Question

Process of freezing food below eutectic temperature and converting solid ice crystals directly into vapour form is known as

• A. Individual quick freezing (IQF)
• B. Freeze drying
• C. Freezing
• D. Freeze encapsulation

Hint:

Think about what happens to ice when a frozen product is kept under vacuum instead of being allowed to melt.

Answer 1

The Correct Option is B

Step 1: Look at what the process actually does. The food is first frozen below its eutectic temperature, the point at which all the water in the product turns to solid ice along with the dissolved solids.

Step 2: Once fully frozen, the product is placed under vacuum and mild heat is applied. Under vacuum, the ice does not melt into liquid water, it sublimes, meaning the solid ice crystals turn directly into vapour and are pulled away.

Step 3: This exact description, freezing below the eutectic point followed by sublimation of ice into vapour, is the definition of freeze drying (also called lyophilization). It is widely used for coffee, fruits, ready-to-eat meals and pharmaceuticals because the solid structure of the food is preserved and shrinkage is minimal.

Step 4: Check the other options. Individual quick freezing (IQF) is a fast freezing method that freezes small pieces separately so they do not stick together, it does not involve turning ice into vapour. Freezing is just the general act of lowering temperature to form ice, no sublimation happens. Freeze encapsulation is not a standard food preservation term and does not match the description.

Step 5: So the process described is freeze drying, option 2.