Food Science

Question 1

Why does food need to be cooked? (5 marks)

Answer 1

1. To make it safe
2. To improve shelf life
3. To develop flavours
4. To improve texture
5. To give variety

Question 2

What is convection and how convection is used to cook food? (3 marks)

Answer 2

Transfers of heat through gases or liquids. Boiling foods using water, oven or grill. E.g. cooking sausages

Question 3

What is radiation and how radiation is used to cook food? (3 marks)

Answer 3

Waves heat energy on an object. toasters, microwaves. E.g. bread into toast

Question 4

What is conduction and how conduction is used to cook food? (3 marks)

Answer 4

The vibration of food particles. When foods heat up. The heat causes the food molecule to vibrate. It is used to boil food. E.g. boiling chicken

Question 5

What is the difference between boiling and steaming

Answer 5

Boiling - rough
Steaming - gentle

Boiling - food in the water
Steaming - above the water

Question 6

Describe blanching

Answer 6

Half cooking the vegetables (boiling) and then immediately freezing them

Question 7

What types of food can be cooked using poaching?

Answer 7

Peaches, eggs

Question 8

Describe simmering

Answer 8

To cook liquids using low heat. Sauces, soups, curries

Question 9

What are the benefits of braising?

Answer 9

To have flavour

Vitamins are absorbed into the water

Question 10

Stir-frying

Answer 10

A quick method of cooking
less oil
healthy 
more vegetables
high heat
using a wok

Question 11

Shallow frying vs Deep frying

Answer 11

speed - deep drying is quicker
health - shallow frying is healthier
more oil - deep frying
does the oil cover the food? - Yes for deep fry

Question 12

Advantages and disadvantages of Baking

Answer 12

Advantages

• Easy to do
• wide variety of food can be cooked
• healthy method of cooking (no oil)
• food will brown and taste nice

Disadvantages

• Long time
• Can become hard and dry if cooked too long

Question 13

Advantages and disadvantages of grilling

Answer 13

advantages

• Healthy (no oil)
• fast method
• nice taste
• crispy texture

disadvantages

• can easily burn
• hard to see if the food has been cooked on the inside

Question 14

Advantages and disadvantages of roasting

Answer 14

advantages

• Nice taste
• crispy texture
• tender and moist

Disadvantages

• long time
• unhealthy method - uses fat

Question 15

Advantages and disadvantages Dry frying

Answer 15

advantages

• no extra fat added
• natural smell

disadvantages
- mainly fatty meats are cooked this way

Question 16

As many facts about Baking as you can list, including pros and cons

Answer 16

Dry heat is used as a dry method of cooking
Examples - cakes, pies, potatoes
Equipment - electric oven

Advantages
Wide variety of food
Food will look nice - brown outside
Quite healthy - no oil

Disadvantage
Long time
Food can become dry if kept in the oven for too long

Question 17

As many facts about Grilling as you can list, including pros and cons

Answer 17

Examples - vegetables, chicken, meat, fish, halloumi cheese

Fast way to cook food

Heat will radiate from coal to heat the food

Advantages
Fast
No fat added/ oil in meat will drip off
Smokey - tastes nice

Disadvantages
Food can easily be burn
Harder to evenly cook food throughout
Cross-contamination

Question 18

As many facts about Roasting as you can list, including pros and cons

Answer 18

Examples - chicken, beef, vegetables

Oven at a high temperature so that foods can brown and be cooked quicker

Fat is added to roasted vegetables and meat to give a nice taste

Advantages
Food will taste nice and will have flavour
Fat from roasted meat can be used to cook potatoes

Disadvantages
Takes a long time
Unhealthy - extra fat

Question 19

As many facts about Dry-frying as you can list, including pros and cons

Answer 19

Cooking without oil or fat in the pan

Examples are minced meat, bacon, sausages

Medium heat whilst cooking, so food does not burn

Advantages
Seasoning can be added to create a distinct aroma
No added fat - healthier

Disadvantages
Take longer to cook because a lower temperature will be needed at the start
Certain foods

Question 20

Name three chemical raising agents

Answer 20

Bicarbonate of soda
Baking powder
Self-raising flour

Question 21

Name a biological raising agent

Answer 21

Yeast

Question 22

Facts about bicarbonate of soda

Answer 22

Is alkaline and has a soapy taste. Best used to full flavoured foods.

