The fore of a previously developed Belehradek type of growth rate model was used to develop a probability model for defining the growth/no growth interface as a function of temperature (10 to 37°C), pH (pH 2.8 to 6.9), lactic acid concentration (0 to 500 mM), and water activity (0.955 to 0.999; NaCl was used as the humectant). Escherichia coli was unable to grow in broth in which the undissociated lactic acid concentration exceeded 11 mM or, with two exceptions, at a pH of 3.9 or less with no lactic acid present. Under experimental conditions at which the pH and the undissociated acid concentrations were the major growth-limiting factors, the growth/no growth interface was essentially independent of temperature at temperatures ranging from 15 to 37°C. The interface between conditions that allowed growth and conditions at which growth did not occur was abrupt. The inhibitory effect of combinations of water activity and pH varied with temperature. Predictions of the model for the growth/no growth interface were consistent with 95% of the experimental data set.

Item Type:	Refereed Article
Research Division:	Engineering
Research Group:	Manufacturing engineering
Research Field:	Manufacturing safety and quality
Objective Division:	Health
Objective Group:	Public health (excl. specific population health)
Objective Field:	Food safety
UTAS Author:	Presser, KA (Ms Kirsty Presser)
UTAS Author:	Ross, T (Professor Tom Ross)
UTAS Author:	Ratkowsky, DA (Dr David Ratkowsky)
ID Code:	14507
Year Published:	1998
Web of Science® Times Cited:	160
Deposited By:	Agricultural Science
Deposited On:	1998-08-01
Last Modified:	2011-08-09
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