The combined effect of pH and temperature on the survival of salmonella enterica serovar typhimurium and implications for the preparation of raw egg mayonnaise

Thilini Piushani Keerthirathne, Kirstin Ross, Howard Fallowfield, Harriet Whiley

Research output: Contribution to journalArticle

2 Citations (Scopus)
1 Downloads (Pure)

Abstract

Raw egg products are often associated with salmonellosis. The Australian guidelines recommend raw egg mayonnaise to be prepared and stored under 5C and adjusted to a pH less than 4.6 or 4.2. Despite these guidelines, a significant amount of salmonellosis outbreaks are recorded annually in Australia. The aim of this study was to investigate the effect of pH and temperature on the survival of Salmonella Typhimurium (ST) in peptone water (PW) and mayonnaise. The pH of PW and mayonnaise was adjusted to 4.2, 4.4 and 4.6 using acetic acid and vinegar, respectively. The PW and mayonnaise were inoculated with ST and incubated at 37C, 23C, and 4C. The survival of Salmonella was determined using the drop plate method. Survival was significantly (p < 0.05) improved at 4C. In both mayonnaise and PW, following 24 h, there was no ST growth at pH 4.2. Resuscitation of ST was rapidly observed at 4C while complete inactivation was observed at 37C at pH 4.2, 4.4, and 4.6 in both PW and mayonnaise. Lower temperatures protected ST from the bactericidal effect of low pH. “The preparation of mayonnaise at pH 4.2 or less and incubating it at room temperature for at least 24 h could reduce the incidence of salmonellosis”.

Original languageEnglish
Article number218
Number of pages10
JournalPathogens
Volume8
Issue number4
DOIs
Publication statusPublished - 4 Nov 2019

Bibliographical note

©2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Keywords

  • Chicken eggs
  • Gastroenteritis
  • Mayonnaise
  • Public health
  • Resuscitation
  • Salmonellosis

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