Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Pasteurization does not destroy all microorganisms present in milk.
Reason (R): Pasteurization is designed to eliminate pathogenic microorganisms and reduce spoilage organisms, not to achieve commercial sterility.
Choose the correct answer from the options below:

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Pasteurization = safe but not sterile. Sterilization requires much higher heat.

Answer 1

The Correct Option is A

Concept: Pasteurization is a mild heat treatment process used primarily to ensure safety of milk by destroying pathogenic microorganisms while minimizing changes in quality.

Step 1: Understanding pasteurization process.
Pasteurization typically involves:
• Heating milk to a specific temperature (e.g., $72^\circ$C for 15 seconds in HTST)
• Rapid cooling after heating

Step 2: Evaluating Assertion (A).
Pasteurization does not destroy all microorganisms because:
• Heat-resistant (thermoduric) bacteria may survive
• Spores are not destroyed at pasteurization temperatures Thus, Assertion (A) is correct.

Step 3: Evaluating Reason (R).
Pasteurization is specifically designed to:
• Kill pathogenic microorganisms (e.g., Mycobacterium tuberculosis)
• Reduce microbial load
• Extend shelf life It is not intended to achieve complete sterility. Hence, Reason (R) is correct.

Step 4: Linking both statements.
Because pasteurization is not designed for complete sterilization, some microorganisms remain alive. This directly explains Assertion (A). Final Conclusion:
Both statements are correct and Reason explains Assertion. Hence, option (1) is correct.