Food science Flashcards
(120 cards)
1
Q
Why do we need to cook foods?
A
To kill bacteria to make them safe To soften the food so we can chew it To make the food digestible To improve and intensify the flavour To make it look more attractive and appealing To reduce the bulk of food To provide variety to our meals To enable certain foods to work together To keep warm
2
Q
What are the three methods of heat transference used when cooking foods?
A
Conduction
Convection
Radiation
3
Q
What is conduction?
A
Transfer of heat by direct contact with a hot surface
4
Q
What is convection?
A
Transfer of heat by the movement of heated particles into a cooler mass/area
5
Q
Give examples of cooking methods that use conduction
A
Fry frying
Griddling
Searing
Sauteing
6
Q
Give examples of dry heat cooking methods that use convection
A
Baking
Roasting
7
Q
Give examples of wet heat cooking methods that use convection
A
Boiling Braising Simmering Poaching Steaming Pressure cooking
8
Q
What is radiation?
A
Transfer of heat using waves of light or heat
9
Q
Give examples of cooking methods that use radiation
A
Toasting
Grilling
Barbecuing
10
Q
How does microwave radiation cook foods?
A
Radiation penetrates 1cm of the food
The radiation agitates the water molecules in food
Causes friction which spread heat energy around the rest of the food
11
Q
What is baking?
A
Food cooked in the dry, hot air of the oven
12
Q
Give examples of baked foods
A
Cakes Pastries Bread Puddings Biscuits Fish
13
Q
What are the advantages of baking foods?
A
Good colour and texture
Several items can be cooked at once
Outside of food goes brown and adds flavour
14
Q
What are the disadvantages to baking foods?
A
Need specific cooking times
Need specific temperatures
15
Q
What is roasting?
A
Cooking food using the dry, hot air of the oven but fat has been added to stop it drying out
16
Q
What are the advantages to roasting foods?
A
Good flavour (added fat)
Crisp texture
Attractive appearance (golden brown)
More than one item can be cooked at a time
17
Q
What are the disadvantages to roasting foods?
A
Can take a long time (joints of meat)
Have to add extra fat (unhealthy)
Meat can become tough and chewy if cooked on too high a heat
18
Q
What is toasting?
A
Dry radiant heat applied to food. Can be directly onto foods.
19
Q
Give examples of foods that can be toasted
A
Bread
Nuts
Seeds
Whole spices
20
Q
What are the advantages to toasting foods?
A
Lower the glycaemic index (food takes longer to digest)
Flavours released
Flavours enhanced
21
Q
What is a disadvantage to toasting foods?
A
Need to be careful not to burn
22
Q
What is grilling?
A
Small pieces of food cooked by the radiant heat of a grill or barbeque
23
Q
What are the advantages of grilling food?
A
Healthy method - fat drains out of the food during cooking
Quick
24
Q
What are the disadvantages to grilling foods?
A
Need to be careful not to burn
Only tender cuts of meat should be grilled
25
What is shallow frying?
Cooking small pieces of food in a small amount of hot oil/fat
26
What are the advantages to shallow frying foods?
Quick method
| Uses a minimal amount of fat
27
What are the disadvantages to shallow frying/
Should not be left unattended
Unhealthy due to added fat
Wet foods can spit and splash when fried
28
What is deep frying?
Foods are submerged in very hot fat/oil
29
What are the advantages to deep frying?
Golden colour
Crunchy surface
Very quick
30
What are the disadvantages to deep frying?
Can't be left unattended
Very unhealthy
Over-heated fat/oil can combust and cause a fire
31
What is stir frying?
Very small pieces of food quickly cooked in a small amount of oil/fat whilst being move continuously.
32
What are the advantages to stir frying?
Very quick
Vegetables remain crunchy
Healthier frying method
Limited loss of water soluble vitamins
33
What are the disadvantages to stir frying?
Needs constant attention and stirring
Needs fat/oil with high smoke point
Food needs to be fully prepared before cooking
34
What cooking methods use dry heat?
Baking
Roasting
Toasting
Grilling
35
What cooking methods use frying?
Deep frying
Shallow frying
Stir frying
36
What cooking methods use moist heat?
