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dc.contributor.author
Zhang, Yifan
dc.contributor.supervisor
Mathys, Alexander
dc.contributor.supervisor
Moeller, Ralf
dc.contributor.supervisor
Blayo, Laurence
dc.date.accessioned
2021-03-22T08:56:08Z
dc.date.available
2021-03-20T16:33:06Z
dc.date.available
2021-03-22T08:56:08Z
dc.date.issued
2020
dc.identifier.isbn
978-3-907234-31-0
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/475539
dc.identifier.doi
10.3929/ethz-b-000475539
dc.description.abstract
Bacterial spores pose the largest hurdle for the preservation of perishable food due to their extreme resistance to processing steps. Conventionally, food industries apply intensive decontamination processing steps, most commonly thermal processing, to inactivate bacterial spores. However, this is not suitable for heat-sensitive products, ingredients, and materials. Moreover, the high thermal load of treated products often leads to reduced quality concerning their organoleptic and nutritional attributes. To meet consumer needs of fresher, minimally processed food products, food industries and scientists have been searching for novel non-thermal, mild but efficient spore control strategies. Among the emerging decontamination technologies, low energy electron beam (LEEB) and high pressure (HP) technologies have shown high potential because of the reduced thermal-load and improved quality retention of the treated foods. Therefore, in this research, these two non-thermal processing technologies were investigated for their spore inactivation efficiency and mechanisms. The results revealed that the inactivation efficiency of LEEB technology was in a comparable range to that of the other ionizing irradiation technologies and was influenced by various factors, including spore species and sporulation conditions. The mechanistic study revealed that DNA damage was one of the causes of spore inactivation by LEEB and the investigation of a newly developed continuous industrial LEEB system demonstrated a high potential to upscale LEEB processing for the decontamination of low water activity food surfaces (e.g. for spices). HP can inactivate bacterial spores by first triggering germination. The key limitation for the application of HP-based germination-inactivation approaches is that spore germination is extremely heterogeneous under HP. This research optimized and thoroughly validated the use of flow cytometry to study spore germination behavior under HP. Results revealed four distinct responses of spores under HP treatment at 150 MPa and 37°C. A protocol based on fluorescence-activated cell sorting was further developed to isolate spores of different physiological states after HP treatment. The methods developed in this study provide a foundation for future research on spore inactivation using LEEB and heterogeneous spore behavior upon HP treatment. The outcome can further help the development and implementation of LEEB and HP technologies as non-thermal, gentle spore control approaches, which will help deliver safe and minimally processed foods to consumers in the future.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
Bacterial spore
en_US
dc.subject
Low energy electron beam
en_US
dc.subject
High pressure processing (HPP)
en_US
dc.subject
Non-thermal technologies
en_US
dc.subject
Microbial inactivation
en_US
dc.subject
Food safety and quality
en_US
dc.title
Mechanisms of low energy electron beam and isostatic high pressure processing as non-thermal spore control strategies
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2021-03-22
ethz.size
180 p.
en_US
ethz.code.ddc
DDC - DDC::5 - Science::570 - Life sciences
en_US
ethz.grant
Isolation and characterization of high pressure superdormant spores
en_US
ethz.identifier.diss
26857
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02070 - Dep. Gesundheitswiss. und Technologie / Dep. of Health Sciences and Technology::02701 - Inst.f. Lebensmittelwiss.,Ernährung,Ges. / Institute of Food, Nutrition, and Health::09571 - Mathys, Alexander / Mathys, Alexander
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02070 - Dep. Gesundheitswiss. und Technologie / Dep. of Health Sciences and Technology::02701 - Inst.f. Lebensmittelwiss.,Ernährung,Ges. / Institute of Food, Nutrition, and Health::09571 - Mathys, Alexander / Mathys, Alexander
en_US
ethz.grant.agreementno
182273
ethz.grant.fundername
SNF
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.program
Projekte Lebenswissenschaften
ethz.date.deposited
2021-03-20T16:33:14Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2021-03-22T08:56:19Z
ethz.rosetta.lastUpdated
2022-03-29T05:54:41Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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