Changing Properties- Carbohydrates

Question 1

What starch process thickens liquids?

Answer 1

Gelatinisation

Starch granules are mixed in a liquid and become suspended but fall to the bottom if you do not stir.

Question 2

List the steps in gelatinisation

Answer 2

60= starch is heated an bonds are broken allowing water in making them swell.
80= starch bursts releasing molecules. They form a 3D network which traps water and thickens the sauce.
100= the sauce completely gelatinises and thickens.
Once cool a gel forms

Question 3

What is it called when starch is exposed to dry heat?

Answer 3

Dextrinisation (eg toast)
Starch molecules breakdown into small molecules called dextrins.
This gives the food a browner colour and crispier texture and a different taste.
The longer the food is cooked the more starch is converted into dextrin causing a darker colour and crispier texture.

Question 4

What does sugar do when heated?

Answer 4

Caramelises.

The sugar molecules breakdown which causes it to turn brown and change flavour.

Question 5

Name the stages of caramelisation.

Answer 5

1. The liquid is runny and is very sweet.
2. Over time it becomes like a smooth caramel.
3. Eventually turns harder and once cooled is like candy.
   Sugar can burn quickly making it black, brittle and bitter. To avoid this add water at the beginning.