Weibullian Inactivation Rate as a Function of Time

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This third of five Demonstrations depicts the change in the momentary Weibullian inactivation rate of a microorganism as a function of time (in minutes) for a chosen temperature history. This is done by setting eight temperature profile and two Weibullian heat resistance parameters. Notice the automatic scaling of the axis; it is different in each example.

Contributed by: Mark D. Normand and Micha Peleg (March 2011)
Open content licensed under CC BY-NC-SA


Snapshots


Details

This is the third of five Demonstrations of functions used to model thermal processing of foods for the purpose of eliminating the presence of pathogenic and spoilage microorganisms. The five Demonstrations allow slider-control manipulation of the plots of:

1) an 8-parameter nonlinear "temperature profile", temperature (in degrees C) versus time (in minutes)

2) a 2-parameter nonlinear Weibullian rate, , as a function of temperature (in degrees C)

3) a 10-parameter nonlinear Weibullian rate, , as a function of time (in minutes)

4) an 11-parameter dynamic microbial log survival, , as a function of time (in minutes)

5) a 12-parameter equivalent isothermal time as a function of time (in minutes)

Please note that not all possible parameter combinations yield a realistic temperature and/or inactivation rate profile.

Snapshot 1: extremely resistant bacterial spores

Snapshot 2: resistant bacterial spores

Snapshot 3: sensitive bacterial cells



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