Validation of High Milk Protein Chocolate Chip Cookie Baking Process and Thermal Death Inactivation Parameters of a 4-Serovar Salmonella Cocktail

This study evaluated the survivability and thermal resistance of 4-serovar Salmonella cocktail in chocolate chip cookies formulated with milk protein concentrate (MPC80), whey protein concentrate (WPC80), and unbleached bread flour. The flour was mist inoculated with 4-serovar Salmonella (Typhimurium, Newport, Agona, and Senftenberg 775 W) cocktail and dried back to its preinoculation water activity levels. The inoculated flour was used to prepare the respective cookie dough formulations and baked, simulating the commercial baking process. Baking cookies at 350 °F (176.7 °C) for 18 min followed by 15 min of ambient cooling resulted in >5-log CFU/g reduction of Salmonella across all formulations. The mean D-values for Salmonella in MPC80, WPC80, and flour cookie doughs at 55, 58, and 61 °C were 57.60 ± 5.24, 21.60 ± 1.35, 12.00 ± 0.40 min; 54.54 ± 1.56, 29.48 ± 0.29, 12.53 ± 1.38 min; and 44.86 ± 0.61, 17.26 ± 0.32, 6.22 ± 0.87 min, respectively. The mean z-values for Salmonella in MPC80, WPC80, and flour-based cookie dough were 8.96 ± 0.77, 9.27 ± 0.49, and 6.99 ± 0.49 °C, respectively. This study presents the first scientific evidence that baking high milk protein cookies formulated with MPC80 or WPC80 at 350 °F (176.7 °C) for at least 18 min ensures >5-log Salmonella reduction, confirming effective lethality in the event of prebaking contamination.