for a visual sign of doneness might continue cooking it until it was cooked and dry. A consumer using a thermometer can feel reassured the food has reached a safe temperature.

Likewise, poultry should reach at least 160°F throughout for safety. At this temperature the meat has not reached a traditional “done” texture and color, and many consumers prefer to cook it longer to higher temperatures. (The red color of poultry does not change to the expected cooked color of white until temperatures are well above 160°F.

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Cutting and Merchandising

Prior to the 1970s it was common practice to ship quarters of beef and intact carcasses of lamb, veal and calves for processing into retail cuts. Currently most beef, veal, calf and lamb carcasses are cut, vacuum packaged, boxed, and shipped as boxed meat to retailers and wholesalers, who may further cut, package, and price the meat. Pork carcasses are similarly processed into wholesale cuts at the packing plant. Some pork cuts, such as the loin, are shipped as fresh cuts. Other cuts, such as ham and belly, undergo further processing, curing and smoking before distribution as processed meats.

All fresh and processed meats require preservation by some means. The most common method is refrigeration at temperatures of 28° to 40°F (-2° to 4°C). Freezing is also used to preserve meat for an extended period of time by placing meat in very cold blast air or in direct contact with condensed gases such as liquid nitrogen or carbon dioxide (dry ice).

Freeze drying is also used to preserve meat. The meat is first frozen, then placed in a vacuum chamber where heat is applied and water is removed as a vapor. Freeze-dried meat retains its original shape but is very porous. When packaged it may be stored at normal environmental temperature. Prior to cooking, the meat is rehydrated by placing it in water.

Numerous processed meat products are canned. In the canning process meat is placed in a metal or glass container that is sealed and heated to sterilize the container and contents. Canned products can be stored at room temperature.

Numerous meat products are cured and smoked. Curing generally involves the application of a mixture of dry or liquid curing ingredients to the meat. Salt is the common ingredient used. Other ingredients – nitrite, sugar, ascorbate, and seasonings – may be included in the curing mixture. In the United States curing ingredients must be in compliance with federal meat inspection standards. Smoking, usually done with curing, involves subjecting the meat product to hardwood smoke or liquid smoke, prepared from smoke generated from burning hardwoods. Curing and smoking impart unique properties of taste, appearance, and increased storage life of meat products.

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