°C, 124°C, 129°C). A graph is plated between these D values and temperature. This curve is known as thermal death curve. It is easy to determine the Z-value graphically then mathematically. Temperature is determined by graph that is required for 1 log reduction as shown in figure.
FDA guides the Biological Indicator manufacturers-
You should provide Z-values for thermal processes. FDA generally recommends that Biological Indicators have a minimum Z-value of 10°C. To determine the Z-value, you should construct a thermal resistance curve. The thermal resistance curve is a semi-logarithmic graph of D-value vs. temperature. The Z-value can be obtained from the slope of the curve by calculating the number of degrees of temperature for a 1-logarithm change in D-value. The greater the number of temperatures studied, the more accurate the resulting Z-value. FDA recommends that studies use at least three different temperatures.Also see: Testing of Biological Indicators
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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