Food science

Question 1

Why is food cooked to make it safe to eat?

Answer 1

-Food may be contaminated with harmful microbes that can cause disease. The high temperatures involved in cooking kill these microbes

Question 2

Why is food cooked to improve shelf life?

Answer 2

cooking kills the bacteria that would cause spoilage but the food should be eaten within a few days of being cooked or frozen. Freezing would give it a bit longer life then putting in the fridge but most fresh food does not have a very long shelf life and should be used as soon as possible.

Question 3

Why is food cooked to develop flavours?

Answer 3

Cooking involves chemical reactions. The chemical reactions that take place alter the flavour of the food. When cooking different foods together, their flavours combine.

Question 4

Why is food cooked to improve texture?

Answer 4

Many foods are harder to swallow, chew or digest pre-cooking. Cooking softens some foods (e.g. cauliflower becomes less rigid and couscous expands as it’s starch molecules become softer). Cooking makes meats more tender because the solid fats in the meats melt and the proteins become softer.

Question 5

Why is food cooked to give variety in the diet?

Answer 5

• you can make foods in different methods EG.grilling

Question 6

What is conduction?

Answer 6

Conduction is the process of heat being transferred between objects through direct contact, and it’s the most common type of heat transfer. For example, in cooking the burners on stoves will conduct heat energy to the bottom of a pan sitting on top of it. From there, the pan conducts heat to its contents.

Question 7

What is convection?

Answer 7

Convection is one of five heat transfer methods commonly used in cooking, including conduction, boiling, condensation, melting, and radiation. Convection is the process by which food is heated by a moving heat source, such as the hot air in an oven, or even the motion of boiling water in a pot.

Question 8

what is radiation?

Answer 8

radiation cooking is when a heat source like fire, gas or energy waves directly contact the food rather than a heating element like a pan or grill grate. Broiling is the easiest example to visualize: Food is cooked – often very aggressively – by a heat source above it.

Question 9

what is boiling ?

Answer 9

boiling, the cooking of food by immersion in water that has been heated to near its boiling point (212 °F [100 °C] at sea level; at higher altitudes water boils at lower temperatures, the decrease in boiling temperature being approximately one degree Celsius for each 1,000 feet [300 metres]).
Eg. Grains, pasta, beans and other legumes, eggs, vegetables, meat or fish:

Question 10

what is steaming?

Answer 10

Steaming is a method of cooking that requires moist heat. The heat is created by boiling water which vaporizes into steam. The steam brings heat to the food and cooks it. Unlike boiling, the food is separate from the water and only comes into direct contact with the team.
Eg. veg,fish,rice,eggs

Question 11

what is simmering ?

Answer 11

a cooking technique in which foods are cooked in a hot liquid which is kept just below the boiling point but above the poaching temperature range.
Eg.beef stew, meatballs in sauce, chicken and rice with broth, seafood gumbo and meat stock

Question 12

what is blanching ?

Answer 12

food, usually a vegetable or fruit, is scalded in boiling water, removed after a short timed break, and then dropped into cold water to stop the cooking process. Blanching foods helps reduce the loss of quality over time.
Almonds (1 minute),Broccoli florets (3 minutes), Cabbage (90 seconds)
Cauliflower florets (3 minutes)

Question 13

what is poaching?

Answer 13

Poaching is a cooking technique that involves heating food submerged in a liquid, such as water, milk, stock or wine. Poaching is differentiated from the other “moist heat” cooking methods, such as simmering and boiling, in that it uses a relatively lower temperature (about 70–80 °C (158–176 °F)).
Eg.Asparagus, chicken, eggs, leeks, meat, peaches, pears, plums

Question 14

what is Braising?

Answer 14

the cooking of meat or vegetables by heating them slowly with oil and moisture in a tightly sealed vessel. Braising differs from stewing, in which the food is immersed in liquid, and from covered roasting, in which no liquid is added. Braising is a combination of covered roasting and steaming.

Question 15

what is Stir-frying?

Answer 15

Small- to medium-size food particles are rapidly cooked in a small amount of very hot fat, with constant agitation.

Question 16

what is shallow-frying?

Answer 16

a small amount of oil is put into a saucepan, the oil is heated, and then the food is added and cooked

Question 17

what is sweating?

Answer 17

to cook something over low heat in a small amount of fat, usually in a covered pan or pot.

Question 18

What is baking?

Answer 18

Baking is a method of preparing food that uses dry heat, typically in an oven, but can also be done in hot ashes, or on hot stones. The most common baked item is bread, but many other types of foods can be baked.

Question 19

Advantages of baking?

Answer 19

The outside of the food will brown and crisp up, which makes it look and taste nice. As no extra fat is used in the cooking process it can be a healthier way to cook.

Question 20

Disadvantages of baking?

Answer 20

Baking food can take a long time. If over baked, food will dry out. Baking requires a lot of energy as the oven has to be kept at high temperatures for a long time.

Question 21

What is grilling?

Answer 21

Grilling is a dry-heat cooking method.
Food is cooked on metal grates that are placed over a heat source in order to produce a smoky, charred flavor. Grills can use gas, electricity, charcoal or wood. Meats, poultry, fish and vegetables can all be grilled.

Question 22

Advantages of grilling?

