Optimizing the application of hydrogen peroxide to control Listeria monocytogenes contamination on the surface of high-moisture cheese

Obj 1. Compare the effect of three different concentrations of hydrogen peroxide (HP) in aqueous dip solutions for the inactivation of L. monocytogenes on high moisture cheese. Obj 2. Determine effect of different submersion times on the initial inactivation of L. monocytogenes on high moisture cheese. Obj 3. Determine the potential for L. monocytogenes survival and growth during shelf life following neutralization of HP on cheese Obj 4. Determine the depletion of HP in dip solutions using the most efficacious treatment identified. Abstract: Previous research in our lab has identified dip applications of hydrogen peroxide (HP) as a promising intervention for the control of L. monocytogenes as surface contaminants on high moisture cheese using Queso Fresco as a model cheese. Results demonstrated that submersion of surface contaminated cheese samples (25g) for 1 minute in a 5% solution of HP at room temperature resulted in 3-log CFU/g reductions within 24 hours of application with no growth thereafter through 35 days of vacuum sealed storage at 7°C. The proposed research seeks to optimize the application of this control to achieve more rapid and complete reductions in L. monocytogenes counts by modifying the treatment concentration and application time. The proposed work will also assess the impact of HP neutralization following application to address potential regulatory and sensory concerns. Last, we will identify the rate of HP degradation in dip solutions during cheese treatment to determine if and how often the concentration will need to be tested and adjusted.