Section C: Cooking and food preparation
Studied by 0 people
Learn
Practice Test
Spaced Repetition
Match
FlashcardsWhy do we cook food?
To destroy harmful bacteria - this includes yeasts, moulds and bacteria
Make food less bulky - volume of food is reduced and foods become more palatable
To destroy natural poisons in food
To have hot food in cold weather - in cold weather we need hot food to provide a ‘feel-good’ factor and to maintain our body temperature
What are the 3 basic methods of heat transference?
Conduction, convection and radiation
1/93
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
|---|
No study sessions yet.
94 Terms
Why do we cook food?
To destroy harmful bacteria - this includes yeasts, moulds and bacteria
Make food less bulky - volume of food is reduced and foods become more palatable
To destroy natural poisons in food
To have hot food in cold weather - in cold weather we need hot food to provide a ‘feel-good’ factor and to maintain our body temperature
What are the 3 basic methods of heat transference?
Conduction, convection and radiation
How is heat transferred in conduction and give examples
Heat is transferred by the contact with heat
Poaching, roasting and simmering
How is heat transferred in convection and give examples
Heat moves through the convection currents. The hot air rises and cool air falls
Baking, boiling and blanching
How is heat transferred in radiation and give examples
Direct rays pass from the heat source to the food
Barbecuing, chargrilling and grilling
How are carbohydrates affected by cooking processes?
Fibre is softened, particularly when cooked by moist methods of cooking
Starch may be reduced when food is cooked in water because the starch dissolves into the liquid
How is fat affected by cooking processes?
The fat content of some foods may be reduced, e.g. by grilling
Cooking food in fat will increase the fat content
How is B1 vitamin affected by cooking processes?
Soluble in water
Easily destroyed by water
How is B2 vitamin affected by cooking processes?
Soluble in water
Destroyed by heat if heated in the presence of an alkali, e.g. bicarbonate of soda
How is B3 vitamin affected by cooking processes?
Soluble in water
More resistant to heat than any of the other B vitamin group
How is B9 vitamin affected by cooking processes?
Folate is less sensitive to heat than other B vitamins
It is destroyed if food is reheated or kept warm for a long time
How is B12 vitamins affected by cooking processes?
Soluble in water
How is vitamin C affected by cooking processes?
Destroyed by moist and dry heat
Dissolves in water
How do cooking methods improve the sensory properties of food?
The flavour and texture of food is often developed by the method of cooking chosen
What is gelatinisation?
When flour is mixed with a liquid and heated
The starch grains cannot dissolve in the liquid
As the liquid is heated, at 60C the starch grains swell
As more heat is applied, at 80C the starch grains break open, causing the mixture to thicken
What is dextrinisation?
When dry heat is applied to flour products, the crust goes brown
The starch in the flour is changed into dextrin
What other starch sources thicken mixtures?
Root vegetables and tapioca
What happens when moist heat is applied on sugars?
The sugar melts and becomes syrup
At 154C the sugar starts to change colour - this is known as caramelisation
How does sugar change the appereance of food?
Sugar which has been browned under a hot grill to create the hard caramel on top of a creme brûlée
Sugar which has changed to syrup and been caramelised in a crème caramel
What happens when dry heat is applied on sugars?
Sugars will also caramelise when dry heat is applied to them
When sugars are mixed with other products, such as eggs and flour in baked products, browning occurs - this is called a Maillard reaction
What is aerating?
When sugar is beaten with a fat or with egg, air is added to the mixture
This helps to make cakes rise and gives them a light texture
What is preserving?
In jams and chutneys, the concentration of sugar is high and this prevents the growth of micro-organisms.
Why are some products designed to have a lower melting point?
This gives consumers a quality in a product that they want, e.g. in a spread that can spread straight from the fridge
What is shortening, why and how does this happen?
When fat is used in rubbbed-in mixtures, the product will have a short, crumbly texture
Fat coats the grains of flour and gives a waterproof coating
What is aeration, why and how does this happen?
Th process of trapping air in a mixture to cause it to rise
When a fat and sugar are creamed together, air is trapped
When the product is heated the air expands, helping the mixture to rise
What is plasticity, why and how does this happen?
The ability of a solid fat to soften over a range of temperatures
What is emulsification, how and why does this happen?
The process of using an emulsifier to prevent a mixture of oil and liquid from separating
Egg yolk contains lecithin, and is used in some salad dressings, as well as in mayonnaise to hold the oil and liquid together and prevent them from separating
What does butter do to a product?
Fats can add moisture to a product, which helps to extend the product’s shelf life
What is coagulation?
