4.1 SCIENCE OF COOKING FOOD

Question 1

Reasons why we cook food:

Answer 1

• to kill pathogenic bacteria and toxins making the food safe to eat (meat, fish, kidney beans)
• to soften food making it easier to chew and to swallow (tenderised meat, softened vegetables)
• the make the food more digestible
• to improve and intensify the flavour of the food

Question 2

dry heat methods of cooking:

Answer 2

• BAKING- dry heat from the oven
• ROASTING- dry, hot air from the oven but food is basted with fat to prevent it from drying out
• TOASTING- dry, radiant heat is applied to food
• GRILLING- small pieces are cooed using the radiant heat produced by a hot grill

Question 3

frying methods of cooking:

Answer 3

• SHALLOW FRYING- small pieces of food are cooked in a shallow amount of very hot oil
• DEEP FRYING- foods are submerged into very hot fat/oil
• STIR FRYING- very small pieces of meat and vegetables are cooked quickly in a minimal amount of hot oil

Question 4

what is boiling?

Answer 4

• moist heat cooking method
• starchy foods are cooked in vigorously boiling water

Question 5

what is simmering?

Answer 5

• moist heat cooking method
• food is submerged into boiling water which is gently bubbling

Question 6

what is poaching?

Answer 6

• moist heat cooking method
• food is cooked in a small amount of gently boiling liquid

Question 7

what is stewing?

Answer 7

• moist heat cooking method
• food is submerged into liquid and cooked slowly to develop flavours

Question 8

what is braising?

Answer 8

• moist heat cooking method
• the vegetables are surrounded. by a liquid with the seared meat cooking in the steam on top o the vegetables

Question 9

what is pressure cooking?

Answer 9

• moist heat cooking method
• food is cooked in a pressure cooker where the temperature can be increased very quickly so food cooks very quickly

Question 10

what is steaming?

Answer 10

• moist heat cooking method
• food is cooked in the steam of boiling water

Question 11

what is blanching?

Answer 11

• moist heat cooking method
• food is plunged briefly into boiling water or steamed, then. removed and placed into chilled water

Question 12

what happens to proteins during cooking?

Answer 12

• they DENATURE and COAGULATE
• the structure of each protein is irreversibly changed

Question 13

what temperature do most proteins coagulate at?

Answer 13

between 71 and 85 degrees celsius

Question 14

what reaction occurs when proteins and carbohydrates are heated with a dry heat?

Answer 14

• Maillard reaction

Question 15

what happens to fats when cooking?

Answer 15

• because they contain a small amount of water, they often liquefy
• they cannot evaporate- they have a property called plasticity
• adds colour and flavour to food

Question 16

what happens to carbohydrates when cooking?

Answer 16

• gelatinisation
• when starch and liquid are heated together, physical changes occur
• occurs at 66 degrees celsius and above

Question 17

what happens when sugar is cooked?

Answer 17

• caramelisation

Question 18

what happens to water when cooking?

Answer 18

• it turns to steam

Question 19

what are foams?

Answer 19

• Chocolate mousse and meringues are examples of foams.
• We make them by trapping gas inside liquids.
• When we agitate liquids storing protein (e.g. by whisking or beating), we cause the liquids’ proteins to denature. The denatured proteins expand, trapping air in the liquid.
• Then, when coagulation happens the air gets trapped and a foam is formed.
• Over-beating or over-whisking will break coagulation bonds, causing the air to escape and the foam to fall apart.
  When some foams are cooked, they become solid (e.g. egg white foams turning into meringues).

Question 20

what is conduction?

Answer 20

• heat energy is transferred through vibrating particles
• particles are tightly packed in solids
• when food is added to the hot pan, the particles in the pan transfer heat energy to those in the food

Question 21

what is convection?

Answer 21

heat energy is transferred through liquids and/ or gases

Question 22

what is radiation?

Answer 22

heat energy is transferred through radiation waves

Question 23

what is the role of gluten?

Answer 23

• form of protein
• wheat flours contain protein
• gluten molecules can bend and stretch

Question 24

what is shortening?

Answer 24

• flour particles gain a waterproof layer when covered in d=fat