Heat inactivation of Listeria monocytogenes and Salmonella enterica serovar Typhi in a typical bologna matrix during an industrial cooking-cooling cycle

J Food Prot. 2006 Dec;69(12):3025-30. doi: 10.4315/0362-028x-69.12.3025.

Abstract

The heat resistance of Salmonella enterica serovar Typhi PF-724 and Listeria monocytogenes 2812 was determined in a commercial bologna batter. The heat inactivation of the two bacterial species was also studied in a semiautomatic pilot smokehouse under cooking conditions that reproduced an industrial bologna process. S. enterica serovar Typhi PF-724 was less heat resistant than L. monocytogenes 2812. The D-values (times required to reduce the population by 1 logarithmic cycle) for S. enterica serovar Typhi PF-724 ranged from 10.11 to 0.04 min for temperatures of 50 to 70 degrees C, while for L. monocytogenes 2812, the D-values were 2.5-, 4.9-, 3.8-, 3.3-, and 2-fold higher at 50, 55, 60, 65, and 70 degrees C, respectively, than for S. enterica serovar Typhi PF-724. However, the z-value (temperature required to reduce log D by 1 logarithmic cycle) for S. enterica serovar Typhi PF-724 (5.72 degrees C) was not significantly different from the z-value for L. monocytogenes 2812 (7.04 degrees C), indicating that a given increase in temperature would have a similar effect on the decimal reduction time for both bacterial species in that meat emulsion. Our data on experimentally inoculated batter also showed that processing bologna at a cooking-cooling cycle commonly used in the industry resulted in a minimum 5-log reduction for both S. enterica serovar Typhi PF-724 and L. monocytogenes 2812.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Colony Count, Microbial
  • Consumer Product Safety
  • Food Handling / methods*
  • Food Microbiology
  • Humans
  • Listeria monocytogenes / growth & development*
  • Meat Products / microbiology*
  • Salmonella typhi / growth & development*
  • Temperature
  • Time Factors