When moist or dry heat is applied to protein foods
If proteins are overheated they become tough and difficult to digest
What happens to meat when it is heated?
Muscle fibres coagulate between 40C and 60C
After 60C, the fibres in the meat shrink and the juice is squeezed out
What happens to meat when it is heated?
The muscles in the fish shrink as they are very short and there is only a small amount of connective tissue
If it is cooked for too long the fibres will become tough
What happens to eggs when it is heated?
Egg white begins to coagulate at 60C
Egg white changes from a opaque to a whiter colour
Egg yolk begins to coagulate at 70C
What is syneresis?
If eggs are heated too quickly the liquid from the egg separates out and the protein becomes tough
What happens to milk when it is heated
A skin forms on top - this is the protein coagulating
What happens to cheese when it is heated?
The protein coagulates
What is foam formation?
A foam is produced when eggs are whisked
When eggs are whisked, they produce a mixture of gas (air) and liquid (egg white)
Aeration in eggs
When egg whites are whisked, the protein (albumin), is stretched and traps air, e.g. when eggs are whisked when making meringues
What is the names of protein food in wheat which form gluten?
Gliadin and glutenin
What is acid denature?
Acids are used to change the shape and structure of protein foods, e.g. to tenderize meat or provide a soft texture
This causes long chains of amino acids to fold
What is oxidisation?
A chemical reaction when fruit or vegetables are exposed to oxygen
Why are raising agents added to mixtures?
To give lightness to the mixture
How can air be added to a mixture?
Sieving flour, rubbing fat into flour and whisking
What are the five senses?
Sight, sound, smell, taste and touch
Why is sight important?
The appereance of food can make it look more or less appetizing
Colour, size, decoration will affect how you feel about the product
Why is smell important?
You can detect the volatile aromas released from foods
The aroma stimulates the digestive juices and makes the food seem more appetizing
What are the five taste buds?
Bitter, sweet, sour, salty and umami - savoury taste
Why is taste important?
Flavour develops when the food is combined through chewing and mixing with saliva
Why is touch important?
The surface of the tongue is sensitive to different sensations
As we bite and chew food we can feel how hard or soft it is through our teeth and jaw. These qualities are known as ‘mouth feel’
How do you set up a testing panel?
Set up a quiet area where people will not be disturbed
Give the testers a drink of lemon-flavored water to clear the palate
Use small quantities of food on plain, identically-sized plates
Serve food at the correct temperatures
Use codes for the products, not the name of the product
What is a ratings test?
Testers give their opinion of one or more samples of food, from ‘extreme like’ to ‘extreme dislike’
They do not give information about specific elements of a food product
What is comparison testing?
These tests are used to see whether people can tell the difference between samples, for example when an ingredient or quantity of ingredient is changed
What is an example of comparison testing?
The triangle test
Three samples are given to the tester. Two samples are the same and the tester is asked to identify the ‘odd one out’
What is a ranking test?
The ranking test is used to sort a variety of foods into order
The tester has to rank the samples in order of either a specific attribute, for example, sweetness or a preference on a hedonic scale
What is a profiling test?
The profiling test can be used to find out what people particulary like or dislike about a food product
The product can then be adapted according to the different areas identified for improvement
What is a star profile used for?
This type of analysis asks testers to describe the appearance, taste and texture of a food product on a star chart
When the food is tasted, the taster assess the identified areas and marks the star diagram as required
The marks on each point are joined together to identify them clearly
The results from a profiling chart can be plotted onto a star profile
What are the conditional needed for bacterial growth?
Warmth, moisture, food and oxygen
How does bacteria grow?
Reproduce by dividing in two and in two - binary fission
Grow rapidly in neutral pH conditions
Most active in the temperature range of 5-65C - the danger zone
Can grow aerobically and anerobically
How temperature affect bacteria growth?
They become dormant below 0C
Most bacteria cant survive above 70C
They are able to form spores that are dormant, they will germinate when the right conditions are provided
What are moulds?
Visible to the eye
Reproducing by producing spores which travel in air and settle, germinate and multiply into new growths
They are only harmful when they produce mycotoxins, which are poisonous substances
What conditions are needed for the growth of mould?
They grow quickly in moist conditions, 20-30C
They grow slowly in dry, cold conditions
What is yeast?
Yeasts are responsible of food spoilage in high-sugar foods such as fruit, jam and fruit yoghurts
What are the conditions needed for growth of yeast?
Active in warm, moist conditions with food for growth and reproduction
Does not need oxygen to grow (anaerobic)
What are the signs of food spoilage?
Fresh foods cannot stored for very long before changes occur which affect the texture, flavour or colour of the food
Some changes are noticeable, e.g. a banana going black or mould on bread
What do enzymes do?
