Explain about the Blanching - Food Processing?

Blanching is used for variety of purposes. It is defined as a mild heat treatment applied to tissue (usually plant) prior to freezing, drying or canning. Why do we need to blanch foods? 

Well, blanching is useful and its functions include:

• Inactivate most enzymes
• Some cleaning action
• Removes substances in some products
• Activates some enzymes (if controlled)
• Removes undesirable odors/flavors
• Softens fibrous material and decreases volume
• Expels air and respiratory gasses
• Preheating of product prior to canning