Question

Which process reduces enzymatic activity in vegetables before freezing?

• A. Fermentation
• B. Blanching
• C. Drying
• D. Smoking

Hint:

Blanching is an essential pretreatment for almost all frozen vegetables.
Peroxidase is often used as an indicator enzyme to verify if the blanching process was successful, as it is one of the most heat-resistant enzymes in plants.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks for the thermal pretreatment step applied to vegetables prior to freezing to deactivate natural enzymes.

Step 2: Key Concepts and Approach:
Freezing slows down physical and chemical changes in food, but it does not completely stop enzyme activity.
If vegetables are frozen raw, endogenous enzymes (such as peroxidase and catalase) will continue to cause browning, loss of vitamins, and off-flavors during frozen storage.

Step 3: Detailed Explanation:

• The Blanching Process: Blanching is a short thermal treatment where vegetables are exposed to boiling water or steam for a brief period (typically 1 to 10 minutes) and then rapidly cooled.

• Enzyme Inactivation: The primary goal of blanching is to denature and inactivate enzymes like polyphenol oxidase, peroxidase, and lipoxygenase.
Inactivating these enzymes preserves the natural color, flavor, and nutritional value of the vegetables during long-term frozen storage.

• Additional Benefits: Blanching also wilts the product (making it easier to pack), removes air from tissues, and reduces the initial microbial load on the surface of the vegetables.

Step 4: Final Answer:
The process that reduces enzymatic activity in vegetables before freezing is blanching, which is Option (B).