C1 - Plant Oils Flashcards
Describe the process of obtaining plant oil
The plant is crushed and then pressed by 2 metal plates to squash the oil out
The oil is then separated from the plant material with a centrifuge or solvents are used to get the oil out
Distillation refines oil and removes water, solvents and impurities
What are the 3 reasons that vegetable oils are used in food?
Provide a lot of energy
Variety of good nutrients
Essential fatty acids which the body needs for many metabolic processes
What are the 3 benefits of using vegetable oil in cooking?
Higher boiling points than water so food can be cooked at higher temperatures
Provides different flavour and brings out the flavour in the food it is cooked with
Increases the energy we get from eating the food
What is the other use of vegetable oils and why are they used for this purpose?
Processed into fuels because they provide a lot of energy
What is the most common example of a vegetable oil fuel?
Biodiesel
How can you work out if an oil is saturated or not?
If it is added to bromine water and the bromine water turns from orange to colourless, it is unsaturated
What is the difference between a monounsaturated fat and a polyunsaturated fat?
Monosaturates have one double bond where polyunsaturates have multiple
How do we stop unsaturated vegetable oils from being liquids at room temperature?
They are hydrogenated
Describe the process of hydrogenation
Unsaturated vegetable oils react with hydrogen in the presence of a nickel catalyst at 60 degrees
The hydrogen has opened up the double bonds
What are the properties of a hydrogenated oil?
Higher melting points meaning they are more solid at room temperature making them useful for spreads
What is interesting about the way margarine is hydrogenated and why is this done?
It is only partially hydrogenated so that it is soft enough to spread easily like butter
Give one advantage and one disadvantage of hydrogenated vegetable oils
They are much cheaper and they keep longer than butter
Partially hydrogenating vegetable oils means you end up with trans fats which increase cholesterol in the bloof
Are vegetable oils and animal fats usually saturated or unsaturated?
Vegetable oils are usually unsaturated and animal fats are usually saturated
What is the problem with saturated fats?
They can increase cholesterol in the blood and increase the risk of heart disease
What is the problem with cooking in oil or fats generally?
Makes the food more fattening
