Define 'plant oil'
Oil extracted from a plant
Some fruits and seeds contain a lot of ____
Some fruits and seeds contain a lot of oil
Give 2 examples of fruits that contain a lot of oil
Give 2 examples of seeds that contain a lot of oil
What two things can plant oils be used for
What are the 2 steps to getting the oil out of the plant material (but not seperating)
1. Crushing the plant material
2. Press the crushed plant material between two metal plates and squash the oil out
Name the 2 ways oil can be separated from the crushed plant material
1. By using a centrifuge
2. By using solvents
What is teh next step after separating oil from crushed plant material, and what does it do?
Refines oil, and removes:
Name 3 advantages of using vegetable oil in food
1. Provide a lot of energy as have a high energy content
2. Other nutrients in vegetable oils
3. Contain fatty acids; needed for many metabolic processes
What kind of nutrient do seed oils contain?
Name 3 benefits of using vegetable oils in cooking
1. Higher boiling points than water - can cook food at higher temp.s and faster* speeds
2. Gives food a different flavour
3. Using oil to cook food increases the energy we get from eating it
(on exam you have to put cooks faster as result of higher boilng point than water to get the mark)
Why do oils give foods a different flavour?
1. Oil gives its own flavour
2. Many flavours come from chemicals that are soluble in oil - the oil 'carries' the flavour, making it more intense
Name 2 types of oil that can be processed and turned into fuels
What makes vegetable oils so suitable for use as fuels?
They contain a lot of energy
Name a particularly useful type of fuel made from vegetable oil
What makes biodiesel such a useful fuel?
It has similar properties to ordinary diesel - burns in the same way, so can use it to fuel a diesel engine (no modifications necessary)
Why do we need to hydrogenate oils to use them as spreads?
They are usually liquids at room temperature
Unsaturated oils contain which kind of carbon bond?
Double bonds between some of the carbon atoms in their carbon chains
What do oils and fats contain?
Long-chain molecules with lots of carbon atoms
Oils and fats are either ____ or ____
Oils and fats are either saturated or unsaturated
What will unsaturated oil do to bromine water, and why?
Decolourise it from orange to colourless, because the bromine opens up the double bond and joins on
How many carbon double bonds do monounsaturated fats contain?
Somewhere in their carbon chains
How many carbon double bonds do polyunsaturated fats contain?
More than one
In their carbon chains
What state are unsaturated vegetable fats at room temperature?
How do you harden/ hydrogenate unsaturated vegetable oils?
By reacting them with hydrogen in the presence of a nickle catalyst at a temp of 60oC
What happens during hydrogenation?
The hydrogen reacts with the double-bonded carbons and opens out the double bonds
Hydrogenated oils have ____ ____ ____ than unsaturated oils, making them ____ ____ at room temperature.
Hydrogenated oils have higher melting points than unsaturated oils, making them more solid at room temperature
How does being more solid at room temperature make hydrogenated oils more useful than unsaturated ones with baking?
Hydrogenated oils are useful as spreads for baking cakes and pastries
Margarine is usually made from ____ hydrogenated vegetable oil.
Margarine is usually made from partially hydrogenated vegetable oil.
Turning all the double bonds to single bonds would make maragarine too hard and difficult to spread. Hydrogenating most of them gives margarine a nice, buttery, spreadable consistency.
In what kind of food are partially hydrogenated vegetable oils usually used in instead of butter?
For what 2 reasons are partially hydrogenated vegetable oils used in processed foods instead of butter?
1. They are cheaper - makes biscuits cheaper
2. They keep longer - gives them a longer shelf life
Name a disadvantage of eating partially hydrogenateed vegetable oils
They contain a lot of 'trans fats'
Evidence to suggest that trans fats are very bad for you
Vegetable oils tend to be ____, while animal fats tend to be ____
Vegetable oils tend to be unsaturated, while animal fats tend to be saturated
Why are saturated fats generally less healthy than unsaturated fats?
Saturated fats increase the amount of cholesterol in the blood, which can block up the arteries and increase the risk of heart disease
Name an advantage of natural unsaturated fats such as olive oil and sunflower oil
They reduce the amount of blood cholesterol
Explain why partially hydrogenated vegetable oils are worse for you than the natural ones
Partially hydrogenated vegetable oils contain trans fats which increase the amount of cholesterol in the blood, increasing the risk of heart disease
Name a disadvantage to cooking food in any sort of vegetable oil
It makes the food more fattening