D-value

Definition

D-value (decimal reduction time) is the time required at a specific temperature to reduce the microbial population by 90%. It is a critical parameter for evaluating the effectiveness of sterilization processes.

5 Must Know Facts For Your Next Test

1. The D-value is used to determine how long it takes to kill 90% of microorganisms at a given temperature.
2. A lower D-value indicates greater sensitivity of the microorganism to the sterilization process.
3. D-values are essential for designing and validating sterilization protocols in various industries, including food and pharmaceuticals.
4. It differs depending on the type of microorganism and environmental conditions such as pH and presence of organic matter.
5. The concept of D-value is often used alongside other parameters like z-value, which indicates thermal resistance.

Review Questions

• What does a lower D-value signify about a microorganism's sensitivity to sterilization?
• How is the D-value utilized in industrial applications?
• Why might D-values vary between different microorganisms?

Related terms

Sterilization: A process that eliminates all forms of microbial life, including spores.

Thermal Death Time (TDT): The shortest time needed to kill all microorganisms in a sample at a specified temperature.

z-value: The temperature change required to change the D-value by one log cycle.