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Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment

A 2014 multistate listeriosis outbreak was linked to consumption of caramel-coated apples, an unexpected and previously unreported vehicle for Listeria monocytogenes. This outbreak was unanticipated because both the pH of apples (<4.0) and the water activity of the caramel coating (<0.80) are...

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Autores principales: Glass, Kathleen A., Golden, Max C., Wanless, Brandon J., Bedale, Wendy, Czuprynski, Charles
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society of Microbiology 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4620460/
https://www.ncbi.nlm.nih.gov/pubmed/26463161
http://dx.doi.org/10.1128/mBio.01232-15
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author Glass, Kathleen A.
Golden, Max C.
Wanless, Brandon J.
Bedale, Wendy
Czuprynski, Charles
author_facet Glass, Kathleen A.
Golden, Max C.
Wanless, Brandon J.
Bedale, Wendy
Czuprynski, Charles
author_sort Glass, Kathleen A.
collection PubMed
description A 2014 multistate listeriosis outbreak was linked to consumption of caramel-coated apples, an unexpected and previously unreported vehicle for Listeria monocytogenes. This outbreak was unanticipated because both the pH of apples (<4.0) and the water activity of the caramel coating (<0.80) are too low to support Listeria growth. In this study, Granny Smith apples were inoculated with approximately 4 log(10) CFU of L. monocytogenes (a cocktail of serotype 4b strains associated with the outbreak) on each apple’s skin, stem, and calyx. Half of the apples had sticks inserted into the core, while the remaining apples were left intact. Apples were dipped into hot caramel and stored at either 7°C or 25°C for up to 11 or 28 days, respectively. Data revealed that apples with inserted sticks supported significantly more L. monocytogenes growth than apples without sticks under both storage conditions. Within 3 days at 25°C, L. monocytogenes populations increased >3 log(10) in apples with sticks, whereas only a 1-log(10) increase was observed even after 1 week for caramel-coated apples without sticks. When stored at 7°C, apples with sticks exhibited an approximately 1.5-log(10) increase in L. monocytogenes levels at 28 days, whereas no growth was observed in apples without sticks. We infer that insertion of a stick into the apple accelerates the transfer of juice from the interior of the apple to its surface, creating a microenvironment at the apple-caramel interface where L. monocytogenes can rapidly grow to levels sufficient to cause disease when stored at room temperature.
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spelling pubmed-46204602015-10-26 Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment Glass, Kathleen A. Golden, Max C. Wanless, Brandon J. Bedale, Wendy Czuprynski, Charles mBio Observation A 2014 multistate listeriosis outbreak was linked to consumption of caramel-coated apples, an unexpected and previously unreported vehicle for Listeria monocytogenes. This outbreak was unanticipated because both the pH of apples (<4.0) and the water activity of the caramel coating (<0.80) are too low to support Listeria growth. In this study, Granny Smith apples were inoculated with approximately 4 log(10) CFU of L. monocytogenes (a cocktail of serotype 4b strains associated with the outbreak) on each apple’s skin, stem, and calyx. Half of the apples had sticks inserted into the core, while the remaining apples were left intact. Apples were dipped into hot caramel and stored at either 7°C or 25°C for up to 11 or 28 days, respectively. Data revealed that apples with inserted sticks supported significantly more L. monocytogenes growth than apples without sticks under both storage conditions. Within 3 days at 25°C, L. monocytogenes populations increased >3 log(10) in apples with sticks, whereas only a 1-log(10) increase was observed even after 1 week for caramel-coated apples without sticks. When stored at 7°C, apples with sticks exhibited an approximately 1.5-log(10) increase in L. monocytogenes levels at 28 days, whereas no growth was observed in apples without sticks. We infer that insertion of a stick into the apple accelerates the transfer of juice from the interior of the apple to its surface, creating a microenvironment at the apple-caramel interface where L. monocytogenes can rapidly grow to levels sufficient to cause disease when stored at room temperature. American Society of Microbiology 2015-10-13 /pmc/articles/PMC4620460/ /pubmed/26463161 http://dx.doi.org/10.1128/mBio.01232-15 Text en Copyright © 2015 Glass et al. http://creativecommons.org/licenses/by-nc-sa/3.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-ShareAlike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/) , which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Observation
Glass, Kathleen A.
Golden, Max C.
Wanless, Brandon J.
Bedale, Wendy
Czuprynski, Charles
Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment
title Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment
title_full Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment
title_fullStr Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment
title_full_unstemmed Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment
title_short Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment
title_sort growth of listeria monocytogenes within a caramel-coated apple microenvironment
topic Observation
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4620460/
https://www.ncbi.nlm.nih.gov/pubmed/26463161
http://dx.doi.org/10.1128/mBio.01232-15
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