Question

The decimal reduction time (D value) depends on which of the following ?

• A. No. of microorganisms present in foods
• B. Time of heating
• C. Temperature of heating
• D. Pressure applied

Hint:

Remember that the \( D \)-value is a time parameter at a constant temperature.
It is unique for a specific microorganism at a specific heating temperature in a given medium.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The decimal reduction time, or \( D \)-value, is a fundamental parameter in thermal death kinetics of microorganisms.
It is defined as the heating time in minutes required at a specific temperature to reduce the microbial population by \( 90\% \) (or by one log cycle).
The \( D \)-value is independent of the initial concentration of microorganisms.

Step 2: Detailed Explanation:
The rate of thermal inactivation of bacteria depends heavily on the intensity of the heat applied.
As the temperature increases, the rate of microbial destruction increases exponentially, causing the \( D \)-value to decrease.
Thus, the \( D \)-value is highly dependent on the temperature of heating.
It does not depend on the initial microbial load or the duration of heating, as it is a rate constant.
Therefore, the heating temperature is the primary factor that determines the \( D \)-value.

Step 3: Final Answer:
The decimal reduction time depends on the temperature of heating.