```
Boiling
Simmering
Poaching
Stewing
Braising
Pressure cooking
Steaming
Blanching
Sous vide
```
37
What is boiling?
Usually starchy foods cooked in boiling water
38
What are the advantages to boiling foods?
Quick
| Healthy as no fat is added
39
What are the disadvantages to boiling foods?
Water soluble vitamins easily lost
Food becomes soft
Unsuitable for meats as it toughens the protein
40
What is simmering?
Food submerged in water that is only gently bubbling
41
What are the advantages to simmering foods?
Good for tender pieces of food as it is a gentle way to cook
42
What are the disadvantages to simmering foods?
Tender food can fall apart if it becomes a boil
| Loss of water soluble vitamins
43
What is poaching?
Food cooked in a small amount of simmering liquid
44
What are the advantages to poaching?
Tender foods cooked very gently
Healthy (no added fat)
Adds flavour if using something other than water
45
What are the disadvantages to poaching?
Loss of water soluble vitamins
Foods can break apart
Can taste bland if only poached in water
46
What is stewing?
Foods submerged in liquid, cooked slowly.
47
Whats the difference between a stew and a casserole?
Stew is cooked on the hob
| Casserole is cooked in the oven
48
What are the advantages to stewing?
Tough meats are tenderised
Good flavour
Water soluble vitamins absorbed into the sauce
49
What are the disadvantages to stewing foods?
Takes a long time (2-3 hours) so need to plan ahead
50
What is braising?
Usually in the oven
Vegetables and liquid at the bottom of the cooking pan, meat is on top so is steamed
Needs a good fitting lid
51
What are the advantages to braising?
Tough meats are tenderised
Good flavour
Water soluble vitamins absorbed into the sauce
52
What are the disadvantages to braising?
Take a long time to cook (1-2 hours) so need to plan ahead
53
What is pressure cooking?
Cooked in a sealed pan where the temperature of boiling liquid can be increased to 105-120oC
54
What are the advantages to pressure cooking?
Really quick (3 x quicker than boiling)
Tough meat is made tender
Less fuel used
Water soluble vitamins not lost so easily
55
What are the disadvantages to pressure cooking?
Easy to over cook foods
Food can become soft
Liquids can quickly cook away so the food burns
56
What is steaming?
Cooking in the steam of boiling water
57
What are the advantages to steaming foods?
Water soluble vitamins not lost
Really healthy way of cooking
Food is easy to digest
58
What are the disadvantages to steaming foods?
Can take longer than boiling
Have to remember to fill the steamer up with water
Kitchen can fill with condensation
59
What is blanching?
Food is plunged briefly into boiling water or steamed, removed and then places into chilled water
60
What are the advantages to blanching foods?
Healthy
Keeps green and brightly coloured foods bright
Retains flavour, colour and texture as it stops enzyme action
61
What are the disadvantages to blanching foods?
Vitamins and minerals can be lost
| Not suitable for all foods
62
What is sous vide?
Vacuum packed foods cooked at very precise temperatures
63
What are the advantages to cooking foods sous vide?
Little loss of moisture or weight
Flavour and aroma of foods preserved
Nutrients not lost into cooking water
Consistent results
64
What are the disadvantages to cooking foods sous vide?
Water bath is expensive
| Foods do not brown
65
What are the disadvantages to microwave cooking?
Cold spots can form so foods must be stirred during cooking
Food needs to be left to stand once cooked
Can only use for foods that have a high water content
Foods do not go brown or crispy
Metal containers cannot be used
66
What are the advantages to microwave cooking?
Quick
| Easy
67
What happens to proteins when they are cooked?
They denature (unravel) and coagulate (set)
68
Is the denaturation (unravelling) of proteins reversible?
No
69
Between what temperature do most proteins coagulate?
71-85oC
70
What term describes proteins and carbohydrates cooking and developing a brown colour and charred flavour?
Maillard reaction
71
What does the term plasticity mean in relation to fats?
How fats soften and liquify when heated
72
Can fats evaporate?
No
73
When cooked what does fat add to foods?
Colour and flavour
74
What does the term gelatinisation mean?
When starch granules and liquid are heated the granules soften and swell whilst absorbing liquid this causes the mixture to thicken e.g. roux sauce
75
At what temperature do starches start to gelatinise?
