Question

The ........... value is defined as the number of minutes required to destroy a stated number of organisms with a specific Z value at a defined temperature usually $121^\circ C$.

• A. F
• B. Z
• C. D
• D. T

Hint:

Remember: D = 1 log reduction. F = Multiple log reductions (total process time). Z = Temperature change for D.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the specific thermal processing term that describes the cumulative time required for sterilization at a reference temperature.

Step 2: Detailed Explanation:

• F-value: The F-value (or Sterilization value) is the total time (in minutes) required to achieve a specific level of microbial destruction at a given reference temperature (usually $11^\circ C$ or $250^\circ F$ for canning). It represents the integrated lethality of a heat process.

• Reference F-value ($F_0$): When the reference temperature is $121^\circ C$ and the $z$-value is $10^\circ C$, the value is specifically called $F_0$.

• D-value (Option C): This is the "Decimal Reduction Time," which is the time required to kill 90% (1-log reduction) of a specific population at a constant temperature. The F-value is a multiple of the D-value (e.g., $F = n \times D$).

• Z-value (Option B): This is the temperature increase required to reduce the D-value by a factor of 10. It measures the temperature sensitivity of the organism.
• Distinction: While D-value is a characteristic of the organism at a temperature, the F-value is a measure of the "dose" or "total treatment" given to a product.

Step 3: Final Answer: The term defined is the F-value.