1. C1b Oils, Earth and Atmosphere
Oils from Plants

2. Solar powered Plants use energy from the sun: energy from sun
6CO2 + 6H C6H O2
Plants turn glucose into other chemicals
Can be useful to us

3. Vegetable oils Rapeseed – vegetable oil
Collect seeds after plant has flowered
Crushed, pressed to extract oil
Impurities removed
Important food stuff
Extraction using steam
Lavender oil - distillation
Plants boiled in water
Steam contains oil
Collected, water and impurities removed

4. Oils as foods Contain loads of energy Hydrocarbon molecules
May be saturated or unsaturated
Tested with bromine water
Food/oil
Energy in 100g (Kj)
Vegetable oil
3900
Sugar
1700
Animal protein (meat)
110

5. Cooking with veg oils: Boiling point
Temperature depends on forces between molecules
Bigger force = higher boiling temperature
Molecules in veg. oils are much larger than water molecules
Bigger forces
Higher boiling point
Higher temperatures = different reactions
Food cooks differently

6. Soak it up Why can too much fried food be bad for you?
Food absorbs some of the oil it’s cooked in
Veg oils very high in energy
Increases the energy content of the food
Needs to be used

7. Hydrogenated oils Unsaturated oils are liquid at RToC
Double bond stops molecules fitting together well
Reduces the forces between molecules
Boiling point can be increased
Adding hydrogen, replacing double bonds
Molecules fit together better
Increased forces = higher boiling point

8. Hydrogenated oils Higher melting point – solid at RToC
“Hardening” of vegetable oils
Hydrogenated oils
Can be used to make spreads, margarine etc.

9. Smooth operator Texture of food is very important
Ice cream, mayonnaise etc.
Mixture of oil and water – don’t mix!
Can be persuaded
Very small droplets of oil
Spread throughout water
Emulsion
Milk is an everyday example

10. Emulsifiers Encourages oil and water to stay mixed
Egg yolk in mayonnaise
Gives a thick texture

11. Emulsion paint Emulsion paint is NOT an emulsion!
It is a powder suspended in a liquid
Colloid

12. Preservation Need to make food last longer – preserve it
Salt (remove water)
Vinegar (pickling)
Alcohol (kill microbes)
Knowledge of chemistry
Also use chemistry to improve flavours or appearance

13. Food additives Substance added to a food Approved for use in Europe
Given an ‘E’ number
Identify them rather than name them
Eg.E102 is tartrazine (yellow colouring)
E220 is sulphur dioxide (preservative)
Six types of additive

14. Food additives E number Additive What it does Example E1xx Colours
Improve the appearance of food. Can be natural, brownings or additives
E150 – caramel colour
E2xx
Preservatives
Helps food last longer = less wastage
E211 – sodium benzoate
E3xx
antioxidants
Help stop food reacting with oxygen
E300 – vitamin C
E4xx
Emulsifiers, stabilisers and thickeners
Help improve the texture of food
E440 – pectin
E5xx
Acidity regulator
Helps control pH and taste
E501 – potassium carbonate
E6xx
Flavourings
Blends flavours of food – sweet, sour, bitter, salt and savory
E621 – monosodium glutamate

15. Detecting additives Food scientists – investigate what has been added
Complicated versions of simple techniques
Chromatography
How well something dissolves in a solvent
Solubility determines how far they move across a surface
Separation technique

16. Fuels from plants
Biodiesel - Name given to fuel made from vegetable oil
Oil is treated to remove unwanted chemicals
Used on its own
Mixed with diesel refined from crude oil
Other by-products:
Solid material = high energy cattle feed
Glycerine = used in soap

17. Benefits and advantages
Biodiesel gives off carbon dioxide when burnt
Biodiesel is grown
Crops used absorb carbon dioxide as they grow
C02 produced is absorbed by plants
Carbon neutral
No greenhouse gases
Very clean in terms of pollution
Very little sulphur dioxide
Not harmful to animal and plant life
If spilled, breaks down much faster than ‘normal’ diesel

18. Other bio-fuels Ethanol (alcohol) Gives off CO2 when burnt
Fermenting sugar from sugar cane
Used in Brazil a lot – added to normal petrol
Gives off CO2 when burnt
Absorbed by plants during photosynthesis
Ethanol can also be made from ethene
C2H4 + H20  C2H5OH
Not carbon neutral