Survival of Listeria monocytogenes in commercial cheese brines

Abstract

The survival of Listeria monocytogenes was determined in commercial cheese brines collected from cheese factories in Wisconsin and northern Illinois. Survival of L. monocytogenes inoculated into commercial cheese brines ranged from <7 d to over 259 d. Survival did not correlate with pH, salt content, nitrogen content, mineral content, or inherent microbial populations but was negatively associated with addition of sodium hypochlorite at the dairy plant. The L. monocytogenes generally survived longer in brines held at 4°C than at 12°C. Sodium hypochlorite or hydrogen peroxide inactivated L. monocytogenes when added to commerical brines in the lab at 10 to 100 ppm or 0.001% to 0.02%, respectively. Addition of 1% potassium sorbate or 1% sodium benzoate also decreased survival of L. monocytogenes. Laboratory nitration of commercial brines had a negative effect on survival in one of three brines tested. The L. monocytogenes did not grow during incubation in any of the commercial brine samples tested.