Thermal inactivation of cells of Salmonella spp. in pot pies prepared with a beef, chicken, or meat alternative filling, with and without gravy, during cooking in a convection oven

Authors: Porto-Fett, Anna; Shane, Laura; Shoyer, Brad; Osorio, Manuela; BECZKIEWICZ, AARON - Food Safety Inspection Service (FSIS); BARLOW, KRISTI - Food Safety Inspection Service (FSIS); WEBB, BRAD - Food Safety Inspection Service (FSIS); MERRILL, BRYCE - Food Safety Inspection Service (FSIS); Vinyard, Bryan; Luchansky, John

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bakery products containing a protein-based filling such as pot pies are a popular entrée enjoyed worldwide for both lunch and dinner, or simply as a snack. At times, such products may harbor elevated levels of spoilage bacteria and, on occasion, may harbor low numbers of food borne pathogens such as Salmonella spp. via their association with the raw flour/dough used for the top/bottom crust or the raw beef, chicken, vegetables, and/or gravy used for the filling components. As a result, there have been a handful of recalls and illnesses over the years directly attributable to pot pies due to insufficient cooking by either the processor or consumer, and by post-process contamination and/or improper handling or storage of the finished product. Thus, we determined if cooking dough-wrapped bakery products containing a protein-based filling, namely pot pies, would deliver sufficient kill of cells of Salmonella as required by regulators. The three temperatures and associated dwell time parameters tested, with or without the inclusion of gravy in the filling, were sufficient to lower levels of Salmonella by more than 3.2 million cells per gram of filling for beef or meatless chick’n pot pies or by more than 10 million cells per gram of filling for chicken pot pies. This study provides much needed data for processors and consumers on heat inactivation of Salmonella in pot pies. These data may potentially lessen the likelihood of future recalls or illnesses attributed to bakery products containing meat.

Technical Abstract: Select cooking parameters elaborated in the U.S. Department of Agriculture’s Food Safety and Inspection Service Cooking Guideline for Meat and Poultry Products (Appendix A) were evaluated for inactivation of Salmonella spp. in pot pies. All-purpose flour, butter, unsalted sugar, salt, and water were mechanically mixed, divided into portions (65 or 85 g each), and flattened into circular sheets (ca. 13 or 15 cm diameter, ca. 0.5 cm thick). The larger (85 g) sheets were placed into aluminum pans (ca. 19.4 cm diameter) and hand pressed to the contour of the pan. Next, a 100-g portion of beef, chicken, or meatless chick’n filling, with or without added gravy (55 g of meat and 45 g of gravy), was inoculated with a nine-strain cocktail of Salmonella spp. (ca. 6.5 or 7.5 log CFU/g of filling) and uniformly distributed onto the pie crust. After covering with the 65-g sheet of dough, the edges were crimped/fluted and the pies were heat sealed within nylon polyethylene bags and stored at -20°C for up to 72 h. Beef and meatless chick’n pot pies were cooked in a convection oven to an internal temperature of 136°F (57.8°C) instantaneous, 145°F (62.8°C) and held for 4 min, 153°F (67.2°C) and held for 34 sec, or 160°F (71.1°C) instantaneous, whereas chicken pot pies were cooked to an internal temperature of 136°F (57.8°C) instantaneous, 145°F (62.8°C) and held for 13 min, 153°F (67.2°C) and held for 96 sec, or 165°F (73.9°C) instantaneous. Regardless of the protein source or inclusion or not of gravy, the time and temperature parameters tested herein delivered reductions in levels of Salmonella spp. of 3.6- to =5.8-log CFU/g of pot pie. Moreover, with few exceptions, when pathogen levels decreased to below detection by direct plating (0.5 log CFU/g), cells of Salmonella were not recoverable by enrichment. Thus, temperature and dwell time cooking parameters in Appendix A were effective for delivering the requisite reductions (=6.5 or =7.0 log CFU/g) of salmonellae and, in turn, lessening the threat of illness associated with ingestion of improperly cooked or poorly handled bakery products containing meat.