Extracting oils from plants.
Some fruits & seeds contain a lot of oil (eg avocados, olives, peanuts, sesame seeds etc) which can be extracted and used for food/fuel. To extract the oil:
1) The plant material must be crushed.
2) Then, the crushed plant material is pressed between metal plates, which squashes the oil out. (This is the traditional method of producing olive oil.)
3) Oil can be separated from plant material by centrifuge. Or solvents can be used to get oil from the plant material.
4) Distillation refines oil, and removes water, solvents and impurities.
Uses of plant oils.
Vegetable oils are used in food.
-> They provide a lot of energy.
-> They contain essential fatty acids, which the body needs for metabolic processes.
-> There are other nutrients in vegetable oils. E.g. Seed oils contain vitamin E.
Vegetable oils have benefits for cooking.
-> They have higher boiling points than water- they can cook foods at higher temperatures at faster speeds.
-> It gives the food a different flavour- many flavours come from chemicals that 'real soluble in oil, which makes the flavour seem more intense.
-> It increases the energy we get from eating it.
Vegetable oils can be used to produce fuels.
-> Oils such as rapeseed oil & soybean oil can be processed and turned into fuels.
-> Since vegetable oils provide a lot of energy, they're really suitable as fuels.
-> An example of a useful vegetable oil fuel is biodiesel, which has similar properties to ordinary diesel fuel, so you can use it in a Diesel engine.