Modeling microbial survival during exposure to a lethal agent with varying intensity

Area of Science:

• Microbiology
• Food Science
• Chemical Engineering

Background:

• Traditional microbial inactivation models assume first-order kinetics, which often deviate from reality.
• Assessing preservation and disinfection efficacy under dynamic industrial conditions (e.g., changing temperatures or chemical concentrations) is challenging.
• Existing models require assumptions about mortality kinetics or extrapolation, limiting their applicability.

Purpose of the Study:

• To develop a kinetic-independent method for predicting microbial survival curves under non-constant environmental conditions.
• To provide a more accurate assessment of disinfection and preservation process efficacy in dynamic industrial settings.
• To eliminate the need for traditional D and Z values and thermal death times in survival curve analysis.

Main Methods:

• Constructing survival curves from isothermal data without assuming specific mortality kinetics.
• Utilizing a differential equation solved numerically to model microbial inactivation under time-varying agent intensity.
• Demonstrating the method with simulated data for *Clostridium botulinum* spores and a hypothetical *Listeria*-like organism under various dynamic conditions.

Main Results:

• A method was established to derive survival curves under dynamic conditions directly from isothermal data, independent of assumed mortality kinetics.
• The approach successfully predicted survival curves for simulated heating, cooling, oscillating temperature, and dissipating chemical agent scenarios.
• The method bypasses the limitations of traditional D and Z values and thermal death time calculations.

Conclusions:

• The proposed kinetic-independent approach offers a robust framework for predicting microbial inactivation under fluctuating industrial process conditions.
• This method enhances the accuracy of disinfection efficacy assessment, particularly for dynamic processes.
• The findings have significant implications for food safety, pharmaceutical manufacturing, and other industries relying on microbial control.