Protocol Document
Lethality Constant (F0).
F0 is the integrated measure of microbial kill potential over time, normalized to 121.1 C reference behavior. For dense hydrated systems, useful F0 is achieved only when thermal lag is accounted for in cycle design.
Operational Definition
L = 10^((T_actual - 121.1) / 10)
F0 = integral(L dt)
A pass condition represents achieved integrated lethality, not just elapsed cycle time.
Interpretation Guide
- - Equal timer durations can produce unequal lethality across altitude and mass profiles.
- - Core temperature lag is a first-class variable in dense media cycles.
- - Ledger publication of F0 supports transparent pass/fail accountability.
Lethality Inputs -> Decision Impact (Quick Reference)
T_actual profile
Instantaneous thermal input used to compute lethality rate L
Higher profile -> faster F0 accumulation
Thermal lag
Delay between chamber behavior and core media temperature
Lag requires hold extension
Hold duration
Integration window for cumulative F0 under observed temperature conditions
Time alone is insufficient
Cumulative F0
Integrated lethality output used for release disposition
Release threshold pass/fail
Worked Example Framework
Numerical worked example - Coming soon. We will publish this section when a fully approved, batch-traceable dataset is cleared for public release.
- - Step 1: Define time-series temperature inputs and sampling cadence.
- - Step 2: Convert each interval to lethality rate using the published relation.
- - Step 3: Integrate interval lethality to cumulative F0.
- - Step 4: Compare cumulative F0 to release threshold and record disposition.
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