Question

Which freezer is known as ultra-rapid freezer?

• A. Air blast freezer
• B. Cryogenic freezer
• C. Fluidised-bed freezers
• D. Plate freezer

Hint:

Ultra-rapid cryogenic freezing is highly preferred for delicate, high-value food items like IQF (Individually Quick Frozen) prawns, strawberries, and raspberries, as it perfectly preserves their cellular structure and firmness upon thawing.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The rate of freezing is critical to food quality.
Fast freezing produces very small, uniform intercellular ice crystals that do not damage the cell membranes of food tissues, maintaining texture and reducing drip loss upon thawing.

Step 2: Detailed Explanation:
- Cryogenic Freezing: This process utilizes liquified gases (cryogens) such as liquid nitrogen (\(\text{N}_2\)) at \(-196^\circ\text{C}\) or liquid carbon dioxide (\(\text{CO}_2\)) at \(-78.5^\circ\text{C}\) sprayed directly onto the food.
- Due to the extreme temperature differences, heat transfer is almost instantaneous.
- This achieves an exceptionally high rate of freezing, which is why it is classified as an ultra-rapid freezer.
- Air blast and plate freezers are fast-freezing systems but cannot match the near-instantaneous speed of cryogenic systems.

Step 3: Final Answer:
The ultra-rapid freezer is the Cryogenic freezer, which corresponds to option (B).