Growth, injury, and survival potential of Yersinia enterocolitica, Listeria monocytogenes, and Staphylococcus aureus in brine chiller conditions

Abstract

A model brine system was used to evaluate growth, injury, and survival potential of Yersinia enterocolitica, Listeria monocytogenes, and Staphylococcus aureus. Each strain was incubated for up to 30 days at -12 to 28°C in brain heart infusion broth containing 0.5 to 20% NaCl. Samples were enumerated on a dual agar plating system to assess growth and injury. Y. enterocolitica grew at -2°C in 0.5% brine and at 5°C in 5% NaCl. L. monocytogenes grew at 5°C in 5% NaCl and at 12°C in 9% NaCl. S. aureus grew at 12°C in 5% NaCl. Significant injury was observed for two of the pathogens, but not for L. monocytogenes. Bacteriostatic or lethal conditions were maintained for the thee organisms at -2°C and 9% NaCl. While lethal NaCl and temperature combinations were defined for E enterocolitica and S. aureus, L. monocytogenes survived for 30 days at -12°C in 20% NaCl. This study provides safety criteria and recommendations for use in the operation of recycle brine systems for cooling processed foods.