Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Edible lactose is normally dried to 0.5% and pharmaceutical lactose to 0.1% moisture content. The drying process is done to a product temperature of 93 \(^{\circ}\text{C}\)
Reason (R) : If the lactose solution is dried rapidly, crystals do not have an opportunity to form, and the result is the non crystalline glass, which contains the equilibrium mixture of the alpha- and beta-lactose.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Lactose glass is highly hygroscopic; it absorbs water from the air, which can lead to "instantizing" problems or caking in milk powders.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Lactose (milk sugar) is a byproduct of cheese/casein making. Its physical state (crystalline vs. amorphous glass) and moisture level determine its shelf stability and functional properties in food and medicine.

Step 2: Detailed Explanation:
- Analysis of Assertion (A): Industrial standards for lactose require very low moisture to prevent caking and chemical degradation. Edible grade is typically dried to $\approx$ 0.5% and pharmaceutical grade (highest purity) to $\approx$ 0.1%. The drying air or product temperature in high-efficiency fluid-bed or spray dryers often reaches around 93$^{\circ}$C to drive off surface and bound moisture efficiently. This is true.
- Analysis of Reason (R): Rapid drying (as in spray drying) prevents the orderly arrangement of molecules into a crystal lattice. This creates "Amorphous Lactose" or "Lactose Glass." Because there is no time for mutarotation to favor one form, the glass captures the $\alpha/\beta$ ratio present in the solution at that moment. This is true.
- Relationship: While both are technically true statements regarding lactose technology, the reason does not explain *why* edible lactose is dried to 0.5%. The specific moisture limits in Assertion (A) are dictated by regulatory and stability requirements, not by the mechanism of glass formation mentioned in Reason (R). Therefore, (R) is not the correct explanation for (A).

Step 3: Final Answer: (2) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).