D-value
D-value
D-value (pronounced: /diːˈvæl.juː/) is a term used in microbiology to denote the time required at a certain temperature to kill 90% of the organisms being studied. This term is particularly significant in the field of food processing and sterilization.
Etymology
The term "D-value" is derived from the word "decimal", referring to the 90% or one decimal logarithm reduction of the microbial population.
Definition
In microbiology, the D-value is a measure of the thermal resistance of a specific microorganism. It is defined as the time (in minutes) required to kill 90% of a population of the microorganism at a certain temperature. The D-value allows for the comparison of the thermal resistance of different microorganisms, thereby aiding in the selection of the appropriate sterilization process.
Calculation
The D-value is calculated using the formula:
D = t / log(N0/N)
where:
- t is the duration of the treatment,
- N0 is the initial number of viable organisms,
- N is the number of viable organisms after the treatment.
Related Terms
- Z-value: The temperature change needed to reduce the D-value by a factor of ten.
- F-value: The time in minutes at a specific temperature necessary to kill a population of cells or spores.
- Sterilization: The process of eliminating all forms of life, including transmissible agents such as fungi, bacteria, viruses, spore forms, etc. from a surface, a piece of equipment, food, or biological culture medium.
See Also
External links
- Medical encyclopedia article on D-value
- Wikipedia's article - D-value
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