Effect of high pressure processing on the inactivation of foodborne pathogens in egg salad.

The objectives of this study were to determine the effect of high pressure processing (HPP) on the survival of Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157: H7 in egg salad, and to evaluate the number of sub-lethally injured cells based on treatment conditions. HPP at 500 MPa for 30 s was sufficient for the complete inactivation of L. monocytogenes and S. Typhimurium directly plated on selective agar or plated after resuscitation, while 2 min treatment was required for E. coli O157: H7. HPP at 600 MPa for 30 s completely inactivated L. monocytogenes and S. Typhimurium, while 1 min treatment was needed for E. coli O157: H7. HPP at 400‒500 MPa injured a large number of pathogenic bacteria. No significant changes (p > 0.05) in pH and color of egg salad were observed between HPP-treated and non-treated samples during 28 days of storage at refrigerated temperature. Our findings could be useful in predicting the HPP-mediated inactivation patterns of foodborne pathogens in egg salad for practical applications.