Define D Value In Microbiology

Another value we discussed was the z value.

Define d value in microbiology. D values can be determined from survivor curves when the log of population is plotted against time or by the formula. D value decimal reduction value it is the time required at temperature t to reduce a specific microbial population by 90 or by a factor of 10. This time to reduce the survivors by 90 is the decimal reduction d value or in fig. In microbiology d value refers to decimal reduction time or decimal reduction dose and is the time or dose required at a given condition e g.

Please provide feedback on this tutorial by selecting like. The time needed to reduce the amount of bacteria by 1012 bacteria per gram or milliliter. Glossary of microbiology terms meaning and definition of d value. Z value z value is the number of degrees of temperature change necessary to change the d value by a factor of 10.

For radiation inactivation the d value is stated in the terms absorbed dose kgy. The target of reduction in canning is the 12 d reduction of clostridium botulinum which means that processing time will reduce the amount of this bacteria by 10 12 bacteria per gram or milliliter. For the term d value may also exist other definitions and meanings the meaning and definition indicated above are indicative not be used for medical and legal or special purposes. A d value is denoted with the capital letter d.

The time needed to reduce the bacterial population by 90 or one log10 at a given temperature. 1 d 240 1 min. In microbiology in the context of a sterilization procedure the d value or decimal reduction time or decimal reduction dose is the time or dose required at a given condition e g. Temperature or set of conditions to kill 90 or 1 log of the exposed microorganisms.

The subscript after the d indicates temperature at which the d value was determined. The d value at an unknown temperature can be calculated knowing the d value at a given temperature provided the z value is known. The d value is used in microbiology to know how long it would take to kill 90 of microorganisms in some kind of sample at a very specific temperature. D value is the time required to kill 90 of the spores or vegetative cells of a given microorganism at a specific temperature in a specific medium.