Topic 2 Flashcards
What happens at the first stage of making yoghurt?
The milk is homogenised then pasteurised at 85-95°c to destroy micro-organisms
What are the 4 different types of raising agents?
Chemical, mechanical, physical, biological
Examples of a chemical raising agent
Cream of tartar
Bicarbonate of soda
Baking powder
Examples of mechanical raising agents
Beating
Folding
Creaming
Whisking
Examples of physical raising agents
Moisture(steam)
Examples of biological raising agents
Yeast
What 2 raising agents make baking powder?
Cream of tartar + bicarbonate of soda
Protein definition
Long chain of amino acids
How many amino acids are there?
21
How many essential amino acids do adults need?
8
How many essential amino acids do children need?
10
What does HBV stand for and mean?
High biological value-contains all the essential amino acids
What does LBV stand for and mean?
Low biological value-doesn’t contain all the essential amino acids
Examples of HBV foods
Fish Milk Meat Soya beans Cheese Quinoa
Examples of LBV foods
Sunflower seeds Bulgur wheat Bread Brazil nuts Lentils Beans
3 functions of proteins
Energy
Growth
Repair
Describe what can happen if you are deficient in protein?
Fatigue, weakness, stop growing, lose hair, more likely to get an infection/other illnesses (kwashiorkor)
Describe what can happen if you have excess protein
Too much nitrogen, which is in protein can affect the liver and kidneys, which can lead to liver and kidney damage or failure
Non-pathogenic definition
Micro-organism not harmful to humans and doesn’t cause food poisoning
Homogenised definition
Forcing milk through a fine sieve to break up the fat into tiny droplets
Pasteurised definition
Heating to 72°c for 15 seconds
Blue cheese making differences to normal cheese
- They poked holes in the cheese so that air can get inside and created mould in the cheese
- They added blue mould to make the cheese
- The didn’t press the cheese, they let the whey drain naturally using gravity
- They didn’t add the rennet at the start
- Curds are taken out of the moulds and allowed to continue to drain during the ripening process
What are micro-organisms and where are they found?
They are tiny forms of life and include; bacteria, moulds, yeasts
They are found in many places- water, soil, air, dust, people, animals, sewage, food, etc.
What are the 5 conditions micro-organisms need to multiply?
- the right temp
- moisture
- food
- time
- the right pH
What are enzymes?
They are natural substances (most are proteins) found in food and all living things. They are called biological catalysts.
What do enzymes do?
Enzymes cause fruits and vegetables to riled, change colour, texture, flavour e.g bananas, eventually breaking down the cells and tissues in them. They also cause tissues of meat and fish to break down once an animal has been killed.
How can we control the action of enzymes?
Enzymes are proteins, so their cation can be controlled by causing them to denature - using heat or adding an acid
What causes enzymic browning?
When enzymes in the cytoplasm and oxygen from the air mix with substances in the vacuole, this causes oxidation, which causes enzymic browning
What are the 2 functions of carbohydrates?
Giving the body energy (main source of our diet)
To help the body get rid of waste products
What are the 2 main sources of carbohydrates?
Sugars (sweet) Complex carbohydrates(not sweet)
What are the 3 monosaccharides?
Glucose
Fructose
Galactose
What are the 3 disaccharides?
Lactose
Maltose
Sucrose
What are the 2 types of fibre?
Soluble
Insoluble
What does soluble fibre do?
Absorbs water, increases bulk, faeces soft and bulky, easy to pass through digestive system- such as whole meal flour, cereals, pasta
What does insoluble fibre do?
Slows down digestion and absorption of carbohydrates- thus helps to control bloody sugar and stops us feeling hungry
What are the 2 starch thickening molecules?
Amylose and amylopectin
What does denaturing mean?
When the chemical bonds that hold the protein molecule bond together break, which makes the protein molecule bundle unfold and change shape
What are the 5 main ways denaturation can be caused by?
Heat Acids Air bubbles Mechanical agitation Salt
What is coagulation?
Denatured protein molecules are larger and take up more space than they used to, because of this, they knock into other denatured protein molecules and start to join together in large groups
What is syneresis?
I’d a good containing protein is over cooked, the coagulated molecules tighten up and squeeze out the water they were holding, this is why overcooked meat or fish is dry and chewy
How do moulds multiply?
Moulds multiply by sending tiny airborn spores that land on food and germinate
What does a fruiting body mean?
Mould on surface
Fridge temp
0°c-5°c
Freezer temp
-18°c
What happens at 60°c of gelatinisation?
The starch molecules start to expand when heated
What happens at 80°c in gelatinisation?
The molecules burst and release starch molecules
What happens at 100°c in gelatinisation?
The mixture has completely thickened into a sauce
What are starch molecules made of ?
1000s of glucose molecules joined together
What happens at the cool down stage of gelatinisation?
A the cooked sauce cools, the starch molecules start to form longer chains and the water molecules stay trapped which forms a solid gel
What does amylose do in gelatinisation?
It makes the sauce cloudy and opaque
What does amylopectin do in gelatinisation?
Makes the sauce translucent
What temp does caramelisation happen?
160/170°c
Why does sugar go black when making a caramel?
Because only carbon is left and the hydrogen and oxygen evaporate
What is shortening?
When the fat coats the flour particles and prevents them from absorbing water. Which reduces the formation of gluten development which causes the dough to be elastic
What is plasticity?
Plasticity means it’s ability to be shaped and spread with light pressure, the more plasticity, the more spreadable and soft something is
What is emulsification?
When an emulsifier is added to a mixture to stop the mixture separating out again
Example of an emulsifier
Lecithin which is found in egg yolk
What is aeration?
When a fat is able to trap air bubbles when they are beaten or creamed with something
What is foam formation?
When an egg is whisked a foam is produced by trapping millions of tiny air bubbles in a liquid Whisking water and air produces hundreds of bubbles but they soon ‘pop’, leaving only water and air again. Eventually the protein coating of the air pockets link together, making a foam.
What is the difference between LBV and HBV foods?
If a food is missing one or more of the amino acids, it has a LBV, if a food/ meal has all the essential amino acids, it is a HBV food
Example of high risk foods?
raw and cooked meat, including poultry such as chicken and turkey, and foods containing these, such as casseroles, curries and lasagne.
dairy products, such as custard and dairy-based desserts like custard tarts and cheesecake.
eggs and egg products, such as quiche.
smallgoods such as hams and salamis.
What is the Danger zone that bacteria thrive in?
5°c - 60°c
Why are high risk foods high risk?
High risk foods share a tendency to spoil as a result of unsuitable storage conditions or improper cooking methods.
What do microorganisms do?
Microorganisms (bacteria) are used to make a wide range of food products. Bacteria are used to make cheese, yoghurt and bread.
What is the most important bacteria in food manufacturing?
Lactobacillus species
What are the 3 main functions of protein?
- to make the body grow
- to repair the body
- to give the body energy
What is gluten formation
Wheat and other related grains (including barley, and rye) contain a mixture of two proteins glutenin and gliadin. When flour made from grinding these grains is mixed with water the two proteins combine and form gluten. Without water, gluten is not formed. The more the dough is kneaded, the more gluten is developed.
What is dextrinisation?
When dry heat turns a starch brown e.g. toast
What is caramelisation?
The colour of sugar changes from white to brown when heated e.g making a caramel
