A batch of 12500 L milk initially contains 10 Coxiella burnetii organisms per mL and is packed in 500 mL pouches. Decimal reduction time at 72°C is 14 s. Find the F-value in seconds for the source’s stated no-survivor pasteurization process.
The official process answer is 126 s, corresponding to nine decimal reductions: F=9D=9×14. Initially the full batch contains 1.25×10⁸ organisms; this treatment reduces its expected survivor count to 0.125 (5×10⁻⁶ per pouch). A finite first-order treatment cannot mathematically guarantee exactly zero survivors, and the source does not separately specify a sterility probability. The solution therefore makes the keyed nine-D convention explicit.
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