Yeast Mixtures 20/4.

Question 1

Why is self raising flour not suitable for yeast mixtures?

Answer 1

Because it contains baking powder and has a low gluten content.

Question 2

What type of flour best suits yeast mixtures?

Answer 2

Plain flour as yeast is the raising agent.

Question 3

Why would we use strong, plain flour from spring wheat for yeast mixtures?

Answer 3

Has a high gluten content which is required to produce a strong elastic dough.

Question 4

Why would we use or not use whole meal flour for a yeast mixture?

Answer 4

It provides extra dietary fibre (NSP), B vitamins, adds colour and a nutty flavour but it has less gluten, gives a close texture and it is more difficult for yeast to rise.

Question 5

What is yeast?

Answer 5

Yeast is a microscopic living fungus.

Question 6

Under the right conditions, what will yeast produce?

Answer 6

Under the right conditions, yeast will produce carbon dioxide gas and alcohol in a series of chemical reactions known as fermentation.

Question 7

What are the correct condition for fermentation to take place?

Answer 7

• A source of food from the sugar or flour.
• The correct temperature is between 25°C - 29 °C.
• Moisture.

Question 8

What happens to yeast in high temperatures?

Answer 8

As the temperature becomes higher the yeast is gradually destroyed.

Question 9

What happens to yeast in lower temperatures?

Answer 9

At lower temperatures, yeast activity slows down, until at freezing point it is still alive, but dormant.

Question 10

Define fermentation.

Answer 10

Yeast produces carbon dioxide and alcohol with food, moisture, warmth and time.

Question 11

Enzymes in the yeast bring about the fermentation process:

Answer 11

• Amylase in the yeast changes starch to maltose.
• Maltase in the yeast changes maltose to glucose.
• Zymase in the yeast changes glucose to carbon dioxide and alcohol.

Question 12

How should the liquid used in a yeast mixture be to suit the yeast?

Answer 12

The liquid should be measured accurately and should be blood heat to activate the yeast.

NOTE - too cold = inactive yeast.
too hot = becomes denatured.
Freezes = dormant.

Question 13

Why is salt added to a yeast mixture?

Answer 13

Salt is added to strengthen the gluten and improve the flavor.

Question 14

Why is fat added to a yeast mixture?

Answer 14

Fat may be added to improve the keeping qualities, add color and flavor.

Question 15

Flow chart to summarise the method of making bread:

Answer 15

mixing → kneading → shaping → proving → baking.

Question 16

Why would a bread loaf come out small and dense (3 reasons)?

Answer 16

• Insufficient fermentation and proving.
• Insufficient liquid resulting in a dough that is too stiff for all expansion.
• Inactive yeast, which has not produced enough carbon dioxide gas.

Question 17

Why would a bread loaf come out not risen well, hard and has a coarse texture (2 reasons)?

Answer 17

• Yeast was killed before the loaf was baked.
• The dough has over fermented (too much pressure from the carbon dioxide gas causes gas pockets to break down which leaves large, uneven holes in baked dough).

Question 18

Four examples of yeast dough foods:

Answer 18

Pizza.
Bread rolls.
Chelsea buns.
Doughnuts.

Question 19

What are the 7 rules to follow when making bread with yeast?

Answer 19

• Dough must be soft.
• Knead thoroughly.
• Leave to rise in a warm place.
• After rising, knock back the dough.
• Shape and prove in a warm place.
• Leave until double in size.
• Bake in a hot oven.

Question 20

Why should the dough must be soft?

Answer 20

So gas can push up the mixture.

Question 21

Why would we knead thoroughly?

Answer 21

To develop gluten and evenly distribute the yeast.

Question 22

Why should we leave to rise in a warm place?

Answer 22

Encourages fermentation.

Question 23

Why should after rising, knock back the dough?

Answer 23

To break up large bubbles of gas.

Question 24

Why should we shape and prove in a warm place.

Answer 24

For more carbon dioxide to be produced.

Question 25

Why should we leave until double in size.

Answer 25

For good open texture.

Question 26

Why we should bake in a hot oven.

Answer 26

To stop the rising process.

Question 27

What are the 6 purposes of kneading?

Answer 27

- Carried out using the heel or knuckles of the hand or dough hook in the mixer. - Develops gluten which form an elastic dough. - Forms a smooth dough. - Helps distribute the yeast. - Stimulates the action of yeast. - Breaks down large bubbles of gas for an even texture of finished dough.

Question 28

``` What changes during the baking of bread? CLUES - Rapid rising. Water. Gas. Gluten. Due to high temperature. Gluten. Starch absorbs. Alcohol. Crust form. Dextrinisation. Caramelisation. ```

Answer 28

- Rapid rising and more carbon dioxide is produced due to heat in the oven. - Water is converted to steam. - Gas expands. - Gluten stretches. - Due to high-temperature yeast is destroyed therefore rising stops. - Gluten coagulates. - Starch absorbs water and gelatinizes. - Alcohol is given off. - Crust forms on the surface of the loaf. - Dextrinisation of starch occurs. - Caramelization of sugar (browning).

Question 29

Where and when should proving be done?

Answer 29

Proving must be done in a warm place after the dough has been shaped.

Question 30

Why should you avoid over-proving?

Answer 30

Avoid over-proving as this will result in the dough collapsing.

Question 31

What does proving replace?

Answer 31

Proving replaces the carbon dioxide that is lost during kneading and allows the dough to double in size.

Question 32

What will you have to do to prove a dough in the refrigerator?

Answer 32

The refrigerator does not kill the yeast but slows down the process but can prove overnight in the refrigerator.

Question 33

Why would we sieve flour and salt when making bread dough?

Answer 33

To aerate the mixture and to remove lumps and impurities and the salt is to strengthen the gluten and add flavor.

Question 34

Why would we cut fat into small pieces and rub into flour using fingertips?

Answer 34

Cut fat to make it easier when rubbing in. Rub in to combine fat and flour. Keep the mixture as cool as possible. Fat adds color and flavour.

Question 35

Why would we add dried yeast and sugar to flour mixture?

Answer 35

Sugar acts as food for yeat and yeast produces carbon dioxide gas that makes the bread rise.

Question 36

Why do we warm milk to blood temperature and add milk to dough?

Answer 36

Warm milk activates the yeast.

Question 37

Why would we knead to elastic consistency and place in mixing bowl.

Answer 37

To develop gluten. Evenly disperse the sugar and yeast. To make a smooth dough.

Question 38

Why would we cover the dough with a damp tea towel and place the dough in a warming drawer to prove?

Answer 38

Proving replaces the carbon dioxide and allows the dough to double in size.