Document Detail

Inactivation kinetics and factors of variability in the pulsed light treatment of Listeria innocua cells.
MedLine Citation:
PMID:  18044429     Owner:  NLM     Status:  MEDLINE    
Pulsed light (PL) treatment can effectively reduce microbial populations in clear substrates and on surfaces, but its effectiveness varies as a function of substrate or treatment-related factors. For PL to be successfully adopted by the food industry, all factors of influence, as well as the inactivation kinetics for the microorganisms of concern, must be elucidated. In this study, the inactivation kinetics of Listeria innocua and the effect of inoculum size on PL inactivation were investigated. Stainless steel coupons (50.8 by 101.6 mm) of defined surface properties and transparent glass chamber slides (25.4 by 50.8 by 10 mm) were each inoculated with 1 ml of aqueous suspensions of L. innocua containing inoculum populations of up to 10(9) CFU. The thickness of the liquid layer in the glass slides was 1.16 mm. The inoculated substrates were exposed to PL treatment of up to 17 J/cm2 in a static PL chamber equipped with a pulsed Xenon lamp. Survivors were recovered and enumerated by both standard plate counting and most-probable-number procedures. The data indicated that in clear liquids, PL resulted in more than a 6-log reduction of L. innocua after a 12-J/cm2 treatment, regardless of the initial inoculum size. For the stainless steel surfaces, less than a 4-log reduction after a 12-J/cm2 treatment and a noticeable effect of substrate characteristics and inoculum size on inactivation were observed. The survivor curves showed pronounced tailing for all substrates used in the study. The Weibull model accurately predicted the survivor ratios for the PL treatment of L. innocua in clear liquids, with a shape and scale parameter of 0.33 and 3.01, respectively. The Weibull model resulted in significant overestimation of PL effectiveness for the stainless steel substrates, where the influence of various substrate properties and inoculum level on inactivation was significant.
Aaron R Uesugi; Sarah E Woodling; Carmen I Moraru
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of food protection     Volume:  70     ISSN:  0362-028X     ISO Abbreviation:  J. Food Prot.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-11-29     Completed Date:  2007-12-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703944     Medline TA:  J Food Prot     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2518-25     Citation Subset:  IM    
Department of Food Science, Cornell University, Stocking Hall, Ithaca, New York 14853, USA.
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MeSH Terms
Colony Count, Microbial
Food Irradiation*
Food Microbiology
Food Preservation / methods*
Listeria / growth & development*,  radiation effects*
Models, Biological*
Stainless Steel
Ultraviolet Rays
Reg. No./Substance:
12597-68-1/Stainless Steel

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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