Question

A type of freezing where resistance to heat transfer is minimized due to intimate contact between food or package and refrigerant

• A. Indirect contact freezing
• B. Air freezing
• C. Immersion freezing
• D. Fluidized-bed freezing

Hint:

Think about cooling a hot object. Plunging it into cold water (immersion) cools it much faster than leaving it in a cold room (air) or placing it on a cold block (indirect contact). The same principle applies to freezing.

Answer 1

The Correct Option is C

Step 1: Concept Overview:
Freezing efficiency is determined by the speed of heat removal. Direct contact between food and refrigerant maximizes heat transfer by minimizing resistance.
Step 3: Detailed Breakdown:
- Immersion freezing: Food (packaged or unpackaged) is directly submerged in a liquid refrigerant (chilled brine, glycerol, or liquid nitrogen). This provides complete surface contact, resulting in rapid heat transfer and freezing.
- Indirect contact freezing: Food is placed on refrigerant-cooled metal plates. Contact is indirect and may not be uniform.
- Air freezing: Cold air is used as the refrigerant. Air's poor heat conductivity results in a lower heat transfer rate.
- Fluidized-bed freezing: Air freezing where small particles are suspended in air, improving upon standard air freezing but still using air contact.
Step 4: Conclusion:
Immersion freezing offers the closest contact between food and refrigerant, minimizing heat transfer resistance. Therefore, option (C) is correct.