Plant Oils Flashcards
How can vegetable oils be extracted?
- Crushing and pressing the plant material
- Then, removing the water and other impurities
OR:
- By distilling plant material mixed with water
- This produces a mixture of oil and water which can be serparated
What are the uses of vegetable oils?
- Can be eated, provide lots of energy and nutrietns
- Release a lot of energy when burnt in air so can be used as fuels
- Used to make biofuels such as biodiesel
What does polyunsaturated mean?
There are several double bonds in each molecule
What type of molecule are vegetable oils?
Hydrocarbons
Why is food often cooked in vegetable oils?
- Vegetable oils have higher boiling points than water. This means food can be cooked at higher temperatures. This means it can be cooked faster
- Changes the flavour, colour, and texture of foods
- Some of the oil is absorbed so the energy content of the food increases
What is hardening/hydrogenation?
- Unsaturated oils can be reacted with hydrogen so that some/all of the double bonds become single bonds
- Done at 60° using a nickel catalyst
- Called hardening because the hydrogenated oils are solids at room temp.
Why are hydrogentated oils useful?
- They are solids at room temperature
- This means they can be used as spreads
- And to make pastries and cakes that require solid fats
How do oil and water interact?
They do not mix.
Instead, they seperate and form two layers
What happens if we shake, stir, or beat oil and water together?
Tiny droplets form that can be slow to seperate.
This mixture is called an emusion
What are emulsions?
A mixture of liquids that do not dissolve in each other
What are the properties of emulsions?
- Opaque and thicker than the oil and water they are made from
- This improves their texture, appearance, and ability to coat and stick to solids
Give some examples of emulsions
- Milk
- Cream
- Salad dressings
- Mayonnaise
- Ice cream
- Water-based paints
- Many cosmetics
What are emulsifiers?
Substances that help to stop the oil and water seperating into layers.
Most emulsions contain emulsifiers to keep the emulsion stable
How do emulsifiers work?
- Emulsifier molecules have a small hydrophilic part and a long hydrophobic part
- The hydrophilic part or ‘head’ is attracted to water
- The hydrophobic part or ‘tail’ is attracted to oil
- The hydrophobic parts of many emulsifier molecules go into each oil droplet, so the droplets become surrounded by the hydrophilic part
- This keeps the droplets seperate within the water, preventing them from joining together and separating out
What are the advantages of using vegetable oils in foods?
- High in energy
- Contain important nutrients
- Contain unsaturated fats which are believed to be better for your health than saturated fats