66oC
76
What does the term dextrinisation mean?
When starches and cooked by dry heat and turn brown
77
What does the term caramelisation mean?
When sugar is cooked and turns brown and changes flavour
78
What happens to water in foods during cooking?
Heats up, turns to steam and then evaporates
79
What is the pH value of neutral foods?
pH 7
80
What can acids do during cooking?
```
Soften connective tissue in meat
Give meringues a marshmallowy texture
Set proteins in milk to make cheese
Preserve fruits and vegetables
Denature proteins when used as a marinade
```
81
What can alkalis do during cooking?
Act as a raising agent
| Destroy vitamin C
82
What term describes fruits and vegetables going brown when exposed to oxygen?
Enzymic browning
83
What gives red meat its bright red colour?
Myoglobin
84
What colour do red meats go during storage?
Brown/burgundy
85
What term describes fats that have been exposed to oxygen for too long?
Rancid
86
Why are meats hung after slaughtering but before butchering?
So that enzymes can soften muscle fibres and develop the flavour
87
Give examples of the use of microorganisms in food production
Yeasts in bread making
Lactic acid with milk to make cheese and yoghurt
Probiotics in yoghurt to aid digestion e.g. yakult
Lactic acid used to make salami, pepperoni and chorizo
Sauerkraut is fermeted cabbage
Soy sauce is fermented soya beans
Moulds to make blue cheeses
Mushrooms are edible fungus
88
What are five methods of adding air to foods so it can act as a mechanical raising agent?
```
Sieving
Whisking
Rubbing in
Creaming
Lamination
```
89
How does sieving add air to products?
Traps air as it is sieved and falls
90
What are unleaved products?
Products made without a raising agent
91
How does whisking eggs add air to products?
When eggs are whisked they trap air so create a foam
| They trap air as the proteins unravel and stretch
92
How does creaming products together add air?
As you cream fat and sugar together tiny bubbles of air are trapped. Shown when the mixture becomes pale and fluffy
93
What is lamination in relation to pastry making?
Trapping air between the layers of pastry each time it is rolled and folded
Used in rough puff and flaky pastry
94
How does air act as a raising agent?
When heated it expands so the food swells and rises creating a light and airy texture
95
How does steam act as a raising agent?
During cooking water in mixtures becomes steam and forces its way upwards through the mixture creating hollow, risen foods
96
What gas creates a light, airy texture in cakes?
CO2
| Carbon dioxide
97
Why is bicarbonate of soda used in products with a strong flavour?
Because it can have a strong soapy flavour
98
What is yeast?
Microorganism
99
What two forms can yeast be bought in?
Fresh
| Dried
100
What gas does yeast produce?
CO2
| Carbon dioxide
101
At what temperature does yeast produce gas the quickest?
Generally room temperature
| Specifically 37oC
102
What does yeast feed on?
Natural sugars found in flour
103
What is the name of the process when yeast feeds on naturally occurring sugars?
Fermentation
104
What two proteins form gluten?
Gliadin and glutenin
105
What type of flour contains the most gluten?
Strong flour
106
What is an emulsion?
Mixture of fat and liquid (that normally don't mix)
107
What emulsifier is used in mayonnaise?
Egg
108
What is a foam?
A food that has been aerated
109
What is added to foods to make a foam?
Gas
110
What happens to the proteins in eggs when they are whisked?
Denature
111
Why is flour commonly used in dishes?
Bulk (volume)
| Thickening (gelatinisation)
112
Why is fat commonly used in dishes?
Flavour
Moisture
Colour
Traps air
113
Why are eggs commonly used in dishes?
Colour
Flavour
Set a liquid (coagulation)
Trap ait (aeration)
114
Why is sugar commonly used in dishes?
Flavour
Colour
Texture
115
At what temperature does water boil?
100oC
116
What does the term heat transfer mean?
The way heat moves from one area to another through conduction, convection or radiation
117
What does the term denaturation mean?
Altering a proteins molecular characteristics
118
What is the maillard reaction?
Chemical reaction between protein and starchy carbohydrates that turns foods brown e.g. charred steak
119
What does the term unleavened mean?
Breads and other baked goods made without a raising agent
120
What does the term plasticity mean?
The ability of fat to hold its shape (how soft it is)
