Food Science Flashcards

1
Q

Why do we cook food?

A
  • To make it safe to eat
  • To improve shelf life
  • To develop flavour
  • To improve texture
  • To give variety in the diet
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2
Q

How does different cooking methods change food?

A

Change their sensory properties (appearance, favour, texture and smell) and nutritive value.

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3
Q

How does cooking food improve shelf life?

A
  • At high temperatures, mould and bacteria are destroyed.
  • Food can be preserved like this through manufacturing process.
  • E.g. milk is pasteurised so it stays fresh for longer.
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4
Q

How does cooking food develop flavour?

A
  • Chemical reactions take place that change flavour (caramelisation).
  • Roasting meats and veg create more intense flavour and food becomes browner and crispier with more fat added to it as water evaporates.
  • Allows allows the flavours of different foods to combine (braising a meat in a pot of liquid and veg).
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5
Q

How does cooking food improve texture?

A
  • Usually makes it easier to chew, swallow and digest food.
  • Some foods become softer (carrots and broccoli become flexible and rice when starch molecules soften).
  • Meats become more tender as solid fats melt and proteins denature.
  • Other foods become firm (coagulation in eggs).
  • Can also make food more pleasant to eat (roast potato with soft centre and crispy outside).
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6
Q

How does cooking food give variety in the diet?

A
  • Foods can be cooked in different ways to create variety.
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7
Q

What are three ways heat is transferred to cook food?

A
  • Conduction
  • Convection
  • Radiation
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8
Q

What is conduction?

A

The transfer of heat energy through the vibration of particles. In a solid, particles are held tightly together, so when one particle vibrates, it bumps to other particles around them and passes the vibrations on.

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9
Q

What is convection?

A

The transfer of heat energy through a liquid or a gas.

When a liquid is heated, the warmer fluid rises above its colder surroundings. As the warmer fluid rises, colder liquid takes it place. Liquid at the bottom heats up and liquid at the top cools down. As this continues, this causes a circulation of fluids.

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10
Q

What is radiation?

A

Transfer of heat energy through waves of radiation (no direct contact). When the waves reach the food, they absorb and heat the food up.

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11
Q

How does conduction help to cook food?

A

When a pan is placed on a hob, heat energy from the hob causes particles in the pan to vibrate more and gain heat energy.

When food is placed in the pan, heat energy is transferred from particles to the pan in the food (and its particles vibrate and pass on heat energy through it) until the food is cooked through.

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12
Q

How does convection help to cook food?

A

Convection occurs in ovens - hot air rises and cool air falls as convection currents.
- Modern ovens are fan-assisted - they have a a fan that helps circulate the air around the oven.

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13
Q

How does radiation help to cook food?

A
  • Cookers like grills and toasters use radiation to cook food.
  • Microwaves use radiation to heat up the fat, sugar, and water molecules in food.
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14
Q

What are six ways water can used to cook food?

A
  • Boiling
  • Steaming
  • Braising
  • Blanching
  • Simmering
  • Poaching
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15
Q

What is boiling?

A

Cooking food by heating it in a pan of boiling liquid, usually water.

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16
Q

What is steaming?

A

Cooking food with steam from boiling water or stock.

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17
Q

What is braising?

A

Slowly cooking food in an ovenproof pot that has the lid on and contains liquid (usually water, stock or wine), and often herbs and vegetables.

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18
Q

What is blanching?

A

Involves part-cooking food in boiling water for a very short time before putting in in cold/iced water.

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19
Q

What is simmering?

A

Foods is cooked in hot liquids kept just below the boiling point of water and above poaching temperature.
A liquid is brought to a boil, then its heat source is reduced to a lower, constant temperature.

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20
Q

What is poaching?

A

Cooking food in a pan of liquid, below boiling point, usually around 80°C.

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21
Q

What are the two types of frying that use different amounts of fat?

A
  • Stir-Frying
  • Shallow frying
  • Dry frying
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22
Q

What is sweating?

A

The gentle heating of vegetables in a little oil or butter, with frequent stirring and turning to ensure that any emitted liquid will evaporate.

This releases moisture from the food, making it more tender and sweet tasting.
While food is sweating, it’s usually covered with a lid to help moisture (in the form of steam) circulate around the food.

