Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Milk from animals treated for mastitis is not suitable for the production of fermented milk products
Reason R: Treated mastitis milk contains antibiotic residues
In light of the above statements, choose the correct answer from the options given below:

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Antibiotic residues are a leading cause of industrial starter culture failure. Always connect "treated mastitis milk" with "antibiotics" and "fermentation failure."

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Fermented dairy products (like yogurt, dahi, and cheese) require active growth of starter culture bacteria to convert lactose into lactic acid.
Contaminants that inhibit these bacteria can cause partial or complete failure of the fermentation process.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion A: Mastitis-infected cows are routinely treated with intramammary or systemic infusions of antibiotics.
The milk harvested from these treated animals during and immediately after therapy contains therapeutic levels of these drugs.
These antibiotic residues are highly inhibitory to lactic acid bacteria (such as Streptococcus thermophilus and Lactobacillus bulgaricus).
As a result, the starter cultures fail to grow, acid production ceases, and the fermentation fails. Thus, Assertion A is true.
- Reason R: The presence of antibiotic residues is the direct physiological cause of starter culture inhibition in treated mastitis milk. Thus, Reason R is true and provides the correct explanation for Assertion A.

Step 3: Final Answer
The correct option is (A).