F value

This article describes the term used in microbiology . For the F-value in information retrieval, see Recall and Precision , for the F-value in the statistics, see F-test and for the F-value of a diaphragm , see f-number , for the F-value of concrete, see fineness number .

The F-value is a term from microbiology and hygiene technology . It is defined as the sum of all lethal effects that act on a microorganism population (for example on a bacterial culture) in the course of heating.

${\displaystyle F=D(\log N_{0}-\log N)}$

In it is

• D (D value, decimal reduction value, decimal bacterial count reduction) = the time in minutes that is required to reduce the number of microorganisms by a power of ten (kill rate 90%); the value depends on the temperature, the species of microorganisms, the medium in which the microorganisms are located and the culture conditions.
• N ₀ = number of microorganisms at the beginning,
• N = the number of microorganisms still viable after the treatment time t.

F ₀ value (lethality product, lethality value)

An F ₀ value of 1 is the effect of heat (killing effect) of 121.1 ° C. within one minute, depending on the z value , which is specific for various microorganisms. The F ₀ value of a microorganism species can be used to determine the length of time required at a different temperature in order to achieve the same reduction in the microorganism content.

Web links

• http://www.florin.de/infothek/hitzekonservierung-lebensmittel.html

See also

• sterilization