Question

Match List-I with List-II:

List-I (Spoilage)	List-II (Associated organism)
(A) Souring	(I) Coliforms
(B) Ropiness	(II) Pseudomonas spp.
(C) Gas production	(III) Lactobacilli and Streptococci
(D) Bitter flavor	(IV) Alcaligenes

Choose the correct answer from the options given below:

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (II), (B) - (I), (C) - (IV), (D) - (III)
• (A) - (III), (B) - (II), (C) - (I), (D) - (IV)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

Souring matches with Lactobacilli/Streptococci (A--III), and Ropiness matches with Alcaligenes (B--IV). These two clear matches are sufficient to identify option (D) as the correct choice.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Different groups of microorganisms cause specific biochemical changes in milk, leading to characteristic spoilage defects.

Step 2: Detailed Explanation:
Let us match the spoilage defects in List-I with their associated microorganisms in List-II:
1. (A). Souring: Caused by the fermentation of lactose to lactic acid by lactic acid bacteria like Lactobacilli and Streptococci. Hence, (A) matches with (III).
2. (B). Ropiness: Characterized by slimy, viscous threads caused by exopolysaccharide-producing bacteria like Alcaligenes (Alcaligenes viscolactis). Hence, (B) matches with (IV).
3. (C). Gas production: Caused by lactose-fermenting Coliforms (such as Escherichia coli and Enterobacter aerogenes), which produce hydrogen and carbon dioxide gas, leading to early blowing in cheese or foaming in milk. Hence, (C) matches with (I).
4. (D). Bitter flavor: Caused by psychrotrophic Pseudomonas spp., which produce heat-stable extracellular proteases that break down milk proteins into bitter-tasting peptides. Hence, (D) matches with (II).
This yields the combination: (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

Step 3: Final Answer
The correct matching sequence is given by option (D).