Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Sweet curdling is a defect caused by aerobic spore-forming bacteria due to the production of rennin-like enzyme and often is accompanied by bitterness
Reason R: Generally, more acid production is observed during sweet curdling in dairy product
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:

The word "sweet" in "sweet curdling" directly implies the absence of sourness or acidity. This helps quickly identify that any statement claiming "more acid production" is false.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Sweet curdling is a bacterial spoilage defect of fluid milk where curdling occurs in the absence of significant acid production.
Understanding the difference between acid coagulation (souring) and enzymatic coagulation (sweet curdling) is essential to analyzing this defect.

Step 2: Detailed Explanation:
Let us evaluate both statements:
- Assertion A: Sweet curdling is indeed caused by aerobic spore-forming bacteria, such as Bacillus cereus and Bacillus subtilis, which survive pasteurization.
These bacteria secrete extracellular proteases (rennin-like enzymes) that hydrolyze casein, leading to coagulation.
This degradation of casein often produces hydrophobic peptides, which impart a bitter taste to the milk. Thus, Assertion A is true.
- Reason R: By definition, "sweet" curdling occurs under near-neutral pH conditions with minimal acid production.
If substantial acid production were present, it would be classified as acid curdling or souring, typically caused by lactic acid bacteria. Thus, Reason R is false.
Therefore, Assertion A is true but Reason R is false.

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