Question

The time in minutes necessary at a specific temperature to reduce the number of organisms to $\frac{1}{10}$ of the original value.

• A. F-value
• B. Z-value
• C. D-value
• D. Q$_{10}$ value

Hint:

D-value always corresponds to 90% reduction (one log reduction) in microbial population—very important in food preservation questions.

Answer 1

The Correct Option is C

Concept: In thermal processing and food microbiology, different parameters are used to describe the destruction of microorganisms by heat. One of the most important among them is the D-value (Decimal Reduction Time), which indicates the time required to reduce the microbial population by 90%.

Step 1: Understanding D-value.
D-value is defined as the time required at a specific temperature to reduce the microbial population to one-tenth (i.e., 10%) of its initial value. Mathematically: \[ N = \frac{N_0}{10} \] where:
• $N_0$ = initial number of organisms
• $N$ = remaining organisms after time $t$

Step 2: Understanding other options.

• F-value: Total time required to destroy a given number of organisms at a reference temperature.
• Z-value: Temperature change needed to change the D-value by a factor of 10.
• Q$_{10}$ value: Indicates the rate of increase in reaction rate with a 10°C rise in temperature.

Step 3: Matching with the definition.
The question clearly states reduction to $\frac{1}{10}$, which corresponds exactly to the definition of D-value.

Step 4: Conclusion.
Thus, the correct answer is D-value.