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 serotype 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 Salm. 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 Salm. 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.

Automated summary

The study aimed to investigate the impact of high-pressure processing (HPP) on the viability of Listeria monocytogenes, Salmonella serotype Typhimurium, and Escherichia coli O157:H7 in egg salad, as well as evaluate sub-lethally injured cells under different treatment conditions. HPP at 500 MPa for 30 s effectively killed L. monocytogenes and Salm. Typhimurium, while 2 min treatment was needed for E. coli O157:H7. HPP at 600 MPa for 30 s completely inactivated L. monocytogenes and Salm. Typhimurium, whereas 1 min treatment was sufficient for E. coli O157:H7. HPP at 400-500 MPa caused significant injury to pathogenic bacteria. No significant changes in pH and color of egg salad were observed during 28 days of refrigerated storage between HPP-treated and non-treated samples. The findings have practical implications for predicting the effectiveness of HPP in reducing foodborne pathogens in egg salad.