Watson Dairy Consulting
Pasteurisation Equivalence & P* Calculator
Find the holding time at one temperature that gives the same lethality as another, and the P* pasteurisation value — for process comparison, temperature-deviation decisions and equivalent-combination checks.
What this is for: the UK/EU minimum is 72 °C for 15 s (or 63 °C for 30 min, or any equivalent combination giving a negative phosphatase test). Use this to convert between time and temperature, and to read the P* value — the recognised pasteurisation index, where 15 s at 72 °C = 1 unit (z = 8 °C) and a compliant process needs P* ≥ 1.
Inputs
Quick presets:
HTST 72°C/15s → check at 71°C
Why 72/15 ≈ 63/30 (C. burnetii)
Cream min 75°C/15s → at 72°C
8°C = P* equivalence index (recognised basis). 4.3°C = C. burnetii death (why 72/15≈63/30). 5°C = phosphatase.
Results
Equivalent time at T₂—
Equivalent time at T₂ (minutes)—
P* of reference process (vs 72°C/15 s, z=8)—
Enter inputs to calculate.
| Temperature (°C) | Equivalent time |
|---|