Question

Which of the following processes results in instant solubility of dried milk?

• A. Sublimation process
• B. Microfluidization process
• C. Re-wet process
• D. Extrusion process

Hint:

The re-wet agglomeration process improves the solubility of milk powder by binding individual fine particles into large, porous aggregates that absorb water rapidly via capillary action.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Standard spray-dried milk powder consists of fine, individual particles that do not disperse easily in water, often clumping to form wet aggregates with dry cores.
"Instantilization" processes modify the physical structure of these particles to improve their wettability, dispersibility, and solubility.

Step 2: Detailed Explanation:
The primary method used to manufacture instant milk powder is the re-wet process.
In this process, fine spray-dried milk powder is humidified with steam or water in an agglomeration chamber.
This humidification causes the surface of the powder particles to become sticky, allowing them to collide and adhere to one another to form porous aggregates (agglomerates).
These agglomerates are then dried in a fluid-bed dryer to remove the added moisture.
The porous structure of these agglomerated particles allows water to enter rapidly via capillary action when reconstituted.
This rapid water absorption prevents clumping and allows the powder to dissolve quickly and completely.
Other listed processes do not produce this specific physical structure:
Sublimation (freeze drying) is slow and expensive for bulk milk powder production.
Microfluidization is a high-shear liquid homogenization process.
Extrusion is used for high-viscosity food structuring rather than producing soluble powders.

Step 3: Final Answer:
Therefore, the re-wet process is the method used to achieve instant solubility in dried milk.