Titre :
|
Development of thermal inactivation models for Salmonella enteritidis and Escherichia coli O157:H7 with temperature, pH and NaCl as controlling factors
|
Auteurs :
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C. Blackburn ;
L. Curtis ;
L. Humpheson ;
AL Et
|
Type de document :
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article/chapitre/communication
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Année de publication :
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1997
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Format :
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p. 31-44
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Langues:
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= Anglais
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Catégories :
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INDUSTRIE AGRO-ALIMENTAIRE
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Mots-clés:
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PRODUIT ALIMENTAIRE
;
BACTERIE PATHOGENE
;
TEMPERATURE
;
PH
;
MODELE
;
CHLORURE DE SODIUM
|
Résumé :
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The thermal inactivation of Salmonella enteritidis phage type 4 and Escherichia coli O157:H7 as affected by temperature (54.5-64.5 °C), pH (4.2-9.6 with HCl or NaOH) and NaCl concentration (0.5-8.5% w/w) was studied. Cell suspensions in modified tryptone soya broth were heated in a submerged-coil heating apparatus and survivors were enumerated on tryptone soya agar incubated aerobically. For most thermal inactivation data there was a logarithmic decrease in the viable cell concentration over the initial 4-6 log(10) reduction and D-values were fitted. In some cases, tailing of the survivor curves was observed with cells surviving longer than the D-values predicted. Models describing the effect of temperature, pH and NaCl concentration on the thermal inactivation of S. Enteritidis and E. Coli O157:H7 were produced. For both organisms, predicted z-values of 4.6-7.0 C° were obtained depending on conditions, with larger z-values at higher levels of NaCl. Optimum survival occurred between pH 5 and pH 7 and increasing acidity or alkalinity caused a decrease in the predicted D-values. At equivalent pH, acetic acid and lactic acid (at 0.5, 1 and 2% w/w) generally had a similar, or increased, lethal effect compared with HCl, whereas in most cases citric acid had a less lethal effect.
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Source :
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International Journal of Food Microbiology, vol.38
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