Instant-read Food Thermometer Accuracy in Measuring End-point Temperature in Ground Beef Patties Prepared by Three Methods

The accuracy of three dial and three digital consumer instant-read food thermometer models was assessed. Thermometer models were compared to a thermocouple in ground beef patties cooked to 71. 1 degree C via three preparation methods. Patties were prepared to reflect methods used in scientific studies (flipped every 30 s) and two consumer methods (patties containing onion or topped with cheese and flipped once). Instant-read thermometer temperatures were recorded after the display had stabilized for 3 s. Dial thermometer models required 18-55 s to stabilize, while digital thermometers required 16-40 s. Both dial and digital thermometer models performed more accurately in ground beef patties flipped every 30 s than in those prepared by the other methods, measuring within 2.1 degree C of the thermocouple standard. Only one thermometer model accurately measured end-point temperature when consumer cooking methods were used; overestimation of patty temperature, a food safety risk, was observed. Flipping ground beef patties every 30 s produced a more uniform environment for temperature measurement, with a smaller temperature gradient throughout the patty. Both dial and digital food thermometers can be recommended for consumer use in ground beef patties if inserted through the side to measure the geometric center, if patty temperature gradient has time to equilibrate somewhat, and if the thermometer reading is allowed adequate time to stabilize.