Food Science Flashcards
Why does food need to be cooked? (5 marks)
- To make it safe
- To improve shelf life
- To develop flavours
- To improve texture
- To give variety
What is convection and how convection is used to cook food? (3 marks)
Transfers of heat through gases or liquids. Boiling foods using water, oven or grill. E.g. cooking sausages
What is radiation and how radiation is used to cook food? (3 marks)
Waves heat energy on an object. toasters, microwaves. E.g. bread into toast
What is conduction and how conduction is used to cook food? (3 marks)
The vibration of food particles. When foods heat up. The heat causes the food molecule to vibrate. It is used to boil food. E.g. boiling chicken
What is the difference between boiling and steaming
Boiling - rough
Steaming - gentle
Boiling - food in the water
Steaming - above the water
Describe blanching
Half cooking the vegetables (boiling) and then immediately freezing them
What types of food can be cooked using poaching?
Peaches, eggs
Describe simmering
To cook liquids using low heat. Sauces, soups, curries
What are the benefits of braising?
To have flavour
Vitamins are absorbed into the water
Stir-frying
A quick method of cooking less oil healthy more vegetables high heat using a wok
Shallow frying vs Deep frying
speed - deep drying is quicker
health - shallow frying is healthier
more oil - deep frying
does the oil cover the food? - Yes for deep fry
Advantages and disadvantages of Baking
Advantages
- Easy to do
- wide variety of food can be cooked
- healthy method of cooking (no oil)
- food will brown and taste nice
Disadvantages
- Long time
- Can become hard and dry if cooked too long
Advantages and disadvantages of grilling
advantages
- Healthy (no oil)
- fast method
- nice taste
- crispy texture
disadvantages
- can easily burn
- hard to see if the food has been cooked on the inside
Advantages and disadvantages of roasting
advantages
- Nice taste
- crispy texture
- tender and moist
Disadvantages
- long time
- unhealthy method - uses fat
Advantages and disadvantages Dry frying
advantages
- no extra fat added
- natural smell
disadvantages
- mainly fatty meats are cooked this way
As many facts about Baking as you can list, including pros and cons
Dry heat is used as a dry method of cooking
Examples - cakes, pies, potatoes
Equipment - electric oven
Advantages
Wide variety of food
Food will look nice - brown outside
Quite healthy - no oil
Disadvantage
Long time
Food can become dry if kept in the oven for too long
As many facts about Grilling as you can list, including pros and cons
Examples - vegetables, chicken, meat, fish, halloumi cheese
Fast way to cook food
Heat will radiate from coal to heat the food
Advantages
Fast
No fat added/ oil in meat will drip off
Smokey - tastes nice
Disadvantages
Food can easily be burn
Harder to evenly cook food throughout
Cross-contamination
As many facts about Roasting as you can list, including pros and cons
Examples - chicken, beef, vegetables
Oven at a high temperature so that foods can brown and be cooked quicker
Fat is added to roasted vegetables and meat to give a nice taste
Advantages
Food will taste nice and will have flavour
Fat from roasted meat can be used to cook potatoes
Disadvantages
Takes a long time
Unhealthy - extra fat
As many facts about Dry-frying as you can list, including pros and cons
Cooking without oil or fat in the pan
Examples are minced meat, bacon, sausages
Medium heat whilst cooking, so food does not burn
Advantages
Seasoning can be added to create a distinct aroma
No added fat - healthier
Disadvantages
Take longer to cook because a lower temperature will be needed at the start
Certain foods
Name three chemical raising agents
Bicarbonate of soda
Baking powder
Self-raising flour
Name a biological raising agent
Yeast
Facts about bicarbonate of soda
Is alkaline and has a soapy taste. Best used to full flavoured foods.
When it is heated, the bicarbonate of soda breaks down to produce CO2 bubbles that expand the mixture to rise
Chocolate cake, gingerbread
Facts about baking powder
A mixture of bicarbonate of soda (alkali) and tartaric acid (acid).
pH is balanced due to neutralisation reaction - no strong taste.
Cakes, biscuits and bread
Facts about self-raising flour
Plain flour and baking powder
Pancakes, Cakes
Facts about yeast
Yeast = Microorganism that releases carbon dioxide.
The dough is mixed and left to ferment in a warm place, causing the dough to rise
Bread
Tell me what you remember on starch gelatinisation?
Gelatinisation- Thickening ( custard, gravy and sauces)
Molecules break allowing water to enter. Once the molecules are absorbed in the water the granules will be in a certain size and softer.
Granules will still need to be mixed in order to make the sauce thicker.
Tell me what you remember on starch dextrinization?
Dry heat is used to cook bread
When the bread is toasted, the starch molecules in the bread begin to break down into dextrins (dextrinization).
Browner colour and crisper texture + different taste
The longer food is cooked, the more starch that is converted into dextrins and the darker and crisper it becomes
Sugar caramelisation
Sugar is heated, it will turn brown and change flavour. (sugar caramelisation)
very sweet taste
Smoother
Becomes solid and hard
I.e. apple pie, creme brulee
Onions have natural sugars which will cause caramelisation when cooked.
Name three ways a protein can be denatured?
Changes in temperature
Physical agitation (beating, whisking)
Acids (lemon juice)
Tell me what you know about coagulation?
Coagulation = Joining together
The coagulation will change the appearance and texture of food.
Still some water between the protein molecules
I.e. eggs will start off a see-through colour but will become a white liquid when cooking
Overcooked = less water between molecules.
How are foams like chocolate mousse and whipped cream made?
Physical agitation (beating, whisking)
Eggs whites being whisked - egg whites
To make a foamy texture, the gas will become trapped inside of the liquid
This will cause the proteins to stretch as the proteins will be denatured.
Once physical agitation has finished, the proteins will be coagulated (joined together) making a foamy texture.
Tell me what you know about gluten?
Gluten is a protein that is found in wheat flours
Water mixed with flour to make a dough (bread, pasta, cake)
Molecules of gluten in the dough can stretch and bend - making the dough stronger, longer, stretchier
Change in temperature will force gluten to coagulate.
Food will be cooked. If overcooked the food will be dry.
Short strands of gluten are essential when making shortcrust pastry.
Name the process that stops gluten from forming long strands. (1 mark)
Shortening
Explain how rubbing fat into flour creates these short strands of gluten (2 marks)
Rubbing fat into flour makes the flour waterproof (1 mark) stops gluten from being able to be stretched (1 mark)
When making a cake using the creaming method, fat and sugar are beaten together.
Why are fat and sugar beaten together in this method? (1 mark)
To trap air into the mixture (aerate)
Different fats have different ranges of plasticity
What is meant by the plasticity of fats? (1 mark)
The ability to spread and stretch
Explain why margarine has more plasticity than lard? (2 marks)
Because margarine is made out of triglycerides (1 mark)
it will be soft and will melt at a lower temperature than lard.
Hollandaise sauce is an example of an emulsion sauce. It is made from butter, egg yolk, lemon juice and water.
What is the role of egg yolk in hollandaise sauce? (3 marks)
Egg yolk contains lecithin (1 mark) which mixes with the butter and water which allows the two to join (1 mark) and keeps the two together (1 mark)
Give an example of an emulsifier?
lecithin
