The live bacterial load and microbiota composition of prepacked “ready-to-eat” leafy greens during household conditions, with special reference to E. coli
(2022) In International Journal of Food Microbiology 377.- Abstract
Ready-to-eat (RTE) leafy greens are popular products that unfortunately have been associated with numerous foodborne illness outbreaks. Since the influence of consumer practices is essential for their quality and safety, the objective of this study was to analyze the microbiota of RTE products throughout shelf life during simulated household conditions. Products from different companies were analyzed in terms of plate counts, and resealed and unopened packages were compared. High bacterial loads were found, up to a total plate count of 9.6 log10 CFU/g, and Enterobacteriaceae plate counts up to 6.0 CFU/g on the expiration date. The effect of consumer practice varied, thus no conclusions regarding resealed or unopened bags... (More)
Ready-to-eat (RTE) leafy greens are popular products that unfortunately have been associated with numerous foodborne illness outbreaks. Since the influence of consumer practices is essential for their quality and safety, the objective of this study was to analyze the microbiota of RTE products throughout shelf life during simulated household conditions. Products from different companies were analyzed in terms of plate counts, and resealed and unopened packages were compared. High bacterial loads were found, up to a total plate count of 9.6 log10 CFU/g, and Enterobacteriaceae plate counts up to 6.0 CFU/g on the expiration date. The effect of consumer practice varied, thus no conclusions regarding resealed or unopened bags could be drawn. The tested products contained opportunistic pathogens, such as Enterobacter homaechei, Hafnia paralvei and Pantoea agglomerans. Amplicon sequencing revealed that the relative abundance of major taxonomic groups changed during shelf life; Pseudomonadaceae and Xanthomonadaceae decreased, while Flavobacteriaceae and Marinomonadaceae inceased. Inoculation with E. coli CCUG 29300T showed that the relative abundance of Escherichia-Shigella was lower on rocket than on other tested leafy greens. Inoculation with E. coli strain 921 indicate growth at the beginning of shelf-life time, while E. coli 731 increases at the end, seemingly able to adapt to cold storage conditions. The high levels of live microorganisms, the detection of opportunistic pathogens, and the ability of E. coli strains to grow at refrigeration temperature raise concerns and indicate that the shelf life may be shortened to achieve a safer product. Due to variations between products, further studies are needed to define how long the shelf-life of these products should be, to ensure a safe product even at the end of the shelf-life period.
(Less)
- author
- Uhlig, E. LU ; Kjellström, A. LU ; Oscarsson, E. LU ; Nurminen, N. ; Nabila, Y. ; Paulsson, J. ; Lupan, T. ; Velpuri, N. S.B.P. ; Molin, G. LU and Håkansson LU
- organization
- publishing date
- 2022-09-16
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- E. coli, Food safety, Leafy green vegetables, Native microbiota
- in
- International Journal of Food Microbiology
- volume
- 377
- article number
- 109786
- publisher
- Elsevier
- external identifiers
-
- pmid:35716582
- scopus:85132215799
- ISSN
- 0168-1605
- DOI
- 10.1016/j.ijfoodmicro.2022.109786
- language
- English
- LU publication?
- yes
- id
- a6988ec1-8097-402f-a0b7-23be531f5ff2
- date added to LUP
- 2022-09-26 15:59:09
- date last changed
- 2024-04-04 07:49:34
@article{a6988ec1-8097-402f-a0b7-23be531f5ff2,
abstract = {{<p>Ready-to-eat (RTE) leafy greens are popular products that unfortunately have been associated with numerous foodborne illness outbreaks. Since the influence of consumer practices is essential for their quality and safety, the objective of this study was to analyze the microbiota of RTE products throughout shelf life during simulated household conditions. Products from different companies were analyzed in terms of plate counts, and resealed and unopened packages were compared. High bacterial loads were found, up to a total plate count of 9.6 log<sub>10</sub> CFU/g, and Enterobacteriaceae plate counts up to 6.0 CFU/g on the expiration date. The effect of consumer practice varied, thus no conclusions regarding resealed or unopened bags could be drawn. The tested products contained opportunistic pathogens, such as Enterobacter homaechei, Hafnia paralvei and Pantoea agglomerans. Amplicon sequencing revealed that the relative abundance of major taxonomic groups changed during shelf life; Pseudomonadaceae and Xanthomonadaceae decreased, while Flavobacteriaceae and Marinomonadaceae inceased. Inoculation with E. coli CCUG 29300<sup>T</sup> showed that the relative abundance of Escherichia-Shigella was lower on rocket than on other tested leafy greens. Inoculation with E. coli strain 921 indicate growth at the beginning of shelf-life time, while E. coli 731 increases at the end, seemingly able to adapt to cold storage conditions. The high levels of live microorganisms, the detection of opportunistic pathogens, and the ability of E. coli strains to grow at refrigeration temperature raise concerns and indicate that the shelf life may be shortened to achieve a safer product. Due to variations between products, further studies are needed to define how long the shelf-life of these products should be, to ensure a safe product even at the end of the shelf-life period.</p>}},
author = {{Uhlig, E. and Kjellström, A. and Oscarsson, E. and Nurminen, N. and Nabila, Y. and Paulsson, J. and Lupan, T. and Velpuri, N. S.B.P. and Molin, G. and Håkansson}},
issn = {{0168-1605}},
keywords = {{E. coli; Food safety; Leafy green vegetables; Native microbiota}},
language = {{eng}},
month = {{09}},
publisher = {{Elsevier}},
series = {{International Journal of Food Microbiology}},
title = {{The live bacterial load and microbiota composition of prepacked “ready-to-eat” leafy greens during household conditions, with special reference to E. coli}},
url = {{http://dx.doi.org/10.1016/j.ijfoodmicro.2022.109786}},
doi = {{10.1016/j.ijfoodmicro.2022.109786}},
volume = {{377}},
year = {{2022}},
}