Question

Match List-I with List-II. 

List-I (Critical \(a_w\))	List-II (Foods Generally Within the Range of \(a_w\))
(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) - (I), (C) - (III), (D) - (II)
• (A) - (IV), (B) - (III), (C) - (I), (D) - (II)
• (A) - (III), (B) - (I), (C) - (IV), (D) - (II)

Hint:

Low-moisture dehydrated powders like milk powder (\(a_w < 0.3\)) are highly stable against microbial spoilage because most microorganisms require \(a_w > 0.6\) to survive and replicate.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Water activity (\(a_w\)) represents the ratio of water vapor pressure of a food product to that of pure water.
It is a key indicator of food stability and is directly related to moisture content and chemical composition.

Step 2: Detailed Explanation:
- (D) Whole milk powder with low moisture (\(2\%-3\%\)) is highly dehydrated and has a low water activity in the range of \(0.30-0.20\) (D - II).
- (C) Dried pasta (\(12\%\) moisture) is shelf-stable with water activity in the intermediate range of \(0.60-0.50\) (C - IV).
- (B) Rolled oats (\(10\%\) moisture) typically have a water activity in the range of \(0.75-0.65\) (B - I).
- (A) Pulses with a higher moisture content (\(15\%-17\%\)) have a higher water activity of \(0.87-0.80\) (A - III).

Step 3: Final Answer:
Matching the pairs gives (A)-(III), (B)-(I), (C)-(IV), (D)-(II), which is Option (D).