Question

In sterilization process, death rate is almost _______ the initial number of viable cells.

• A. Proportional to
• B. Half of
• C. Double
• D. Four times

Hint:

Because thermal death follows first-order kinetics, complete sterilization (zero survival) is mathematically impossible, which is why safety is calculated using a probability of survival (e.g., 12D concept).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Microbial inactivation during thermal sterilization follows first-order chemical reaction kinetics.
Key Formula or Approach:
The rate of microbial death is mathematically described by: \[ \frac{dN}{dt} = -k N \] Where \(N\) is the number of viable cells at any time \(t\), and \(k\) is the death rate constant.

Step 2: Detailed Explanation:
The logarithmic reduction equation demonstrates that the number of microorganisms dying per unit time is directly proportional to the population size present at that instant.
As the concentration of viable cells increases, the absolute number of cells killed per unit of heat exposure also increases proportionally.

Step 3: Final Answer:
Therefore, the microbial death rate is proportional to the initial number of viable cells.