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United States Department of Agriculture

Agricultural Research Service

Title: Accuracy and Response Time of An Instant-Read Digital Probe Thermometer in Cooked Ground Beef Patties and Chicken Breasts

Authors
item Liu, Martha
item Vinyard, Bryan
item Boarman, Janice
item Solomon, Morse

Submitted to: International Congress of Meat Science and Technology Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 13, 2005
Publication Date: N/A

Interpretive Summary: Consumers have been advised to use thermometers during cooking to ensure that meat products have been cooked to safe internal temperatures to prevent illness. The accuracy and reliability of consumer instant-read thermometers have not been evaluated in meat products. A consumer digital probe thermometer was tested in 80 percent and 90 percent lean ground beef patties cooked to 71 C on gas grills and electric griddles, and for boneless and bone-in split chicken breasts cooked to 77 C on gas grills and baked in consumer ovens. After the meat product reached the target endpoint temperature, the product was removed from the heating source and the thermometer was inserted into the cooked meat perpendicular and close as possible to the thermocouple. With this thermometer model, the consumer would end up over cooking their ground beef patties and chicken breasts. This would ensure that the products were cooked to a temperature necessary to destroy harmful microorganisms; however, it would have a negative effect on the eating quality of the product.

Technical Abstract: The only way to determine if meat products have been cooked to an internal temperature necessary to inactivate pathogens is to use a thermometer. To date, the accuracy and reliability of consumer instant-read thermometers have only been evaluated in water-baths, not in meat products. A consumer digital probe thermometer (PT) was tested for accuracy compared to a calibrated thermocouple (TC) and response time in preformed 80 percent (80GB) and 90 percent (90GB) lean ground beef patties cooked to 71 C on gas grills (GG) and electric griddles (EG), and boneless (BCB) and bone-in split (CB) chicken breasts cooked to 77 C on GG and baked in consumer ovens (CO). Once the meat product reached the target endpoint temperature using the TC, the product was removed from the heat source and the PT was inserted into the product perpendicular and as close as possible to the TC. Times and temperatures of the PT and TC were recorded at two predetermined times; 15 s (MT, manufacturer recommended time) or 30 s (EPT, predetermined endpoint time) or if the PT reached the target temperature. The test was discontinued when the PT reached the target endpoint temperature or EPT. In both 90GB-GG and BCB-CO, the PT did not register any of the samples as cooked at the EPT. The PT showed the highest percentage of the samples being cooked in the CB-GG; 27.8 percent at the MT and 44.4 percent at the EPT. The PT reading ranged from 4.7 to 14.2 C less than the TC temperature reading at the MT and 5.5 to 9.3 C less at the EPT. For those samples that reached the target endpoint temperature, the PT took on average 10.0 to 17.8 s to register the target temperature. These results indicate that consumers using this type of instant-read digital thermometer would cook ground beef patties and chicken breasts to higher temperatures than necessary to destroy harmful microorganisms. Although cooking to these temperatures would ensure a microbiologically safe product, it would negatively affect the sensory quality of the products.

Last Modified: 7/25/2014