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23
Q

What are some examples of food that are boiled?

A
  • Tougher cuts of meat
  • Potatoes
  • Rice
  • Pasta
  • Veg
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24
Q

What are some examples of food that are steamed?

A
  • Fish
  • Rice
  • Vegetables
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25
Q

What are some examples of food that are braised?

A
  • Big or tough joints of meat (gentle cooking helps tenderise)
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26
Q

What are some examples of food that are blanched?

A
  • Tomatoes and almonds (make them shrivel up, making skins easier to remove).
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27
Q

What are some examples of food that are simmered?

A

Soups and curries

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28
Q

What are some examples of food that are poached?

A
  • Eggs
  • Fruit
  • Fish
29
Q

What is stir-frying?

A

A frying method done in a wok, coated in a small amount of oil. Food is cooked very quickly and needs to be moved around constantly so it doesn’t burn.

30
Q

What are examples of food that are stir-fried?

A
  • Noodles
  • Vegetables
  • Tofu
  • Small pieces of meat
  • Fish
31
Q

What is shallow frying?

A

A frying method done in a frying pa cooked in a medium amount of fat or oil.
The fat is heat up, and when the food is placed in the pan, the food sizzles as soon as it hits the pan.

32
Q

What are examples of food that are shallow fried?

A
  • Fish
  • Eggs
  • Pancakes
  • Meats (bacons, sausages and chops)
33
Q

What is baking foods?

A

Cooking food using dry heat, usually in an oven.

34
Q

What are examples of food that can be baked?

A
  • Bread
  • Pastries
  • Cakes
  • Potatoes
  • Whole fishes (sea bass or salmon)
35
Q

What are the advantages of baking?

A
  • Wide variety of food can be baked
  • The outside of foods brown and crisps up, which looks and taste nice
  • Quite healthy cause no extra fat is added + solid fats leave during baking.
36
Q

What are the disadvantages of baking?

A
  • Can take a long time
  • Food can become dried out
  • Uses a lot of energy as it requires oven to be at high temperatures for a long time.
37
Q

Why are ovens more useful for baking?

A
  • Food bakes more evenly as all parts of oven is at a similar temperature.
  • Oven heats up quicker and food cooks quicker - so less energy is used.
38
Q

What is grilling?

A
  • Uses a dry heat at a higher temperature than baking or roasting.
  • As food is grilled, fat drips out of the food and the outside becomes golden and crisp.
39
Q

What is barbecuing?

A
  • Similar to grilling, but heat radiates from hot food and food is cooked at lower temperatures for longer.
40
Q

What are the advantages of grilling?

A
  • Foods cooks quickly at a high temperature
  • Fairly healthy as not fat is added and fat from food drips off
  • Golden outside of food loos and tastes nice, and can have a crispy texture
  • Grilling on a barbeque can give a smoky flavour which is popular.
41
Q

What are the disadvantages of grilling?

A
  • High heat used can make it hard to cook food evenly
  • Easy to burn food
  • Easy to have food cooked outside and raw inside (could lead to food poisoning)
  • Handing raw and cooked meat on same barbeque can lead to cross-contamination.
42
Q

What are some ways fat can be added to food during roasting?

A
  • Fat can be added or the fat that has melted from the food can be put back on top - this is called basting.
43
Q

What is roasting?

A
  • Roasting uses dry heat from an oven.
  • Usually done at a higher temperature than baking, so foods cook and brown more quickly.
  • Fat is often added to the outside (e.g. potatoes or veg) to help it brown and stay moist.
44
Q

What are the advantages of roasting?

A
  • Extra fat and high temperature helps to brown and crisp outside of food, which looks and tastes delicious.
  • Fat from roasted meat can be used to cook other food (potatoes or fried bread).
  • Food can be tasty and moist.
  • It can produce meat with a are (undercooked) centre, which lots of people like.
45
Q

What are the disadvantages of roasting?

A
  • Roasted food isn’t always that healthy, as extra fat is often added.
  • Like baking, it takes a long time to roast food and uses a lot of energy.
46
Q

What is dry frying?

