Document Detail


Effect of challenge temperature and solute type on heat tolerance of Salmonella serovars at low water activity.
MedLine Citation:
PMID:  11526015     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Salmonella spp. are reported to have an increased heat tolerance at low water activity (a(w); measured by relative vapor pressure [rvp]), achieved either by drying or by incorporating solutes. Much of the published data, however, cover only a narrow treatment range and have been analyzed by assuming first-order death kinetics. In this study, the death of Salmonella enterica serovar Typhimurium DT104 when exposed to 54 combinations of temperature (55 to 80 degrees C) and a(w) (rvp 0.65 to 0.90, reduced using glucose-fructose) was investigated. The Weibull model (LogS = -bt(n)) was used to describe microbial inactivation, and surface response models were developed to predict death rates for serovar Typhimurium at all points within the design surface. The models were evaluated with data generated by using six different Salmonella strains in place of serovar Typhimurium DT104 strain 30, two different solutes in place of glucose-fructose to reduce a(w), or six low-a(w) foods artificially contaminated with Salmonella in place of the sugar broths. The data demonstrate that, at temperatures of > or =70 degrees C, Salmonella cells at low a(w) were more heat tolerant than those at a higher a(w) but below 65 degrees C the reverse was true. The same patterns were generated when sucrose (rvp 0.80 compared with 0.90) or NaCl (0.75 compared with 0.90) was used to reduce a(w), but the extent of the protection afforded varied with solute type. The predictions of thermal death rates in the low-a(w) foods were usually fail-safe, but the few exceptions highlight the importance of validating models with specific foods that may have additional factors affecting survival.
Authors:
K L Mattick; F Jørgensen; P Wang; J Pound; M H Vandeven; L R Ward; J D Legan; H M Lappin-Scott; T J Humphrey
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  67     ISSN:  0099-2240     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2001 Sep 
Date Detail:
Created Date:  2001-08-29     Completed Date:  2001-12-04     Revised Date:  2013-04-17    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4128-36     Citation Subset:  IM    
Affiliation:
PHLS Food Microbiology Research Unit, Heavitree, Exeter EX2 5AD, United Kingdom. kmattick@phls.org.uk
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MeSH Terms
Descriptor/Qualifier:
Culture Media
Food Handling / methods
Food Microbiology
Hot Temperature*
Models, Biological
Salmonella typhimurium / classification,  growth & development*
Sodium Chloride / pharmacology*
Temperature
Water*
Chemical
Reg. No./Substance:
0/Culture Media; 7647-14-5/Sodium Chloride; 7732-18-5/Water
Comments/Corrections

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


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