Question

When moisture content of the food fall below critical moisture content the rate of drying slowly decreases until it approaches zero at equilibrium moisture content and is called as falling rate period : A. Non-hygroscopic food have single falling rate period B. Hygroscopic food have two or more falling rate period C. Surface temperature remain close to wet bulb temperature during falling rate period D. During falling rate period the water moves from interior of the food at the same rate as it evaporates from the surface. E. The size of food particle have impact on falling rate period.

• A. A Only
• B. B Only
• C. A, B, C and E Only
• D. A, C and D Only

Hint:

Understanding the characteristics of non-hygroscopic and hygroscopic foods helps in predicting their drying behavior during processing.

Answer 1

The Correct Option is C

Step 1: Concept
Falling Rate Period in Food Drying

Step 2: Meaning
The falling rate period is a phase during food drying where the moisture content of the food falls below its critical value. The drying rate decreases and eventually approaches zero at equilibrium moisture content.

Step 3: Analysis
- Option A: Non-hygroscopic foods do not absorb water from their surroundings, so they will have only one falling rate period as there is no internal moisture movement to affect the drying process. - Option B: Hygroscopic foods can absorb and release moisture, leading to multiple falling rate periods due to varying internal moisture content. - Option C: During the falling rate period, surface temperature remains close to the wet bulb temperature because the air near the surface is saturated with water vapor from evaporation. - Option D: The statement that water moves from the interior of the food at the same rate as it evaporates from the surface is incorrect. In reality, there is a lag between internal and external moisture loss due to diffusion. - Option E: The size of the food particle does impact the falling rate period because larger particles have slower internal moisture movement compared to smaller ones.

Step 4: Conclusion
Options A, B, C, and E are correct in describing aspects of the falling rate period. Final Answer: (C)