Extracting Microbial Inactivation Parameters from Final Isothermal Survival Ratios
Extracting Microbial Inactivation Parameters from Final Isothermal Survival Ratios
Theoretically, at least, when a microbe’s thermal inactivation kinetics follows a three-parameter model, the three parameters can be estimated directly from the final survival ratio after three heat treatments, avoiding the need to record the entire survival curve. This Demonstration shows the method with simulated isothermal survival data of two bacterial cells and two bacterial endospores using the Weibull Log-Logistic (WeLL) model with a constant shape factor. The WeLL model’s three parameters are the temperature, , marking the inactivation onset; , the slope of the rate parameter rise at temperatures well above ; and , the shape factor of the isothermal inactivation times’ distribution, assumed to be practically temperature independent in the pertinent range. The three parameters are determined by numerically solving the three simultaneous survival equations of which they are the three unknowns.
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