D-value

How it is used

A basic number in thermal process design, written with the temperature as a subscript, such as D121. A '12D process' lasts twelve times the D-value. The related z-value is the temperature change that changes the D-value tenfold. Process engineers use both to calculate lethality.

Example sentences

1. If the D-value at 121 °C is 0.2 minutes, a 12D process needs 2.4 minutes.

2. Bacterial spores have a much higher D-value than vegetative cells.

Common collocations

• z-value
• 12D process
• log reduction
• thermal death time
• decimal reduction time

Related terms

• sterilizationA treatment, usually with high heat, that destroys microorganisms and their spores so that a food can be stored at room temperature without spoiling or becoming unsafe.
• heat treatmentAny process that uses heat to make food safe, extend its shelf life or change its properties, such as pasteurization, sterilization, blanching or cooking.
• Clostridium botulinumA spore-forming bacterium that grows without oxygen and produces botulinum toxin, one of the strongest known poisons, which causes the rare but potentially fatal illness botulism.
• canningPreserving food by sealing it in airtight containers such as cans or jars and heating it enough to destroy the microorganisms that could grow during storage.
• pasteurizationA mild heat treatment that kills most disease-causing and many spoilage microorganisms while keeping the taste and nutrients of the food as unchanged as possible.

More terms: Preservation and Heat Treatment

• refrigeration
• freezing
• drying
• UHT