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https://hdl.handle.net/2440/133251
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Type: | Journal article |
Title: | Acidification and extended storage at room temperature of mayonnaise reduce Salmonella Typhimurium virulence and viability |
Author: | McWhorter, A.R. Khan, S. Sexton, M. Moyle, T.S. Chousalkar, K.K. |
Citation: | Food Research International, 2021; 141:110117-1-110117-9 |
Publisher: | Elsevier |
Issue Date: | 2021 |
ISSN: | 0963-9969 1873-7145 |
Statement of Responsibility: | Andrea R. McWhorter, Samiullah Khan, Margaret Sexton, Talia S. Moyle, Kapil K. Chousalkar |
Abstract: | Despite food safety recommendations, raw egg-based foods, such as mayonnaise, are frequently identified as the source of Salmonella during outbreaks. Acidification and storage temperature have been linked with reduced bacterial culturability. Raw egg-based sauces stored at 25 ◦C have historically been linked with faster decline of Salmonella culturability than preparations stored at 5 ◦C. This study aimed to determine whether reduced culturability in acidified mayonnaise correlated with reduced in vitro bacterial motility, invasiveness and viability as well as disease-causing capacity in BALB/c mice. Acidification of mayonnaise and incubation at 25 ◦C for 4 h significantly reduced culturability of Salmonella Typhimurium DT9 but was dependent on initial bacterial load. Bacteria recovered from acidified mayonnaise exhibited reduced invasiveness into polarized cultured intestinal epithelial cells and 12 h post inoculation were no longer invasive suggesting a reduced capacity to cause disease. To confirm this, BALB/c mice were inoculated with Salmonella Typhimurium contaminated mayonnaise stored at 5 ◦C or 25 ◦C for 12, 24, 48, 72, and 96 h. Mice inoculated with mayonnaise incubated at 5 ◦C for 12 and 24 h exhibited mild to moderate disease symptoms; all other mayonnaise treatment groups did not exhibit disease symptoms. In acidified mayonnaise, Salmonella Typhimurium DT9 exhibited a global downregulation of metabolism, stress response, and virulence genes upon addition to mayonnaise. After 4 h of incubation at both 5 ◦C and 25 ◦C, however, the vast majority of genes were upregulated which was maintained over the 96-hour experiment suggesting that bacteria were severely stressed. Salmonella Typhimurium DT9 cells were isolated from mayonnaise samples and ATP production was quantified. At both 5 ◦C and 25 ◦C, ATP production decreased in acidified mayonnaise preparations. At 25 ◦C, ATP production decreased more rapidly than at 5 ◦C. After 24 h, ATP production of bacteria in mayonnaise stored at 25 ◦C was not significantly different from the dead control group. Thus, the current recommendation of only serving freshly prepared raw egg-sauces or refrigerating immediately after preparation, could be placing consumers at higher risk for contracting salmonellosis. |
Keywords: | Salmonella Typhimurium; Acidification; Raw egg sauces; Virulence; Invasion; BALB/c mice |
Description: | Available online 12 January 2021 |
Rights: | Crown Copyright © 2021 Published by Elsevier Ltd. All rights reserved. |
DOI: | 10.1016/j.foodres.2021.110117 |
Published version: | http://dx.doi.org/10.1016/j.foodres.2021.110117 |
Appears in Collections: | Animal and Veterinary Sciences publications Aurora harvest 8 |
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