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

Abstract

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. To prepare dough for pot pies, flour, butter, sugar, salt, and water were mixed, portioned into balls (65 or 85 g each), flattened (ca. 13 or 15 cm diameter, ca. 0.5 cm thick), and hand-pressed into pans (ca. 19.4 cm diameter). Next, a 100-g portion of beef, chicken, or a meat alternative, with or without added gravy (55 g of protein and 45 g of gravy), was inoculated with a cocktail of Salmonella spp. (ca. 6.5 or 7.9 log CFU/g of filling) and distributed onto the pie crust. After covering with a 65-g sheet of dough, pies were heat sealed in nylon polyethylene bags and stored at −20 °C for up to 72 h. Frozen pot pies containing a beef or meat alternative filling were cooked in a convection oven to an internal temperature of 57.8 °C (136°F) instantaneous, 62.8 °C (145°F) and held for 4 min, 67.2 °C (153°F) and held for 34 sec, or 71.1 °C (160°F) instantaneous; whereas chicken pot pies were cooked to an internal temperature of 57.8 °C (136°F) instantaneous, 62.8 °C (145°F) and held for 13 min, 67.2 °C (153°F) and held for 96 sec, or 73.9 °C (165°F) instantaneous. Cells of Salmonella spp. were recovered from uncooked or cooked pot pies by stomaching each pie in peptone water and enumerating pathogen levels via direct plating. Cooking delivered Salmonella spp. reductions of ca. 3.6 to ≥6.3 log CFU/g of pot pie. With few exceptions, when pathogen levels decreased to below detection by direct plating (0.5 log CFU/g of pot pie), cells of Salmonella were not recovered by enrichment. In addition, there were minimal differences in the a_w and moisture content of the protein filling before and after cooking, suggesting that enclosing a meat, poultry, or meat alternative filling within a dough wrapping maintained moisture in the filling during the cooking process.