A
  • Cooking food in a pan without fat or oil.
  • Dry foods with natural fat can be cooked (minced meat/bacon), and as the food heats up, the fats inside the food melt into the pan and begin to cook the food.
47
Q

What food can be cooked by dry frying (or usually called ‘dry roasting’) ?

A
  • Nuts
  • Seeds
  • Spices
48
Q

What foods (with natural fat) can be cooked via dry frying?

A
  • Minced meats
  • Bacon
49
Q

What are the advantages of dry frying?

A
  • No extra fat or oils are added, so this is healthier cooking method.
  • Can be sued to give a more distinct aroma to nuts, seeds and spices.
50
Q

What are the disadvantages of dry frying?

A
  • Takes than longer than other frying methods to cook meat thoroughly because lower temperatures are needed at the start.
  • Can be used for only a small range of food types compared to other cooking methods.
51
Q

What are the benefits of blanching food?

A
  • Cold water stops cooking process which helps to preserve colour, texture and vitamins.
  • Can be used to reduce harsh flavours in food.
  • Used to prepare fruit and veg for freezing.
52
Q

What are the benefits of braising food?

A

Great for big and tough joins of meat - gentle cooking of meat helps tenderise it.
- Before it is braised, meat is lightly fried to brown and seal it - helps keep juices inside meat and gives a caramelised flavour.
- Flavours from the liquid and any any vegetables and herbs in the pot are absorbed by the joint.

53
Q

What are the drawbacks of blanching food?

A

Lack of nutrients in cooking water
- High energetic costs
- High water consumption

54
Q

What are the drawbacks of braising food?

A
  • Braised dishes may contain fat.
  • Takes a long time to cook.
  • Food may have a lack of texture.
55
Q

What are the benefits of simmering food?

A

It preserves more nutrients than boiling.

56
Q

What are the drawbacks of simmering food?

A

It can cause the food to lose its water-soluble vitamins and other nutrients by leaching into the cooking liquid.

57
Q

What are the benefits of boiling food?

A
  • Healthy way to cook as no fat is added.
  • Boiling foods in small volumes of water, with lid covering the pan, use less energy than other methods (e.g. roasting, simmering)
58
Q

What are the drawbacks of boiling food?

A
  • Harsh method of cooking - can’t be used on delicate foods as bubbles could break up food.
  • Over-boiling and make foods like pasta too soft.
  • If veg in boiled for too long, colour, flavour and water-soluble vitamins are lost in the water
  • Boiled food is not as tasty/attractive as food cooked by other methods (e.g. roasting).
59
Q

What are the benefits of steaming food?

A
  • Healthiest way to cook - no fat is added, veg keep more their their taste, texture, colour and nutrients than being boiled.
  • Gentle way to cook - good for delicate food (fish) but not for tougher meats.
60
Q

What are the drawbacks of steaming food?

A
  • Food may not have as much flavour compared to food which has been roasted or fried.
61
Q

What are the benefits of poaching food?

A
  • A gentle way to cook food and helps keep food tender.
  • If food is poached in a tasty sauce, the food can absorb flavours and give variety.
62
Q

What are the drawbacks of poaching food?

A

Nutrients and flavours are transferred to the liquid, lowering the nutritional content and tastiness of the food.

63
Q

What are examples of food that are grilled?

A
  • Smaller bits of meat (sausages or steaks)
  • Vegetables (courgettes and aubergines)
  • Cheeses (halloumi r gat’s cheese)
64
Q

What are examples of food that are roasted?

A
  • Large cuts of meat (leg f lamb, cut of beef)
  • Potatoes
  • Vegetables (root vegetables, onions and peppers)
  • Chestnuts
65
Q

What is denaturation?

A

When food is cooked, the chemical bonds in proteins (which hold their complex structure of strings of amino acids), break down.

The proteins unravel and their shape changes - in most cases this is irreversible.

66
Q

How can denaturation occur?

A
  • Physical agitation (e.g. whisking, beating, kneading)
  • Changes in temperature
  • Acids (lemon juice and marinades)
67
Q

What is coagulation?

A

When denatured proteins join together, changing the appearance and texture of the food.
During this, water becomes trapped between the protein molecules.

68
Q

How do eggs coagulate?

A

Egg whites, when cooked, turn from a translucent liquid to a white solid.