Question

Match List-I with List-II. 

List-I (Critical \(a_w\))	List-II (Foods within the Range)
(A) 0.87–0.80	(I) Rolled oats of 10% moisture
(B) 0.75–0.65	(II) Whole milk powder of 2%–3% moisture
(C) 0.60–0.50	(III) Pulses of 15%–17% moisture content
(D) 0.30–0.20	(IV) Pasta of 12% moisture content

Choose the correct answer from the options given below.

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

Hint:

Milk powder is dried to extremely low moisture contents (\(2-3\%\)) to reach the highly stable monolayer water activity region of \(0.20 - 0.30\).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Water activity (\(a_w\)) represents the energy state of water in a food system, which does not map linearly to total moisture content due to water-binding capacity.

Step 2: Detailed Explanation:
- Pulses of 15%-17% moisture (III) contain higher levels of free/bound water, yielding a relatively high water activity in the range of 0.87 - 0.80 (A).
- Rolled oats of 10% moisture (I) typically exhibit a moderate water activity in the range of 0.75 - 0.65 (B).
- Pasta of 12% moisture (IV) is a tightly bound starch matrix with a water activity of 0.60 - 0.50 (C).
- Whole milk powder of 2%-3% moisture (II) is extremely dry, resting in the monomolecular layer region with a very low water activity of 0.30 - 0.20 (D).
Matching these pairs yields: (A) - (III), (B) - (I), (C) - (IV), (D) - (II).

Step 3: Final Answer:
The correct matching corresponds to Option D.