Growth and Survival of Escherichia coli O157:H7 and Listeria monocytogenes in Egg Products Held at Different Temperatures

Abstract

Growth and survival of Escherichia coli O157:H7 and Listeria monocytogenes in steamed eggs and scrambled eggs held at different temperatures (5, 18, 22, 37, 55, and 60°C) were investigated in the present study. Among the holding temperatures tested, both pathogens multiplied best at 37°C followed by 22, 18, and 5°C. In general, E. coli O157:H7 grew better in the egg products than L. monocytogenes did at all the storage temperatures tested except at 5°C. E. coli O157:H7 did not grow in steamed eggs and scrambled eggs held at 5°C. L. monocytogenes showed a slight population increase of ∼0.6 to 0.9 log CFU/g in these egg products at the end of the 36-h storage period at 5°C. The population of both pathogens detected in the egg products was affected by the initial population, holding temperature, and length of the holding period. It was also noted that L. monocytogenes was more susceptible than E. coli O157:H7 in steamed eggs held at 60°C. After holding at 60°C for 1 h, no detectable viable cells of L. monocytogenes with a population reduction of 5.4 log CFU/g was observed in steamed eggs, whereas a lower population reduction of only ∼0.5 log CFU/ml was noted for E. coli O157:H7.