Document Detail

Staphylococcus aureus growth boundaries: moving towards mechanistic predictive models based on solute-specific effects.
MedLine Citation:
PMID:  11916706     Owner:  NLM     Status:  MEDLINE    
The formulation of shelf-stable intermediate-moisture products is a critical food safety issue. Therefore, knowing the precise boundary for the growth-no-growth interface of Staphylococcus aureus is necessary for food safety risk assessment. This study was designed to examine the effects of various humectants and to produce growth boundary models as tools for risk assessment. The molecular mobility and the effects of various physical properties of humectants, such as their glass transition temperatures, their membrane permeability, and their ionic and nonionic properties, on S. aureus growth were investigated. The effects of relative humidity (RH; 84 to 95%, adjusted by sucrose plus fructose, glycerol, or NaCl), initial pH (4.5 to 7.0, adjusted by HCl), and potassium sorbate concentration (0 or 1,000 ppm) on the growth of S. aureus were determined. Growth was monitored by turbidity over a 24-week period. Toxin production was determined by enterotoxin assay. The 1,792 data points generated were analyzed by LIFEREG procedures (SAS Institute, Inc., Cary, N.C.), which showed that all parameters studied significantly affected the growth responses of S. aureus. Differences were observed in the growth-no-growth boundary when different humectants were used to achieve the desired RH values in both the absence and the presence of potassium sorbate. Sucrose plus fructose was most inhibitory at neutral pH values, while NaCl was most inhibitory at low pH values. The addition of potassium sorbate greatly increased the no-growth regions, particularly when pH was <6.0. Published kinetic growth and survival models were compared with boundary models developed in this work. The effects of solutes and differences in modeling approaches are discussed.
Cynthia M Stewart; Martin B Cole; J David Legan; Louise Slade; Mark H Vandeven; Donald W Schaffner
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  68     ISSN:  0099-2240     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2002 Apr 
Date Detail:
Created Date:  2002-03-27     Completed Date:  2002-07-12     Revised Date:  2013-06-09    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1864-71     Citation Subset:  IM    
Nabisco, Inc., East Hanover, New Jersey 07936, USA.
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MeSH Terms
Colony Count, Microbial
Enterotoxins / metabolism
Food Microbiology*
Fructose / pharmacology
Glycerol / pharmacology
Hydrogen-Ion Concentration
Models, Biological*
Predictive Value of Tests
Risk Assessment
Sodium Chloride / pharmacology
Sorbic Acid
Staphylococcus aureus / growth & development*
Sucrose / pharmacology
Reg. No./Substance:
0/Enterotoxins; 110-44-1/Sorbic Acid; 30237-26-4/Fructose; 56-81-5/Glycerol; 57-50-1/Sucrose; 7647-14-5/Sodium Chloride

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