When it is heated, the bicarbonate of soda breaks down to produce CO2 bubbles that expand the mixture to rise
Chocolate cake, gingerbread

Question 23

Facts about baking powder

Answer 23

A mixture of bicarbonate of soda (alkali) and tartaric acid (acid).

pH is balanced due to neutralisation reaction - no strong taste.
Cakes, biscuits and bread

Question 24

Facts about self-raising flour

Answer 24

Plain flour and baking powder

Pancakes, Cakes

Question 25

Facts about yeast

Answer 25

Yeast = Microorganism that releases carbon dioxide. The dough is mixed and left to ferment in a warm place, causing the dough to rise Bread

Question 26

Tell me what you remember on starch gelatinisation?

Answer 26

Gelatinisation- Thickening ( custard, gravy and sauces) Molecules break allowing water to enter. Once the molecules are absorbed in the water the granules will be in a certain size and softer. Granules will still need to be mixed in order to make the sauce thicker.

Question 27

Tell me what you remember on starch dextrinization?

Answer 27

Dry heat is used to cook bread When the bread is toasted, the starch molecules in the bread begin to break down into dextrins (dextrinization). Browner colour and crisper texture + different taste The longer food is cooked, the more starch that is converted into dextrins and the darker and crisper it becomes

Question 28

Sugar caramelisation

Answer 28

Sugar is heated, it will turn brown and change flavour. (sugar caramelisation) very sweet taste Smoother Becomes solid and hard I.e. apple pie, creme brulee Onions have natural sugars which will cause caramelisation when cooked.

Question 29

Name three ways a protein can be denatured?

Answer 29

Changes in temperature Physical agitation (beating, whisking) Acids (lemon juice)

Question 30

Tell me what you know about coagulation?

Answer 30

Coagulation = Joining together The coagulation will change the appearance and texture of food. Still some water between the protein molecules I.e. eggs will start off a see-through colour but will become a white liquid when cooking Overcooked = less water between molecules.

Question 31

How are foams like chocolate mousse and whipped cream made?

Answer 31

Physical agitation (beating, whisking) Eggs whites being whisked - egg whites To make a foamy texture, the gas will become trapped inside of the liquid This will cause the proteins to stretch as the proteins will be denatured. Once physical agitation has finished, the proteins will be coagulated (joined together) making a foamy texture.

Question 32

Tell me what you know about gluten?

Answer 32

Gluten is a protein that is found in wheat flours Water mixed with flour to make a dough (bread, pasta, cake) Molecules of gluten in the dough can stretch and bend - making the dough stronger, longer, stretchier Change in temperature will force gluten to coagulate. Food will be cooked. If overcooked the food will be dry.

Question 33

Short strands of gluten are essential when making shortcrust pastry. Name the process that stops gluten from forming long strands. (1 mark)

Answer 33

Shortening

Question 34

Explain how rubbing fat into flour creates these short strands of gluten (2 marks)

Answer 34

Rubbing fat into flour makes the flour waterproof (1 mark) stops gluten from being able to be stretched (1 mark)

Question 35

When making a cake using the creaming method, fat and sugar are beaten together. Why are fat and sugar beaten together in this method? (1 mark)

Answer 35

To trap air into the mixture (aerate)

Question 36

Different fats have different ranges of plasticity What is meant by the plasticity of fats? (1 mark)

Answer 36

The ability to spread and stretch

Question 37

Explain why margarine has more plasticity than lard? (2 marks) Because margarine is made out of triglycerides (1 mark)

Answer 37

it will be soft and will melt at a lower temperature than lard.

Question 38

Hollandaise sauce is an example of an emulsion sauce. It is made from butter, egg yolk, lemon juice and water. What is the role of egg yolk in hollandaise sauce? (3 marks)

Answer 38

Egg yolk contains lecithin (1 mark) which mixes with the butter and water which allows the two to join (1 mark) and keeps the two together (1 mark)

Question 39

Give an example of an emulsifier?

Answer 39

lecithin