Raising Agents.

Question 1

What is a raising agent?

Answer 1

A raising agent is a substance that is added to flour mixtures which can be chemical, physical or biological which will produce carbon dioxide and cause the mixture to rise and have a light, pleasant texture.

Question 2

What are raising agents used for?

Answer 2

Raising agent are used to introduce a gas into the mixture.

Question 3

What do gases do when heated?

Answer 3

Gases expand when heated, and can raise a mixture in the process.

Question 4

What are the 3 gases used as raising agents?

Answer 4

• Carbon dioxide.
• Air (a mixture of gases).
• Steam (water in a gaseous state).

Question 5

What are three categories raising agents fall into?

Answer 5

• Mechanical raising agent (physically incorporated).
• Chemical raising agent (commercially made).
• Biological (living organism e.g. yeast).

Question 6

What are the 5 methods of mechanical raising agent?

Answer 6

• Sieving.
• Creaming.
• Whisking.
• Folding and rolling.
• Rubbing in.

Question 7

How is sieving a form of incorporating air and give an example?

Answer 7

Air becomes trapped between its many fine particles e.g. flour for chocolate biscuits.

Question 8

How is creaming a form of incorporating air?

Answer 8

Air becomes trapped in the form of tiny bubbles e.g. fat and sugar (Victoria sponge).

Question 9

How is whisking a form of incorporating air and give an example?

Answer 9

Eggs and sugar trap large volumes of air e.g. eggs (swiss roll).

Question 10

How is folding and rolling a form of incorporating air and give an example?

Answer 10

Air is trapped between layer, and sealed in e.g. rough puff pastry.

Question 11

How is rubbing in a form of incorporating air and give an example?

Answer 11

Air is trapped as the fat is rubbed into the flour e.g. scones.

Question 12

How is carbon dioxide incorporated into mixtures using chemical raising agent (3 ways)?

Answer 12

Bicarbonate of soda - alone.
Bicarbonate of soda plus an acid.
Baking powder (contains bicarbonate of soda and acid).

Question 13

What are the 3 objectives of using bicarbonate of soda (an alkali)?

Answer 13

Has an unpleasant taste.
Has a yellow discoloration.
Usually used for strong-flavored mixtures such as gingerbread.

Question 14

What does the acid in the bicarbonate of soda plus an acid do?

Answer 14

The acid helps prevent the unpleasant washing soda taste and color.

Question 15

What are the four acids you can use with bicarbonate of soda?

Answer 15

• Cream of tartar.
• Tartaric acid.
• Lactic acid (in sour milk).
• Citric acid (lemon juice).

Question 16

What are 2 benefits and disadvantages of using cream of tartar with bicarbonate of soda?

Answer 16

• Often used.

- Produces a colorless residue and is almost tasteless.

Question 17

What are 3 benefits and disadvantages of using tartaric acid with bicarbonate of soda?

Answer 17

• Not used often.
• Very effective.
• Resulting residue is slightly bitter.

Question 18

What are 3 benefits and disadvantages of using lactic acid (in sour milk) with bicarbonate of soda?

Answer 18

• Produced by lactic acid bacteria.
• Not very accurate.
• Often used in scone making.

Question 19

What is benefit and disadvantage of using citric acid (lemon juice) with bicarbonate of soda?

Answer 19

• Not very accurate - hard to gauge strength of the acid.

Question 20

What 3 things does baking powder consist of?

Answer 20

• Bicarbonate of soda.
• Acids.
• Starch.

Question 21

What would happen to bicarbonate of soda and acid if any moisture was absorbed from the atmosphere from the starch in it?

Answer 21

This would cause a reaction between the bicarbonate of soda and acid releasing carbon dioxide, making the baking powder ineffective.

Question 22

How is self-raising flour prepared?

Answer 22

Self-raising flour is prepared from soft cake flour and a standard strength raising agent.

Question 23

What is self-raising flour useful for?

Answer 23

It is useful for plain cake mixtures (fruit cake and rock cakes).

Question 24

What 5 things are self-raising flour not suitable for and why?

Answer 24

• Scones - too weak on its own.
• Rich cakes - too much raising agent.
• Bread, pastries, biscuits - chemical raising agent not required.

Question 25

Yeast is a fungus used as a biological raising agent. There are three types of yeast that are used in baking:

Answer 25

• Dried yeast.
• Fast action yeast.
• Fresh yeast.

Question 26

How do you activate dried yeast?

Answer 26

This is added to a liquid, then should be allowed to dissolve for a few seconds before being stirred. Sugar should be added.

Question 27

What conditions should dried yeast be kept in and how long will it stay in that condition?

Answer 27

It will keep for a few months in a cool dry place.

Question 28

How do you activate fast action yeast?

Answer 28

This is added directly to the flour before the liquid is added.

Question 29

How is fresh yeast compacted?

Answer 29

This is compacted in blocks.

Question 30

How should fresh yeast be stored and why?

Answer 30

It must be stored in a cold place, covered, to prevent it from drying.

Question 31

What are the 4 correct conditions for yeast?

Answer 31

• A source of food (sugar or flour).
• The correct temperature, is between 25 - 29°C.
• Moisture.
• The presence of enzymes.

Question 32

When does yeast fermentation take place?

Answer 32

Fermentation takes place during rising or proving.

Question 33

What is fermentation (yeast as a raising agent)?

Answer 33

Under the correct condition yeast will produce carbon dioxide gas and alcohol in a series of chemical reaction known as fermentation.

Question 34

When is steam produced?

Answer 34

Steam is produced during baking from the liquid present in the mixture.

Question 35

Steam production happens slowly, what does this make steam as a raising agent suitable for (examples)?

Answer 35

Steam is only a suitable raising agent for mixtures that contains a lot of liquid such as batters, choux pastry and flaky pastry.

Question 36

What must the oven temperature be like for steam production and why?

Answer 36

The oven temperature must be high to raise the liquid to boiling point so that the liquid can be converted to steam.

Question 37

Whatis gluten and where is it found?

Answer 37

Gluten is a protein that is found in wheat flour.

Question 38

When is gluten produced?

Answer 38

It is only produced when water is added to it.

Question 39

What happens to gluten when it is kneaded?

Answer 39

When kneaded the gluten becomes elastic giving flour mixtures the ability to stretch.

Question 40

What must be a quality for a mixture to rise?

Answer 40

In order for a mixture to rise, it must have the ability to stretch and hold its shape.