Kitchen Thermometers
Total Page:16
File Type:pdf, Size:1020Kb
United States Department of Agriculture Food Safety and Inspection Service Food Safety Information USDA Photo Kitchen Thermometers t is essential to use a food thermometer when cooking meat, poultry, and egg products to prevent Iundercooking, verify that food has reached a safe minimum internal temperature, and consequently, prevent foodborne illness. lamb and veal steaks, chops, and roasts to a Why Use a Food Thermometer? Photo USDA minimum internal temperature of 145°F as measured Using a food thermometer is the only reliable way to with a food thermometer before removing meat from ensure safety and to determine desired “doneness” the heat source. For safety and quality, allow meat to of meat, poultry, and egg products. To be safe, these rest for at least three minutes before carving or foods must be cooked to a safe minimum internal consuming. For reasons of personal preference, temperature to destroy any harmful microorganisms consumers may choose to cook meat to higher that may be in the food. temperatures. “Doneness” refers to when a food is cooked to a Cook all poultry to a safe minumum internal desired state and indicates the sensory aspects of temperature of 165°F as measured with a food foods such as texture, appearance, and juiciness. thermometer. For reasons of personal preference, Unlike the temperatures required for safety, these consumers may choose to cook meat to higher sensory aspects are subjective. temperatures. Color is Not a Reliable Indicator A food thermometer should also be used to ensure that cooked food is held at safe temperatures until served. Cold food should be held at 40 °F or below. Many food handlers believe that visible indicators, Hot food should be kept hot, at 140 °F or above. such as color changes, can be used to determine if foods are cooked to a point where pathogens are killed. However, recent research has shown that Types of Thermometers color and texture indicators are unreliable. For example, ground beef may turn brown before it Food thermometers come in several types and styles, reaches a temperature where pathogens are and vary in level of technology and price. destroyed. A consumer preparing hamburger patties and using the brown color as an indicator of Digital Food “doneness” is taking a chance that pathogenic Thermometers microorganisms may survive. A hamburger cooked to 160 °F, as measured with a meat thermometer, Thermocouple: regardless of color, is safe. Safety Versus Doneness Of all food thermometers, thermocouple The temperature at which different pathogenic thermometers reach microorganisms are destroyed varies, as does the and display the final “doneness” temperature for different meat and temperature the fastest - within 2 to 5 seconds. The poultry. A consumer looking for a visual sign of temperature is indicated on a digital display. “doneness” might continue cooking it until it is overcooked and dry. However, a consumer using a A thermocouple measures temperature at the food thermometer to check for “doneness” can feel junction of two fine wires located in the tip of the assured the food has reached a safe temperature probe. Thermocouples used in scientific laboratories and is not overcooked. Cook all raw beef, pork, have very thin probes, similar to hypodermic needles, while others may have a thickness of 1/ 16 of an inch. The Food Safety and Inspection Service (FSIS) is the public health USDA Meat & Poultry Hotline agency in the U.S. Department of Agriculture responsible for ensuring that the nation’s commercial supply of meat, poultry, and egg products 1-888-MPHotline is safe, wholesome, and correctly labeled and packaged. (1-888-674-6854) Kitchen Thermometers Since thermocouple thermometers respond so rapidly, Thermometer Fork Combination: the temperature can be quickly checked in a number of locations to ensure that the food is safely cooked. This utensil combines a cooking This is especially useful for cooking large foods, such fork with a food thermometer. A as roasts or turkeys, when checking the temperature temperature-sensing device is in more than one place is advised. The thin probe of embedded in one of the tines of the thermocouple also enables it to accurately read the fork. There are several the temperature of thin foods such as hamburger different brands and styles of patties, pork chops, and chicken breasts. thermometer forks on the market; some using Thermocouples are not designed to remain in the food thermocouples and some using while it’s cooking. They should be used near the end thermistors. The food of the estimated cooking time to check for final cooking temperature is indicated on a temperatures. To prevent overcooking, check the tem- digital display or by indicator perature before the food is expected to finish cooking. lights on the handle within 2 to 10 seconds (depending on the type). These lights