Enzymes speed up ripening and natural decay
They’re food in all foods
They are proteins that speed up the rate of reaction
What are the helpful properties of bacteria?
Some bacteria are used in food manufacture, e.g. making cheese and yoghurt
Probiotic foods contain large numbers of naturally-occurring live bacteria
These bacteria are known ‘good’ or ‘friendly’ bacteria
They help to maintain a healthy digestive system and strengthen the immune system
What are the helpful properties of mould?
Some moulds are used in food products, e.g. blue—veined cheeses
What is the important of the product name on food labels?
Informs the consumer what the product is
Pictures used must not be misleading
If a food has been processed then it must be included in the name of the product, e.g. smoked salmon
What is the importance of storage conditions on food labels?
Informs the consumer how to store the product to prevent food spoilage
What is the importance of date marking on food labels?
Use by date for high-risk foods, e.g. raw and cooked meat and chilled foods
Best before data for low-risk foods, e.g. biscuits, crisps and UHT milk
What is the importance of manufacturer’s name and address on the food label
Product can be returned if faulty, or a complaint can be made in writing
Examples of allergies on food labels
Milk, eggs and peanuts
What is the importance of genetically modified ingredients on food labels?
Products and ingredients from genetically modified sources must be labeled
Foods such as milk, where the cows have been fed on genetically modified food, do not need to be labelled
What visual checks do you do when buying food?
It looks fresh, it is within date and the packaging is not damaged
What should you ensure when buying food from a reputable supplier?
The shop is clean
The food is stored in the correct conditions
What temp should your refrigerator be and why is it used?
A domestic refrigerator should be between 0C and 5C
Growth of bacteria are slowed down in a refrigerator
How do you sensibly use your refrigerator?
Avoid opening the door
Do not put hot food in a refrigerator
Cover food
Keep raw and high-risk foods away from other foods
Store high-risk foods on the bottom shelf of the refrigerator
What temp should your freezer be and why is it used?
A domestic freezer should be kept at -18C
Most bacteria are dormant at this temperature, as water is not available for micro-organisms to grow
What is thawing?
When food is changed from its frozen state to unfrozen state
You should never refreeze food after it has thawed
What does thawing do?
When food is thawed, the structure may be damaged and so there may be loss of colour, flavour, texture and nutritional value
Why do some foods not freeze well?
Foods that contain a large proportion of water and have a delicate cell structure
Ice crystals damage the cell structure, causing the food to collapse
What is freezing vegetables like?
Most vegetables, with the exception of salad vegetables, freeze well
Blanch vegetables before freezing to half enzyme activity
What is freezing fruit like?
Many fruits will freeze successfully
Those with a high water content will not freeze successfully e.g. strawberries
What is a freezer burn?
Greyish-white marks appear on the food when it has been packaged badly
The food dehydrates and, although safe to eat, will change colour, texture and flavour
What are the rules for food hygiene?
Wash hands thoroughly before handling food and between handling different types of food
Keep raw and cooked foods separate and use different equipment to prepare them
Wear clean protective clothing, cover cuts and never cough or sneeze over food
Keep all working surfaces and utensils clean. Clean surfaces and equipment between tasks
Cover and cool all cooked food rapidly and refrigerate as quickly
Keep pets away from preparation areas
Keeps bins covered and empty and wash and disinfect them regularly
What does cross-contamination do?
Lead to food poisoning
How do you prevent cross-contamination?
Avoid raw and cooked foods touching each other
Avoid blood and juices from raw foods to dripping onto cooked foods, this is called direct contamination
Avoid poor food handling - when bacteria is transferred during handling or preparation, this is called indirect contamination
What is food poisoning, who is more prone to it and symptoms of it?
The bacteria that cause food poisoning are called pathogenic bacteria
Pregnant women, young children and elderly are most susceptible to food poisoning
Why does food-poisoning occur?
High-risk foods stored at room temperature
Undercooking high-risk foods
Not reheating foods to the correct temperature or for long enough
Name 2 bacterias that cause food poisoning and it’s possible sources
Salmonella - poultry, eggs and meat
E.coli - cattle, raw meat and raw milk
Give 3 examples of high-risk foods
Raw fish, meat and poultry
Dairy products
Shellfish and seafood
Give 2 examples of low-risk foods
High acid content foods, e.g. pickles and chutney
High sugar content foods, e.g. jams
What is the critical temperature during cooking?
The temperature should reach 70C for two minutes through the thickets part of the food
What is the critical temperature for reheated food
Should be at least 75C
What is the critical temperature for keeping food hot?
It must be at or above 63C