Modelling the effects of temperature, water activity, pH and lactic acid concentration on the growth rate of Escherichia coli.
An extended square root-type model describing Escherichia coli growth rate was developed as a function of temperature (7.63-47.43 degrees C), water activity (0.951-0.999, adjusted with NaCl), pH (4.02-8.28) and lactic acid concentration (0-500 mM). The new model, based on 236 growth rate data, combines and extends previously published square root-type models and incorporates terms for upper and lower limiting temperatures, upper and lower limiting pH, minimum inhibitory concentrations of dissociated and undissociated lactic acid and lower limiting water activity. A term to describe upper limiting water activity was developed but could not be fitted to the E. coli data set because of the difficulty of generating data in the super-optimal water activity range (i.e. >0.998). All data used to generate the model are presented. The model provides an excellent description of the experimental data.
Ross
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Centre for Food Safety and Quality, School of Agricultural Science, University of Tasmania, GPO Box 252-54, Hobart 7001, Tasmania, Australia. Tom.Ross@utas.edu.au
Ratkowsky
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Mellefont
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McMeekin
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D002455:Cell Division / Q000187:drug effects; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019344:Lactic Acid / Q000494:pharmacology*; D008954:Models, Biological; D013696:Temperature; D014867:Water / Q000378:metabolism*
D014867:Water; D019344:Lactic Acid