Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): The fruity flavor in milk is due to the production of esters.
Reason (R): The esters are produced by lipases and esterases elaborated by Pseudomonas spp.
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:

Pseudomonas = Psychrotroph = Extracellular enzymes = Fruity flavor (Esters). This chain of logic is fundamental to dairy spoilage microbiology.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Psychrotrophic bacteria, particularly Pseudomonas species, are the primary cause of spoilage in raw milk held under refrigeration.
These bacteria produce extracellular enzymes that remain active even after the bacteria themselves are killed by pasteurization.

Step 2: Detailed Explanation:
1.Analysis of Assertion (A): Fruity flavors (described as strawberry-like or apple-like) are common defects in milk and butter. Chemically, these are indeed caused by the presence of esters such as ethyl butyrate and ethyl hexanoate. Thus, the assertion is correct.
2.Analysis of Reason (R): Pseudomonas species (P. fragi and P. fluorescens) produce extracellular lipases and esterases. These enzymes catalyze the reaction between alcohols (present in traces) and fatty acids (released during lipolysis) to form esters. Thus, the reason is correct.
3.Relationship: The reason explains the biological origin of the chemical compounds (esters) mentioned in the assertion. Therefore, (R) is the correct explanation for (A).

Step 3: Final Answer:
Both (A) and (R) are true and (R) is the correct explanation of (A).