Question

The time taken to kill 90 percent of the organisms or spores in a sample under specified condition is:

• A. Thermal death time (TDT)
• B. Decimal reduction time (D value)
• C. Generation time
• D. Doubling time

Hint:

The D value is used to measure the time needed to reduce the microbial population by 90%.

Answer 1

The Correct Option is B

Step 1: Understanding D Value 
The decimal reduction time (D value) is the time required at a specific temperature to reduce the microbial population by 90%. 
Step 2: Evaluating the Options 
- Thermal death time (TDT): The time needed to kill all the organisms at a given temperature, not just 90%. 
- Decimal reduction time (D value): Correct, the D value measures the time to kill 90% of the organisms. 
- Generation time: Time it takes for a population to double, unrelated to microbial death. 
- Doubling time: Similar to generation time, refers to population growth. 
Step 3: Conclusion 
The correct term for killing 90% of organisms is the decimal reduction time (D value).