Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics

Ultraviolet (UV) lasers have been employed for many applications such as in the food industry, medicine and dentistry. The use of laser and other pulsed light systems for phototherapy and other microbial disinfections are based on spectral characteristics and configuration of the light used. The obj...

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Main Author:	Kundwal, Moses Elisha
Format:	Thesis
Language:	English
Published:	2016
Subjects:	QC Physics
Online Access:	http://eprints.utm.my/id/eprint/78229/1/MosesElishaKundwalPFS2016.pdf
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id	my-utm-ep.78229
record_format	uketd_dc
spelling	my-utm-ep.782292018-07-30T08:51:28Z Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics 2016-01 Kundwal, Moses Elisha QC Physics Ultraviolet (UV) lasers have been employed for many applications such as in the food industry, medicine and dentistry. The use of laser and other pulsed light systems for phototherapy and other microbial disinfections are based on spectral characteristics and configuration of the light used. The objective of this study was to use a flash lamp-pumped passive Q-switched Nd:YAG laser for inactivation two pathogenic bacteria, namely Escherichia coli and Listeria monocytogenes. A 1064 nm pulsed infrared (IR) laser and its 2nd and 3rd harmonics were used to irradiate Escherichia coli at various values of fluence. A 350 nm continuous wave (CW) UV lamp was also used in the inactivation process for the purpose of comparison with the 3rd harmonic (355 nm) pulsed laser. The result indicates that there is a statistical significant difference between mean log10 reductions for the three laser wavelengths. The mean log10 reductions for the 355 nm pulsed (UV) laser are higher than the corresponding mean log10 reductions for the CW UV light. A t-test conducted on the mean log10 reductions obtained for the pulsed UV laser and the CW UV light indicates that there is a significant difference between the two sets of mean log10 reductions. When E. coli and L. monocytogenes samples were irradiated with the pulsed UV laser at three different pulse frequencies, the result shows higher inactivation effect at higher pulse frequency than at lower pulse frequency. Statistical analysis, using two-way ANOVA, shows that the mean log10 reductions for the three pulsed frequencies were significantly different. However, no statistical significant difference was observed between mean log10 reductions obtained for treatment with the pulsed UV laser and the CW UV light on three different sample volumes of E. coli and L. monocytogenes. 2016-01 Thesis http://eprints.utm.my/id/eprint/78229/ http://eprints.utm.my/id/eprint/78229/1/MosesElishaKundwalPFS2016.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:97152 phd doctoral Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QC Physics
spellingShingle	QC Physics Kundwal, Moses Elisha Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics
description	Ultraviolet (UV) lasers have been employed for many applications such as in the food industry, medicine and dentistry. The use of laser and other pulsed light systems for phototherapy and other microbial disinfections are based on spectral characteristics and configuration of the light used. The objective of this study was to use a flash lamp-pumped passive Q-switched Nd:YAG laser for inactivation two pathogenic bacteria, namely Escherichia coli and Listeria monocytogenes. A 1064 nm pulsed infrared (IR) laser and its 2nd and 3rd harmonics were used to irradiate Escherichia coli at various values of fluence. A 350 nm continuous wave (CW) UV lamp was also used in the inactivation process for the purpose of comparison with the 3rd harmonic (355 nm) pulsed laser. The result indicates that there is a statistical significant difference between mean log10 reductions for the three laser wavelengths. The mean log10 reductions for the 355 nm pulsed (UV) laser are higher than the corresponding mean log10 reductions for the CW UV light. A t-test conducted on the mean log10 reductions obtained for the pulsed UV laser and the CW UV light indicates that there is a significant difference between the two sets of mean log10 reductions. When E. coli and L. monocytogenes samples were irradiated with the pulsed UV laser at three different pulse frequencies, the result shows higher inactivation effect at higher pulse frequency than at lower pulse frequency. Statistical analysis, using two-way ANOVA, shows that the mean log10 reductions for the three pulsed frequencies were significantly different. However, no statistical significant difference was observed between mean log10 reductions obtained for treatment with the pulsed UV laser and the CW UV light on three different sample volumes of E. coli and L. monocytogenes.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Kundwal, Moses Elisha
author_facet	Kundwal, Moses Elisha
author_sort	Kundwal, Moses Elisha
title	Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics
title_short	Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics
title_full	Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics
title_fullStr	Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics
title_full_unstemmed	Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics
title_sort	inactivation of escherichia coli and listeria monocytogenes with nd: yag laser and its harmonics
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2016
url	http://eprints.utm.my/id/eprint/78229/1/MosesElishaKundwalPFS2016.pdf
_version_	1747817938668224512

Inactivation of escherichia coli and listeria monocytogenes with Nd: YAG laser and its harmonics

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