Abstract

Numerical and statistical procedures based on pseudo-zero for the lag and first order reaction kinetics for the exponential growth phase were developed to analyze non-isothermal microbial spoilage. Arrhenius model parameters and their accuracy were estimated for a mixture of Pseudomonas fluorescens, Staphylococcus aureus and Achromobacter lwoffi growing in a seafood model. Linear regressions used with isothermal experiments generated initial values for nonlinear estimations of the frequency (K0) and activiation energy (E(a)) constants. An optimization technique was used to minimize the square difference between experimental and estimated values while parameter accuracy was assessed using a bootstrap method. E(a) and in(K0) were 109 +/- 3.4 and 48.3 +/- 1.5 kJ/mole for the exponential, and 152 +/- 4.0 and 64.4 +/- 1.7 kJ/mole for the lag phase, respectively. The Mann-Whitney-Wilcoxon rank sum test showed no significant differences between parameters generated by two different temperature profiles (5% significance level).