PDA Technical Glossary
PDA Technical Reports are highly valued membership benefits because they offer expert guidance and opinions on important scientific and regulatory topics and are used as essential references by industry and regulatory authorities around the world. These reports include terms which explain the material and enhance the reader’s understanding.
The database presented here includes the glossary terms from all current technical reports. The database is searchable by keyword, topic, or by technical report. Each definition provided includes a link to the source technical report within the PDA Technical Report Portal.
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F-Value (Lethality Factor)
A measurement of sterilization effectiveness, the F-value is the calculated equivalent lethality (using a specified z-value), in terms of minutes at a reference temperature (Tref), delivered by a sterilization cycle. (TR1) (TR3) (TR30) (TR48) (TR61)
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F-Value (Lethality Factor) -- FBiological
A term used to describe the delivered lethality, measured in terms of actual kill of microorganisms on or in a BI challenge system. The FBiological-value is calculated as DT × LR, where DT is the D-value of the BI system at the reference temperature (T) and LR is the actual logarithmic reduction (log N0 – log NF) of the BI population achieved during the cycle. (TR1)
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F-Value (Lethality Factor) -- FO
A term used when the specific reference conditions of Tref = 121.1°C and z = 10°C are used to calculate the equivalent lethality. For example, when the z-value of the BI is 10°C a cycle with an F(T=121.1°C, z=10°C), or F0, equal to 8 minutes is equivalent (in terms of delivered lethality) to a square wave cycle of 8 minutes at 121.1°C. A square wave cycle that provided an exposure of 25.9 minutes at 160deg;C would also yield an F0 of 8 minutes. (TR1)
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F-Value (Lethality Factor) -- Fphysical
A term used to describe the delivered lethality calculated based on the physical parameters of the cycle. The FPhysical-value is the integration of the lethal rate (L) over time. The lethal rate is calculated for a reference temperature (Tref-) and z-value using the equation: L = 10(T-Tref- )/z. (TR1)
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Fraction-Negative Methods
Fraction-negative methods use the starting population of a biological indicator (N0) and data in the quantal range to create a two-point line from which the DT-value can be determined. The quantal range is the exposure period over which a set of replicate test units exhibit a dichotomous response – some are positive for growth and the rest are negative for growth. (TR01)