2.5.functional properties of additional ingredients

Question 1

What are the 3 categories of raising agents?

Answer 1

Mechanical
Biological
Chemical

Question 2

Describe mechanical raising agents?

Answer 2

involves adding air to mixtures. This can be achieved by whisking egg whites, creaming butter and sugar together, rubbing in butter to flour, seiving flour

Question 3

Describe biological raising agents?

Answer 3

the fermentation of yeast to produce carbon dioxide is a raising agent used in many types of bread.

Question 4

Describe chemical raising agents?

Answer 4

-Bicarbonate of soda or baking powder to produce carbon dioxide to create a baked products such as cakes, scones and biscuits.
-Water converted to steam to create choux pastry and profiteroles, Popovers and Yorkshire pudding.

Question 5

What is fermentation?

Answer 5

when during the bread making process, yeast feeds on the sugar contained with the bread dough, to produce carbon dioxide and alcohol.

Question 6

How does the fermentation of yeast cause bread to rise?

Answer 6

• yeast produces carbon dioxide which is trapped in the dough causing it to rise.
• As the dough is baked, the carbon dioxide expands and causes the bread to rise further.
• Fermentation also produces alcohol but during baking this evaporates.

Question 7

What are the conditions required for fermentation

Answer 7

Moisture - liquid such as milk or water
Warmth (27 - 32℃).
Food - the presence of starch in flour or added sugar.
Time - for the yeast to grow

Question 8

How does bicarbonate of soda act as a chemical raising agent?

Answer 8

• is an alkali of sodium bicarbonate.
  -used to create carbon dioxide in strongly flavoured cakes e.g. Ginger Cake, Chocolate Cake.
• disadvantage -has a strong aftertaste and yellow colour.
  -An acid can be added to neutralize the effect.

Question 9

How does baking powder act as a chemical raising agent?

Answer 9

-an alkali and acid blend that forms carbon dioxide when mixed with liquid and heat, causing a mixture to expand and rise. EG.

bicarbonate of soda + Cream of tartar
(sodium bicarbonate) (potassium hydrogen tartrate)
Alkali Acid

-The acid is added to neutralise the disadvantages of the alkali causing a bitter aftertaste and yellow colour.

Question 10

How does self raising flour act as a chemical raising agent?

Answer 10

-is a low gluten content plain flour that has baking powder added to it in an appropriate proportion to make risen products such as cakes and some types of biscuits.

Question 11

Why can the type of chemical raising agent used change?

Answer 11

-is affected by the desired texture required and the interaction of the raising agent with other ingredients

Question 12

Describe how steam acts as a raising agent?

Answer 12

-Choux pastry contains water and when the pastry is heated it creates steam (water vapour) which causes the pastry to rise.
-The same process of using steam as a raising agent is used in:
Choux pastry - profiteroles, éclairs, paris brest, croque en bouche
Batters - yorkshire pudding, popovers

Question 13

Describe how whisking egg whites act as a raising agent?

Answer 13

-by using a hand or electric whisk air is created and trapped into a mixture. eg. egg proteins trap air in products such as meringues and souffles to give them the light and aerated texture of a foam.
-Air expands when it is heated and the egg coagulates creating a solid foam.

Question 14

How does creaming butter and sugar act as a raising agent?

Answer 14

-used to make cakes and biscuits.
-The sugar crystals are “creamed” with a solid fat (e.g. butter) and this traps air.
-The air then expands when the mixture is cooked.
-Egg present in the mixture coagulates to set the mixture in this aerated state.

Question 15

how does rubbing in butter to flour?

Answer 15

-used to give shortcrust pastry and scones their “short” or crumbly texture.
-Fat (often butter) is rubbed into flour.
-The flour is coated with a layer of fat and so the proteins in the flour cannot be easily hydrated to form long gluten strands.
-The gluten strands are “short” and the names of shortbread biscuits and shortcrust pastry illustrate this characteristic.

Question 16

how does folding and rolling act as a raising agent?

Answer 16

• air can be trapped to create flaky layers. Puff pastry, flaky pastry and croissant dough all use folding techniques which trap air.
• Also water trapped in the mixture will be a chemical raising agent alongside the mechanically added air.

Question 17

Function and use of cream of tartar/ acetic acid

Answer 17

-Used to create invert sugar - splits the disaccharide sucrose into the monosaccharides glucose and fructose.
-This gives confectionary a smooth texture, & baked products retain moisture.

Question 18

Function and use of lactic acid?

Answer 18

• used to denature proteins and give a distinctive sour taste to create yogurt and cheese.

Question 19

Function and use of cream of tartar

Answer 19

-Used alongside bicarbonate of soda to create baking powder as a raising agent in cakes and other baked products.

Question 20

Function and use of acetic acid

Answer 20

-Used As a preservative in pickle and chutney such as pickled onions.
-used to speed up the coagulation of proteins when poaching eggs.

Question 21

Function and use of citric acid

Answer 21

-Used As an antioxidant to prevent browning of fruit and vegetables.
- used to marinade meat as the meat is tenderised by the denaturation of the proteins.
- used for the formation of egg white foams to speed up the denaturation of the proteins to create meringues and pavlovas.
-important to jam making and if the fruits have a low pectin content.

Question 22

Function and use of Citric acid/
Tartaric acid/ Phosphoric acid

Answer 22

Provide a distinctively sharp taste in jams and soft drinks.

Question 23

Give an example of an alkali and its function and use

Answer 23

-Sodium bicarbonate
-is used as a raising agent.
-can raise the pH of a dough.
-helps create an alkaline dough where coagulation of protein is slowed down during baking.
-During baking the dough can spread to create the same thickness of biscuit before the egg coagulates and sets.

Question 24

Function of salt in Sauerkraut and Kimchi

Answer 24

-used as a preservative to draw out water from the cabbage cells by a process of osmosis.
-The salted cabbage is then fermented.

Question 25

Function of salt in cheese making

Answer 25

-to increase the firmness of the curds. This is because salt increases coagulation and removes water from within the proteins of the curd.
- Salt also helps prevent microbial spoilage of the cheese.

Question 26

Function of salt in breads using yeast

Answer 26

-helps strengthen the gluten in bread, which gives a higher volume and finer crumb texture. The amount of salt is in a ratio of 1.5 to 2.0% salt to weight of flour.

Question 27

Function of salt in chocolate and caramel?

Answer 27

Adding salt such as sea salt to chocolate or caramel helps enhance the complexity of the flavour. This is due to hedonic escalation.

Question 28

Function of salt in vegetables

Answer 28

Boiling vegetables in salted water prevents the chlorophyll leaching out. The vegetable is then placed into iced water to stop the cooking process.

Question 29

function of salt in processed meats. eg. salami

Answer 29

In processed meats, salt inhibits the growth of microorganisms and so is used as a preservation technique. Salt also adds to the flavour and texture of the processed meat.