Type of Document	Dissertation
Author	Linton, Richard Howard
URN	etd-06062008-164544
Title	Use of the Gompertz equation to model non-linear survival curves and predict temperature, pH, and sodium chloride effects for Listeria monocytogenes Scott A
Degree	PhD
Department	Food Science and Technology
Advisory Committee	Advisor Name Title Hackney, Cameron Raj Committee Member Johnson, Janet M. Committee Member Marcy, Joseph E. Committee Member Pierson, Merle D. Committee Member
Keywords	Food
Date of Defense	1994-05-05
Availability	unrestricted
Abstract Numerous examples of non-linear survival curves, plotted as log surviving cells vs. time, for bacteria exposed to heat have been reported. Factors which may affect the shape of a survival curve and the heat resistance of bacteria include temperature, pH, and NaCl concentration. Many studies have examined the effect of these factors individually, but little information exists on the combined effects. The objective of this study was to mathematically model non-linear survival curves to account for these factors and their interactions simultaneously. Heat resistance of Listeria monocytogenes(L. monocytogenes) was determined in O.lM KH2P04 buffer and in infant formula at three temperatures (50, 55, and 60 C), three pH levels (5, 6, and 7), and three NaCl concentrations (0, 2, 4%). Survival curves were fit using linear regression, non-linear regression with a modified logistic equation, and non-linear regression with a modified Gompertz equation.
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