Thermocouples can be calibrated for accuracy. will tell if the food has reached rare, medium, well done, etc. Particularly useful for grilling, the Thermistors: thermometer fork will accurately measure the internal temperature of even the thinnest foods. The Thermistor-style food thermometer fork should be used to check the thermometers use a temperature of a food towards the end of the resistor (a ceramic estimated cooking time. Thermometer forks are not semiconductor bonded in designed to remain in a food while in the oven or on the tip with temperature- the grill. Thermometer forks cannot be calibrated. sensitive epoxy) to measure temperature. The Dial Food Thermometers thickness of the probe is approximately 1/ 8 of an inch and takes roughly 10 seconds to register the Bimetallic-coil Thermometers: temperature on the digital display. Since the semiconductor is in the tip, thermistors can measure These thermometers contain a coil in the probe made temperature in thin foods, as well as thick foods. of two different metals that are bonded together. Because the center of a food is usually cooler than The two metals have different rates of expansion. the outer surface, place the tip in the center of the The coil, which is connected to the temperature thickest part of the food. indicator, expands when heated. This food thermometer senses temperature from its tip and up Thermistors are not designed to remain in the food the stem for 2 to 2 1/ 2 inches. The resulting while it’s cooking. They should be used near the end temperature is an average of the temperatures of the estimated cooking time to check for final along the sensing area. These food thermometers cooking temperatures. To prevent overcooking, check have a dial display and are available as “oven-safe” the temperature before the food is expected to finish and “instant-read.” cooking. “Oven-safe” Bimetallic-coil Thermometers: Not all thermistors can be calibrated. Check the This food thermometer is manufacturer’s instructions. designed to remain in the food while it is cooking in Oven Cord Thermometers: the oven, and is generally used for large items such This food thermometer allows the cook to check the as a roast or turkey. This temperature of food in the oven without opening the food thermometer is oven door. A base unit with a digital screen is convenient because it attached to a thermistor-type food thermometer constantly shows the probe by a long metal cord. The probe is inserted temperature of the food into the food, and the cord extends from the oven to while it is cooking. However, if not left in the food the base unit. The base can be placed on the while cooking, they can take as long as 1 to 2 counter or attached to the stovetop or oven door by minutes to register the correct temperature. a magnet. The thermometer is programmed for the desired temperature and beeps when it is reached. The bimetal food thermometer can accurately While designed for use in ovens, these measure the temperature of relatively thick foods thermometers can also be used to check foods (such as beef roasts) or deep foods (foods in a cooking on the stove. Oven cord thermometers stockpot). Because the temperature-sensing coil on cannot be calibrated. the stem is between 2 to 2 1/ 2 inches long and the Food Safety Information 2 Kitchen Thermometers stem is relatively thick, it is not appropriate to the temperature is reached. These sensors cannot measure the temperature of any food less than 3 be left in a food while it is cooking. They should be inches thick. used near the end of the estimated cooking time. To prevent overcooking, check the temperature before There is concern that because heat conducts along the food is expected to finish cooking. the stem’s metal surface faster than through the food, the area of the food in contact with the Disposable temperature indicators are made from thermometer tip will be hotter than the area a short materials approved by the FDA for contact with food. distance to the side (the “potato nail effect”). To remedy this, the temperature should be taken in a Pop-Up Timers: second, and even third area, to verify the Commonly used in temperature of the food. Each time the thermometer turkeys and roasting is inserted into the food, let the thermometer chickens since 1965, the equilibrate (come to temperature) at least 1 minute “pop-up” style before reading the temperature. disposable cooking device is constructed of Some models can be calibrated. Check the food grade nylon. The manufacturer’s instructions. inside contains a stainless steel spring “Instant Read” Bimetallic-coil Thermometers: and organic firing material. The organic firing material This food thermometer is specifically designed to dissolve at specific quickly measures the predetermined temperatures. Once the firing temperature of a food in material dissolves, the stainless steel spring about 15 to 20 seconds.