C1b Oils, Earth and Atmosphere

1. C1b Oils, Earth and Atmosphere Oils from Plants

2. Solar powered • Plants use energy from the sun: energy from sun 6CO2 + 6H20 C6H1206 + 6O2 • Plants turn glucose into other chemicals • Can be useful to us

3. 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 Vegetable oils

4. Oils as foods • Contain loads of energy • Hydrocarbon molecules • May be saturated or unsaturated • Tested with bromine water

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. Increases the energy content of the food Needs to be used 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 Soak it up

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 • Food additive • 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

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. 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 Benefits and advantages

18. Other bio-fuels • Ethanol (alcohol) • 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