Validation of high milk protein chocolate chip cookie baking process and thermal death inactivation parameters of a 4-serovar Salmonella cocktail

• Baking high milk protein cookie demonstrates a >5-log Salmonella reduction. • Milk protein cookies exhibit higher Salmonella D and z -values. • Mean z -values of Salmonella were 8.96°C and 9.27°C in MPC80 and WPC80 respectively. 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 775W) cocktail and dried back to its pre-inoculation 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 minutes followed by 15 minutes 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 ± 1.38min; 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 minutes ensures >5-log Salmonella reduction, confirming effective lethality in the event of pre-baking contamination.