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F₀ Calculator (Steady & Variable)
♨️ Steady Temperature (isothermal hold)
°C
min
°C
F₀ (steady)
—
min
📐 Equation & explanation
F₀ = Δt × 10(T − 121.1) / z
- TConstant sterilization temperature (°C) during hold
- ΔtTotal hold time at temperature T (minutes)
- zTemperature coefficient (°C) — typically 10 °C for C. botulinum
- 121.1Reference temperature (°C) — standard for F₀
⚡ Example: 30 min at 121.1 °C with z = 10 °C → F₀ = 30 min
📈 Variable Temperature Profile
min
Must be strictly increasing
°C
F₀ (variable)
—
min
📐 Equation & explanation
F₀ = Σ [ (Δti / 2) × (Li + Li+1) ]
where Li = 10(Ti − 121.1) / z
- TiProduct temperature (°C) at measurement time ti
- ΔtiTime interval between two subsequent measurements (minutes)
- zTemperature coefficient (°C) — typically 10 °C
- LiLethal rate at each measurement point
⚡ Trapezoidal form shown. If all Δti are equal, this reduces to
F₀ = Δt × Σ 10(Ti − 121.1)/z (rectangular / left-point sum).