The Functions and Properties of Food

Question 1

What are the two types of carbohydrates?

Answer 1

Starches and sugars

Question 2

In what foods are starches found?

Answer 2

Flour, potatoes, pasta, rice and bread

Question 3

In what foods are sugars found?

Answer 3

Fruits, drinks and sweet baked products

Question 4

What can starch be used for?

Answer 4

Bulking agent
Thickening agent
Gelling agent

Question 5

What is gelatinisation?

Answer 5

When heated, starch granules absorb liquid and swell and then burst to thicken a liquid

Question 6

What is suspension?

Answer 6

A solid held in a liquid e.g. starch granules do not dissolve in a liquid and so if they are not stirred they sink to the bottom and form lumps

Question 7

Give an example of gelatinisation

Answer 7

Wheat flour is used with fat and milk to make a white sauce

Question 8

What is a gel?

Answer 8

A small amount of a solid mixed in a large amount of liquid that then sets

Question 9

What are modified starches?

Answer 9

Starches that have been modified to perform additional functions e.g. used to thicken food when boiled water is added in cup-a-soup

Question 10

What are the functions of sugar?

Answer 10

Preserves food
Sweetens
Bulking agent
Improves or changes flavour
Aerates food products
Keeps food products moist
Stabilises whisked mixtures
Adds colour
Speeds up fermentation

Question 11

How does sugar help to preserve foods?

Answer 11

In large quantities it creates unsuitable conditions for microorganisms to grow e.g. in jams and chutney

Question 12

How does sugar help to aerate food products?

Answer 12

When sugar is beaten with butter or egg it helps trap air to make cakes light

Question 13

How does sugar help to speed up fermentation?

Answer 13

Increases the rate at which yeast releases carbon dioxide in bread making

Question 14

How does sugar help to add colour?

Answer 14

When sugar is heated it turns golden brown. This is called caramelisation

Question 15

What are protein foods made up of?

Answer 15

Small units called amino acids that are linked together in a chain. When proteins are heated the links in the chain change and this alters the structure of the food

Question 16

What is aeration?

Answer 16

When air is trapped in a mixture

Question 17

What is coagulation?

Answer 17

When eggs are heated, they change from a liquid to a solid, change colour and set. Full coagulation happens at 70°C

Question 18

What is an emulsion?

Answer 18

A mixture of two liquids - unless an emulsifier is added eventually they will separate

Question 19

What is the emulsifier in mayonnaise?

Answer 19

Egg yolk contains a substance called Lecithin, which is also found in soya beans. When egg yolk is mixed with oil and vinegar it stops the liquid separating.

Question 20

What happens in shortening?

Answer 20

The fat coats the flour particles, preventing the absorption of water. This prevents gluten from developing resulting in a crumbly texture

Question 21

What are the functions of fats and oils?

Answer 21

Shortening ability
Prevent lumps of flour forming in a sauce
Add colour
Can form part of an emulsion
Act as cooking medium
Adds distinct flavour

Question 22

How do fats help to aerate foods?

Answer 22

When fat is creamed with sugar it helps trap air

Question 23

How do fats help to add a flaky texture to pastry?

Answer 23

The fats help to separate layers by creating steam

Question 24

How do fats help to extend the shelf life of foods?

Answer 24

The fat helps the products retain its moisture for longer

Question 25

Why can’t low fat spreads be used for frying and baking?

Answer 25

They have a high water content to replace the fat

Question 26

What is enrobing?

Answer 26

The coating of one product with another ingredient to give it an outer layer e.g. breadcrumbs on a fish finger or coating a biscuit with chocolate

Question 27

What is extruding?

Answer 27

Forcing a mixture through a nozzle in order to shape them e.g. cake icings, pasta

Question 28

What are the aims of tenderising?

Answer 28

To break down or soften the connective tissue or muscle in meat

Question 29

What are the three methods of tenderising?

Answer 29

Marinating: in lemon juice, vinegar or wine
Mechanical: using a mallet or chopping
Cooking: slow and moist cooking