What is blanching? Explain its purposes and methods.

1. 1 · Open in two lines. Blanching is a short heat treatment of vegetables in hot water or steam, followed by quick cooling. It is done before freezing, drying or canning.
2. 2 · Purposes.
   • Inactivates enzymes (peroxidase, catalase, polyphenol oxidase).
   • Reduces surface microbes and removes trapped air.
   • Softens tissue for packing and sets the green colour.
3. 3 · Methods.
   • Hot water at about 95-100 °C.
   • Steam: less leaching of nutrients.
   • Cool at once in cold water.
4. 4 · Draw the flow. [Flow: wash → cut → blanch → cool → test → freeze / dry / can]
5. 5 · Test. Peroxidase test: no brown colour with guaiacol and hydrogen peroxide means enough blanching.
6. 6 · Nutrition link. Short times and steam save vitamin C and B vitamins.
7. 7 · Close in one line. Correct blanching keeps colour, flavour and nutrients through long storage.

Scoring tip: Name at least two enzymes and the peroxidase test; these are what examiners look for.