Validation of the microbiological safety of cheese brines

Obj 1. Determine the efficacy of hydrogen peroxide to inactivate Listeria monocytogenes and Staphylococcus aureus in cheese brines at various levels of salt concentrations and pH stored at several temperatures (32, 45, and 55°F; 0, 7.2, and 12.8°C). Abstract. Salting is an important step in the manufacturing process of cheese to add flavor, to remove lactose that could be converted to lactic acid by lactic acid bacteria and also to inhibit surface mold growth. However, brine can serve as reservoir of salt tolerant pathogen such as L. monocytogenes and Staphylococcus aureus. It has been verified that Listeria can survive in commercial cheese brines (Durmaz, et al., 2009; Ingham, et al., 2000; Larson, et al., 1999; Schirmer, et al., 2014). S. aureus can similarly survive in high salt media. Because commercial cheese brines are often used repeatedly, it is important to monitor the quality of cheese brines to ensure its safety. Several hurdles have been proposed to mitigate a potential food safety incident. Developing and monitoring GMP’s during the brining process is the most important hurdle to prevent cross-contamination. In addition, sanitation and environmental monitoring program around the brining zone have to be established. Salinity, pH, temperature, and solids of the brine should also be monitored regularly as salinity and pH have been confirmed to be important hurdles in previous studies (Durmaz, et al., 2000; Schirmer, et al., 2014). Antimicrobial treatments is also considered as one of the mitigation steps. Hydrogen peroxide treatment has been shown to be effective in the past (Larson, et al., 1999). This study is designed to validate the ability of hydrogen peroxide to reduce the populations of Listeria monocytogenes (at minimal levels with the goal of regulatory acceptance) and S. aureus in cheese brines with various levels of salt and pH.