Question

The uptake of moisture due to Improper packaging and storage of skim milk powder, causes
(A). Lactose crystallization
(B). Maillard browning
(C). Coagulation of casein
(D). Caking of SMP
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

To prevent caking and Maillard browning, skim milk powder must be stored in hermetically sealed multi-layer packaging that maintains a water activity level below 0.3.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Skim Milk Powder (SMP) is highly hygroscopic due to its high concentration of amorphous lactose, which readily absorbs moisture from the atmosphere if not packed in barrier packaging.

Step 2: Detailed Explanation:
When Skim Milk Powder absorbs moisture during improper storage:

• (A) Lactose Crystallization: Amorphous lactose absorbs water, transitions from a glassy state to a rubbery state, and crystallizes into \(\alpha\)-lactose monohydrate. (Correct)

• (D) Caking of SMP: As lactose crystallizes, it releases bound water and forms crystalline bridges between adjacent powder particles, causing them to clump together into hard lumps (caking). (Correct)

• (B) Maillard browning: The absorbed moisture increases water activity (\(a_w\)), which accelerates the Maillard reaction between the reducing sugar lactose and the lysine residues of milk proteins, leading to a brown discoloration and off-flavors. (Correct)

• (C) Coagulation of casein: Coagulation is a distinct enzymatic (rennet) or severe acid-induced precipitative process. Simple moisture absorption during powder storage does not cause casein coagulation. (Incorrect)
Therefore, the correct consequences of moisture uptake are (A), (B), and (D) only.

Step 3: Final Answer
The effects of moisture uptake in SMP are lactose crystallization, Maillard browning, and caking.