Question

Constant rate period of drying, represents a period when the food surface.............

• A. Remains dry
• B. Remains wet
• C. Develops cracks
• D. Melts

Hint:

In the constant rate period, drying is controlled entirely by exterl mass and heat transfer parameters (air temperature, humidity, velocity). The physical state of the surface remains wet until the critical moisture point is reached.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Drying or dehydration is a mass transfer process consisting of removing water from food materials.
A typical drying curve is divided into distinct phases: an initial adjustment period, a constant rate drying period, and one or more falling rate drying periods.

Step 2: Detailed Explation:
During the constant rate drying period, the rate of water evaporation from the food surface is constant.
This occurs because moisture is freely available at the surface, and the rate of interl water migration to the surface is equal to or greater than the rate of evaporation.
As a result, the entire surface of the food material remains saturated with water (i.e., it remains wet).
The evaporation of moisture during this period behaves identically to evaporation from a free water surface.
The temperature of the wet food surface remains constant and is approximately equal to the wet-bulb temperature of the drying air.
Once the interl moisture can no longer migrate to the surface fast enough to keep it wet, the critical moisture content is reached, and the drying process enters the falling rate period where the surface begins to dry out.

Step 3: Fil Answer:
During the constant rate period, the food surface remains saturated with water, which means it remains wet.
Hence, the correct option is (B).