Answer 22

Grilled Food Has Less Fat.
Grilled Vegetables Are Healthier.
Meat Preserves Nutrients.
No Butter In Grilling

Question 23

Disadvantages of grilling?

Answer 23

Barbecuing gives food a smoky flavour. A high heat can make it difficult to cook food evenly. The food can be burned easily if you are not careful. You can cross contaminate on a barbecue as you handle raw and cooked meat.

Question 24

What is Roasting?

Answer 24

Roasting is a slow-cooking process, using indirect, diffused heat to cook its ingredients. It is a dry-heat cooking method where hot air surrounds the food and cooks it evenly on all sides at a temperature of at least 300 °F (or 150 °C). The heat can also be derived from an open flame, an oven, or another heat source.

Question 25

Advantages of Roasting?

Answer 25

Roasting is a food processing technique that employs the principle of heating to cook the product evenly and enhance the digestibility, palatability and sensory aspects of foods with desirable structural modifications of the food matrix

Question 26

Disadvantages of Roasting?

Answer 26

Roasting can be a long process and requires prior planning,Some cuts of meat or large vegetables can be expensive and may require a higher level of skill to cook properly.
Roasting can create a mess in the kitchen with grease and drippings.

Question 27

What is Dry frying?

Answer 27

A method of cooking foods that are high in fat, eg bacon or ground beef in a non-stick pan where only the melted fat from the meat is used. To dry fry place the meat in a cold non stick frying pan, over a low heat cook until some fat runs out, increase the heat and fry the meat for the recommended cooking time.

Question 28

Advantages of Dry frying?

Answer 28

Dry frying is good for foods high in natural fat, like steak, because once the fats melt they start cooking the food. Dry frying releases oils, which makes the food more flavoursome.

Question 29

Disadvantages of Dry frying?

Answer 29

Slower than other forms of frying (uses lower temperatures).
Only a limited range of foods can be cooked by this method.

Question 30

What happens when proteins are cooked?

Answer 30

• they denature-chemical bonds holding their structure together break down

Question 33

What is gelatinisation?

Answer 33

the process of gelatinisation occurs when starch granules are heated in a liquid, causing them to swell and burst, which results in the liquid thickening.

Question 34

What is dextrinization?

Answer 34

When foods containing starch are heated they can also produce brown compounds due to dextrinisation. Dextrinisation occurs when the heat breaks the large starch polysaccharides into smaller molecules known as dextrins which produce a brown colour.

Question 35

what is caramelization?

Answer 35

Breaking up of sucrose molecules (sugar) when they are heated. This changes the colour, flavour and texture of the sugar as it turns brown into caramel.

Question 36

what is emulsification?

Answer 36

Emulsification: when two liquids are combined that would usually not mix. with the aid of an emulsification agent e.g. lecithin in egg yolk holds. mayonnaise together

Question 37

what is coagulation?

Answer 37

the change in the structure of protein (from a liquid form to solid or a thicker liquid) brought about by heat, mechanical action or acids. Enzymes may also cause protein coagulation e.g. cheese making.

Question 38

What is aeration?

Answer 38

Aeration involves getting air into something. We trap air in mixtures when we beat fats with sugar (known as creaming). The added air lightens the mixture and gives it a fluffy texture. Aeration causes cakes to turn out spongy and light when they’re cooked.

Question 39

What is plasticity?

Answer 39

Fats can be spread, manipulated and shaped. Plasticity means the ability to be spread and shaped. Some fats are easier to spread than others. Take margarine for example. It can be spread straight from the fridge, whereas butter can be much harder to spread when cold.

Question 40

What is shortening?

Answer 40

A shortening is defined as a fat, solid at room temperature, which can be used to give foods a crumbly and crisp texture such as pastry. Examples of fat used as “shorteners” include butter, margarine, vegetable oils and lard.

Question 41

What is a chemical raising agent ?

Answer 41

Chemical raising agents are those that require a chemical reaction in order to function. Common examples of chemical raising agents include: baking soda (bicarbonate of soda); baking powder (bicarbonate of soda + cream of tartar);

Question 42

What is a biological raising agent ?

Answer 42

A biological raising agent is added which produces CO2 gas. The Fermentation process is activated during bread production when yeast is combined with sugar in a warm moist condition. When the fermented yeast is added to the flour and warm liquid it increases in size during the “proving” stage.

Question 43

what is a steaming raising agent?

Answer 43

When very liquidy mixtures (e.g. Yorkshire puddings) are cooked in hot ovens, water escapes as steam. The rising steam helps to raise the mixture. The mixture bakes and solidifies as water escapes.

Answer 44

Air is introduced into mixtures in different ways. This is called a mechanical raising agent. The air is trapped in mixtures by: sieving flour, rubbing in fat to flour (e.g. shortcrust pastry) creaming fat and sugar (sponge cake), whisking (Swiss roll), beating (batters) folding and rolling (flaky pastry).

Question 45

what is a mechanical raising agent?

Answer 45

Air is introduced into mixtures in different ways. This is called a mechanical raising agent. The air is trapped in mixtures by: sieving flour, rubbing in fat to flour (e.g. shortcrust pastry) creaming fat and sugar (sponge cake), whisking (Swiss roll), beating (batters) folding and rolling (flaky pastry).