Glossary
Z-value
The temperature difference required to change the D-value of a biological indicator by a factor of ten.
Details
The Z-value links the effect of temperature change on the rate of kill, and is used to interpret the equivalent lethality of a heat sterilisation cycle. Inspections may cite disagreement between the certified value for the BI lot and the Z-value used in the calculation, and temperature sensor error or worst case locations not taken into account. Look at the BI certificate, the cycle calculations, sensor calibration, heat distribution and penetration, and review of the raw data.
