Question

The freezing time to get 90% overrun in Ice-cream for continuous freezer.

• A. 24 sec
• B. 30 min
• C. 7 min
• D. 15 min

Hint:

Continuous freezers are extremely fast—most industrial ice cream processes occur in seconds, not minutes.

Answer 1

The Correct Option is A

Concept: Overrun in ice cream refers to the percentage increase in volume due to incorporation of air during freezing. Continuous freezers are designed for rapid freezing and efficient incorporation of air, leading to high overrun in a very short time.

Step 1: Understanding Overrun.
Overrun is defined as: \[ \text{Overrun} = \frac{\text{Volume of ice cream} - \text{Volume of mix}}{\text{Volume of mix}} \times 100 \] A 90% overrun means the volume nearly doubles due to air incorporation.

Step 2: Continuous Freezer Mechanism.
In continuous freezers:
• Mix is continuously fed into the freezing chamber.
• Rapid heat removal occurs through refrigerant-cooled walls.
• Dasher rotates at high speed incorporating air quickly.

Step 3: Time Requirement.
Due to high efficiency, continuous freezers achieve:
• Rapid freezing
• High overrun in seconds rather than minutes

Step 4: Evaluating Options.

• 24 sec → Matches industrial rapid freezing
• 7 min, 15 min → Too slow for continuous systems
• 30 min → Applicable for batch freezers, not continuous

Step 5: Conclusion.
Thus, the correct freezing time is 24 seconds.