Chemical functions of Carbohydrates

Question 1

Chemical Functions

Answer 1

Caramelisation, dextrinisation, gelatinisation

Question 2

What is dextrinisation

Answer 2

Starchy foods are clocked by a dry heat that develop a brown colour on the outside.

Question 3

Examples of dry heat methods

Answer 3

Backing grilling toasting

Question 4

Example foods of dextrinisation

Answer 4

Bread, cakes, scones, biscuits, pastry.

Question 5

What is the chemical process of dextrinisation

Answer 5

Starch molecules get broken down into smaller groups of glucose molecules called dextrin

Starch molecules + dry heat = dextrin

Question 6

Changes when dextrination has been applied

Answer 6

Colour smell texture

Question 7

What is carbohydrates made up of

Answer 7

Carbon + hydrogen + oxygen

Question 8

How is burned toast formed

Answer 8

Dry heat drives the oxygen and hydrogen away as the water evaporates. Leaving the black carbon to form.

Question 9

What is caramelisation

Answer 9

The process of heating sugar (sucrose) that is used in cooking

Question 10

Changes when caramelisation has been applied

Answer 10

Texture, taste, colour

Question 11

Chemical reactions of caramelisation

Answer 11

When sugar is heated it melts and forms syrup then boils. The molecules of sucrose break up.
Carbohydrates +heat= water evaporation leaving carbon.

Question 12

Colour changes order for caramelisation

Answer 12

Clolourless, golden brown, dark brown, black = carbon

Question 13

Taste/ flavour changes order in caramelisation

Answer 13

Very sweet, toffee, caramel, bitter burned

Question 14

Texture changes order in caramelisation

Answer 14

Crystals if sugar, syrup , brittle toffee when cool

Question 15

What can be added to to help avoid sugar burning in caramelisation

Answer 15

Water can help form caramel and flavour development

Question 16

What not to do when caramelising

Answer 16

Do not stir the syrup - will cause crystallisation and hard lumps.

Question 17

What is the temperature of caramelisation caramel colour

Answer 17

160-170°C

Question 18

Example foods of caramelisation

Answer 18

Onions - naturally contain sugars

Question 19

Process of caramelisation

Answer 19

Sugar sucrose is t melts and forms a syrup and boils. Molecules of sucrose break up, water evaporates as heating continues and syrup turns golden brown, eventually it will burn and turn bitter as water evaporates and carbon is left.

Question 20

Caramelisation

Answer 20

The breaking up of sucrose
(sugar) molecules when
heated = a change in
colour, flavour + texture of
the sugar as it turns into a Caramel

Question 21

Gelatinisation

Answer 21

When starch is heated in a liquid , it gelatinises

Question 22

Chemical list of the order of gelatinisation

Answer 22

When the starch granules are put into cold water they sink, when starch is heated with water they absorb the water and swell bigger, it will thicken as there is no room for the swollen granules to move. At 80° the starch granules bust and release the starch molecules into the liquid.

Question 23

What should you always do when gelatinising anything and why

Answer 23

Stir regularly, prevents sticking to bottom and lumpy texture

Question 24

What happens at 80° with gelatinisation

Answer 24

At 80oC, the starch granules are so swollen
that they start to burst and release the starch molecules into the liquid.

Question 25

What happens at 100° for gelatinisation

Answer 25

These released starch molecules form a 3D
network that traps water molecules.
At 100oC, the sauce completely thickens.

Question 26

When something has been gelatinised to 100° what should happen after

Answer 26

Let it cool down to get a solid gel

Question 27

Examples of gelatinisation

Answer 27

Sauces, pasta , potatoes (same when cooking foods that contain starch)

Question 28

Summary of gelatinisation

Answer 28

60oC
Starch granules are
heated in liquid
Starch granules become
swollen
80oC
Starch granules burst
100oC
The liquid thickens and
gelatinises
Forms a gel when cooled