Q36: In a two-stage drying system, the moisture content of powder... - Fluid Milk Processing, Dairy Products Manufacture, Sensory Evaluation & Packaging - ICAR AIEEA PG Dairy Technology 14 July 2023 Shift-1 Paper | Agrigyan

In modern milk powder plants employing two-stage drying (spray dryer followed by a fluidized bed dryer), the powder leaves the primary spray chamber at a moisture content $2 - 3\%$ higher than the target final moisture (around $6 - 8\%$ vs final target of $3.5 - 4.0\%$) to preserve heat-sensitive properties and maximize thermal efficiency.

Option analysis:

• $2 - 3\%$ higher than the final moisture content desired: Correct, spray chamber exhausts powder at $6 - 8\%$ moisture, which is then dried to $3.5 - 4.0\%$ in the fluid bed.
• $6 - 7\%$ higher than the final moisture content desired: Too wet, would cause severe wall sticking and lumping in the chamber cone.
• $9 - 10\%$ higher than the final moisture content desired: Excessive moisture, characteristic of semi-drying.
• Exactly the same moisture as desired in final product: Represents single-stage drying, which requires higher outlet temperatures causing thermal damage.