Question

Sandiness in milk powders is due to

• A. Proteins
• B. Fats
• C. Calcium
• D. Lactose

Hint:

Whenever you see the defect "sandiness" in a dairy context, the cause is almost always lactose crystallization. This is a very common question related to ice cream, milk powder, and condensed milk.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
"Sandiness" is a textural defect in some dairy products, characterized by a rough, gritty mouthfeel similar to fine sand. The question asks for the component responsible for this defect in milk powder.
Step 2: Detailed Explanation:
Lactose is the sugar present in milk. Milk is a supersaturated solution of lactose. During the manufacturing of products where water is removed (like milk powder, ice cream, or condensed milk), the concentration of lactose increases dramatically.
If the processing conditions (especially the rate of cooling and drying) are not properly controlled, the lactose can crystallize out of the solution into large, hard crystals of alpha-lactose monohydrate. These crystals are slow to dissolve in the mouth, and their size is large enough to be detected by the tongue, creating the "sandy" or "gritty" sensation.
Proteins, fats, and calcium do not cause this specific defect.
Step 3: Final Answer:
The defect of sandiness in milk powders and other concentrated dairy products is caused by the crystallization of lactose.