Question

The process of preserving food by rapid freezing followed by dehydration under vacuum is known as_________

• A. Sterilization
• B. Pasteurization
• C. Lyophilization
• D. Dehydration

Hint:

Lyophilization = Freezing + Sublimation. It's the most expensive but best quality drying method. Used for instant coffee and space food.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question describes a advanced dehydration process that involves two distinct phases: freezing and vacuum-induced water removal. This process is commonly known as freeze-drying.

Step 2: Detailed Explanation:

• The Process: Lyophilization involves freezing the product to convert its water content into ice. Then, the pressure is reduced in a vacuum chamber, and a small amount of heat is applied.

• Sublimation: Under vacuum conditions, ice converts directly into water vapor without passing through the liquid phase. This is called sublimation.

• Advantages: Because the food is never heated to high temperatures in a liquid state, the structural integrity, color, flavor, and heat-sensitive nutrients (like vitamins) are preserved much better than in conventional hot-air drying. The resulting product is highly porous and rehydrates almost instantly.

• Other Options:
• Sterilization/Pasteurization: These are heat treatments to kill microbes.

• Dehydration: A broad term, usually referring to convective drying.

Step 3: Final Answer:
The scientific term for freeze-drying is Lyophilization. Option (C) is correct.