C1.6 Plant Oils Flashcards
What’s oil used for?
Cooking
Cars
Cosmetics like soap and perfume
Biodiesel
What’s pressing?
Fruits, seeds or nuts are crushed and pressed to extract the oil and then you remove the impurities
Eg. Sunflower and olive oil
What’s distillation?
Plant seeds are crushed and it is mixed with water. Oil is placed in distillation flask and oil mixture is heated. The steam goes through the plant and the oil evaporates. Oil (and water) is collected by condensing it eg. lavender oil. Oil floats to the top - impurities are removed.
Are saturated or unsaturated things more healthy?
Unsaturated are healthier
Have less energy
Butters and oils, which ones are saturated and unsaturated?
Hard oils like butter and lard are saturated
Oils like vegetable oil are unsaturated
What are properties of vegetable oils?
High boiling points
Quite viscous
Contains lots of stored ‘chemical energy’
What are uses of vegetable oils?
Food ingredients
Fuel like biodiesel
Emulsifiers
What are the two ways of extracting oil?
Pressing
Distillation
What are the advantages of cooking with vegetable oil?
High boiling point Cook at higher temperatures than by boiling Cook faster Different flavours Food has higher energy storage
What are the similarities and differences between fats and oils?
Both lipids
Fats are solids are room temp but oils are liquids
Fats are more saturated
Fats are generally an animal product where as oils are often a plant derived product
What’s hydrogenation?
When you take unsaturated oils an turn them into saturated oils. This is done by adding hydrogen to the unsaturated oil. The temperature is 60 degrees c and in presence of a nickel catalyst.
What’s the process of turning unsaturated oils into saturated fats?
Hydrogenation
What are immiscible liquids?
They don’t mix together
Eg. Oil and water
What are emulsions?
Substances that mix together in the presence of an emulsifier.
Eg. Paint and mayonnaise
What’s an emulsifier?
Mixes together two immiscible substances. The substance made is an emulsion.
What are the features of an emulsifier to bond oil and water?
They have a hydrophilic head which is attracted to water and a hydrophobic tail which is attracted to oil.
The tails dissolve in oil making tiny droplets. The surface of each oil droplet is charged by the heads sticking out into the water. As like charges repel, the oil droplets repel each other and this keeps them spread throughout the water, stopping the oil and water separating.
Give some examples of emulsions.
Mayonnaise
Butter
Milk
Paint
Why are emulsions useful?
Have different textures, tastes and coating properties
What are additives?
They’re in processed foods to improve appearance, taste and shelf-life. And also stops ingredients separating- emulsifiers
Food additives can be….
Emulsifiers
Flavour enhancers
Antioxidants
Food colours
What are antioxidants?
An additive that improves shelf life because they stop reactions with oxygen.
What are E numbers?
Represent additives
How are unsaturated fats in vegetable oils good for you?
Include vitamin E so clear arteries and reduce heart disease and have lower cholesterol
But they cause obesity
