Plant Oils Flashcards
What does vegetable oil provide?
Lots of energy and important nutrients
What are vegetable oils also used as?
Biofuels such as biodiesel
What do vegetable oil molecules have?
Hydrocarbon chains
If there are several double bonds in each molecule what are the bonds called?
Polysaturated
What are carbon-carbon double bonds called?
Unsaturated
What do unsaturated oils react with and what colour does it turn?
Bromine water which goes from orange to colourless if it is unsaturated
What are the boiling points of vegetable oils?
Higher bp than water so food is cooked at higher temperatures in oil so it cooks faster
What does vegetable oil change about your food?
Flavour and texture
Does vegetable oil increase the energy content of your food?
Yes as the food absorbs the food increases
What happens when unsaturated oils react with hydrogen?
The double bonds become single, this is called hydrogenation
Give some details about the hydrogenation reaction
Done at about 60 degrees and uses a nickel catalyst
What do hydrogenated oils have?
Higher melting points as they are more saturated
What is hydrogenation also known as?
Hardening as they are solids at room temperature
Does oil dissolve in water?
No but they can be used to make emulsions
What’s an emulsion?
A mixture of liquids that do not dissolve each other
What happens if you shake oil and water?
Tiny droplets form that can be slow to separate
How do emulsions of oil and water compare to oil and water?
They are opaque and thicker. This improves texture, appearance and their ability to coat and stick to solids
Examples of emulsions
Milk
Ice cream
Salad dressing
Mayo
How can you recognise an emulsion?
Opaque and coats solids
What are emulsifiers
Substances that help stop the oil and water from separating into layers
How do emulsifiers work?
They have a hydrophilic head which is attracted to water and hydrophilic tail which is attracted to oil. The hydrophobic parts go into each oil droplet and so the droplets became surrounded by the hydrophilic parts. This keeps the droplets apart in the water, preventing them from joining together and separating out
Why can you not see through an emulsion?
The liquids re,aim as tiny droplets and do not dissolve but in abolition Ruth’s substances dissolve which means they mix completely and the solution is clear
Are unsaturated or saturated fats better for you?
Unsaturated
What do saturated fats have links to?
Heart disease
What is good about emulsions but also bad?
They make foods smoother and creamier but are High in fats so you are tempted to eat more
How can vegetable oil be extracted from seeds, nuts and fruits?
Pressing or distillation followed by removing water and other impurities
