Question

Inorder to protect the green color, which chemical is added to water before blanching process?

• A. Calcium Oxide
• B. sodium carbonate
• C. sorbates of potassium and calcium
• D. both a and b

Answer 1

Answer:

D. both a and b

Blanching:

            Blanching is defined as a mild heat treatment applied to tissue (usually plant) primarily to inactivate enzymes prior to freezing, drying or canning. It is also known as scalding.

Functions of Blanching:

               Major function of blanching is inactivation of enzymes for frozen or dehydrated food. Because, such enzymes can cause rapid changes in colour, flavour and nutritive value of such food products.

Types of blanching:

1. Hot water blanching
2. Steam blanching

Chemicals added while blanching:

                 Sodium carbonate (0.125% w/w) or calcium oxide may be added to blancher water to protect chlorophyll and retain the colour of green vegetables. Although the increase in pH might increase losses of ascorbic acid, these are used. It prevents the conversion of chlorophyll into pheophytin, which is an unattractive brownish-green colour compound.

Efficacy of blanching:

• There are various types of enzymes such as lipoxygenase, poly-phenolase, poly-galacturonase and chlorophyllase, which cause loss of quality and therefore, must be inactivated.
• Normally, two heat resistant plant enzymes such as catalase and peroxidase, are used to evaluate blanching efficacy, as appropriate time and temperature is required to inactivate them.