Thermal Inactivation of Salmonella spp. Within Refrigerated or Frozen Turkey Burgers Following Pan Frying

Authors: DUONG, MINH - North Carolina State University; Porto-Fett, Anna; Shoyer, Brad; Shane, Laura; Osorio, Manuela; CHAPMAN, BENJAMIN - North Carolina State University; Luchansky, John

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2021
Publication Date: 4/1/2021
Citation: Duong, M., Porto Fett, A.C., Shoyer, B.A., Shane, L.E., Osoria, M., Chapman, B., Luchansky, J.B. 2021. Thermal Inactivation of Salmonella spp. Within Refrigerated or Frozen Turkey Burgers Following Pan Frying. Journal of Food Protection. https://doi.org/10.4315/JFP-21-051.
DOI: https://doi.org/10.4315/JFP-21-051

Interpretive Summary: The demand for poultry continues to increase in the U.S., with the per capita availability of boneless turkey reported to have increased from 13.7 pounds in 2000 to 28.5 pounds in 2015. However, poultry is also among the most common vehicles of foodborne illness in the U.S., as expected, due to cells of Campylobacter and Salmonella remaining associated with undercooked and/or improperly handled products. Since several outbreaks and recalls over the past decade have been traced to raw (ground) turkey products being contaminated with Salmonella, in this study we tested different cooking temperatures for thermal inactivation of a nine-strain cocktail of Salmonella cells within inoculated ground turkey patties that were subsequently pan fried. In addition to temperature, other parameters evaluated included product thickness (1.25 or 2.5 cm), volume of cooking oil (15 or 30 ml), and state of the inoculated meat prior to cooking (refrigerated or frozen). The results confirmed that greater kill was achieved as the target endpoint temperature increased from 57.2degC (135degF), to 65.6degC (150degF), to 73.9degC (165degF), and to 82.2degC (180degF). Greater kill of Salmonella was also observed using 30 ml of canola oil. For patties stored refrigerated and then cooked to 57.2deg, greater kill was observed for smaller rather than lager patties. Collectively, these data confirmed that irrespective of the state of the meat or the volume of the cooking oil tested, cooking inoculated turkey patties on a non-stick frying pan to the recommended internal temperature of 73.9degC or greater eliminated at least one million cells per gram of Salmonella. Our study also validated the importance of proper use of a thermometer to confirm doneness by achieving an endpoint temperature of 73.9degC or greater in each burger.

Technical Abstract: Viability of Salmonella was monitored in turkey burgers during pan frying. Raw ground turkey (99% lean, 1% fat) was inoculated (ca. 6.5 log CFU/g) with a nine-strain cocktail of Salmonella spp. and then formed into 1.25 cm (112 g) or 2.5 cm (225 g) thick patties that were stored at 4degC (18 h) or -20degC (30 d). Next, patties were cooked in a sauté pan containing either 15 or 30 ml of canola oil to endpoint internal temperatures of 57.2degC (135degF), 65.6degC (150degF), 73.9degC (165deg), or 82.2degC (180degF). In general, the higher the temperature, the greater the volume of oil, and the thinner the patty, the greater the reduction of the pathogen. Regardless of the volume of cooking oil used, cooking smaller (1.25 cm thick) burgers that were previously stored refrigerated to 57.2, 65.6, 73.9, or 82.2degC delivered reductions ranging from ca. 4.8 to =6.0 log CFU/g, whereas reductions ranging from ca. 3.0 to =5.0 log CFU/g were achieved for otherwise similar burgers that were previously stored frozen. Likewise, cooking larger (2.5 cm thick) burgers that were previously stored refrigerated to 57.2, 65.6, 73.9, or 82.2degC in 15 or 30 ml of canola oil delivered reductions ranging from ca. 2.8 to =6.1 log CFU/g, whereas reductions ranging from ca. 2.4 to =5.1 log CFU/g were achieved for otherwise similar burgers that were previously stored frozen. The average internal temperatures achieved when patties were cooked to target temperatures of 57.2, 65.6, 73.9, or 82.2degC ranged from 38.3 to 96.2, 48.0 to 99.4, 55.2 to 98.5, or 59.4 to 98.3degC, respectively. These data validated that cooking refrigerated or frozen turkey burgers on a non-stick frying pan to the recommended target internal temperature of =73.9degC delivered the requisite 5.0-log reduction of Salmonella. These data also confirm the importance of using a thermometer to ensure that the required minimum endpoint temperature was achieved.